Abstract
It has been proposed that the maintenance of acute hormonal responses reveal an efficacy of a training stimulus to evoke ongoing increases in strength and muscle mass. We previously observed that maximum strength continued to improve throughout a 10‐week period in an accentuated eccentric loading group (AEL) but not a traditional isoinertial loading (ISO) group. Therefore, this study investigated whether the magnitude of acute hormonal responses was greater (i.e., maintained) in AEL compared to ISO at the end of the training period. Subjects in AEL (eccentric load = concentric load + 40%) and ISO performed experimental loading tests (three sets of 10 repetitions in the leg press and knee extension exercises) during weeks 2 and 9 of the training period. Blood samples collected during these experimental loadings were analyzed for serum testosterone, growth hormone and cortisol concentrations. Maximum isometric knee extension torque (MVC) and lower‐limb lean mass were assessed before and after 5 and 10 weeks of training. Acute testosterone, growth hormone and cortisol responses to traditional isoinertial loading were reduced at the end of the training period but were not reduced after accentuated eccentric load training (P < 0.05‒0.1 between‐groups). Increases in MVC and lower‐limb lean mass over weeks 6‒10 were greater in AEL compared to ISO (MVC: 7.3 ± 5.4 vs. −0.4 ± 7.2%, P = 0.026 for between‐group difference; lower‐limb lean mass: 1.6 ± 2.2 vs. −0.2 ± 1.4%, P = 0.063 for between‐group difference). 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. However, since relationships between hormonal responses and training‐induced adaptations were not statistically significant, the 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.
Highlights
Hormones that regulate the anabolic/catabolic environment are a primary target for manipulation given that their presence has diverse, largely positive, effects on multiple tissues (Cuneo et al 1991; Bhasin et al 1996; Florini et al 1996)
There was a significant between-group difference in T response measured at post-loading during week 9 (P = 0.05, g = 0.94, 95% confidence intervals (95%CI) = À0.06–1.94, Fig. 3C) where no acute change in T concentration was observed in isoinertial loading (ISO)
A traditional isoinertial (10-RM) lower limb strength training session elicited similar acute testosterone (T), growth hormone (GH) and cortisol (C) responses as a training session performed with accentuated eccentric loading in already strength-trained individuals
Summary
Hormones that regulate the anabolic/catabolic environment are a primary target for manipulation given that their presence has diverse, largely positive, effects on multiple tissues (Cuneo et al 1991; Bhasin et al 1996; Florini et al 1996). Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society AEL Maintains Hormone Responses After Training bodybuilders, produce the greatest acute elevations in serum testosterone (T), growth hormone (GH) and cortisol (C) concentrations (e.g., Kraemer et al 1990; H€akkinen and Pakarinen 1993). These acute elevations could be a result of greater production and secretion into circulation or reduced uptake by target tissues through their receptors or a combination of both events. There is controversy as to whether such acute hormonal elevations induce, or even contribute to, outcomes such as muscle hypertrophy (Schroeder et al 2013)
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