Monday, April 10, 2017

Rest-Pause Yields 36% Greater Gains in Thigh Size in 6-Week Study With Trained Subjects - Awesome!? Well...

Yet another study, where reading only the abstract - let alone the conclusion - may be utterly misleading. Always ask for effect sizes and absolute changes.
Not even hot off the press, but still weeks before its official publication is the latest paper by Jonato Prestes and colleagues from the Catholic University of Brasilia, the Rocky Mountain College in the USA and the Faculty Estacio of Vitoria in Brazil (Prestes 2017). The corresponding study was designed to eventually fill the research gap that exists with respect to the longitudinal effects of the rest-pause method on muscle strength and hypertrophy; or, as the authors write, "the purpose of the present study was to compare the longitudinal effects of six weeks of rest-pause versus a traditional multiple-set RT on muscle strength, hypertrophy, localized muscular endurance, and body composition in trained subjects" (Prestes 2017).
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In that, Prestes et al. started with the "initial hypothesis [...] that RT with the rest-pause method would increase muscle mass and strength to a greater extent versus traditional multiple-set training, with no differences between protocols in altering body composition.
Figure 1: Overview of the exercises. Overall the subjects performed four weekly sessions. Routine A was performed 2 days per week (Monday and Wednesday) and routine B was performed 2 days per week (Tuesday and Thursday).
If you scrutinize the data in Figure 2 you will see that the effects of the two resistance training programs (A/B routines done on Monday and Wednesday | see Table 1) on the subjects' body composition was only marginal, anyway.
Figure 1: Neither of the two protocols yielded significant changes in body composition (lean or fat mass); this is not surprising in the absence of diet and in view of the fact that the subjects were trained, already (Prestes 2017).
And that war irrespective of the training program they'd followed and thus notwithstanding the exercise duration (57 and 35 minutes for the traditional and rest-pause methods, respectively) and the way in which the prescribed 18 repetitions at 80% of 1 RM for each exercise were performed:
  • rest-pause group: an initial set with 80% of 1-RM was performed until failure with subsequent sets performed with a 20 sec inter-set rest interval until a total of 18 repetitions were completed; 2-3 min of rest between exercises.
  • traditional multi-set group: exercises were performed for three sets of 6 repetitions with 80% of 1-RM; 2-3 min of rest between sets and exercises.
All training sessions were carefully supervised by a certified strength and conditioning professional, and adherence to the training program was ~90% for both groups. Also, during microcycles, no reduction in training intensity or assistance was provided for the rest-pause group as recommend by Marshall et al (2012), because that could have messed with the results.

Just in case you haven't seen it, yet: Another very recent study shows that cluster-training, which differs from rest-pause because it prescribes when you stop your set (here: 3x2 reps vs. rest-pause e.g. 3 reps, 2 reps 1 rep) builds power and explosiveness, but no extra size (learn more in the SuppVersity Faceboook News)
To which extent the last-mentioned principle reduced the observed superiority of the rest-pause regimen in terms of its effect on localized muscular endurance during the leg press (not shown; 27 ± 8% for rest-pause versus 8 ± 2% for traditional training) and muscle hypertrophy of the thigh (see Figure 3) isn't clear. What is clear, however, is that it's probably no coincidence that both the muscle endurance and the size of the thigh muscle (rest-pause: 11 ± 14% versus traditional 15 multiple-set: 1 ± 7%) significantly increased.
Figure 3: Relative changes (%) in muscle circumference with the two training protocols; all calculated effect sizes are "trivial", again; p < 0.05 for the inter-group difference in the increase in thigh muscle thickness (Prestes 2017).
The observation that 'the legs' benefit most, may be disappointing for the average gym bro who feels that he doesn't have to train legs, because his legs would be too big already, for the advanced trainer and trainee, on the other hand, it is convincing evidence that the rest-pause method may or should be used muscle specific and in order to turn the overall "trivial" gains of experienced strength trainees, like the ones who volunteered for the study at hand, from an almost too small to see 1.3 cm increase to a similarly trivial 1.9 cm increase in thigh size ;-)
Related - SuppVersity Related Classic: Building Extra-Strength With Cluster Training (6x1 With 25s Rest) - Works, but Don't Make the Mistake to Underestimate the Efficacy of Classic Strength Training, Bro! | learn more
Bottom line: If you'd read only the scientists conclusion that their study would suggest that "the rest-pause method resulted in greater gains in localized muscular endurance and hypertrophy for the thigh musculature," (Prestes 2017) you'd probably expect more than a 0.9% additional improvement in thigh circumference, standard deviations that exceed the inter-group differences and effect sizes that are still "trivial" in both, the technical and literal sense of the word, right? Unfortunately, that's exactly what the scientists found in this small scale study: small absolute differences, a high inter-subject variability, and "trivial" effect sizes, which highlight that the likelihood that your legs will grow like crazy when you incorporate the rest-pause technique into your training routine is "trivial", as well.

Does this mean that using rest-pause is a waste of time and effort? Well, take another look at the figures and let me repeat my concluding remark that the study would provide "convincing evidence that the rest-pause method may or should be used muscle specific and in order to turn the overall "trivial" gains of experienced strength trainees [...] from an almost too small to see 1.3 cm increase to a similarly trivial 1.9 cm increase in thigh size". I guess by now you will realize that the rest-pause technique may not deliver the steroid-like gains some people expect whenever they read about "greater gains" in the conclusions of scientific papers. This doesn't mean, however, that it couldn't, provide the extra growth stimulus experienced athletes and their trainers need to make those, often trivial extra gains that make the difference between victory and defeat | Comment
  • Marshall, Paul WM, et al. "Acute neuromuscular and fatigue responses to the rest-pause method." Journal of Science and Medicine in Sport 15.2 (2012): 153-158.
  • Prestes J., et al. "Strength and muscular adaptations following 6 weeks of rest pause versus traditional multiple-sets resistance training in trained subjects". Journal of Strength and Conditioning Research. Published Ahead of Print DOI: 10.1519/JSC.0000000000001923.