Impairment of muscle strength has been associated to diabetes and is linked to disability. We investigated neuromuscular function in the upper and lower limb of sedentary diabetic patients with lower (1st quartile; D1) and higher (4th quartile; D2) motor nerve conduction velocity, of exercise trained diabetic patients (DT) and of non-diabetic control subjects (CO).

Maximal isometric strength (MVC) and isokinetic strength for a wide range of angular velocities (15, 30, 60, 90, 120, 180, 240°/s) were assessed for the knee extensors (KE) and elbow flexors (EF). At the same time, EMG activity in the vastus lateralis (VL) and biceps brachii (BB) muscles was recorded by means of array electrodes to estimate motor unit conduction velocity (MUCV).

EF and KE MVC was similar between groups. KE isokinetic strength was similar in D1 and D2 but lower compared to CO. MUCV of VL was significantly lower in diabetic patients compared to CO, with no difference between D1 and D2. In DT, VL MUCV was higher than in sedentary diabetic patients but still lower than CO. A similar picture was observed for MUCV at the BB, despite EF strength was not significantly different between groups.

The present data suggest that isometric and dynamic strength are differently affected by diabetes and that MUCV represents a sensitive marker for monitoring neuromuscular function impairment and exercise training induced reconditioning.