Short-Term Strength Training Does Not Alter Skeletal Muscle Capillarization In Young Or Older Women

Abstract

0399 It is well-established that regular aerobic exercise training may increase skeletal muscle capillarization in young and older men and women. In addition, a number of studies have reported improved skeletal muscle capillarity in young and older men following strength training (ST). However, few studies have examined the effects of ST on skeletal muscle capillarization in women, especially in older women. PURPOSE: To examine the effects of ST on skeletal muscle capillarization in young (YW; n = 11; 26 ± 1 yr; 62 ± 12 kg) and older (OW; n = 11; 68 ± 3 yr; 68 ± 9 kg) women. METHODS: Needle biopsy samples of the vastus lateralis muscles of both legs were obtained before and after nine weeks of unilateral ST during which only the dominant leg was trained. Muscle samples were stained for capillary analyses using the PAS method. Baseline muscle samples and those obtained after ST were compared using ANOVA with repeated measures to examine the effects of age and ST on capillary density (CD), capillary per fiber ratio (CFR), and capillary contacts per fiber (CCF). RESULTS: Although ST led to significant increases in 1 RM strength and muscle fiber cross sectional area (CSA) in the trained leg of YW and OW, there were no significant changes in CD (YW: 259 ± 37 vs. 265 ± 16; OW: 267 ± 30 vs. 237 ± 27; cap/mm2), CFR (YW: 3.4 ± 0.4 vs. 3.5 ± 0.3; OW: 3.4 ± 0.5 vs. 3.6 ± 0.4; cap/fiber area/mm2), or CCF (YW: 4.9 ± 0.5 vs. 4.9 ± 0.7; OW: 4.8 ± 0.5 vs. 5 ± 0.2; cap/fiber) as a result of ST (all p > 0.05). There were also no significant differences in capillarization between YW and OW at baseline, and no changes in capillarization in the control leg. CONCLUSION: These data indicate that although short-term heavy-resistance ST may induce improvements in muscular strength and muscle fiber CSA in women, it does not result in significant alterations in skeletal muscle capillarity. Supported by NIA Research Contract #1AG-42148