Groeller, H., & Sampson, J. (2009). The effect of detraining on muscle strength and cross-sectional area following unilateral resistance training. ACSM 56th Annual Meeting, Seattle, Washington. Presentation number 727.

"Muscle strength appears well preserved following short periods of detraining, despite a decline in muscle cross-sectional area and muscle activation." This study determined the effect a 12-week unilateral elbow flexor resistance training regimen followed by eight weeks of detraining on muscle cross-sectional area, muscle activation, and dynamic and static strength in trained and non-exercising contralateral limbs. Males (N = 10) completed a four-week pre-treatment training period (50-80%1 RM) before commencing the experimental resistance training regimen. Ss attended three sessions per week for 12 weeks of experimental training. They exercised at 85%1 RM. Each S's trained limb and contralateral limb was assessed for 1 RM, maximum voluntary contraction, and EMG at baseline, after 12 weeks of training, and at four and eight weeks of detraining. Muscle cross-sectional area was determined by MRI at baseline, after experimental training, and at eight weeks of detraining in six Ss.

Muscle cross-sectional area, 1 RM, maximum voluntary contraction, and muscle activation declined in the trained limb after eight weeks of detraining. In contrast, after detraining no significant decline was observed in contralateral limb 1 RM. Additionally, trained limb 1 RM, maximum voluntary contraction strength, and muscle activation after detraining remained significantly elevated over baseline values. These changes were observed despite a decline in muscle cross-sectional area over the same period.

Implication. Dynamic and static strength declined following detraining but not to pretraining values. The decline in muscle activation and muscle cross-sectional area appears to contribute to the loss of strength. In contrast, neurally mediated gains in dynamic strength of the contralateral limb did not decline.

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