Strength decline after 72 h of hand immobilization is driven by impaired neural drive with no alterations in muscle contractility

Objective

Although the effects of long-term immobilization on muscle function are well documented, the neuromuscular consequences of short-term disuse, particularly in the upper limbs, remain poorly understood. This study investigated the impact of 72 h of hand immobilization on muscle strength and the underlying neuromuscular mechanisms.

Methods

Twenty-eight participants were assigned to either an immobilization group (n = 14), who underwent 72 h of and hand immobilization followed by a 7-day recovery period, or a control group (n = 14). Maximal voluntary contraction, voluntary activation, first dorsal interosseous electromyographic activity, and electrically evoked contractile properties were assessed before, immediately after, and seven days post-immobilization.

Results

Immobilization resulted in significant reductions in muscle strength, which persisted after one week of recovery. The strength decline was accompanied by significant reductions in voluntary activation and electromyographic activity, whereas the contractile properties of the muscles remained unchanged.

Conclusions

The findings demonstrate that short-term upper-limb immobilization induces rapid and sustained strength loss, primarily driven by diminished neural drive rather than alterations in muscle contractility.

Significance

The results emphasize the importance of preserving neural function during brief periods of disuse and highlight the utility of short-term upper-limb immobilization protocols for studying the central mechanisms of strength loss.