Variability in the 1 RM in athletes

Many of the coaches are following an old trend to measure the 1 RM and prescribe training loads that may not be the intended ones. Yes, 1 RM can change faster than you think. If the 1 RM changes, so does the prescribed load and that can affect the training stimulus and adaptations. In this case, velocity could be one of your best solutions and allow you to estimate the 1 RM with submaximal loads to ensure that you are prescribing the correct load. In this blog, I am going to cover different issues when it comes to training monitoring and training load prescription:

• What is strength and why is it important in sports performance?
• Which tests can be performed to measure strength and prescribe training load?
• Why does the 1 RM experience some fluctuations?
• Velocity to estimate the 1 RM
• Considerations about daily estimation of the 1 RM and %1 RM

Muscular strength

Has been defined as the ability to exert force on an external object or resistance²⁹ ²⁷. There are different strength requirements depending on the sports demands. Indeed, an athlete may have to exert larger forces to manipulate their own body mass (e.g., sprinting, gymnastics, diving, etc.) and the opponent’s body mass (e.g., American football, rugby, wrestling, etc.), or manipulate an implement or projectile (e.g., baseball, weightlifting, shotput, etc.)⁴³. Eventually, and based on Newton’s second law (i.e., force = mass x acceleration), the force exerted over time (impulse) will change the motion of a body in space. Therefore, strength may be the primary factor for producing an effective and efficient movement of an athlete’s body or an external object⁴³.

Despite the strength demands of any given sport, maximal strength has been related to sport-specific abilities such as sprinting, change of direction, jumping, and throwing. Indeed, it has been reported that stronger individuals are able to jump higher than weaker individuals³¹ ¹⁶ ³⁸ ¹³ ²⁶. Strength levels highly correlate with sprinting ability and change of direction capability³⁸ ¹³ ⁷ ¹⁸ ⁴ ²⁸ ³⁹. Muscular strength has been correlated with VO2 Max due to an increased running economy⁵. Indeed, improved strength would require less muscle activation, decreasing the demand of motor unit recruitment³⁰. Also, higher levels of lower-body strength exert a protective effect against fatigue-induced reductions in performance¹⁰. Lastly, maximal strength has also been reported to decrease injury risk¹⁷ ¹⁴ ⁹. Therefore, maximum strength will allow athletes to perform well in their sports with a delay in fatigue onset and a decreased injury risk. Given the importance of maximal strength in athletic performance, it is necessary tools and protocols to monitor and measure it in the most optimal way.

Maximum strength can be used to monitor the neuromuscular status and prescribe and adapt training programs to provide an optimal training stimulus for athletes. Also, regular monitoring can assist in the understanding of the relationships between maximal strength and performance. Different isometric, dynamic, and reactive strength tests can be used with previous purposes; however, we will mainly focus on maximum and sub-maximal dynamic strength tests.

Maximum isometric tests:

Isometric mid-thigh pull, isometric half squat or squat with the use of a force plate can provide useful information about force-time derived variables. These kinds of tests are time efficient, especially with larger groups of athletes. However, it can be taxing for the athlete, which may require to slightly modify the training on testing day and require a highly expensive material to measure that not every practitioner can access. Importantly for coaches, isometric strength tests don’t provide a maximum load lifted and can’t be used with training prescription purposes. For the last reason, we will specially focus on maximum dynamic tests.

Maximum dynamic tests: Dynamic maximum test may be one of the most common methods to measure the athlete’s strength³¹. A dynamic maximum test can be accomplished by performing a repetition maximum test (RM) in which the athlete must perform a specific number of repetitions (1RM-6RM) with the maximum weight possible³¹. Different basic (e.g., bench press, back squat, front squat) and weightlifting exercises (e.g., power clean, hang clean, etc.) can be performed in a 1RM test and in contrast with the maximum isometric test, it can be used to prescribe training intensities. What’s more, dynamic maximum strength test is viewed as more relevant to athletes’ abilities due to their similarities to the movement completed in competition as they also assess eccentric and concentric muscle actions³¹. Despite the advantages of the isometric test, dynamic maximum tests require a highly technical mastery in the resistance training or weightlifting exercise performed and are highly taxing for the athlete preventing the coach from frequently measuring. Only one study until the date has performed a daily 1 RM in powerlifters reporting some interesting findings that I will speak about in the following section⁴¹. However, fatigue affects more the explosivity and reflexive capacity, than the absolute strength and while those powerlifters still improved in their max, it may have cost a lot for the in-field performance of a team-sport athlete. This is why in the literature we can find studies that report increases in absolute strength without any significant change in jumping and/or sprinting performances. Explosive and reflexive abilities are especially sensitive to fatigue. For these reasons, some practitioners may discourage the idea of “maxing out” and alternative methods can be applied to estimate the 1RM. Certainly, the set rep best method described by Stone O’Bryant uses loads prescribed in training for a specific repetition scheme and estimates loads for other repetition schemes and 1RM²⁹. This approach may be also useful to estimate the 1 RM for exercises that do not have any specific criteria for a successful 1 RM such as the weightlifting pulling derivatives. But there are better ways…

Summarizing, 1 RM test may be time consuming, highly taxing, and may present some risk of injury if performed with an incorrect technique or with novice athletes. Especially in novice athletes, the 1 RM can change quite fast after only a few training sessions, and often the obtained values are not the athletes’ true maximum¹⁵. When performed by several repetitions (1-6 RM) it also requires the athlete to conduct the set until the failure and may not be optimal for some athletes¹⁸ ²⁰. As we have mentioned before, if done acutely it can affect the explosiveness and reflexive capacity of the athlete. Worse, some auto-regulatory methods can require performing as many repetitions as possible frequently and this can bring some negative adaptations for power-sports athletes. Indeed, proximity to muscle failure can induce gains in muscle mass with a decreased expression of the fastest myosin isoform (i.e., MHC-IIX) and low to no improvements in vertical jump and sprint performance²⁰. Finally, literature researching the effects of training at different velocities, reported that adaptations are velocity dependent. Therefore, it is expected that the athlete that performs frequent repetitions to failure will not attain the desired adaptations to the needs of the explosive actions of the sport.

