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Lifelong Exercise and Mild (8%) Caloric Restriction Conserve Cell Morphology of the Plantaris in the Aging Fischer‐344 Rat
Author(s) -
Kim JongHee,
Kwak HyoBum,
Leeuwenburgh Christiaan,
Lawler John M
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.4.a806-c
Subject(s) - plantaris muscle , sarcopenia , caloric theory , skeletal muscle , muscle hypertrophy , medicine , endocrinology , fiber , muscle fibre , chemistry , anatomy , biology , soleus muscle , organic chemistry
Sarcopenia is a reduction of skeletal muscle mass as a result of reduced muscle fiber cross‐sectional area and fiber number, resulting in impaired contractile function. Exercise training, either resistive or endurance ameliorates sarcopenia in aging muscle. Recent data indicate that moderate caloric restriction (30–40%) conserves skeletal muscle fiber cross‐sectional area, and fiber number, particularly in muscle with a high % of fast‐twitch fibers. We tested the hypothesis that 8% CR or lifelong wheel running + 8% CR would conserve fiber morphology in the plantaris muscle. We divided male Fischer‐344 rats at 11 weeks into four groups: fed ad libitum until 6 mo. old (6AL, n=12); fed ad libitum until 24 mo. old (24AL, n=11); 8% caloric restriction from 11 wk to 24 mo of age (24CR, n=12); wheel running from 11 wk to 24 mo. with 8% caloric restriction (24ExCR, n=12). Aging increased the number of plantaris fibers/μm2 in 24AL; however, fiber number/μm2 was similar in both 24CR and 24ExCR to 6AL. Mean plantaris fiber cross‐sectional area decreased markedly in 24 AL compared with 6 AL; however, fiber area in 24 CR and 24 ExCR significantly greater than 24AL. In addition, 24CR and 24ExCR protected against the large increase (+373%) in connective tissue found in 24 AL plantaris when compared with 6AL. These results support the hypothesis that lifelong voluntary exercise and mild caloric restriction preserve fast‐twitch muscle morphology in the aging plantaris. Supported by an NIH Grant R01AG17994‐01