Effects of strength and endurance training on muscle fibre characteristics in elderly women.
The effects of 18 weeks' intensive strength and endurance training on fibre characteristics of the vastus lateralis muscle were studied in 76- to 78-year-old women. Type I and type IIa fibres constituted over 90% of the cell population and were almost equally represented. No changes were observed in the proportions of the different fibre types. When comparing the baseline and the 18-week measurements within the groups, the strength group showed a mean increase of 34% (P = 0.028) in mean type I fibre area. The frequency histograms showed an increased proportion of larger type I fibres after strength training and a decreased proportion of smaller type IIa fibres after endurance training. In the control subjects, the proportion of smaller type I and type IIa fibres increased during the experimental period. The results indicate that intensive strength training induces type I fibre hypertrophy, whereas the effects of endurance training are less evident. The considerable variation found in the change in muscle fibre cross-sectional areas is also noteworthy.
Sipilä
S
S
Department of Health Sciences, University of Jyväskylä, Finland.
Elorinne
M
M
Alen
M
M
Suominen
H
H
Kovanen
V
V
D000368:Aged; D000375:Aging / Q000473:pathology / Q000502:physiology; D005081:Exercise Therapy; D005260:Female; D006801:Humans; D006984:Hypertrophy; D018656:Muscle Fibers, Fast-Twitch / Q000166:cytology / Q000502:physiology; D018485:Muscle Fibers, Skeletal / Q000166:cytology* / Q000502:physiology*; D018657:Muscle Fibers, Slow-Twitch / Q000166:cytology / Q000502:physiology; D009133:Muscular Atrophy / Q000209:etiology / Q000473:pathology / Q000628:therapy; D010807:Physical Endurance / Q000502:physiology*