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: firstname.lastname@example.org
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).