Changes in muscle size and architecture following 20 days of bed rest.

Yasuo Kawakami, Y. Muraoka, K. Kubo, Y. Suzuki, T. Fukunaga

Research output: Contribution to journalArticle

55 Citations (Scopus)

Abstract

Five healthy men carried out a program of head-down bed rest (BR) for 20 days. Before and after BR, a series of cross-sectional scans of the thigh were performed using magnetic resonance imaging, from which volumes of the quadriceps muscles were determined and physiological cross-sectional areas (PCSA) were calculated. Muscle thickness and pennation angles of the triceps brachii, vastus lateralis, and triceps surae muscles were also determined by ultrasonography. During BR, subjects performed unilateral isokinetic knee extension exercises every day. The contralateral limb served as a control. Decrease in PCSA after BR was greater in the control (-10.2 +/- 6.3%) than in the trained limb (-5.2 +/- 4.2%). Among the quadriceps, vastus intermedius in the control limb was predominantly atrophied by BR with respect to the volume and PCSA, and the rectus femoris showed the greatest training effect and retained its size in the trained limb. Decreases in muscle thicknesses in leg muscles were not prevented by the present exercise protocol, suggesting a need for specific exercise training for these muscles. Neither trained nor control muscles showed significant changes in pennation angles in any muscles after BR, suggesting that muscle architecture does not change remarkably by muscle atrophy by up to 10%.

Original languageEnglish
Pages (from-to)53-59
Number of pages7
JournalJournal of gravitational physiology : a journal of the International Society for Gravitational Physiology
Volume7
Issue number3
Publication statusPublished - 2000
Externally publishedYes

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Bed Rest
Muscles
Quadriceps Muscle
Extremities
Exercise
Muscular Atrophy
Thigh
Ultrasonography
Leg
Knee
Head
Magnetic Resonance Imaging

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Changes in muscle size and architecture following 20 days of bed rest. / Kawakami, Yasuo; Muraoka, Y.; Kubo, K.; Suzuki, Y.; Fukunaga, T.

In: Journal of gravitational physiology : a journal of the International Society for Gravitational Physiology, Vol. 7, No. 3, 2000, p. 53-59.

Research output: Contribution to journalArticle

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