Acute effect of short-term immobilization on lower leg muscle tissue hardness in healthy adults

BACKGROUND: Previous studies have reported altered neural activity in the motor cortex after short-term cast immobilization, even in healthy participants. However, the effects of short-term movement restriction on tissue structure are not well understood. OBJECTIVE: To investigate the effects of short-term lower limb immobilization on muscle tissue hardness. METHODS: Seventeen healthy participants were enrolled in the study. Each participant's non-dominant lower limb was fixed with a soft bandage and medical splint for 10 h. Gastrocnemius muscle tissue hardness was measured using a tissue hardness meter before cast application and immediately after cast removal. Measurements were performed five times for each lower limb, and the three values with the lowest coefficient of variance were adopted as the value of muscle tissue hardness. RESULTS: Gastrocnemius muscle tissue hardness in the immobilized limb was lower after cast removal than that before cast application (from 53.6 to 51.8; p < 0.01), whereas the non-fixed limb showed an increase in muscle tissue hardness at the end of the experiment (from 52.9 to 54.3; p = 0.03). CONCLUSION: The findings indicate that 10 h movement restriction induced a reduction in muscle tissue hardness, suggesting acute adverse effects of cast immobilization for orthopedic treatment.