In this article, a series of actions are indicated to program the training in each of the cycles that are programmed throughout the sporting life of the trained subject, always keeping in mind the previous considerations exposed in previous articles.

In this series of articles we deal with some of the most important concepts of strength training, collecting notes from the recently published book Strength, Speed ​​and Physical and Sports Performance written by renowned researchers Juan José González Badillo and Juan Ribas Serna.

1. Select the variables that determine the load

Select the minimum speed of the first repetition in the series of the entire training cycle (relative maximum intensity of the cycle), the velocity loss in the series for the relative maximum intensity and the Effort Index (IE).

The IE is determined by the two previous indicators, and it could be the first thing to be programmed, if one had experience in the use of this index and data recorded and analyzed from previous training cycles, but since the same IE can be obtained with intensities different relative speeds and losses in the series, which would also give rise to different effects, First of all, it is necessary to choose the maximum relative intensity of the cycle (the load that moves at the slowest speed within the cycle) as a reference for the evolution of the training load throughout sporting life.

Therefore, in practice, it will be the first thing to decide. The second decision will be about the loss of speed in the series with the maximum relative intensity and the rest of the relative intensities.

The relative intensities could be expressed through real percentages of the RM, as it is more comfortable, intuitive and easier for assessment and communication between professionals and athletes. But these percentages of the RM will always be expressed and quantified through the speed with which the load must be moved, never by the calculation on a RM.

The decision on the values ​​of the relative intensities and speed losses in the series will be made based on age, experience in strength training, the strength needs of the sport and the initial situation of the subject.

2. Select the minimum intensity of the cycle and the loss of speed in the series with this load.

The next step to program training is to select the minimum intensity of the cycle (highest speed of the first repetition within the cycle), that is, the speed with which the first training sessions of the cycle are carried out, with the lightest loads, and the speed loss in the series for this relative intensity.

The speed losses with the lighter intensities will always be lower than with the higher intensities within the cycle. It must be taken into account that the same speed loss under a light load means greater IE (greater fatigue) than under higher loads. Therefore, the use of the same speed loss in the series before all the intensity would mean performing a higher IE with light loads. The basic orientation is that the loss of speed with light loads is lower.

With small loads, by reducing the loss of speed in the series, the repetitions performed will be proportionally further away from the possible repetitions in the series and the IE will be less than or equal to that achieved with high loads.

3. Determine the duration of the cycle.

This is a necessary step, but it is not conditioned by the fact that speed is used as a reference for training organization. The duration of the cycle, as a general rule, should not be more than 8-12 weeks. In addition, you can do cycles of 4-6 weeks that can also be very effective in certain situations. The duration of the cycle will tend to be longer at the beginning of the season and in the early stages of sporting life.

When the number of competitions in the season is not very frequent, for example, only in 2-4 short periods of time per year, the length of the cycles, apart from the adaptation times, is highly conditioned by the dates of the competitions. .

If the competitions are very frequent, what determines the duration or length of the cycles will be the adaptation times.

4. Determine training frequency

This is also a necessary step, but it is not conditioned by the fact of using speed as a reference for programming training. Two strength training sessions a week are compatible in most cases with the specific training of many sports specialties. But the most important thing is to choose well the frequency with which each exercise is trained, which preferably should not be more than twice a week. Weightlifting is naturally excepted from this general suggestion.

However, it must be taken into account that increased frequency does not necessarily mean increased load. If the same job is divided into two sessions, the frequency will increase, but the load will be the same or, with high probability, less, since the fatigue values ​​per session would be lower.

5. Distribution of the maximum intensities of each session, between the minimum and the maximum of the cycle

Depending on the values ​​of the minimum and maximum intensities chosen, it is decided how many intermediate maximum intensities will be used. For example, if the minimum intensity is equivalent to an intensity of 50% of 1RM and the maximum to 70%, 1RM (loads that, naturally, would be determined by speed), training could be programmed with intermediate intensities equivalent to 55, 60 and 65 % of 1RM.

Therefore, there would be five maximum intensities in total for all sessions. Once the training frequency of the exercise and the set of maximum intensities of each session are known, training can be programmed by distributing these intensities among the frequencies.

For example, if for the indicated intensities there were 20 sessions, which could correspond to 10 weeks of training, with two sessions per week the simplest distribution would be to train four times with each maximum intensity. Naturally, the distributions could be different depending on the cases.

This is not the time to develop all the possible alternatives, but as a guideline, it must be taken into account that given the same intensities and weekly training frequency, training can be programmed with different resulting global loads. This overall load will depend on the greater or lesser frequency with which the maximum expected intensities are used.

If instead of performing each maximum intensity four times, as indicated, 50% is performed 5 times, 55% 6 times, and the remaining three intensities are performed 3 times each, the average intensity of the cycle will decrease. If, on the contrary, a redistribution is made by increasing the frequency of the two higher intensities, the average intensity will rise. These changes in the frequency distribution of the maximum relative intensities is a way of modifying the load and progressing in the training demand without modifying the range of intensities used during the cycle.

6. Decide the number of series before each training intensity, especially before the maximum intensities of each session

The most frequent number of series to perform with each of these intensities will be between 2 and 4. And within this range, the most common is to do 3 series with the maximum intensity of the day. With the warm-up intensities, it is usual to use one series for each intensity, progressing until reaching the maximum intensity established (main load of the session). As already indicated, the repetitions to be performed in each series with the maximum intensities of the session are not programmed, as they will be determined by the selected loss of speed.

schedule training

In this article he focuses on the speed of execution as a reference for training programming, dosage and control. In the previous article on Character of Effort (EC) some ideas related to speed of execution have been introduced that may be useful.

In this series of articles we deal with some of the most important concepts of strength training, collecting notes from the recently published book Strength, Speed ​​and Physical and Sports Performance written by renowned researchers Juan José González Badillo and Juan Ribas Serna.

SUMMARY

• The speed at which each percentage of the RM is performed is very stable depending on each exercise.
• Loss of speed is shown to be an important predictor of metabolic and hormonal stress.
• For the same loss of speed, each person may have performed a different number of repetitions before the same load.
• Using the speed of execution as a reference to dose and control the training far exceeds what the 1RM percentage provides

A few years ago it was said: “If the maximum speed of the movements could be measured every day and with immediate information, this would possibly be the best point of reference to know if the weight is adequate or not”… “a certain decrease speed is a valid indicator for suspending training or lowering the weight of the bar”… “we could also have recorded the maximum speed reached by each lifter with each percentage, and based on this, assess the effort” ( González Badillo, 1991, p.172).

It is based on the assumption that although the value of 1RM can change between different days, the speed at which each percentage of the RM is performed is very stable. Therefore, speed control could inform us with more precision about what real percentage or what effort is being made at each moment. This hypothesis, proposed in 1991 (González Badillo, 1991, p. 172), when we said “we could also have recorded the maximum execution speed reached by each lifter with each percentage, and based on this, assess the effort… ”, has been confirmed, because each percentage of 1RM has its own speed (González-Badillo, 2000; González-Badillo and Sánchez-Medina, 2010).

Therefore, the own speed of each percentage of 1RM determines the real effort. This means that the speed of the first repetition of a set determines the degree of effort that the load represents. Thus, the training load (weight) is determined by the speed of the first repetition, therefore, what must be programmed is not the percentage of 1RM, but the speed of execution of the first repetition of the series.

But speed control not only allows us to know very precisely the true effort that a given load represents when doing the first repetition, but also allows us to know in what proportion or percentage speed is lost as repetitions are made within from the series.

And this is important because the loss of speed in the series is a highly valid indicator to know the degree of effort that the subject is making, since it presents a high relationship with indicators of the degree of mechanical, metabolic and hormonal stress caused by the exercise. training.

loss of speed is shown to be an important predictor of metabolic and hormonal stress

Thus, we found high relationships between the loss of velocity in the series and the loss of velocity with the load that was moving at 1 m/s before the effort, both in the bench press (1= 0.97) and in the squat. (r = 0.91), and with the loss of height (loss of speed) in the jump after the effort (r = 0.92), with ammonium (R* = 0.93) and lactate (r = 0.95-0.97) (Sánchez-Medina and González-Badillo, 2011).

Testosterone (r = 0.83), growth hormone (r = 0.82) and insulin (r = 0.88) are also discharged, and these relationships increase for ammonium (p = 0.94 -96) and lactate (p = 0.98) when using Spearman’s rank correlation coefficient (data from the same previous study, but not yet published. Sánchez-Medina’s Doctoral Thesis, 2010).

All these relationships indicate that the greater the loss of speed in the series, the greater the mechanical stress, that is, the greater the effort, at the same time that the loss of execution speed is shown to be an important predictor of metabolic stress and hormonal.

The question that arises at the moment is what should be the optimal loss of speed in each case. This question, of course, does not have an easy answer, but being able to formulate it and have the appropriate mechanical and physiological data available to try to find an answer is already a great advance. In fact, at this time we could give an indicative and useful answer for most of the subjects.

For example, ammonium is practically unchanged in the bench press and full squat exercises if the number of repetitions performed does not exceed half of the repetitions that can be performed (Sánchez-Medina and González-Badillo, 2011). That the ammonia remains at its resting values ​​means that the emergency pathway of energy production, which is responsible for the increase in ammonia, has not been put into operation.

This path consists of the fact that, given the high and continuous demand for energy, it is not enough to use ADP+CP to produce ATP and the system has to resort significantly to the use of 2 ADP (ADP+ADP) to produce ATP, which which leads to the production of adenosine monophosphate (AMP), inosine monophosphate (IMP) and the degradation into ammonia (NH3) and ammonium (NH4), hypoxanthine, xanthine uric acid, formation of free radicals and losses of purines, this supposes a loss nucleotides (Hellsten-Westing et al., 1993), which can lead to chronic ATP depletion and increased recovery time if sessions that significantly trigger these processes are frequently repeated (Stathis et al. ., 1994, 1999).

