Content » Vol 47, Issue 6

Original report

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

Andreas Vigelsø , Martin Gram , Caroline Wiuff , Jesper L. Andersen, Jørn W. Helge, Flemming Dela
XLAB – Center for Healthy Aging, Department of Biomedical Sciences, Panum Institute, 12.4, Blegdamsvej 3b, DK-2200 N, Denmark. E-mail:
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).

Lay Abstract


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