Muscle strength appears well preserved following short periods of detraining, despite a decline in muscle cross-sectional area and muscle activation.
PURPOSE: This study determined the effect a 12-week unilateral elbow flexor resistance training regimen followed by 8 weeks of detraining on muscle cross-sectional area, muscle activation, and dynamic and static strength in trained and non-exercising contralateral limbs.
METHODS: Ten males volunteered for the investigation and completed a 4-week pre-treatment training period (50-80%1RM) prior to commencing the experimental resistance training regimen. Subjects attended 3 sessions per week over 12 weeks of experimental training wherein they exercised at 85%1RM. Each subjects trained limb and contralateral limb was assessed for 1RM, MVC and EMG at baseline, after 12 weeks of training, and at 4 and 8 weeks of detraining. Muscle cross-sectional area was determined by MRI at baseline, after experimental training, and at 8 weeks of detraining in 6 subjects.
RESULTS: A significant decline in muscle cross-sectional area (15.1 ±3.0%), 1RM (1.92 ±0.3kg), MVC (9.65 ±4.6Nm) and muscle activation (10.2 ±1.8%) was observed in the trained limb after 8 weeks of detraining. In contrast, after detraining no significant decline was observed in contralateral limb 1RM. Additionally, compared to baseline, trained limb 1RM, MVC strength and muscle activation after detraining remained significantly elevated by 4.0 ±0.3kg, 10.5 ±5.6Nm and 20.2 ± 1.8% respectively. These changes were observed despite a 4.6 ±1.7% decline in muscle cross-sectional area over the same period.
CONCLUSION: A significant reduction in dynamic and static strength was observed following detraining in the trained limb. A decline in muscle activation and muscle cross-sectional area appeared to contribute to the observed loss of strength. In contrast, neurally mediated gains in dynamic strength of the contralateral limb did not decline.