Acute Myosin Heavy Chain Isoform mRNA Expression in Response to Two Resistance Exercise Intensities With Equal Volume Load in Resistance-Trained Men.
The purpose of this study was to determine if resistance exercise intensity, in the context of equal volume load, differentially affected myosin heavy chain (MHC) isoform messenger RNA (mRNA) expression in resistance-trained men. In a crossover, uniform-balanced design, 10 male participants (23.7 ± 2.8 years, 178.8 ± 5.9 cm, 85.9 ± 9.2 kg) completed 2 lower-body resistance exercise sessions of different intensities with equal volume load. For the higher-intensity exercise session, participants performed 5 sets of 6 repetitions at 80% of 1 repetition maximum (1RM). For the lower-intensity exercise session, participants performed 3 sets of 16 repetitions at 50% of 1RM. Muscle samples from the vastus lateralis were acquired before exercise (PRE), 45 minutes postexercise (45MINPE), 3 hours postexercise (3HRPE), 24 hours postexercise (24HRPE), and 48 hours postexercise (48HRPE). Statistical analyses of mRNA expression were performed using separate 2 × 5 two-way repeated-measures analyses of variance for each criterion variable (p ≤ 0.05). There were no statistically significant interactions between intensity and time. Likewise, there were no significant differences between exercise intensity in MHC expression. Expression of mRNA for all MHC isoforms decreased at all postexercise time points, except 3HRPE (p = 0.051), compared with PRE following both exercise bouts (p ≤ 0.05). The results of this study found no difference in mRNA expression of MHC isoforms as a function of resistance exercise intensity. In addition, in contrast to results found in previous studies of untrained men, MHC mRNA expression seems to decrease in response to acute resistance exercise in previously resistance-trained men.
1Department of Health, Physical Education, and Leisure Studies, University of South Alabama, Mobile, Alabama; and 2Exercise and Biochemical Nutrition Laboratory, Department of Health, Human Performance, and Recreation, Baylor University, Waco, Texas.
Neil A
NA
Schwarz
Mike B
MB
Spillane
Sarah K
SK
McKinley
Thomas L
TL
Andre
Joshua J
JJ
Gann
Darryn S
DS
Willoughby
D000328:Adult; D018592:Cross-Over Studies; D006801:Humans; D008297:Male; D018995:Myosin Heavy Chains / Q000235:genetics*; D005082:Physical Exertion / Q000502:physiology*; D020033:Protein Isoforms / Q000235:genetics; D052097:Quadriceps Muscle / Q000502:physiology*; D012333:RNA, Messenger / Q000378:metabolism*; D055070:Resistance Training / Q000379:methods*; D055815:Young Adult
D020033:Protein Isoforms; D012333:RNA, Messenger; D018995:Myosin Heavy Chains