An Investigation and Evaluation of Acoustic Myography

[摘要] The study of vibrations from muscles (AMG) has recently been used to monitor force production from skeletal muscle both in vivo and in vitro. It has been found that the amplitude of the vibrations increases with an increase in force, similar to the relationship between the electrical activity (EMG) from the muscle and force. During fatiguing isometric contractions the amplitude of the vibrations have been found to follow the force of the contraction more accurately than the amplitude of the EMG signal. It has been proposed that the vibrations from muscle would be an easy and convenient method of monitoring contractions of skeletal muscle. The series of experiments described in the following pages investigated the relationships of force, EMG and AMG, using isometric contractions of biceps and triceps brachii, first dorsal interosseus, adductor pollicis and rectus femoris. It was found that in all cases increases in force produced increases in both EMG and AMG, although the results from the fatiguing contractions were less conclusive, with the AMG amplitude being very variable. The median frequencies of the EMG and AMG signals were also analysed. The EMG frequencies were much higher than the AMG frequencies, being around 60- 100 Hz compared with 12-15 Hz, and much clearer changes in EMG frequency were seen with changes in force. The EMG median frequency increased with the increase in force, and showed decreases during the fatiguing contractions. The AMG median frequency showed no distinct trends remaining around the same value throughout the contractions. In conclusion, AMG is probably not as useful as was originally thought, due to the variability of the signal. However, it may prove to be a diagnostic aid when used in conjunction with the more conventionally used EMG.

[发布机构] University:University of Glasgow

[关键词] Physiology