If we also know, from extensive practical experience, that doing half or less of the repetitions that can be performed produces notable improvements in muscular strength and sports performance, It would not be very advisable to frequently exceed (in some cases it would never be necessary) half of the repetitions that can be done in a series.

it would not be very advisable to frequently exceed (in some cases it would never be necessary) half the repetitions that can be done in a series

If we analyze the relationship between the loss of speed in the series and the number of repetitions performed, we can state that in the bench press exercise the loss of speed when half of the possible repetitions have been done is between 25 and 30% of the speed of the first repetition, and that in the complete squat the loss of speed of execution in the same conditions would be approximately 15-20%.

Therefore, if it is possible to know what degree of effort each percentage of speed loss means, the application of speed as a way of training control is very useful, probably the best procedure, using the mechanics way, to know with high precision and immediately the training load.

Knowledge of these data would allow not only to program the intensity or degree of effort based on the speed of the first repetition, but also to determine the degree of effort in the series, by being able to decide the loss of Speed ​​that is allowed in the series itself.

By way of example, at this time we can anticipate that in the exercise of the bench press, the relationship between the percentage of speed loss in the series (PPVS) and the average percentage of repetitions performed in the series (PMRR), for the intensities of 50, 55, 60, 65 and 70% of the RM is practically the same.

The percentage of repetitions performed for the same loss of speed must be 2.5% higher when the relative intensity is 75%, 5% higher for 80% and 10% higher for 85% (González-Badillo et al., 2017).

The data corresponding to the intensities between 50 and 70% appear in Table 1.

Tabla 1. Loss of speed in the series and average percentage of repetitions performed with intensities of 50 to 70% of the RM in bench press.

• PPVS: Percentage loss of speed in the series.
• PMRR: Mean percentage of repetitions performed.
• SD: standard deviation.
• CV (%): Coefficient of variation.

for the same loss of speed in the series, each person may have performed a different number of repetitions under the same relative load

It can be seen that, given the low CV values, the PMRR for the different percentages are practically the same. Therefore, when repetitions are performed at the maximum speed possible with any of these RM percentages, the percentage of repetitions performed for a given loss of execution velocity in the series can be known with considerable precision.

It should be remembered here that for the same loss of speed in the series, each person may have performed a different number of repetitions under the same relative load. This means an important advance in the precision to quantify and assess the CE in the series and training session. One more application of speed as a reference to dose and control training derives from the fact that each exercise has its own speed for its RM (González-Badillo, 2000).

The speed at which the RM of an exercise is reached determines its characteristics and its own training intensities for each objective.

Although, as we will see in later chapters, the load with which maximum power is reached is not relevant either for training dosage or for assessing its effect, these loads are determined precisely by the speed of the RM of each exercise. For example, the faster the speed with which the RM of an exercise is reached, the greater the percentage with which the maximum power is reached in the exercise.

There is a very high positive trend between the own speed with the RM in four exercises (snatch, power clean, squat and bench press) and the percentage of the RM with which maximum average power is reached (r = 0.94). (González-Badillo, 2000). It must be taken into account that these power values ​​are calculated through the product of the force and velocity values ​​provided by a linear velocity or position meter, in which the force is determined by the equation F = m( g+a), and the speed is measured directly by displacing the charge (mass).

The speed at which the RM is reached can range from less than 0.2 m/s in the bench press exercise to values ​​close to 1 m/s in the power clean or snatch. These observations confirm that, depending on the exercise with which you train, the same percentage can mean a very different magnitude and type of load, and that to obtain the same effect, you would have to use different percentages.

For example, if a subject intended to train with the maximum average power load in the bench press, he would have to train with 37-40% of the RM, while in the power clean he would have to train with 87% of the RM. Therefore, if we train both exercises, for example, with 80% of their respective RMs, in the case of the bench press we will be training with a load well above that with which maximum power is reached and in the case of the power clean with a load below that of maximum power.

an exercise like the full squat should never be trained with loads greater than 80% of the RM

However, and use this idea to better understand the consequences of, for example, “training with the maximum power load” in all the exercises, a training with 37-40% of the RM in the bench press, with 6 -8 repetitions per series, it is a very light effort that anyone can do at any time, and its effect, load and The degree of fatigue would be very low, however, training with 87% of the RM in a clean exercise is a significant effort, which is very close to the RM of the clean exercise.

Another example could be the following: for the same subject or group of subjects practicing a sport, an exercise like the full squat should never be trained with loads greater than 80% RM (personal suggestion based on extensive experience and results of competition studies), while this same group of subjects could always train, from the beginning of their sporting life, at least with loads equal to or greater than 75-80% of the real RM in the power clean exercise.

These differences in training loads are due, especially, to the fact that the speeds of the RMs of both exercises are very different, much higher in the power clean than in the squat.

From all the above it follows that use the speed of execution as a reference to dose and control the training It far exceeds what the 1RM percentage provides and comes to offer the same contributions as the Character of Effort (it really is another way of applying the CE) but with a much higher precision and eliminating the risk of subjectivity.

Therefore, the existence of a high relationship between speed and the different percentages of 1RM, as well as between the loss of speed in the series and the percentage of repetitions performed in the series allows:

• Evaluate the strength of a subject without the need to perform a 1RM test or an XRM test at any time.
• Determine with high precision what actual percentage of 1RM the subject is using as soon as they perform the first repetition with a given load at the maximum speed of execution possible.
• Program, dose and control training with high precision through speed, and not through a percentage of 1RM.
• If the speed is measured every day, it can be determined if the load proposed to the subject (kg) faithfully represents the true degree of effort (% of real 1RM) that represents the first repetition and the degree of effort that represents the number of repetitions performed (valued for the loss of speed in the series).
• Use strength training with all subjects, from children to the most advanced athletes or adults and seniors you intend. improve your health, without the need to do maximum effort tests (1RM, or XRM, for example) in any case.
• Estimate the improvement in performance each day without the need to perform any tests, simply by measuring the speed with which an absolute load moves. YES, for example, the difference in speed between 70 and 75% of the RM of a specific exercise is 0.08 m/s, when the subject increases speed by 0.08 m/s under the same absolute load , the load with which he trains will represent 5% less than the RM of the subject at that moment, which, naturally, will have increased in value. Naturally, if what is produced is a loss of speed under the same absolute load, we can be quite sure that the subject is below its previous performance, and in an average proportional to the loss of speed.
• Estimate, through the loss of speed in the series, the percentage that represents the number of repetitions performed with respect to those achievable under any load.
• Being able to calculate the Effort Index, probably the best indicator of the degree of effort and fatigue that can be used to estimate these training variables.

Therefore, as we have indicated, what is programmed or should be programmed is not the percentage of 1RM, but the speed of execution of the first repetition of a series (Of course, if we associate the percentages with their corresponding speeds, it would be indifferent to use one procedure or another) and the loss of speed in the series allowed. The speed with each percentage of 1RM is not modified or it does so in a very slight way when the subject modifies the value of his RM after a period of training.

What most determines the slight speed changes between a test and a post-test with each percentage of 1RM, if they occur, is the speed with which the RM is performed and measured (González-Badillo and Sánchez-Medina , 2010), in such a way that two MRIs could not be compared if they were performed at different speeds. But this problem disappears if, as we have indicated, we never measure the RM, neither to take it as a reference to program the training nor to assess its effect, but instead we use the speed and speed changes before the same loads for both objectives.

what is programmed or should be programmed is not the percentage of 1RM, but the speed of the first repetition of a series

Our proposal, therefore, is that the average propulsive velocity should always be used to assess the training load and the performance of the subject (if necessary, the article Sánchez-Medina et al., 2010 can be consulted).

A definition of effort is the so-called character of physical effort (CE), originally presented and explained by González-Badillo, in González-Badillo and Gorostiaga (1993, 1995). The CE is defined by the relationship between what the subject does and what he could do. In other words, the relationship between what has been done and what can be done.

In this series of articles we deal with some of the most important concepts of strength training, collecting notes from the recently published book Strength, Speed ​​and Physical and Sports Performance written by renowned researchers Juan José González Badillo and Juan Ribas Serna.

Summary

• The character of the effort (CE) is the relationship between what has been done and what is achievable.
• The character of the effort is defined by the maximum speed possible in the first repetition and the loss of speed in the series.
• What should be programmed in training is not the number of repetitions but the loss of speed in the series.
• A light CE would be to perform less than half of the possible repetitions, a medium CE would be to perform around half of the possible repetitions and a high one would be to perform more than half of the possible ones.

In the so-called “strength training” it would be expressed by the relationship between the number of repetitions that are done in a series (what is done) and those that could be done (what is achievable). If a subject can do 10 repetitions with a weight (absolute intensity) and does 6, we would be facing an EC of 6 out of 10. If we do 3 times that same physical effort, we will have done 3×6(10), that is, 3 series of 6 repetitions with a weight with which we could do 10 in the first series. In this sense, it is important to take into account the difference between load and effort.

To advance in the proper definition of CE, two indicators must be taken into account. On the one hand, the difference between the repetitions performed and those possible or achievable, and on the other, the total number of possible repetitions. For example, if 2(4) is done, the difference between what has been done and what is achievable is the same as if 8(10) is done, but the effect and characteristics of the training are different.

This is so because, although what is “left undone” is the same, 2 repetitions, the number of repetitions that could be done in each case is different, which implies acute effects, and at least in the short term, also different : degree of fatigue, metabolic stress, percentage loss of speed in the series, central and peripheral effects…

Character of physical effort is defined by two indicators: 1) the maximum possible speed of the first repetition and 2) the loss of speed in the series.

In addition, the CE expresses the degree of physical effort in two ways.

