|Extra gains, testosterone, and GH in one scientific paper? That will catch every gymrats interest, right?|
What is particularly interesting about the study that has just been published in "Physical Reports" is the fact that Walker et al measured both, the hormonal response that is usually evaluated only acutely, i.e. in studies where the subjects train only once, and the corresponding strength and size gains... and guess what: (1) The hormonal response to the allegedly slightly artificial "leg-extension only"-training program diminishes with time, unless (2) the workouts are kept challenging by increasing the weight on the eccentric portion of the exercise and thus maximizing the stimulus on the leg extensors.
This study only looks as if it was your ordinary "legs only, that's not the real world" trial
Before we jump to any unwarranted conclusions that are probably totally unwarranted, anyway, I'd suggest that we take a closer look at what exactly the Finish-Australian-Chinese co-production (talking about the home Universities of the authors, here) did to their N=18 healthy, young, male subjects who had a strength training background of 2.7 ± 2.3 years and an initial 10‐RM inclined leg press load of roughly 2kg per kilo body weight. While both groups performed the same three sets of bilateral leg press, three sets of unilateral knee extension and three sets of bilateral knee flexion twice a week (at least 48 h recovery between training sessions) and with a weight equal to their individual 6 rep max (RM) for 8 weeks (week 1 and 10 were testing weeks), ...
- the isoinertial (ISO) group performed the exercises with the same load for both concentric and eccentric phases, while
- the accentuated eccentric (AEL) group performed the exercises with 40% greater load during the eccentric phase compared to the concentric phase (i.e., eccentric load = concentric load + 40%)
|Figure 1: Relative improvements (mean ± SD) in maximum isometric knee extension torque (A) and lower limb lean mass (B) from pre‐ to mid‐training and mid‐ to post‐training. *P < 0.05 within group, #P < 0.05 between groups (Walker 2017).|
This is not a leg-training only study: If you're now mad that this is not exactly a realistic workout, you will be happy to hear that the subjects were instructed to continue with their normal upper body strength training program (albeit at least 24h away from the leg training sessions). The results should thus be representative of what you could see if you applied the same training principles to your workouts, even if you're training your upper body, as well. Moreover, the subjects' training logs show that they had a lot of other exercises going on... now that's realistic, but it's impossible to exclude that their non-competitive recreational activities (1‒3 times per week) didn't affect the study outcomes in one way or another.
|Figure 2: If you compare the hormonal response early (solid) and late (dashed) line you will see the attenuation of T, cortisol, and GH that occurred in the ISO group (left) over time (Walker 2017).|
As the authors rightly point out, "the maintenance of acute hormonal responses and continued strength gain in AEL but not ISO are consistent with the hypothesis that maintained acute responses indicate an efficacy of a training stimulus to evoke ongoing adaptation" (Walker 2017). What this does not mean, however, is that the hormonal response is not in as much a result of this stimulus as the gains you see in Figure 1.
You want to dig deeper into the hormonal response seen in this study? I'd suggest you read the excellent discussion Walker et al provide in their open access paper - simply click here!We thus have to be careful: Correlation, i.e. the stimulus triggers both the gains and the increase in GH and testosterone, doesn't necessarily equal causation, i.e. the increase in GH and testosterone trigger the gains. But how de we know which of the two hypothesis is accurate? Well if the latter was the case, the scientists should at least have found a statistically significant relationship between the hormonal response and the gains of their subjects. Such a relationship, however, did not exist - and that's in line w/ previous research (West 2012; Schoenfeld 2013; Egerman 2014), where correlations were - if at all - only found on a group level.
|Figure 3: West's and Philipps' 2012 paper showed that the post-workout cortisol- (right), not testosterone- (middle) or GH- (left) response predicts the total lean mass gains in response to weight training in a large cohort trained men (West 2012).|
Don't (ab-)use these results to argue in favor of a causal involvement of the PWO increase in growth hormone and testosterone in muscle gains!
Accordingly, their "data suggest that tracking of acute hormonal responses on an individual level may not provide a sensitive enough guide for decisions regarding program design and periodization" (Walker 2017) - or, in other words, we're back to square one, i.e. the realization that PWO cortisol, GH, and testosterone levels are probably not worth bothering with.
- Egerman, Marc A., and David J. Glass. "Signaling pathways controlling skeletal muscle mass." Critical reviews in biochemistry and molecular biology 49.1 (2014): 59-68.
- Schoenfeld, Brad J. "Postexercise hypertrophic adaptations: a reexamination of the hormone hypothesis and its applicability to resistance training program design." The Journal of Strength & Conditioning Research 27.6 (2013): 1720-1730.
- Walker, Simon, et al. "Acute elevations in serum hormones are attenuated after chronic training with traditional isoinertial but not accentuated eccentric loads in strength‐trained men." Physiological Reports 5.e13241 (2017) DOI: 10.14814/phy2.13241
- West, Daniel WD, and Stuart M. Phillips. "Associations of exercise-induced hormone profiles and gains in strength and hypertrophy in a large cohort after weight training." European journal of applied physiology 112.7 (2012): 2693-2702.