ABSTRACT
Purpose : To investigate the cooling effect on muscles prior to continuous isometric muscle contraction. Furthermore, tissue compliance, pressure pain threshold, deep tissue temperature, and tissue circulation volume were measured to investigate the cooling effect on a physical reaction. Method : The biceps brachii muscle was contracted isometrically and continuously at the 90(-) degree in flexion position with 40% of maximum contraction. The task was ceased when subjects could not keep over 70 degrees of elbow flexion. An injection type cooling stimulator was used on the biceps brachii muscle as a cooling modality. Results : The continuous contraction time in the cooled group increased significantly compared with the control group. In addition, tissue compliance and pressure pain threshold showed significant differences between the two groups. Conclusion : This study suggested that the isometric continuous contraction time in cooled muscles can be extended to 40% of MVC. The inhibition of muscle metabolism, an increase in the pressure pain threshold, and tissue compliance may affect muscle endurance.
ABSTRACT
A study was conducted to investigate muscle fatigue during isometric contraction of the indicis proprius using EMG analysis (BIMUTAS Ver. 2. 1) .<BR>The subjects were 8 healthy men (ranging in age from 19 to 42 years) .<BR>Plummets (ranging from 300g to 600g) were placed on the distal knuckle of the index finger to create loads on the indicis proprius muscle. EMG was recorded until the plummet dropped, and the total time required was divided into 10 equal parts. In each part, the EMG record for the first 1000 ms was picked out. Then the mean power frequency (MePF) and median power frequency (MdPF) of the power spectrum were calculated.<BR>The results were as follows:<BR>1) Both MePF and MdPF showed shits to lower frequency bands.<BR>2) Integrated values of the EMG power spectrum increased with time.<BR>3) The time courses of the MePF and MdPF in each EMG sample for the 8 subjects were determined by the 3-point moving average method.<BR>A break-point was observed in each MePF and MdPF diagram.<BR>It was considered that two-break points observed in the time courses of the EMG record were valid as an objective index of local muscle fatigue.