The first occurs when the first repetition of the series is performed before any load (weight). At this time, the CE is defined by the speed of the first repetition, provided that this is performed at the maximum speed possible for the subject. This already defines to a large extent the effect that is expected from the training and the CE that the displaced load supposes, since it allows us to estimate with enough precision the percentage that this load represents from the RM (González-Badillo and Sánchez-Medina, 2010). .

But this is not enough to fully define the CE, since it is easily understandable that the final or total degree of physical effort also depends on the percentage or proportion of repetitions of the maximum possible that is done within the series. It is not the same to do 1 repetition with a load with which you can do 6, than to do 6 repetitions with the same load.

Therefore, since as repetitions are performed at the maximum speed possible in a series with the same load, the speed decreases progressively until the last repetition is reached, CE is defined by two indicators: 1) the maximum possible speed of the first repetition and 2) the loss of speed in the series.

The use of the speed of the first repetition and the loss of speed in the series means a great advance in the definition of the concept of “character of the physical effort”. These two indicators allow to reach the maximum precision in the expression of the degree of effort that a training represents when it comes to displacing external loads. But we find the product of both values: the speed of the first repetition multiplied by the value, percentage, of the loss of speed, we will have the Effort Index, which has been shown to present a high relationship with fatigue, that is, with the degree of physical effort made in the series (Rodríguez-Rosell et al., 2019)

Continuing with the progress in this knowledge, it has been concluded that we can even do without knowing the number of repetitions that can be done in the series (initial indicator necessary to define the CE). The important thing in this case is to know the loss of velocity in the series, because it has been observed in laboratory studies that before the same loss of speed in the series, the percentage of repetitions performed with respect to the possible (achievable) is the same before any load between 50 and 70% of the RM, 2.5% higher for 75%, 5% higher for 80% and 10% higher for 85% (González-Badillo et al., 2017).

This comes to solve the problem that arises from the fact that Given the same relative intensity (same speed in the first repetition in the series), not all subjects can perform the same number of repetitions. Therefore, the loss of speed in the series equals the efforts, the degree of fatigue generated, although two people have done a different number of repetitions before the same relative load and the validation of the loss of speed in the series as an indicator of fatigue has been verified in previous studies (Sánchez-Medina and González-Badillo, 2011).

Therefore, what would best express the degree of physical effort, and what should be programmed, is the speed of the first repetition and the loss of speed in the series, not the number of repetitions to perform in the series before a relative load. Dadaist. Despite the progress that this load assessment procedure means (physical effort, fatigue…), we will continue to refer to the repetitions performed in the series, because we understand that it will not always be possible to measure speed.

What would best express the degree of physical effort, and what should be programmed, is the speed of the first repetition and the loss of speed in the series, not the number of repetitions to perform in the series before a given relative load.

Therefore, the CE is a very useful expression of the load and it comes to overcome the problems that we have detected for the expression of the intensity through the percentages of 1RM and XRM. The systematic observation of the evolution of the difficulty (degree of physical effort) with which the subject moves a load allows us to permanently verify the physical condition of the subject without the need to apply any test. If we can measure the speed, the training load will be quantified very precisely, as we have indicated in the previous paragraph.

If we cannot measure speed, we will have to resort to procedures for estimating the degree of effort that the subject makes. In this case, if we estimate that a subject is capable of performing a certain number of repetitions with a weight (absolute load), and after several sessions we estimate that he is capable of performing more repetitions with said load, the conclusion is that this weight it has become a “physical effort”, a relative, lower intensity, and this is information we need to check the effects of training and to make decisions about whether or not to modify the absolute load.

This is so because what has to be kept under control is the relative physical effort (relative intensity) that represents the absolute load with which you train. To achieve this we have to modify the absolute load when appropriate, and to decide if we have to modify it, we must take the execution difficulty as a reference. Thus, by modifying the weight, we do not modify the training, without maintaining the programmed effort: the speed of the first repetition, the CO real percentage of the RM.

As a guide, although without establishing strict limits, since it must always be considered as a continuum, the CE can be considered as light or small, medium, high or very high or maximum. The CE will be light or small when the number of repetitions performed in the series is very far from the feasible or possible repetitions.

In terms of speed loss in the set it would mean that you lose a maximum of about 5-10% of your speed on the first rep. Therefore, this corresponds to a small loss of speed in the series, and the number of repetitions performed will always be less than half of the possible ones.

As examples of light or small effort (EC), these values ​​could be considered: from 4-6 repetitions performed, being able to do 16-30 or more. But, as we have indicated in previous paragraphs, although both examples could be considered as a light CE, their effects are quite different and they would be used in very different situations.

The CE is considered as medium when an average number of repetitions is done, which means a loss of speed in the series close to 20-25%, and the number of repetitions in the series is around half of those possible.. For example, 6-7(12-14), 4-5(8-10).

The CE can be considered high or very high when more than half of the possible repetitions are done, which means a loss of speed somewhat greater than 25-30%, but 2-4 repetitions are left out in the series. For example: 3(5), 4(7) 5-68), 8(12).

The CE is considered maximum when the maximum or almost maximum number of repetitions possible within the series is done, the loss of speed is very high (60-70%) and half of the possible repetitions are clearly exceeded. For example, when doing 9-10(10), 7-8(8) or 3-4(4). In the international literature, this last type of physical effort or type of training (without using the term CE) is called XRM, that is, the maximum possible number of repetitions with a given load, as we have indicated in the previous point.

All this information that we give here in relation to the CE values ​​is indicative, because in our proposal, if the possibility of measuring speed is available, the number of repetitions is not programmed, but rather the loss of speed at a certain relative load, which will give rise to the fact that the number of repetitions may be different between subjects for the same degree of physical effort (same degree of fatigue).

In this article, a review will be made about the loss of speed and percentage of repetitions performed and how these parameters affect the character of the effort and the degree of fatigue regardless of the total number of repetitions performed in the series.

In an attempt to move towards a further development of the applications of speed control in strength training, it is worth asking the following: What is the relationship between 1) the speed of the first repetition, 2) the loss of speed in the series and 3) the percentage of repetitions performed in the series before a certain loss of speed? An adequate answer to this question can provide very relevant information to improve dosage and training control.

In this series of articles we deal with some of the most important concepts of strength training, collecting notes from the recently published book Strength, Speed and Physical and Sports Performance written by renowned researchers Juan José González Badillo and Juan Ribas Serna.

To the first two questions, the speed of the first repetition and the loss of speed in the series, we now add another concept, the percentage of repetitions performed in the series before a certain loss of speed. The reason why this new problem is addressed is because it has always been observed that not all subjects perform the same number of repetitions with the same ease at the same relative intensity, that is, at the same speed in the first repetition.

Once the intensity or relative load has been determined, whether it is expressed through inappropriate indicators, such as the percentage of 1RM or an XRM or nRM, or by the speed of the first repetition of a series, the training volume must be decided, of which the number of repetitions performed in the series is a decisive part. To decide on this component of the global training load, two criteria are followed: either do all the possible repetitions in the series, which, as is recognizable in all the literature, is usually the most frequent and almost the only alternative for many specialists, or fail to do all the possible repetitions in the series.

About the drawbacks of getting to do all the possible repetitions in the series has already been discussed previously.. Of all of them, the inconvenience that must be addressed in this case is related to the probable fact that being able to do the same maximum number of repetitions in a series before a determined absolute load (individual loads for each subject) does not mean that you are training with the same percentage of RM, since it has already been observed that there is variability between individuals in the number of repetitions that can be performed in a series before the same relative intensity (Richens & Cleather, 2014; Sakamoto & Sinclair, 2006; Shimano et al., 2006; Terzis, Spengos, Manta, Sarris, & Georgiadis, 2008).

Therefore, the hypothesis is that if several subjects have been able to perform, for example, 10 repetitions before certain absolute loads, a part of them will be training with a load close to 75% of 1RM, because the average number of repetitions that can be done with this percentage is ~10 repetitions, but there will be subjects who are training with 80%, because they are clearly capable of doing more repetitions per series than the average with any load, and others who are working with 7 0%, for the opposite reason.

doing the same maximum number of repetitions in a series before a certain absolute load (individual loads for each subject) does not mean that you are training with the same percentage of the RM

To try to analyze to what extent the subjects differ from each other when doing the maximum possible number of repetitions before the same relative load, determined in this case by the speed of the first repetition in the series, a study was carried out (González-Badillo et al., 2017) in which a group of 27 subjects performed, with intervals of 4 to 7 days, the maximum number of repetitions possible with loads equivalent to 50, 55, 60, 6 5, 70, 75, 80 and 85% of the RM. These percentages were determined each day based on the speed with which the absolute loads were moved in the first repetition.

Tabla 1. Descriptive variables related to performing the maximum number of repetitions possible in the series with different relative intensities. (González-Badillo et al., 2017).

• Data are expressed as mean ± SD and (range)
• Repetitions: number of repetitions performed in the series; VMPmax: maximum average propulsive speed in the series; Final VMP: average propulsive velocity in the last repetition of the series.
• Diferencias significativas con respecto al: ͣ60% 1RM, ^b 65% 1RM; ^C 70% 1RM; ^d 75% 1RM; ^e 80% 1RM; ^f 85% 1RM.
• Table 1 shows the results corresponding to the bench press exercise.
• In the first column the percentages and the speeds corresponding to said percentages in the first repetition are indicated.
• The second column indicates the actual average speed at which the loads indicated in the first column were made and the range around the average. It can be seen that the average coincides with the target speed and that the maximum deviation in any subject was ±0.02 m·s^–¹ in any of the loads. This represents the maximum adjustment that can be required in any study or in training practice, since it cannot be expected that in all subjects the speed coincides exactly with the predicted speed. This small margin is tolerable and realistic to carry out any study or to carry out training.

The third column has an important informative value, because it indicates the average speed of the last repetition with each load. It can be seen that in all loads the final speed is practically the same. This speed, as we have always maintained, must coincide with the speed of the RM, because the last possible repetition in a series is precisely the last because it is done at the speed of the RM.

