Strength training counteracts motor performance losses during bed rest

Minoru Shinohara, Yasuhide Yoshitake, Motoki Kouzaki, Hideoki Fukuoka, Tetsuo Fukunaga

Research output: Contribution to journalArticle

56 Citations (Scopus)

Abstract

The purpose of the study was to determine the effect of bed rest with or without strength training on torque fluctuations and activation strategy of the muscles. Twelve young men participated in a 20-day bed rest study. Subjects were divided into a non-training group (BRCon) and a strength-training group (BRTr). The training comprised dynamic calf-raise and leg-press exercises. Before and after bed rest, subjects performed maximal contractions and steady submaximal isometric contractions of the ankle extensor muscles and of the knee extensor muscles (2.5-10% of maximal torque). Maximal torque decreased for both the ankle extensors (9%, P < 0.05) and knee extensors (16%, P < 0.05) in BRCon but not in BRTr. For the ankle extensors, the coefficient of variation (CV) for torque increased in both groups (P < 0.05), with a greater amount (P < 0.05) in BRCon (88%) compared with BRTr (41%). For the knee extensors, an increase in the CV for torque was observed only in BRCon (22%). The increase in the CV for torque in BRCon accompanied the greater changes in electromyogram amplitude of medial gastrocnemius (122%) and vastus lateralis (59%) compared with BRTr (P < 0.05). The results indicate that fluctuations in torque during submaximal contractions of the extensor muscles in the leg increase after bed rest and that strength training counter-acted the decline in performance. The response varied across muscle groups. Alterations in muscle activation may lead to an increase in fluctuations in motor output after bed rest.

Original languageEnglish
Pages (from-to)1485-1492
Number of pages8
JournalJournal of Applied Physiology
Volume95
Issue number4
Publication statusPublished - 2003 Oct 1
Externally publishedYes

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Keywords

  • Electromyogram
  • Knee extension
  • Plantarflexion
  • Steadiness

ASJC Scopus subject areas

  • Physiology
  • Endocrinology
  • Orthopedics and Sports Medicine
  • Physical Therapy, Sports Therapy and Rehabilitation

Cite this

Shinohara, M., Yoshitake, Y., Kouzaki, M., Fukuoka, H., & Fukunaga, T. (2003). Strength training counteracts motor performance losses during bed rest. Journal of Applied Physiology, 95(4), 1485-1492.