Efficacy of 3 days/wk resistance training on myofiber hypertrophy and myogenic mechanisms in young vs. older adults
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- 1 August 2006
- journal article
- clinical trial
- Published by American Physiological Society in Journal of Applied Physiology
- Vol. 101 (2), 531-544
- https://doi.org/10.1152/japplphysiol.01474.2005
Abstract
Resistance training (RT) has shown the most promise in reducing/reversing effects of sarcopenia, although the optimum regime specific for older adults remains unclear. We hypothesized myofiber hypertrophy resulting from frequent (3 days/wk, 16 wk) RT would be impaired in older (O; 60–75 yr; 12 women, 13 men), sarcopenic adults compared with young (Y; 20–35 yr; 11 women, 13 men) due to slowed repair/regeneration processes. Myofiber-type distribution and cross-sectional area (CSA) were determined at 0 and 16 wk. Transcript and protein levels of myogenic regulatory factors (MRFs) were assessed as markers of regeneration at 0 and 24 h postexercise, and after 16 wk. Only Y increased type I CSA 18% ( P < 0.001). O showed smaller type IIa (−16%) and type IIx (−24%) myofibers before training ( P < 0.05), with differences most notable in women. Both age groups increased type IIa (O, 16%; Y, 25%) and mean type II (O, 23%; Y, 32%) size ( P < 0.05). Growth was generally most favorable in young men. Percent change scores on fiber size revealed an age × gender interaction for type I fibers ( P < 0.05) as growth among Y (25%) exceeded that of O (4%) men. Myogenin and myogenic differentiation factor D (MyoD) mRNAs increased ( P < 0.05) in Y and O, whereas myogenic factor (myf)-5 mRNA increased in Y only ( P < 0.05). Myf-6 protein increased ( P < 0.05) in both Y and O. The results generally support our hypothesis as 3 days/wk training led to more robust hypertrophy in Y vs. O, particularly among men. However, this differential hypertrophy adaptation was not explained by age variation in MRF expression.Keywords
This publication has 65 references indexed in Scilit:
- From Birth to Death: The Complex Lives of Eukaryotic mRNAsScience, 2005
- Sarcopenia is not due to lack of regenerative drive in senescent skeletal muscleAging Cell, 2005
- Diminished overload-induced hypertrophy in aged fast-twitch skeletal muscle is associated with AMPK hyperphosphorylationJournal of Applied Physiology, 2005
- Time course of molecular responses of human skeletal muscle to acute bouts of resistance exerciseJournal of Applied Physiology, 2005
- Age differences in knee extension power, contractile velocity, and fatigabilityJournal of Applied Physiology, 2005
- Effects of Aging on Muscle Fibre Type and SizeSports Medicine, 2004
- Effects of Resistance Training on Older AdultsSports Medicine, 2004
- Changes in electromyographic activity, muscle fibre and force production characteristics during heavy resistance/power strength training in middle‐aged and older men and womenActa Physiologica Scandinavica, 2001
- Changes in Muscle Morphology, Electromyographic Activity, and Force Production Characteristics During Progressive Strength Training in Young and Older MenThe Journals of Gerontology: Series A, 1998
- Enhanced Expression of Myogenic Regulatory Genes in Aging Skeletal MuscleExperimental Cell Research, 1995