In this case, this speed is even slightly below the average speed of the MRI of this exercise, which, as we have seen in the previous chapter, is 0.16-0.18 m·s-¹. Naturally, there is also a small range of speeds around the average. The importance of this variable lies in the fact that if the last repetition had not been performed at the speed typical of the MRI, the test would not be valid, since this would be proof that the subjects had not performed the maximum possible number of repetitions in their tests.

The loss of speed in the series, shown in a fourth column, decreases as the relative intensity increases, since each time you start from a lower speed and always reach the same final speed. It is not relevant information, but it can serve as a reference to differentiate the intensities in relation to the maximum loss of speed that can be experienced with them.

The fifth column shows the repetitions performed with each percentage. The average values ​​inform us of the approximate number of repetitions that can be done with certain intensities, but with the particularity that in this case we can have high confidence that the intensities with which the tests have been done adjust with high precision to the actual intensities under analysis.

there is a wide range of repetitions achievable by different subjects at the same relative intensity

But the most relevant information in this column is that there is a wide range of repetitions that can be performed by different subjects at the same relative intensity. The average coefficient of variation is approximately 20% and there is a subject that doubles the number of repetitions that another can do at all intensities. If we take into account the standard deviations, we find that, for example, in the smallest load, 50% of the RM, 68% of the subjects would be in repetition values ​​between 19.9 and 31.5 repetitions, a percentage difference of 58% between the maximum and minimum value. And at the highest load, 85% RM, 68% of the subjects would be between 3.7 and 6.1 repetitions, a 65% percentage difference between the maximum and minimum value. Two important practical applications can be deduced from the results of this study.

The first is that, if the maximum possible number of repetitions is programmed for all the subjects, most of them would train with intensities (RM percentages) different from the others, given the variability that exists in the maximum number of repetitions that can be done at the same relative intensity.

Secondly, if we consider the case in which the maximum possible number of repetitions in the series is not programmed, the usual thing is to program the same number of repetitions for all the subjects with the same percentage of the RM. This way of determining the load has fewer drawbacks than most, but still has the same problem related to the discrepancy between the degree of effort programmed and the actual effort that represents the same number of repetitions for each subject.

This is so because even assuming that the first repetition of the series was done with the same relative intensity, doing the same number of repetitions with said intensity does not mean that all the subjects are making the same degree of effort: same loss of speed in the series. This is justified with the same argument previously exposed: the variability in the number of repetitions possible with the same relative intensity.

Indeed, given that not all subjects can perform the same repetitions at the same relative load, if a non-maximum number of repetitions is performed in the series, but common to all subjects, each subject will have done a different percentage of the total number of repetitions possible for him. This means that, having trained with the same relative intensity and number of repetitions in the series, the degree of fatigue, the loss of speed in the series, the degree of effort or character of the effort could have been different in each case.

This situation, which seems to lead us to a “dead end”, can be addressed and solved if we manage speed properly. If we start from the same speed before the first repetition of a series, that is, from the same relative intensity, it is reasonable to think that the degree of effort that the first repetition means is the same or extremely similar for all subjects (González-Badillo & Sánchez-Medina, 2010). Therefore, what we have left to solve is the degree of fatigue or effort that is added to the effort that the first repetition has represented. Naturally, this added effort will be determined by the number of repetitions done in the series, or more precisely, by the loss of speed in the series.

So, if we take into account that the degree of effort or fatigue generated in the series has a high relationship with the loss of speed in the series (Sánchez-Medina and González-Badillo, 2011), what we should control would be precisely this loss of speed. Indeed, given that fatigue can be estimated and controlled through the loss of speed (Edman, 1992; Allen, Lamb, & Westerblad, 2008; Sánchez-Medina & González-Badillo, 2011), it is reasonable to assume that in the event of the same loss of speed in the series, the degree of fatigue, effort or the nature of the effort will be very similar.

Once all of the above is accepted and the hypothesis formulated, what remains to be confirmed is whether, indeed, in the face of the same loss of speed, the nature of the effort is similar, that is, if in the face of the same loss of speed in the series, the relationship between the repetitions that are done and those that can be done in the series is the same or very similar in all cases.

If this is the case, it can be assumed that the degree of effort made is very similar for all subjects who have trained with the same relative intensity (same speed in the first repetition of the series) and have lost the same speed in the series, even though the number of repetitions performed has not been the same for all. Indeed, in the study that we have been commenting on (González-Badillo et al, 2017) it has been verified that when a certain percentage of execution speed is lost in the series, the same percentage of possible repetitions in the series has been performed regardless of the number of repetitions that can be done in the series itself.

It has been verified that when a certain percentage of execution speed is lost in the series, the same percentage of the possible repetitions in the series has been performed, regardless of the number of repetitions that can be done in the series itself.

Tabla 2. Percentage of repetitions performed with respect to the total number of possible repetitions in the series before different percentages of loss of speed in relative intensities between 50 and 70% of the RM (González-Badillo et al., 2017)

VMP: mean propulsive velocity; CV: Coefficient of variation.

Table 2 shows the data related to intensities between 50 and 70% of the MR. In this range of intensities, it can be seen that when faced with the same loss of speed in the series, the subjects tend to perform the same percentage of the total number of repetitions possible in the series at all intensities. For example, with a loss of 15% of the speed of the first repetition, at all these intensities practically the same percentage of possible repetitions has been performed, with an average of 31.2%.

Confidence in this data is based on the low coefficient of variation that accompanies it, of only 2.7%, which is also the highest of all the coefficients. If the standard deviation is taken as a reference, 68% of the subjects would be between 30.4 and 32% of repetitions performed with respect to the total possible, an extremely narrow range. Furthermore, it can be seen that the coefficient of variation decreases as the speed loss increases. This indicates that the greater the loss of speed in the series, the more similar is in all the subjects the percentage of repetitions performed before the same loss of speed in the series with all the relative intensities from 50 to 70% real of the RM.

Therefore, given the same relative intensity between 50 and 70% of the RM, if the same loss of speed occurs in the series, we can consider that the degree of effort will be similar, even though each subject has performed a different number of repetitions.

At intensities of 75, 80, and 85% of the RM, the percentage of repetitions performed at the same loss of speed is 2.5, 5, and 10% higher than that performed with intensities between 50 and 70%, respectively. For example, for the same percentage of repetitions performed, when at intensities between 50 and 70%, 10% with 80% and 5% with 85%. The speed losses for the same percentage of repetitions performed are in figure 1.

Figure 1. Losses of speed in the series with relative intensities from 50 to 85% of the RM (the 4 “X” axes) for the same percentage of repetitions performed (“Y” axis) (González-Badillo et al., 2017)

These differences are easily understandable, since as the number of repetitions possible in the series is reduced, each repetition represents a greater percentage of the total number of repetitions that can be performed. However, this natural tendency only starts to manifest itself after you can do ~10 reps in the set (~75% of 1RM). If the number of repetitions possible is greater, as occurs from 50 to 70% of the RM, the number of repetitions possible in the series does not even influence the common percentage of repetitions performed between different intensities before the same loss of speed.

The data that we have provided in relation to the bench press exercise has also been studied in the full squat exercise (Rodríguez-Rossell et al., 2019). Table 16.3 presents the results of the study in the squat with the four relative intensities that were directly analyzed: 50, 60, 70 and 80% of the RM.

Tabla 3. Characteristics of the bench press and squat efforts with loads of 50, 60, 70 and 80% of 1RM: basic similarities and differences (Rodríguez-Rosell et al., 2019).

In the squat exercise in Table 3, it can be seen that the measurements of the speed of the first repetition coincide with the speed of the percentages that are analyzed. It can also be seen that the last repetition of the series with each intensity is typical of RM, and even somewhat below average, which indicates that the subjects really performed the maximum number of repetitions possible.

The number of repetitions performed in the squat exercise for the same relative intensity is slightly lower than in the bench press, between 2 and 3 repetitions less. The coefficient of variation in the number of repetitions is somewhat higher than in the bench press, with an approximate average of 30%.

Given the characteristics of the squat exercise in terms of the degree of demand or effort required to perform series until exhaustion, in this exercise only the four indicated relative intensities were measured. Taking these four intensities and the corresponding number of repetitions performed with each of them as a reference, we have calculated the number of repetitions that could be done with a greater range of relative intensities. The fit of the four relative intensities and the repetitions performed with them was almost perfect: R² = 0.9996. This adjustment is presented in Figure 2.

Based on the regression equation corresponding to the relationship between these two variables, we have estimated the repetitions with other intensity values. Table 4 presents these data. The first column indicates the percentages of the RM, in the second the estimation of the number of repetitions performed with each percentage of the RM and in the third the number of repetitions measured directly with the percentages of 50, 60, 70 and 80% of the RM.

It can be seen in this table that the differences between the number of repetitions measured and the one estimated with these intensities are practically nil. Then the estimated replicate values ​​can be considered. Very adjusted to the real mean of repetitions that a population of young subjects familiar with strength training would do, with a mean of 115 kg RM for 76 kg of mean body weight, and with a range from 91 to 153 kg of RM value. Therefore, these results would be applicable to a wide population.

Figure 2. Relationship between the relative intensities of 50, 60, 70 and 80% of the RM and the number of repetitions performed with each of them in the squat exercise (Graphic prepared with data extracted from Rodríguez-Rosell et al., 2019).

Tabla 4. Estimated repetitions with intensities between 40 and 90% of the RM and repetitions measured directly with the intensities of 50, 60, 70 and 80% of the RM in the squat exercise.

Following the same reasoning exposed for the bench press, once the speed with which each percentage of the RM is moved in the squat and the number of repetitions that can be performed with each percentage in this exercise is known, what remains to be solved is the degree of fatigue or effort that is added to the effort represented by the first repetition in the series.

