Sex difference in the heat shock response to high external load resistance training in older humans

2017 
Abstract Background Literature reports on the effects of resistance training on heat shock protein70 (Hsp70) adaptation in older subjects are scarce. Moreover, the optimum training load required to obtain a beneficial adaptation profile is lacking. Therefore, the aim of this study was to determine the effects of resistance training at various external loads on extracellular Hsp70 (eHsp70) resting levels in older humans. Methods Fifty-six community-dwelling older (68 ± 5 years) volunteers were randomized to 12 weeks of resistance training (3 ×/week) at either high-resistance (HIGH, 8 males, 10 females, 2 × 10–15 repetitions at 80% 1RM), low resistance (LOW, 9 Males, 10 Females, 1 × 80–100 repetitions at 20% 1RM), or mixed low resistance (LOW +, 9 Males, 10 Females, 1 × 60 repetitions at 20% 1RM followed by 1 × 10–20 repetitions at 40% 1RM). Serum was available from 48 out of the 56 participants at baseline and after 12 weeks for determination of eHsp70. Mid-thigh muscle volume (computed tomography), muscle strength (1RM & Biodex dynamometer) and physical functioning (including 6 min walk distance [6MWD]) were assessed. Results There was a sex-related dichotomy in the heat shock response to high external load training. We observed a significant decrease in eHsp70 concentration in the HIGH group for female, but not male, subjects. At baseline, men had a larger muscle volume, leg press and leg extension 1RM compared to women (all p  Conclusions Our results show that resistance training at high external load decreases the resting levels of eHsp70 in older females. Whether this reflects a better health status requires further investigation.
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