Maximal instantaneous muscular power after prolonged bed rest in humans

Guido Ferretti, Hans E. Berg, Alberto E. Minetti, Christian Moia, Susanna Rampichini, Marco V. Narici

Research output: Contribution to journalArticlepeer-review

Abstract

A reduction in lower limb cross-sectional area (CSA) occurs after bed rest (BR). This should lead to an equivalent reduction in maximal instantaneous muscular power (Wp) if the body segments' lengths remain unchanged. Wp was determined during maximal jumps off both feet on a force platform before and on days 2, 6, 10, 32, and 48 after a 42-day duration BR. CSA of thigh muscles was measured by magnetic resonance imaging before and on day 5 after BR. Before BR, Wp was 3.63 ± 0.43 kW or 48.6 ± 3.3 W/kg. On days 2 and 6 after BR, Wp was reduced by 23.7 ± 6.9 and 22.7 ± 5.4% (P <0.01), respectively. Thigh extensors CSA (CSAEXT) was 16.7 ± 4.7% (P <0.01) lower than before. When normalized per CSAEXT, Wp was reduced by only 4.8 ± 4.5% (P <0.05). By day 48 of recovery, Wp had returned to baseline values. Therefore, if Wp is appropriately normalized for CSA of the extensor muscles, the reduction in CSAEXT explains most of the decrease in Wp decrease after BR. Other factors such as a deficit in neural activation or a decrease in fiber-specific tension may account for only 5% of the Wp loss after BR.

Original languageEnglish
Pages (from-to)431-435
Number of pages5
JournalJournal of Applied Physiology
Volume90
Issue number2
Publication statusPublished - 2001

Keywords

  • Muscle cross-sectional area
  • Spaceflight simulation

ASJC Scopus subject areas

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

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