Quantitative and Qualitative Evaluation of Knee Electromyograms by a Bluetooth-communication Gait Analyzer: Integration and Power Spectral Analysis of Surface Electromyograms

[Purpose] We observed the action of muscles during gait using a Bluetooth Gait Analyzer (sampling frequency 1 kHz), by integrating electromyograms and performing power spectral analysis. Analyzer was described in the quantitative and qualitative evaluation of these muscles. [Subjects] The subjects were 15 healthy adult males. [Methods] A Bluetooth electromyography gait analyzer was used to observe the action of the vastus medialis muscle (Quad muscle) and the long head of the biceps femoris muscle (Hamstrings) during slow, medium, and fast gait. Electromyograms were subjected to integration and power spectral analysis evaluation. [Results] The integrated electromyograms of the Quad muscles and the Hamstrings increased significantly with increases in gait speed. Power spectral analysis showed the mean power frequency of the Quad muscles tended to decrease, and the high frequency component (81-250 Hz) was significantly reduced. The mean power frequency of the Hamstrings increased with increases in gait speed, but the high frequency component was significantly increased. [Conclusion] The observed tendencies might have resulted from the induction of positive action in type I muscle fibers in the Quad muscles with increased gait speed and of the muscle action of type II fibers in the Hamstrings. We suggest that, as the gait speed increases, the Quad muscles are forced to play the role of a braking muscle.