Skeletal muscle responses to lower limb suspension in humans

J Appl Physiol (1985). 1992 Apr;72(4):1493-8. doi: 10.1152/jappl.1992.72.4.1493.


Eight subjects participated in a 6-wk unilateral lower limb suspension (ULLS) study to determine the influence of reduced weight bearing on human skeletal muscle morphology. The right shoe was outfitted with a platform sole that prevented the left foot from bearing weight while walking with crutches, yet it allowed freedom of movement about the ankle, knee, and hip. Magnetic resonance images pre- and post-ULLS showed that thigh muscle cross-sectional area (CSA) decreased (P less than 0.05) 12% in the suspended left lower limb, whereas right thigh muscle CSA did not change. Likewise, magnetic resonance images collected post-ULLS showed that muscle CSA was 14% smaller (P less than 0.05) in the left than in the right leg. The decrease in muscle CSA of the thigh was due to a twofold greater response of the knee extensors (-16%, P less than 0.05) than knee flexors (-7%, P less than 0.05). The rectus femoris muscle of the knee extensors showed no change in CSA, whereas the three vastus muscles showed similar decreases of approximately 16% (P less than 0.05). The apparent atrophy in the leg was due mainly to reductions in CSA of the soleus (-17%) and gastrocnemius muscles (-26%). Biopsies of the left vastus lateralis pre- and post-ULLS showed a 14% decrease (P less than 0.05) in average fiber CSA. The decrease was evident in both type I (-12%) and II (-15%) fibers. The number of capillaries surrounding the different fiber types was unchanged after ULLS.(ABSTRACT TRUNCATED AT 250 WORDS)

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Adenosine Triphosphatases / metabolism
  • Adult
  • Capillaries / pathology
  • Female
  • Humans
  • Leg
  • Magnetic Resonance Imaging
  • Male
  • Muscles / blood supply
  • Muscles / metabolism
  • Muscles / pathology*
  • Muscular Atrophy / etiology*
  • Muscular Atrophy / metabolism
  • Muscular Atrophy / pathology
  • Periodic Acid-Schiff Reaction
  • Weightlessness / adverse effects*


  • Adenosine Triphosphatases