Kojima, K., Kitanp. K., Stager, J. M., & Abe, T. (2013). Is site-specific sarcopenia observed in masters swimmers? Medicine & Science in Sports & Exercise, 45(5), Supplement abstract number 2044.

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This study compared the distributed (site-specific) and whole body skeletal muscle mass of masters swimmers (N = 9) to those of young recreationally active college students (N = 9). Muscle thickness and subcutaneous fat thickness were measured by ultrasound at 11 sites on the anterior and posterior aspects of the body (forearm, upper arm, trunk, thigh, and lower leg). Percent body fat (%fat) was estimated from subcutaneous fat thickness and fat-free mass was calculated. Skeletal muscle mass was estimated using an ultrasound-derived prediction equation from muscle thickness. Muscle thickness ratios were calculated to assess the site-specific thigh sarcopenia. Walking performance (straight and zig-zag walk) and maximum voluntary isometric contractions (knee extension and flexion) were measured.

No significant differences were found in %fat, fat-free mass, total skeletal muscle mass, or maximum voluntary isometric contractions between the two groups. Masters swimmers, however, demonstrated significantly lower muscle thickness at the 50% and 70% sites of the anterior thigh and slower zig-zag walking time. The A50:P70 tended to be lower in masters swimmers than in college students. Moreover, zig-zag walking time was significantly correlated with muscle thickness at the 70% site of the anterior thigh.

Implication. Age-related loss of total skeletal muscle mass was not observed in masters swimmers compared with active college students. Nonetheless, site-specific sarcopenia was observed in the anterior thigh among masters swimmers which appeared to be associated with attenuated performance in zig-zag walk.

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