Naturally, this added effort will be determined by the number of repetitions done in the series, but, as we can see in Table 3, as in the bench press, the maximum number of repetitions to exhaustion can vary greatly between subjects, so we will have to resort to the loss of speed in the series to try to equalize the efforts or fatigue, ruling out the number of repetitions to be carried out in the series as a priority reference in programming.

Therefore, from a practical point of view, we would have to establish what percentage of the total repetitions has been performed when a certain speed has been lost in the series. In the study that is being discussed (Rodríguez-Roseel et al., 2019) this data has also been verified when a certain percentage of the speed of execution is lost in the series with the intensities of 50, 60, 70 and 80% of the RM. Table 5 shows the results.

Table 5. Percentage of repetitions performed before a certain loss of speed in the series in relation to the maximum possible repetitions in the series until exhaustion in the bench press and squat exercises with the indicated RM percentages (Rodríguez-Rosell et al., 2019).

*1RM = 1 repetition máximum; BP = bench press; SQ = full squat.

• Data are mean ± SD.
• Statistically significant differences with respect to: 50% 1RM.
• Statisticaly significant differences with respect to: 60% 1RM.
• Statisticaly significant differences with respect to: 70% 1RM.
• BP exercise.

In the first column of table 16.5 we have the loss of speed in the series and in the rest the percentage of repetitions performed before each loss of speed with the different relative intensities in each exercise. It can be observed that the percentage of repetitions performed before the same loss of speed in the series is always higher in the squat (SQ) than in the bench press (BP), and the difference tends to increase the higher the intensity.

In addition, while in the bench press the percentage of repetitions performed for the same loss of speed remains practically stable up to 70% of the RM, as we have already seen when analyzing this exercise in previous paragraphs, in the squat only stability is maintained. with 50 and 60%, increasing the percentage of repetitions performed for the same loss of speed with 70% and even more with 80%.

The circumstance occurs that the increases in the percentage performed before the same loss of speed begin in both exercises when with the corresponding intensity it is possible to do an average of ~10 maximum repetitions, which corresponds to 70% in the squat and 75% in the bench press. It seems, therefore, that the influence of the possible number of repetitions in the series on the percentage of repetitions performed for the same loss of speed in the series is maintained in the squat. (Note: naturally, in Table 5, the value of speed loss of 65% with the relative load of 80% should be discarded, which is a mistake, since it would exceed 100% of the repeats that can be carried out).

Unfortunately, the information on the squat exercise is somewhat scarcer than the bench press, as only four percentages of the RM could be analyzed, but it allows for very useful applications.

On the one hand, based on the data obtained, the values ​​corresponding to 55% of the RM can be estimated, since, if the values ​​of the percentages of repetitions performed are the same with 50 and 60%, it is reasonable to accept that the values ​​corresponding to 55% would also be equal to both. This is logical, but it is also reinforced by the results obtained in the bench press: the intermediate values ​​(55, 60 and 65%) between 50 and 70% are equal to those of these two extreme values, which are also equal to each other. In addition, an estimate of the corresponding 75% values ​​could also be made, which must be of an intermediate value between 70 and 80%, in the same way that it occurred in the bench press between 75, 80 and 85%.

But perhaps the most useful thing is to check that when 20% of the speed has been lost in the squat exercise, we are slightly below half of the possible repetitions in the series with all percentages of the RM except 80% where we are practically half. If it is taken into account that in the investigations carried out to date (Pareja-Blanco et al., 2017; Rodríguez-Rosell, Doctoral Thesis) in which the loss of speed in the series has been taken as a reference to control the training dosage, it is observed that exceeding a loss of 20% of the loss of speed in this exercise already begins to cause a decrease in the training effect, being able to control losses of 10, 15 and 20%, even 25%, allows the control of most or all of the training that an athlete must do in his sporting life.

In addition, we can also remember those other studies, although somewhat less controlled, in which doing half of the possible repetitions offered a better result than reaching muscular failure (maximum loss of speed in the series) (Izquierdo-Gabarren et al., 2010 )

This practical application, naturally, translates into the possibility of being able to tell the athlete to perform the movement at the maximum possible speed until losing 10, 15 or 20% of the speed of the first repetition, without indicating the number of repetitions. what it has to do.

This would make it possible to equalize the effort (the degree of fatigue) that we are asking of all the athletes, which could not be done by prescribing an equal number of repetitions to all the subjects.

En relación con el grado de esfuerzo o fatiga, en este estudio se confirmo la alta relación entre la pérdida de velocidad en la serie y la fatiga, determinada por la pérdida de velocidad pre-post esfuerzo con la carga que se podía desplazar a 1 m·s^–¹. A relationship was found between these two variables of r = 0.97 in the bench press and r = 0.99 in the squat. It must be taken into account that, as can be seen in table 16.3, the range of repetitions with the percentages analyzed was wide, so this relationship occurred independently of the number of repetitions performed by each subject.

One question that we ask ourselves is whether the relationship of these tests with the maximum possible number of repetitions in the series was reliable or not. To verify this, we did a repetition of the test one week apart with a load of 60% of the RM. Table 16.6 shows the results of both tests.

VMP: mean propulsive velocity.

Tabla 6. Data on performing a test to exhaustion on two occasions with a load equivalent to 60% of the MRI (Data taken from Rodríguez-Rosell’s doctoral thesis).

It can be seen that all the data are practically the same in both tests, which confirms the stability of carrying out tests with these characteristics. Special attention should be paid to the column of the last repetition of the series, which is repeated almost exactly, with the same average speed and range of speeds, as well as the column of repetitions performed, with the same number and range of repetitions, which It confirms, on the one hand, the stability in the number of repetitions that a person can do at a given relative intensity, and on the other, the stability in the variability between subjects in the number of repetitions that can be performed at the same initial speed.

In addition, the percentages of repetitions performed before different speed losses in the series were practically the same in both tests (table 7).

Tabla 7. Percentages of repetitions performed for different speed losses in the series in two tests with 60% of the RM (Data taken from Rodríguez-Rosell’s doctoral thesis).

Another issue that caused concern was whether, having reached the same loss of speed in the series, the subjects who tended to do more repetitions in the series had experienced more fatigue than those who did less. To do this, the subjects were divided into two halves, one made up of the subjects who had done more repetitions (high repetitions group: GAR) and the other by those who had done less (low repetitions GBR group). Table 16.8 presents the results of the grouping of the subjects and the average number of repetitions performed with each percentage of the RM. It can be seen that the GAR performed an average of 32% more repetitions than the GBR in the bench press and 59% more in the squat, giving rise to statistically significant differences between both groups in all relative intensities.

Do the subjects who do more repetitions in the series fatigue more in the face of the same loss of speed and relative intensity?

Tabla 8. Distribution of the subjects in two groups based on the repetitions performed before each percentage of the RM in the bench press and squat exercises (Rodríguez-Rosell et al., 2019).

• GBR: half of the subjects who performed the lowest number of repetitions per series
• GAR: half of the subjects who performed the highest number of repetitions per series
• PB: Bench press; Squat: Full squat;
• Differences between groups: *** p ˂ 0.001

Once the subjects were grouped, it was verified what the speed loss had been with the load that, prior to the tests, could be moved at 1 m·s^–¹. This loss of speed is the variable that would serve as an indicator of the degree of fatigue reached by each subject. The results are presented in Figure 16.3.

No significant differences were observed between the groups. This analysis, really compromised for the authors of the study, confirmed the importance of controlling the loss of speed in the series as an indicator of the degree of fatigue generated in the series or set of series of a training session, despite the fact that the number of repetitions performed by each subject was different, as well as the use of the load that can be moved at 1 m s^-¹ as a criterion to assess and validate the degree of fatigue generated by training.

If what is programmed for each training session is a certain degree of effort or fatigue, and this seems hardly debatable, the probably most reasonable and precise way of knowing the degree of effort that is programmed and performed is by controlling the loss of speed in the series at a certain speed of the first repetition in the series itself. Knowing that, in turn, this speed is the best indicator of what is the relative intensity or real percentage of the RM with which the training of an exercise begins.

The probably most reasonable and precise way of knowing the degree of effort that is programmed and performed is by controlling the loss of speed in the series at a certain speed of the first repetition in the series itself.

Figure 13. Loss of VMP with the load 1 m s^–¹ after each of the tests of the maximum number of repetitions possible in each of the groups in fusion of the number of repetitions performed (GBR vs GAR) for the exercise bench press (A) and full squat (B) (Rodríguez-Rosell et al., 2019).

Therefore, if we know the speed of the first repetition, we know the relative intensity (percentage of the RM) (González-Badillo & Sánchez-Medina, 2010), and therefore the degree of effort that said first repetition represents. In addition, if we measure the loss of speed during the series, we will have the degree of fatigue that has been generated in the series (Sánchez-Medina & González-Badillo, 2011; Rodríguez-Rosell et al., 2019).

And since given the same percentage of loss of speed in the series, the percentage of repetitions performed is the same or very similar for all subjects, regardless of the relative intensity and the number of repetitions that can be done in the series (González-Badillo et al., 2017; Rodríguez-Rosell et al., 2019), if we control the speed of the first repetition and the loss of speed in the series, we will have very precise information on the degree of fatigue (character of the effort, degree of of effort) that has been generated to the subject and, in addition, that this degree of fatigue is very similar for all the subjects with the same relative intensity and the same loss of speed in the series. That is, it is the loss of velocity in the set that equals the effort, not the number of repetitions performed in the set at the same relative intensity.

If we control the speed of the first repetition and the loss of speed in the series, we will have very precise information on the degree of fatigue (character of the effort).

Therefore, the control of the training load, quantified through the degree of effort or character of the effort made, is achieved in the most precise way if we control the speed of the first repetition in the series and the loss of speed in the series. .

