The purpose of this study was to clarify more appropriate joint angle of isometric maximal voluntary contraction (MVC) for recording surface EMG which was employed as a criterion for normalizing surface EMG recorded during dynamic contraction. Subjects who were consisted of seven healthy adult males executed flexion and extension movements about the elbow joint by concentric contraction (CON), eccentric contraction (ECC) and MVC with isokinetic muscular training machine. During their trials, the angles, the angular velocities and the torques about the elbow joint, and the surface EMGs of the biceps brachii and the triceps brachii were measured. The torques during MVCs and the surface EMGs recorded during CON, ECC and MVCs were used for estimating the torque during CON and ECC trials. The errors of their estimations were calculated as the differences between the estimated torques and the actual torques recorded during CON and ECC trials. Under the criterion of minimization of their errors, the MVC trials in which the elbow joint angles made muscle length short were appropriate for normalizing the surface EMG during CON trials. On the other hand, the MVC trials in which the joint angles made muscle length long were appropriate for ECC trials.

View full abstract

An analytical methodology of fluctuation in the body balance is proposed for evaluation of safety of walkway environment which generates a harmful walking mode. First, experiment on transferring platform mock-up is attempted and the motion of human body under some harmful walking environmental condition is measured by motion capture technology on video imaging analysis. Then, the fluctuations in the body balance during walking are extracted as recurrence plot which is originating from applied chaos theory. Furthermore, differences in the fluctuations between on a flat floor as safety environment and on other harmful environments are quantified and extracted as degrees of discordance. By this proposed fluctuation analysis, a safety assessment of various environments is attempted.

View full abstract