Geschatte leestijd: 6 minutenVariation in exercise during strength training leads to a greater increase in muscle strength and mass than variation in intensity. This is the outcome of a study soon to be published by researchers from the University of São Paulo and the University of Tampa (1). I will use this research as the first part of a series on the discussion about finding the right variation in your training. How many different exercises do you do, how often do you change intensity and number of repetitions? These are questions that science struggles to answer easily, as will become apparent in the rest of the series.
Variation for muscle growth
Variation, volume, and resistance are important variables in determining the outcome of a workout. The researchers wanted to know what produces the best results in terms of strength and muscle mass:
- Performing a number of sets and reps (repetitions) of the same exercise, always with the same resistance and intensity (weight)
- The same total number of repetitions, but divided between two exercises again with the same resistance
- The same total number of repetitions and only one exercise, but now with two different resistances, the second time more weight than the first
- The same total number of repetitions, but divided between two exercises and with two different resistances
Study design
The researchers set up four different training programs that would be compared:
- Constant intensity and constant exercise (CICE)
- Constant intensity and variable exercise (CIVE)
- Variable intensity and constant exercise (VICE)
- Variable intensity and variable exercise (VIVE)
These programs would be completed by the subjects over a period of 12 weeks. The exercises focused on the lower body. The researchers compared the cross-sectional area (CSA) of the quadriceps before and after the weeks of training. In other words, if you were to slice the quadriceps like ham, how big was such a slice before and after the weeks of training? They also did this for the four separate muscles that form the quadriceps (heads).
Before and after, the 1RM squat test was performed (the amount of weight you can do one repetition of back squat with) and the size of the various quadriceps muscles was measured using MRI.
70 healthy men were divided into four groups that would go through the different training programs and one control group (C) that would not train. Eventually, 49 men completed the study.
Training programs for muscle growth
The men trained twice a week for 12 weeks. Only the lower body was trained. The “volume” of a workout can be interpreted in different ways. The most common is: The number of exercises X the number of sets X the number of repetitions. This is also the explanation given by the researchers when they state that the total volume was the same in each group. In this context, volume should only be read as the number of sets.
For example, in weeks 1-4, the CICE group Squat: 4 X 8RM. This means they did 4 sets of 8 repetitions where the weight was calculated so that they could do a maximum of 8 repetitions (RM=Repitition Maximum). So, a total of 32 repetitions. In the CIVE group, we see two exercises in the same period: Squat 2X8RM, so 16 repetitions and Leg press 2 X 8 repetitions, for a total of 32 repetitions again. The VICE and VIVE groups also reached a total of 32 repetitions in the first two periods (weeks 1-4). In the following two periods (weeks 5-8 and weeks 9-12), the total volume was increased to 48 and 72 repetitions respectively.
All groups thus performed the same total number of repetitions, but divided over a different number of exercises and with different intensity. In theory, a good way to see what leads to the best results.
Increase in muscle growth and strength
Increase in muscle growth
The researchers looked at the potential increase in size of both the quadriceps as a whole and the four separate muscles that form the quadriceps.
The CSA (cross-sectional area) of the entire quadriceps increased in each group (fig. right):
- CICE: Right leg 11.6%, left leg 12%
- CIVE: Right leg 11.6%, left leg 12.2%
- VICE: Right leg 9.5%, left leg 9.3%
- VIVE: Right leg 9.9%, left leg 11.6%
The difference in muscle growth of all groups compared to the control group was statistically significant (not caused by chance). However, the differences among the groups were too small for statistical significance, so these could have been caused by chance. In the control group, the CSA did not increase (which is not surprising since they had not trained).
Regarding the CSA of the entire quadriceps, there is thus no (statistically significant) difference. However, when the researchers looked at the CSA of the separate muscles, they saw differences. Only in the groups that varied exercises did all four muscles of the quadriceps increase in size.
- CICE: Increase only in vastus intermedius and vastus lateralis (the outside)
- CIVE: Increase in all four muscles
- VICE: Increase in all except the rectus femoris
- VIVE: Increase in all four muscles
By doing different exercises for a muscle group, different motor units of the muscle can be activated (2,3,4). So, it’s not surprising that only when varying exercises, all different heads of the muscle are trained.
Increase in muscle strength
Next, the researchers looked at the difference in 1RM compared to before the training program (the weight with which they could do one repetition of the exercise, in this case, the squat). All groups had a significant increase in strength compared to the control group. The groups that varied the exercise (CIVE and VIVE) increased more in strength than the groups that did not. Remarkably, the group that changed the exercise but not the intensity (CIVE) showed the largest increase of all groups, even more than the group that varied both the exercise and intensity (VIVE).
The training protocol with the highest variability (VIVE group) was more efficient in increasing maximum strength than the training protocol with the lowest variability (CICE group) (ESCLdiff 0.73 – 0.84) and the one that only varied the intensity (VICE) (ESCLdiff 1.55 – 1.61). The training protocol that varied the exercises but not the intensity (CIVE) was the most efficient in increasing maximum strength among all of the training groups
R.M. Fonseca, University of São Paulo
Conclusion
Scientific studies usually conclude with a “discussion” in which the researchers discuss the results of their study and possibly place them in the perspective of similar studies and current science. This is then followed by a description of the practical applications, as in this case.
- The first conclusion is clear: Variation in exercise results in a greater increase in muscle strength and mass than variation in intensity.
- The next conclusion is surprising: Variation in exercise alone results in a greater increase in strength than variation in both exercise and intensity.
- Finally, variation in training leads to a more even distribution of size increase across the four separate parts of the quadriceps.
- With equal total volume of training, the size of the entire quadriceps increases to the same extent for all groups.
Regarding practical application, the researchers suggest the following:
Strength coaches usually vary the training intensity and exercises in a ST program. Our findings suggest that variations in training intensity are not critical to produce strength and muscle hypertrophy gains in the initial phase of a ST program. Varying exercises during this phase seem to be more important to maximize the neural drive and, therefore, the functional adaptations. In addition, exercise variation seems to produce a more complete muscle activation hypertrophying all of the heads of multi-pennate muscles.
R.M. Fonseca, University of São Paulo
This seems like a fairly straightforward conclusion. I share this view regarding the added value of variation in exercises. Fortunately, the researchers nuance their results with a point that I would have made directly here. Namely, I am surprised by the small role of intensity. We also encounter this in studies that I will discuss in subsequent parts. In these studies, I notice that untrained individuals are always used. In this study, the men had not done strength training for at least six months, possibly never.
If there’s one thing every bodybuilder longs for, it’s the “newbie gains”, the increase in muscle strength and mass you achieve in your first months of training. Despite lack of knowledge about training and nutrition, you grow much faster in those months than when you’ve been training for years, despite all the knowledge you’ve acquired. This has to do with the law of diminishing returns, the fact that you have to do more and more to provide your body with the stimuli needed to grow. In other words: As a beginner, you can mess up a lot and still achieve good results.
The researchers rightly say “in the initial stage of a ST (Strength Training) program”. So they emphasize that this data applies in an early stage of strength training. It is therefore questionable how this looks when people have already been training for a year or longer.
References
- Fonseca, R.M.; Roschel, H.; Tricoli, V.; de Souza, E.O; Wilson, J.M.; Laurentino, G.C; Aihara, A.Y.; de Souza Leão, A.R; Ugrinowitsch, C.
- Ebben, WP, Feldmann, CR, Dayne, A, Mitsche, D, Alexander, P and Knetzger, KJ. Muscle activation during lower body resistance training. Int J Sports Med 30: 1-8, 2009.</
