Relationship between Muscle Fiber Conduction Velocity and Muscle Strength in Patients with Joint Disorder of the Lower Limb

The relationship between muscle fiber conduction velocity (MFCV) of the vastus medialis and muscle strength of knee extensors was observed in patients with joint disorder of the lower limb, and the feasibility of MFCV as an index for evaluating the condition of muscular disuse was examined. MFCV was significantly slower in patients with joint disorder (2.91 ± 0.27 m·s-1) than in healthy subjects (3.22 ± 0.22 m·s-1; p<0.01). Muscle strength of knee extensors was significantly lower in patients (198.1 ± 72.2 N) than in healthy subjects (311.2 ± 79.6 N; p<0.01). Muscle strength displayed a significant positive correlation with MFCV in patients with joint disorder (r=0.63, p<0.01). In patients after joint surgery of the lower limb, MFCV increased with muscle strength recovery. Reduced MFCV in patients with joint disorder appears to primarily reflect muscle atrophy of type II fibers. MFCV of patients with joint disorder of the lower limb may thus reflect changes in muscle fiber type and diameter.