Six weeks' aerobic retraining after two weeks' immobilization restores leg lean mass and aerobic capacity but does not fully rehabilitate leg strength in young and older men

J Rehabil Med. 2015 Jun;47(6):552-60. doi: 10.2340/16501977-1961.


Objective: To determine the effect of aerobic retraining as rehabilitation after short-term leg immobilization on leg strength, leg work capacity, leg lean mass, leg muscle fibre type composition and leg capillary supply, in young and older men.Subjects and design: Seventeen young (23 ± 1 years) and 15 older (68 ± 1 [standard error of the mean; SEM] years) men had one leg immobilized for 2 weeks, followed by 6 weeks' bicycle endurance retraining.

Methods: Maximal voluntary contraction, leg work capacity (Wmax), and leg lean mass by dual energy X-ray absorptiometry were measured at inclusion, after immobilization and after 3 and 6 weeks' retraining. Muscle biopsies were evaluated for fibre type, fibre area, and capillarization.

Results: Immobilization decreased maximal voluntary contraction (-28 ± 6% and -23 ± 3%); Wmax (-13 ± 5% and -9 ± 4%) and leg lean mass (only in young, -485 ± 105g) in young and older men, respectively. Six weeks' retraining increased maximal voluntary contraction (34 ± 8% and 17 ± 6%), Wmax (33 ± 5% and 20 ± 5%) and leg lean mass (only in young 669 ± 69 g) in young and older men, respectively, compared with the immobilized value.

Conclusion: Short-term leg immobilization had marked effects on leg strength, and work capacity and 6 weeks' retraining was sufficient to increase, but not completely rehabilitate, muscle strength, and to rehabilitate aerobic work capacity and leg lean mass (in the young men).

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Capillaries / physiology
  • Exercise Therapy*
  • Humans
  • Immobilization
  • Lower Extremity / physiology*
  • Male
  • Muscle Contraction / physiology
  • Muscle Fibers, Skeletal / physiology
  • Muscle Strength / physiology*
  • Muscle, Skeletal / blood supply
  • Physical Endurance / physiology