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The distal part of the vastus medialis (VM) (VM obliquus: VMO) muscle acts as the medial stabilizer of the patella. However, it has been known to facilitate VMO contraction during training of the quadriceps femoris muscle in knee joint rehabilitation. This study aimed to examine the contribution degree of VMO as a knee joint extension torque generator. Sixteen healthy male volunteers participated in this study. Electrical muscle stimulation (EMS) was performed on VMO at 60° knee angle for 20 min to induce muscle fatigue. Knee extension twitch torques (TT) at 90° and 30° knee angle evoked by femoral nerve stimulation were measured before and after EMS. Although each TT at 90° and 30° knee angle significantly decreased after EMS, the decreased TT rate in both joint angles showed no significant difference. Our results show that VMO might contribute to the generation of the knee joint torque at the same level in the range from flexion to extension. Therefore, it was suggested that the facilitating the neural drive for VMO is important during the quadriceps femoris muscle strengthening exercise.

The clamping force of a bolt/nut assembly greatly influences its strength. However it is well-known that the clamping force of a bolt/nut assembly tightened by the torque control method varies widely. In this study, a new tightening method of a bolt/nut assembly that controls the clamping force more accurately has been proposed. In the proposed method, a bolt/nut assembly is tightened by pulling the bolt thread portion protruding through the nut with a force corresponding to the target clamping force. Experiments to verify the usefulness of the proposed method have been performed. The results show that the proposed method can accurately tighten a bolt/nut assembly with an error of approximately ±10% in relation to the target.