From the above, the following can be concluded:

• Being able to do the same number of repetitions in a series before a determined absolute load (individual load for each subject) does not mean that you are training with the same percentage of the RM. Therefore, performing the same number of repetitions at the same relative load means that most athletes make a different effort than others. This is because the number of repetitions performed by each subject at the same relative intensity is quite different.
• If the same loss of speed in the series is taken as a reference before the same relative load (mass), the efforts made will be very similar, although the number of repetitions carried out in each series is different for each subject.
• If a non-maximum number of repetitions is performed in the series, but common to all the subjects, each subject will have done a different percentage of the total number of repetitions possible for him. This means that, having trained with the same relative intensity and the same number of repetitions in the series, the degree of fatigue, degree of effort or character of the effort could have been different in each case.
• Given the same loss of speed in the series, the relationship between the repetitions that are done and those that can be done in the series is the same or very similar for all subjects.
• When a certain percentage of the speed of execution in the series is lost, the same percentage of the possible repetitions in the series has been performed at intensities between 50 and 70% of the RM in the bench press. If the intensities are 75, 80 and 85%, given the same percentage of repetitions performed, the speed losses will be 2.5, 5 and 10% less, respectively. If it is the squat exercise, given the same percentage of speed loss in the series, from 50 to 60% and probably 65%, the percentage of repetitions performed is the same, and increases from 70% of the RM. It seems that the increase in the percentage of repetitions performed for the same loss of speed in the series occurs when the number of repetitions possible in the series is approximately 10.
• If we control the speed of the first repetition and the loss of speed in the series, we will have very precise information on the degree of fatigue (character of the effort). that has been generated to the subject and, furthermore, that this degree of fatigue is very similar for everyone with the same relative intensity and the same loss of speed in the series. That is, it is the loss of velocity in the set that equalizes the effort, not the number of repetitions performed in the set with the same relative load.
• Therefore, the loss of speed in the series equalizes the efforts, the degree of fatigue generated, even if two people have done a different number of repetitions before the same relative load:
  • This means that what would best express the degree of effort, and what should be programmed, is the speed of the first repetition and the loss of speed in the series, not the number of repetitions to perform in the series under a load (relative to or absolute)
  • If speed can be measured, repeats should never be programmed into the set.

WHAT TO DO WHEN YOU CANNOT ALWAYS MEASURE SPEED

One of the immediate concerns for anyone who reads or hears about the benefits of speed control is the impossibility of measuring it. The solution, naturally, is to find a measurement system that allows this information to be obtained permanently, but if this cannot be achieved, we can offer an alternative that, in part, solves the problem of knowing if a subject can be located in the average in relation to the maximum number of repetitions you can do at a certain relative intensity or if it is above or below. For this, it would be necessary to be able to measure speed at least once in sporting life. The procedure would be the following:

• If speed can be measured on one occasion, it is possible to estimate in a very approximate way the number of repetitions in the series that a subject can do at a given relative load without reaching muscular failure (XRM or nRM).
• First, the speed of the first repetition would be taken as a reference. This would indicate the relative intensity with which the test is to be carried out.
• The exercise would then be performed at the maximum speed possible in each repetition until approximately 40-50% of the speed of the first repetition was lost. If it is about the bench press, you can reach 50%, if it is about the squat it is more than enough to reach 40%.
• The evolution of the number of repetitions performed before 2-3 percentages of speed loss in the series is analyzed. For example, 15, 20, 25, 30%…
• The necessary calculation is made to estimate the number of possible repetitions in the series based on the number of repetitions performed with each percentage of speed loss. For this, the tables that we have exposed in this article are consulted.
• The results obtained with each percentage of speed loss are contrasted, and it is verified if in all cases the result is very similar. It should be, unless the subject did not perform the test correctly.
• Once the result is obtained, we will proceed to verify where the subject is located. To do this, five groups could be made: those who are within the measure, those who are 10-15% above or below the measure, and those who are 25-30% or more above or below the measure. half.
• Once the subjects have been located, the number of repetitions programmed at a relative intensity (assumed to be at least close to what it is intended to be) will be different for each one depending on their location within the groups to which they belong.
• Once the subject is located, it is very likely that this will not change throughout his sporting life, so it is information obtained in one day that is useful for a lifetime.
• All this procedure could be done with more than one intensity, at least two, on different days, for example, with 50 and 70% or 60% and 80%. This would help confirm the results. The two tests could be done in a week, 3-4 days apart.

The following article introduces the concept of the Effort Index and its relationship with the loss of speed in the series and the character of the effort.

In this series of articles we deal with some of the most important concepts of strength training, collecting notes from the recently published book Strength, Speed ​​and Physical and Sports Performance written by renowned researchers Juan José González Badillo and Juan Ribas Serna.

SUMMARY

• Given the same relative intensity and the same loss of speed in the series, fatigue is also similar, although the number of repetitions performed in the series by each subject is different.
• The effort index is the result of multiplying the velocity of each percentage of the RM by the value of the loss of velocity in the series or set of series.
• The effort index has a much higher predictive value than any other variable to estimate the loss of speed with a load of 1 m·s^-¹, that is, to estimate the degree of effort.
• Only if the effort rates are equalized can it be ensured that the relative intensity is the independent variable of the training.
• Average ranges of the Effort index between 7.5 and 14.8 for the squat exercise with an intensity of 70 to 85% offer better results than values ​​higher than 22.1.

On the one hand, it has been observed that when training with loads with which a maximum number of repetitions in the series can be done between ~12 and ~4, and efforts are made that go from 50% of the possible repetitions to the maximum possible repetitions (XRM or nRM), there is a close relationship between the loss of speed in the series and the fatigue generated. Fatigue was estimated by the loss of speed before a load that could be moved at 1 m*s-1 and by the loss of jump height.

The relationship between these variables when dealing individually with each of the loads studied is almost perfect. But, in addition, in this case, when they were all considered together, the ratios were also very high. That means that when it comes to determining the intensity through the maximum number of repetitions possible in the series (between 12 and 4 repetitions maximum, in this case), lthe loss of speed in the series, or the number of repetitions performed in the set, remarkably accurately estimates the fatigue generated in the set.

However, in this case, two issues should be taken into account:

i) when training with these loads, not all subjects did so with the same relative intensity, since, as has been seen, performing the same maximum repetitions in the series does not represent the same relative intensity for all subjects, and

ii) A certain number of repetitions were performed with respect to the maximum possible, starting with at least half of the possible repetitions, so we do not know what happens when less than half of the possible repetitions are done in the series, load, which seems to be very important in training.

Therefore, the relative intensity was not the same for all subjects, the loss of speed in the series was not determined before the effort was made, but was measured afterwards, the efforts were always made with at least half of the possible repetitions in the series.

On the other hand, when starting from the same relative intensity, it has been verified that with the same loss of speed in the series, the percentage of repetitions performed in the series is similar, which allows us to admit that Faced with the same relative intensity and the same loss of speed in the series, fatigue is also similar, although the number of repetitions performed in the series by each subject is different..

Faced with the same relative intensity and the same loss of speed in the series, fatigue is also similar, although the number of repetitions performed in the series by each subject is different.

According to what has been exposed, given the same relative intensity, whether it is estimated by the maximum number of repetitions that can be done in a series, or by the speed of the first repetition in the series, the loss of speed in the series is a good estimator of the degree of effort made. However, we still do not have a solution to all possible situations that arise. On the one hand, because taking an XRM as a reference is not appropriate, for the multiple reasons that we have explained in chapter 4, and secondly because we have not contrasted the degree of effort generated at different relative intensities when these are determined by the speed of the first repetition.

In previous articles it has been shown that the definition and quantification of the character of the effort or degree of effort is expressed in the most complete and precise way by the value of the speed of the first repetition and by the value of the loss of speed in the series. If you start from the same speed in the first repetition, that is, from the same relative intensity, this variable is already controlled, so the only thing that remains to be checked is whether the loss of speed in the series correctly expresses the degree of effort. This has been amply verified through the studies commented in the previous sections. But it remains to be verified if, in fact, these two variables are valid when calculating the degree of effort generated with the combination of different relative intensities and different speed losses in the series.

the loss of speed in the series is a good estimator of the degree of effort expended

To address this problem, a study has been carried out, partially published (Rodríguez-Rosell et al., 2018), in which the loss of speed with a load of 1 m s has been analyzed.^–¹ (fatigue) and the jump loss (fatigue) produced in 16 efforts, consisting of four speed losses after three series with the maximum load of the day at four relative intensities. In the bench press the four speed losses with respect to the speed of the first repetition were: 15, 25, 40 and 55%, and in the squat: 10, 20, 30 and 45%. The four relative intensities for both exercises were: 50, 60, 70, and 80% of 1RM. Table 1 presents the scheme of the study.

squat

bench press

Tabla 1. Diagram of the efforts made with the squat and bench press exercises, with four relative intensities and four speed losses in each exercise (Rodríguez-Rosell et al., 2018).

Figure 1 shows an example of the protocol followed to carry out each of the efforts. In each session, during the warm-up phase, the load that the subject was capable of displacing at ~1 m s^-1 was measured.¹ (the three initial dark bars in the figure), the subject continued to warm up until reaching the load with which the expected effort for the session had to be made, performing the three series at the maximum speed possible to reach the expected loss of speed in each series (the three sets of lighter bars in the center of the image).

Immediately after doing the last repetition of the third series, the speed with the load that had previously moved ~1 m s^-¹ (dark bars on the right of the image) was measured again and a blood sample was taken. to measure lactate concentration. When it came to the squat exercise, before warming up with loads, a specific warm-up was done for the vertical jump and it was measured, and at the end of the last repetition of the training session it was measured again.

