G. Pyka et al., MUSCLE STRENGTH AND FIBER ADAPTATIONS TO A YEAR-LONG RESISTANCE TRAINING-PROGRAM IN ELDERLY MEN AND WOMEN, Journal of gerontology, 49(1), 1994, pp. 22-27
Background. To study the effects of resistance training on muscle stre
ngth and size in older people, we enrolled 8 men and 17 women (mean ag
e 68.2 +/- 1 SEM) into a one-year exercise trial. Methods. Subjects we
re randomly assigned to exercise or control groups. Muscle biopsies we
re obtained from 11 subjects (8 exercisers/3 controls) at baseline and
after 15 weeks; exercisers underwent another biopsy at 30 weeks. Afte
r testing maximum strength using the 1-RM method, the exercisers began
a 12-exercise circuit (3 sets of 8 repetitions at 75% of 1-RM), 3 tim
es a week. The controls repeated the strength testing every 15 weeks.
They were asked to continue usual activities and not to start any exer
cise program. Results. With exercise, muscle strength increased, avera
ge increases ranging from 30% (hip extensors) to 97% (hip flexors). St
rength increased rapidly over 3 months, then plateaued for the duratio
n of the experiment. No strength changes were observed in sedentary co
ntrols. Cross-sectional area of type 1 muscle fibers increased in exer
cisers by 15 weeks (29.4 +/- 1%, p < .02) and after 30 weeks (58.5 +/-
13.7%, p < .002) compared to baseline. Type 2 fiber area did not chan
ge at 15 weeks, but increased by 30 weeks of training (66.6 +/- 9.5%,
p < .0002). Conclusions. These results suggest that prolonged moderate
to high intensity resistance training may be carried out by healthy o
lder adults with reasonable compliance, and that such training leads t
o sustained increases in muscle strength. These improvements are rapid
ly achieved and are accompanied by hypertrophy of both type 1 and type
2 muscle fibers.