Effect of strength training on the relationship between magnetic resonance relaxation time and muscle fibre composition |
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| Authors: | Shin-ya Kuno Shigeru Katsuta Masayoshi Akisada Izumi Anno Kunihiko Matsumoto |
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| Institution: | (1) Department of Radiology, Institute of Clinical Medicine, University of Tsukuba, Tennodai 1-1-1, 305 Tsukuba-shi, Japan;(2) Institute of Health and Sport Sciences, University of Tsukuba, Tennodai 1-1-1, 305 Tsukuba-shi, Japan |
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| Abstract: | Summary The effect of muscle hypertrophy on the relationship between magnetic resonance (MR) relaxation time and muscle fibre composition was investigated. Relaxation time and muscle fibre composition were measured in five subjects before and after a 20-week period of strength training. Muscle fibre composition in all subjects exhibited a significant shift to a predominance of fast-twitch (FT) fibres as a result of 20-week strength training (% area FT fibres: mean values from 49.8%, SD 17.9% to 57%, SD 5.6%; P<0.05). Longitudinal relaxation time (T1) and transverse relaxation time (T2) were prolonged significantly after strength training (T1 mean values from 334.9 ms, SD 13.6 to 359.0 ms, SD 9.0, P<0.001; T2 from 27.5 ms, SD 0.9 to 30.8 ms, SD 2.3, P<0.05). A constant relationship was observed in changes caused by strength training in muscle fibre composition (% area FT) and relaxation time, with a high correlation obtained between both parameters. These results indicate that MR relaxation time can be used for non-invasive estimation of muscle fibre composition. |
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| Keywords: | Magnetic resonance imaging Relaxation time Muscle fibre composition Strength training |
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