Figure 1. Real example of an effort protocol of a subject in the squat exercise with the load equivalent to 60% of the RM (0.98 ~1 m s^–¹ of speed in the first repetition of the first series) and a 30% loss of speed in each series. Recovery time between sets was 4 minutes. The average speed loss in the three series was 29.5%, and the speed loss with the 1 m·s^–¹ load after effort was 20.2%. The subject performed 7, 6 and 7 repetitions in the first, second and third series, respectively, until losing the programmed speed. (Rodríguez-Rosell et al., 2018).

Table 2 shows the speed losses with the load of 1 m·s^–¹ and the lactate concentration after the 16 efforts with each of the exercises. Within each exercise, there is a clear tendency to lose more speed (more fatigue) and to reach greater lactate contraction than more speed is lost in the series at the same relative intensity, but the values ​​of these two variables decrease as the relative intensity increases. Although the differences between the exercises in the variables of velocity loss and lactate concentration are indicated at the foot of the table, it must be taken into account that these data have been produced with different values ​​of velocity loss in the series in both exercises.

• SQ = ful back-quat exercise (n = 11); BP = bench press exercise (n = 10); REP = resistance exercise protocol; MPV = mean propulsive velocity; V1 m·s^–¹ = load that elicited
• MPV of ~1 m·s^–¹; RM = repetition maximum.
• Data are men ± SD Post-exercise lactate significantly different (P ˂ 0.001) from pre-exercise for all REPs.
• Significantly different than BP: p ˂ 0.001
• Significantly different than BP: p ˂ 0.01
• Significantly different than BP: p ˂ 0.05

Table 2. Loss of speed post effort with a load of 1 m s^–¹ (central column in each exercise) lactate concentration in the squat (SQ) and bench press (BP) exercises (Rodríguez-Rosell et al., 2018).

the fatigue generated by the training section tends to be greater with the same loss of speed in the series the lower the relative intensity

Therefore, as indicated and shown in table 2, the loss of speed with the load of 1 m s^–¹, as an indicator of the fatigue generated by the training section, tends to be greater with the same loss of speed in the series, the lower the relative intensity. When training with 50% of the RM in the bench press, 29.6% is lost for the four speed losses with which it was trained (15, 25, 40 and 55% of the speed of the first repetition), while with 60, 70 and 80%, 23.2, 20.6% and 17% were lost respectively. In the squat the losses were: 21.6, 18.7, 14.9 and 15% for 50, 60, 70 and 80%, respectively.

Attention should be paid to this detail, since there is a tendency to think that if the relative intensity is lower, the fatigue will also be less, which can lead to important errors: if the loss of speed is the same, the lower the relative intensity (at least from 50% of the RM, but it is very likely that it also occurs at lower intensities), the greater the fatigue. This, on the other hand, should not lead us to another probable error, such as thinking that then what you have to do is train with relatively high loads, which cause less fatigue, because this can also have important negative effects, since with high loads, the average speed of execution must necessarily be very low, which may not always have a positive effect on performance, but rather the opposite.

with high loads, the average execution speed must necessarily be very low, which may not always have a positive effect on performance, but rather the opposite.

Given that the lower the percentage with which you train, the more repetitions you can do until you lose a certain speed in the series, the loss of speed with the load of 1 m s^–¹ It depends on the repetitions that have been made in the series when the percentages oscillate between 50 and 80% of the RM and its values ​​have been estimated by the speed of the first repetition in the first series of the session.

In fact, the relationship between these variables is r = 0.94 (p˂0.001). But it is evident that the fatigue generated by the first repetition must also be included in the assessment of the character of the effort, since it is the first indicator of the degree of effort that a subject is going to make. This would lead us to try to find an index that would represent the degree of fatigue more accurately and with high validity.

This index should include the two variables that, as we have been proposing, can influence the fatigue generated: the speed of the first repetition (relative intensity) and the loss of speed in the series. Therefore, this index could be the result of multiplying the speed of the first repetition by the loss of speed in the session, which in this case consisted of three series.

Three sets at the maximum load for the session is a very common set number and is even considered to be within an effective set range for strength improvement (Rhea et al., 2002a; 2002b; 2003). This index is a way of presenting what has been proposed for years, the “character of effort” (CE), but each time more precisely defined. In this case, we could call this expression of the CE the Effort Index (IE), which is what it really represents, the degree of effort or degree of fatigue generated or caused to the person being trained.

Three series with the maximum load of the session is a very common series number and even considered as included within an effective range of series for the improvement of strength.

But, this IE needs to be validated by comparing its behavior and its values ​​with an indisputable and clearly valid indicator of the degree of fatigue generated, such as the loss of speed under the same absolute load, which in this case is the load that can be moved at ~1 m s.^–¹ before making the effort, as well as the loss of height of the vertical jump, which is equivalent to saying loss of speed in the jump, when it comes to exercises performed with the legs, and that we have been using since before the first contact platforms appeared in the 80s.

The values of this IE will be the result of multiplying the own speed of each percentage of the RM by the value of the loss of speed in the series or set of series. If, for example, the relative load (real percentage of the RM) with which you want to train has an average propulsive velocity of 1 m s^-¹ and the loss of velocity that you want is 15%, the value of the IE resulting will be 15 (1×15).

Of course, when put into practice, this IE will not always have an exact value of 15, as the speed of the first repetition and the loss of speed in the set are not likely to always match the programmed values, but in practice, the differences are very small, so its value is practically the same as what has been programmed.

And if this is so, its effect must also be the same. It would not make sense to think that if instead of 15, the resulting IE had a value of 14.5, the effect would be different, especially since on another day it could be 15.3. To consider that these small differences could have a significant effect on the training result would be to give too much importance and power to IE, more than it already has.

Naturally, for the same loss of velocity in the series, the IE values ​​are lower the higher the relative intensity, since the higher this is, the lower the velocity of the RM percentages. This should give rise, as has been shown in the results of the commented study, to that the speed losses with the load of 1 m s^–1¹ (fatigue) tend to be lower with higher intensities, which, in turn, validates IE itself, because it determines the degree of fatigue (loss of speed in the series) based on its value as a product of the variables that make it up, not just based on the value of one of them.

Tables 3 and 4 show the IE calculations for the bench press and squat exercises.

Tabla 3. IE in the Bench Press Exercise (Rounded Values)

Tabla 4. IE in the Squat Exercise (Rounded Values)

The data in tables 3 and 4 are rounded, and may differ slightly from those published in the 2017 book on speed (González-Badillo et al., 2017). This is due to the fact that in that document the values ​​of the IE were derived directly from the real data of the study, while in this case it is the calculation of each IE according to the own speed of the corresponding percentage and the expected loss of speed. The blank spaces in the tables are due to the fact that with the corresponding relative intensities a loss of speed as indicated cannot be produced.

0.14 and 0.27 m·s^–¹ have been considered as the minimum possible speed in the series until muscular failure for the bench press and the squat, respectively. These values ​​correspond to those obtained as a mean in the respective tests of the maximum possible number of repetitions in the series (tables 1 and 3).

Once these questions related to the concept of EI have been clarified, it is necessary to verify its validity as an indicator of the degree of effort or fatigue generated in training. For this, its relationship with the two reference criteria has been verified, the loss of speed with the load of 1 m·s^–¹ and the loss of vertical jump (CMJ). The relationship of the IE and the loss of speed with the load of 1 m s^–¹ was r = 0.98 (p ˂ 0.001) for the bench press and r = 0.091 (p ˂ 0.001) for the squat (figure 2).

Figure 2. Relationship between IE (degree of effort) and velocity loss with 1 m s^–¹ load in bench press (top figure and squat (bottom figure). TEE standard error of estimate. (Rodríguez-Roseel et al., 2018).

The Effort Index has a much higher predictive value than any other variable to estimate the loss of speed with a load of 1 m s^-¹, that is, to estimate the degree of effort, which is what is programmed when designing a workout.

Therefore, this IE has a much higher predictive value than any other variable to estimate the loss of speed with a load of 1 m s^–¹, that is, to estimate the degree of effort, which, as indicated, is what is programmed when designing a workout. If we quantify these relationships in terms of explained variance, we see that bench press IE explains 96% of the variance of velocity loss with the 1 m s-¹ load, virtually all of the variance, and squat IE 83%.

In other words, in both cases a very high percentage of the variance produced in the loss of speed with the load of 1 m·s^–¹ is explained. The slightly lower value given in the squat may explain the greater technical complexity of this exercise compared to the bench press. In addition, the IE presents a high correlation with the loss of CMJ (r = 0.93; p ˂ 0.001; it explains 86.5% of the variance of the loss of high, and with a very low standard error of estimation: 1.8).

Therefore, these correlation values ​​and their corresponding explained variance values ​​provide us with high confidence in the predictive power of the IE in both exercises, with the particularity that the squat can be assessed by two exercises or fatigue indicator criteria.

But, in addition to what is indicated, the IE generated in the squat offers the opportunity to apply it to other variables related to an exercise frequently used in the training of any athlete, such as sprinting. In the commented study, the degree of fatigue throughout the 20-m race was also assessed. This test was performed ~2 minutes after the end of the effort. The relationships between the IE and a series of variables were: with the increase of the time in 20 m, r = 0.77 (p ˂ 0.001), with the loss of maximum speed, r = 0.84 (p ˂ 0.001) and with the increase of the contact time in the race, r = 0.66 (p ˂ 0.01). As can be seen, the IE in the squat has an important application in the prediction of fatigue in different types of performance.

In this sense, the relationship observed in the IE in the full squat exercise and the reduction in performance in the 20-m race is pertinent and very relevant. Figure 3 shows the graphical presentation of this relationship.

In the graph it can be seen that for an IE of 10, the increase in time in the race is more than 3.5%. This is a very considerable acute negative effect. This is more relevant if we consider that the IE that causes this performance reduction is small. It is equivalent to performing 4-5 repetitions with a relative load of 60% of the RM. Which means that at 60% RM you should lose 10% of your speed for the first rep in the set.