1RM Fluctuations

Another reason to implement different tests for athletes than the 1 RM is the daily fluctuation of the 1 RM. Indeed, athletes can experience daily variations in neuromuscular performance and readiness across the week and the 1RM may change from one training session to another. Changes in day-to-day readiness are caused by normal biological variability, training-related fatigue, or life-style factors such as sleep, stress, and nutrition¹⁵. In the literature, the fluctuation in the 1RM related to these factors can lead up to 36%⁴¹ ¹⁵. Then, the loads prescribed (%RM) with the pre-cycle 1RM value may not truly represent the intended values¹⁵ ²¹. Therefore, pre-designed training loads can be inappropriate for the athlete, decreasing training benefits, increasing fatigue or even causing degeneration or injuries²³. For all of these, a series of regulable and flexible RT methods, known as the auto-regulation methods, were developed to address the disadvantages of traditional RT⁴⁰.

Velocity based training (VBT)

One of the auto-regulation methods, has been defined as a “method that uses velocity to inform or enhance training practice”³⁷. Movement velocity has shown up as a variable of interest to monitor training load and training intensity¹⁵. Indeed, velocity allows the coaches to daily estimate the 1 RM without conducting 1 RM tests. 

Considerations

Daily estimations of the 1 RM can be very useful to monitor changes in maximum strength performance, but most importantly, it can be used to prescribe weights considering the variability in maximum strength instead of relying on pre-training block 1 RM numbers¹⁵. This flexibility of VBT may bring extra advantages over traditional resistance training⁴⁰:

• Estimating the 1 RM with the use of VBT doesn’t increase fatigue and impair recovery status. Therefore, it does not impact on the responses to the training stimulus and the readiness for competition.
• Ensuring that the daily load corresponds to the true intensity programmed can increase the adaptations in the long term as the athlete will train exactly at the intensity that has been programmed.

Figure 1. Daily fluctuation of the 1 RM across 36 maximal training sessions in 3 participants.

VBT is a reliable method to estimate the 1 RM with submaximal loads proposed by Gonzalez Badillo and Sanchez Medina. VBT can help you to generate a load velocity relationship (L-V) and estimate the 1 RM without the requirement to achieve a maximum repetition or performing repetitions until failure. Firstly, you will have to estimate the load-velocity relationship (L-V), which is a linear regression, of every athlete. You can easily model it with the performance of maximum intentional attempts (performing the lift as fast as possible) against multiple submaximum loads (≈ 5 loads)² ²⁴. There is no need to perform the repetition maximum as the velocity of the 1 RM can be obtained from the general values reported in the literature. In this case, the general velocity values of the 1 RM (V1RM) can be used to estimate the 1 RM as there are trivial differences between the between- and within- subject variation²². Once the L-V relationship for an athlete has been estimated, the load for a given % of the 1 RM can be estimated in the warmup of the following training by performing some sets at maximum velocity with sub-maximum loads. In my personal experience, I would recommend using loads corresponding to the 65-75% of the 1 RM to estimate. Loads inferior to 40% may limit the athlete’s output as light loads encourage the athletes to jump. Also, coaches rarely use loads below 60-65% of the RM in resistance training exercises with performance goals. Then a load that is representative of the training load and has lower variability than lighter loads may be found between 65-75% of the 1RM.

Figure 2. Mean propulsive velocity in different resistance exercises. Extracted from Weakley et al., 2021

Conclusion

Lastly, I recommend some aspects for modeling the L-V relationship. Firstly, the V1RM is specific to the resistance training exercise and the athletic population. The V1RM will change depending on the exercise (e.g., squat vs deadlift) so make sure you choose the correct velocity⁶ ¹² ²⁵. Take care of the execution technique as for example, concentric-only vs eccentric-concentric techniques can change the V1RM¹¹ ²¹. Also, do not use the same values for men and women, as men reported higher values for lower 1RM percentages¹ ³⁵. Needless to say, don’t use the same L-V relationship for every athlete, as it is subject specific especially with light relative loads²². Finally, V1RM changes depending on the strength levels, the stronger individuals tend to lift the 1 RM at slower velocities (go to Table 1 and compare powerlifters with athletes). Lastly, remember that Vitruve also offers the ability to do this automatically with its software, calculating an estimated 1RM instantly after a repetition, as it also will recommend the appropriate load depending on the velocity range you choose.

Screenshot from Vitruve App

To summarize:

            1.⁠ ⁠1 RM variability in athletes can influence training prescription and training outcome. Using velocities eliminates this issue.

2.⁠ ⁠⁠1 RM variability is greater with medium-lighter loads and in novice athletes. 

3.⁠ ⁠Prescribing a training load with a pre-established 1 RM can increase injury risk and decrease readiness.

4.⁠ ⁠Velocity based training is of much help when trying to accurately prescribe training intensity 

5.⁠ ⁠When trying to predict training intensity with vbt it is necessary to do with medium to high loads (above 40-45% of the RM) to ensure the athlete is applying the maximum force

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