Sunday, July 2, 2017

Training to Failure Doubles 10Wk Biceps Gains Compared to Volume-Equ. Training - Difference to Control Even Larger

Beware, guys, training like these women may make your guns "bulky" ;-)
No, this is by no means the first article about training to failure I've written. In fact, I've published an article as part of a two-part series on "Intensity Techniques" in February, this year.  The reason(s) the latest study from the University of Brasilia (Martorelli 2017 | SuppVersity veterans will notice that this is yet another example of excellent resistance training research from Brazil I can write about) still made it to the SuppVersity News is that it is (a) one of the rare studies with young, healthy female subjects and (b) has both, a non-failure non-volume-equated and a volume-equated non-failure control group.
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Of the aforementioned strengths of the study (b) is unquestionably the real distinguishing factor. As Schoenfeld et al. pointed out in various reviews and independent research the training volume seems to be the only definite determinant of exercise-induced muscle hypertrophy (e.g. Schoenfeld 2010 & 2014). Accordingly, any meaningful comparison of failure to non-failure training needs to be volume-equated...
Figure 1: Insights from previous studies (Izquierdo 2006) and reviews (Stone 1996; Willardson 2007) of training to failure.
...that, however, reduces the practical significance of the results, because, for the average trainee, training to volume goes hand in hand with an increased training volume. After all, few of you will add extra sets to keep their volume constant when they switch back and forth between training to failure and stopping short before their muscles fail.

The study's most important strength is that it has sufficiently large volume-equated and regular no-failure groups and does, therefore, allow us to distinguish the effects of failure and an increased volume due to training to failure.

For their Experiment, the scientists randomly assigned eighty-nine active young women were randomly assigned to one of the previously hinted at three groups:
  • repetitions to failure (RF; three sets of repetitions to failure)
  • repetitions not to failure with equalized volume (RNFV; four sets of 7 repetitions)
  • repetitions not to failure (RNF; three sets of 7 repetitions)
All groups performed the elbow flexor exercise (bilateral biceps curl) and trained 2 days per week using 70% of 1RM.
Figure 2: The volume standardization worked out quite well (left), the increase in muscular endurance was - within statistical margins - identical in all three groups (right); it did, however, show a non-sign. lower effect size in the non-volume equated vs. volume equated non-failure group after 10 weeks  - volume does, therefore, appear to be a relevant determinant of the exercise-induced adaptational response for muscular endurance - in the long run  (Martorelli 2017).
The scientists' analysis of the results show significant increases (p<0.05) in muscle strength after 5 (15.9% for RF, 18.4% for RNF, and 19.9% for RNFV) and 10 (28.3% for RF, 26.8% for RNF, and 28.3% for RNFV) weeks of training - and that "with no significant differences between groups" (Martorelli 2017 | my emphasis). Similar results were observed for the women's strength endurance, which increased after 5 and 10 weeks, likewise with no differences between groups.
Here's why it's important to wait 5 days before measuring sleeve sizes | more
An important note on how the muscle thickness was measured: All tests were conducted at the same time of the day, and the participants were instructed to hydrate normally for the 24 h before the tests.

Furthermore, measurements were taken 5 days after the last training session so that swelling did not affect the MT measurement). The actual measurement was conducted using B-Mode ultrasound (Philips-VMI, Ultra Vision Flip, model BF). The baseline test and retest intraclass correlation coefficient for the elbow flexor muscle thickness was excellent, namely 0.98 (0.98–0.99).
Differences were however observed for peak torque (PT), which increased significantly at 180°/s in the RNFV (13.7%) and RNF (4.1%) groups (p<0.05), whereas no changes were observed in the RF group (-0.5%) and muscle thickness
Figure 3: Relative changes in biceps size in the three study groups after 5 and 10 weeks (Martorelli 2017).
As you can see in Figure 3, the latter increased significantly (p<0.05) in the RF and RNFV groups after 5 (RF: 8.4% and RNFV: 2.3%) and 10 weeks of training (RF: 17.5%, and RNFV: 8.5%), whereas no significant changes were observed in the RNF group (3.9 and 2.1% after 5 and 10 weeks, respectively) - in fact, the reduction in sleeve size from week 5 to week 10 clearly indicates that the training stimulus of three sets of 7 reps was insufficient to trigger a consistent hypertrophy response (despite measurable, but also declining strength gains | see Figure 2, right).
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So, what's the verdict? As usual, you should keep in mind that this is only a single study. With its two "control" groups, it is yet also the first one I have seen to allow us to effectively distinguish between the effects of going to failure and the effect of the increased training volume that's usually associated with training to failure. In this respect, the data (a) confirm previous studies which point to training volume as a, if not "the" major determinant of skeletal muscle hypertrophy. The greater increase in muscle size in the RF group, however, seems to suggest that (b) training to failure has an additional beneficial effect on lean mass gains in the elbow flexors (biceps).
Beware of overgeneralizing the study results: While I doubt that the gains are sex-specific, I can very well imagine that similar benefits won't be seen on (a) multijoint exercises, where often other muscle groups take over as you approach failure and (b) with workout routines with a generally higher volume [keep in mind, the three sets of 7 in the study at hand are sign. less than what the average trainee is doing for his biceps - both directly (e.g. curls) or indirectly (e.g. pull-ups)] and (c) in other subject groups like the elderly, who appear to suffer from an impaired ability to recruit satellite cells for muscle repair (and growth), or highly trained individuals in whom the overall gains and probably also the inter-group differences could be significantly attenuated.
Whether the same goes for male subjects and other body parts will have to be elucidated in future studies. Plus: We must not forget that the authors rightly conclude that "training of repetitions to failure do not yield additional overall neuromuscular improvements in young women" (Martorelli 2017) - in other words: training your biceps to failure makes sense only if your primary goal is to grow bigger guns. If you want to maximize your peak torque, on the other hand, you better add sets/reps without going to failure - after all, the latter reduced the considerable increase in peak torque from 13.7% in the volume equated no-failure (RNFV) group to zero (statistically speaking) when the subjects trained to failure | Comment!
References:
  • Izquierdo, Mikel, et al. "Differential effects of strength training leading to failure versus not to failure on hormonal responses, strength, and muscle power gains." Journal of Applied Physiology 100.5 (2006): 1647-1656.
  • Martorelli, Saulo, et al. "Strength training with repetitions to failure does not provide additional strength and muscle hypertrophy gains in young women." Eur J Transl Myol 27.2: 113-120.
  • Schoenfeld, Brad J. "The mechanisms of muscle hypertrophy and their application to resistance training." The Journal of Strength & Conditioning Research 24.10 (2010): 2857-2872.
  • Schoenfeld, Brad J., et al. "Effects of different volume-equated resistance training loading strategies on muscular adaptations in well-trained men." The Journal of Strength & Conditioning Research 28.10 (2014): 2909-2918.
  • Steele, James, James Fisher, and Stewart Bruce-Low. "Resistance training to momentary muscular failure improves cardiovascular fitness in humans: a review of acute physiological responses and chronic physiological adaptations." Journal of Exercise Physiology Online 15.3 (2012): 53-80.
  • Stone, Michael H., et al. "Training to Muscular Failure: Is It Necessary?." Strength & Conditioning Journal 18.3 (1996): 44-48.