PROBLEM: Only a handful of studies have evaluated differences in autonomic modulation between resistance-trained (RT) and untrained (UT) individuals in response to an acute bout of resistance exercise (ARE). Therefore, we sought to compare alterations in vagal modulation during recovery from ARE in RT (n=18) and UT (n=8) individuals. METHODS:Vagal modulation was assessed using heart rate variability [log transformed high-frequency power (lnHF)], as well as heart rate complexity [Sample Entropy (SampEn) and Lempel-Ziv entropy (LZEn)]. Data were collected at rest, 15 minutes (Rec1) and 30 minutes (Rec2) during recovery from ARE. The acute bout of resistance exercise utilized 3 sets of 10 repetitions at 75% 1-repetition maximum (1RM) and 2 minutes of rest between sets and exercises on the chest press, leg press, lat pulldown, leg curl and leg extension. RESULTS:The groups were similar (p>0.05) for age, and height, but not weight. The total volume lifted during the acute bout of resistance exercise was significantly different between groups. At rest, all measures of vagal modulation were similar between groups with no 3-way interactions. There were significant time x condition interactions for lnHF, SampEn, and LZEn. Each of these variables were reduced at Rec1 and Rec2 compared to rest, with similar responses between the resistance-trained and untrained groups. CONCLUSIONS: These data demonstrate that both resistance-trained and untrained individuals respond similarly to an acute bout of resistance exercise using weight machines.

231/250