As explained in the graph itself, with 60% you can do about 16 repetitions on average. A 10% loss of speed in the set means that 26.9% of the possible reps have been performed, and this is equivalent to doing 4-5 reps in the set. That is, this training, with three series, is a moderate-low training, which could be very positive for the improvement of performance for many athletes, but that has caused an acute negative effect on a 20 m race at ~2 minutes after doing the squat exercise.

It is natural, on the one hand, that if the interval time had been shorter, as is usual in some training practices, the negative effect would have been greater, and, on the other hand, that, according to the graph itself, with higher EI, the effects would tend to be even more negative.

Conclusion: the supposed “transfer” exercise, in addition to not being such, can be carried out in quite negative conditions.

Figure 3. Relationship between the IE and the change in time in a 20 m race performed ~2 minutes after performing the squat exercise (see text for further explanation) (Data taken from Rodríguez-Rosell’s doctoral thesis).

This sequence of exercises, but with less recovery time between them, is considered in some cases as a “transfer exercise” or executed in this way because in doing the second exercise “something is being transferred” to the second exercise. However, these results indicate that the supposed “transfer” exercise, in addition to not being such, is being carried out under quite unfavorable conditions, with each loss of performance.

It is logical to think that if 20-m runs are done, it is to be done at the subject’s maximum personal speed or close to it, or, in the worst case, with a minimum loss of speed, which would be enough to interrupt the training. However, with this sequence of exercise, so common, neither “transfers” nor trains in proper conditions, but rather the opposite.

In addition to the speed losses with the 1 m·s^-¹ load, the CMJ is also a reference criterion for the assessment of fatigue. This exercise is also very easy to perform, it does not interfere with training and does not cause fatigue, therefore, if the loss of height were related to other exercises and with the loss of speed itself with the load of 1 m s^–¹, could be a very useful exercise to assess the degree of fatigue reached in a training session easily, quickly and cheaply.

As expected, since the jump loss is a loss of speed, the loss of CMJ has a high relationship with the loss of speed with the load of 1 m s-¹, r = 0.96 (p ˂ 0.001), so in the squat exercise, to estimate the degree of fatigue, it would be equivalent to measure the loss of speed with the load of 1 m s^-¹ or jump loss. But, in addition, the loss of CMJ serves as a good predictor of the increase in time in 20 (r = 0.79; p ˂ 0.001) and in 5 m (r = 0.84; p ˂ 0.001), of the loss of speed in the race (r = 0.77; p ˂ 0.001) and of the increase in contact time (r = 0.77; p ˂ 0.00 1).

If we take the regression equations indicated in figure 16.5 for the bench press and the squat, as well as the one associated with the CMJ in its relationship with the IE (y = 0.3306x + 9.3785), we can have a fairly approximate estimate of the loss of velocity with the 1 m s load.^-¹ and of the CMJ before different values of EI (table 16.13).

With these data and those that have been commented on the variables that make up the EI, a wide field of research opens up. The first thing would be to determine the effect of the different IE values ​​(Table 3). With these data and those that we have commented on the variables that make up the IE, a wide field of research opens up. The first thing would be to determine the effect of the different IE values, that is, of the different degrees of effort. There is still not enough data on this, although some guidelines will be given later that can serve as a reference to improve knowledge about the load-effect relationship of training.

Tabla 3. Estimated values ​​of velocity loss with the 1 m·s-¹ load and with the CMJ with a range of IE from 6 to 40.

In addition to what is indicated, the IE, the loss of speed with the load of 1 m·s^-¹ and the CMJ present a high predictive validity of metabolic stress, estimated through the lactate concentration after the effort.

The IE, the loss of speed with the load of 1 m s^-¹ and the CMJ have a high predictive validity of metabolic stress

In the commented study, the lactate concentration presented significant positive relationships with the IE in the bench press (r = 0.95; p ˂ 0.001) and the squat (r = 0.9; p ˂ 0.001), with the loss of speed with the load of 1 m s^–¹ in the bench press (r = 0.95; p ˂ 0.001) and the squat (r = 0.95; 0.001) and with the jump loss (r = 0.98; p ˂ 0.001). As can be deduced from these results, knowing the speed loss with the load of 1 m s^-1¹ and the loss of jump height, a very precise estimate of the lactate concentration can be made, or even better, if the values ​​of these two variables are known, it is not necessary to do any post-exercise lactate concentration test, since what is really important is knowledge of the degree of effort, determined by fatigue, something that the lactate concentration cannot give us.

Taking all these data as a whole, justified by the high validity shown, we can admit that this form of expression of the character of the effort (EC) allows us to advance in the knowledge of the load (effort) that is programmed and, especially, of the load that has been generated in each subject once the training has been completed.

As an initial practical application, if we take into account, as indicated above, that what is programmed is a series or orderly succession of efforts, if one wants to compare the effect of different ranges of intensity on changes in strength, or in other types of performance, one would have to control a key variable in performance itself, such as the effort generated, that is, the CE / degree of effort of each session through the IE.

This means that it would not only be necessary to cIt is not necessary to control that the relative intensity was real and that the loss of speed in the series is also controlled through a precise measurement, but it would be necessary to ensure that the IE was equivalent, and for this it would be necessary that the losses of speed in the series were different for each relative intensity, so that the efforts were equalized.. Only if this is done in this way, it could be accepted that the independent variable of the study is truly the relative intensity.

Only if the effort indices are equalized could it be accepted that the independent study variable is the relative intensity

To our knowledge, this control has never been carried out, so stating that entertainment with a relative intensity is better or worse than another is not relevant if the IE that has been generated with the different intensities is not equivalent.

The character of the effort (EC) quantified through the IE also has an important function as an independent variable, in such a way that it could provide information on the effect that each relative intensity can have, and other variables that constitute the training load, depending on the IE applied or generated.

Apart from the fundamental application as a control variable and as an independent variable, the quantification of the CE through the IE allows a better analysis of the effects of any design, being able to verify the relationship between the IE and the effects produced, apart from other variables with less discriminatory power such as the series, the number of repetitions per series and even the relative intensities, since the same value of these last variables can mean a very different degree of effort depending on what the values ​​of the others are.

As indicated above, today there is not enough data to be able to determine which IE is the one that can offer the best results, as well as with which variables this IE should be quantified or configured. Both issues must be considered, because, naturally, it is not the same to perform a squat training with an IE of 15, quantified by using 60% of the RM with a 15% loss of speed in the series (see table 16.12), than to train the same exercise with the same IE, but derived from using 85% of the RM and a loss of speed in the series of 25%.

Today there is not enough data to be able to determine which effort index is the one that can offer the best results, as well as with which variables this IE should be quantified or configured.

These two IE could generate a similar degree of fatigue, that is, a loss of speed with the load of 1 m s^–¹ very similar, but there is an important differentiating factor between both IE, which is the average speed with which the training would be carried out, much lower when 85% of the RM is used. This could lead to clearly different effects. All these issues must be taken into account if we really want to advance in the knowledge about training in general, and especially if we want to use the speed of execution as a reference for the dosage and control of the load and the effect it produces.

Table 4 presents a series of data that can be considered as the first information about what the trend of the effect of different values ​​of EI with different ranges of relative intensities may be. These are the real effects of two ranges of intensities: from 70 to 85% and from 55 to 70% of the RM in the squat exercise with different speed losses in the series.

In the first range he trained with four speed losses in the series: 10, 20, 30 and 40%. This resulted in the subjects training with certain IE, whose mean values ​​were 7.5, 14.8, 22.1, and 29.4, for losses of 0, 20, 30, and 40%, respectively. If we take into account that the groups that obtained the best results were those that lost 10 and 20% of the speed in the series, and that the extreme values ​​of EI of these two groups were 6 and 17, it can be suggested that these EI ranges are probably more favorable for improving performance with intensities between 70 and 85% than reaching higher values, between approximately 19 and 33. Or also, that average IE between 7.5 and 14.8 offer better results than values ​​higher than 22.1.

Probably average ranges of the Effort index for the squat exercise with an intensity of 70 to 85% between 7.5 and 14.8 offer better results than values ​​higher than 22.1.

In the second range of intensities, he trained with three speed losses: 10, 30 and 45%. This resulted in subjects training with mean EI values ​​of 9.6, 28.5, and 42.7, for speed losses in the set of 10, 30, and 45%, respectively. The group that performed best was the one that lost 10%, with EI values ​​between approximately 8 and 11, while EI values ​​greater than 25 do not seem to offer the best results. Therefore, given a range of relative intensities from 55 to 70%, applying IE between 8 and 11 may be more favorable than using IE of 25 or more.

Tabla 4. Effect of different values ​​of IE before different ranges of relative intensities. Explanations of likely effects are given in the table itself.

conclusions and practical applications on the effort index

• The high validity shown by the expression of the CE through the IE, as we do in this section, allows us to advance in the knowledge of the load (effort) that is programmed and, especially, of the load that has been generated in each subject once the training has been carried out.
• If we wanted to compare the effect of different ranges of intensity on changes in strength, or in other types of performance, it would be necessary to ensure that the IE was equivalent, and for this it would be necessary that the speed losses in the series or session were different for each relative intensity, so that the efforts were equalized. Only if this is done in this way, it could be accepted that the independent variable of the study is truly the relative intensity.
• Therefore, it is not pertinent to affirm that training with a relative intensity is better or worse than with another, if the IE that has been generated with the different intensities has not been controlled.
• The CE expressed through the IE can have at least the following applications:

1. 1. Act as an independent variable of any study on the effect of training.
   2. It is necessary and decisive as a control variable.
   3. It is very useful for a better analysis of the effects of any design, because it allows checking the relationship between the IE (degree of fatigue) and the effects produced.
   4. The choice of the speed of the first repetition and the choice of the loss of speed in the series or session can be done and in some cases should be done depending on the IE or degree of effort that we want to program.