Trunk and Leg Muscle Activities during Forced Expiratory Maneuvers in Different Standing Postures

抄録

This study aimed to determine the activities of the trunk muscles and the hip extensors during forced expiration maneuvers at different flow intensities in different standing postures. Thirteen male subjects participated in this study. Surface electromyographic signals from the external oblique (EO), rectus abdominis (RA), internal oblique (IO), iliocostalis (IC), longissimus (LO), multifidus (MF), gluteus maximus (GM), and biceps femoris (BF) were recorded in three postures: trunk upright, flexed at 30 degrees and extended at 15 degrees. Three forced expiration flows of slight, moderate, and maximal intensities were randomly measured. The percentages of peak expiratory flow (%PEF) and the mean electromyographic discharge (%MED) at maximal voluntary contraction in each muscle during expiration were calculated. Various conditions and muscles were compared at peak flow in each trial in terms of %MED. The results show that the correlation between the mean %PEF (%PEF_mean) and %MED was significant (p<0.05) in all the muscles except BF, GM, and RA in the extended standing posture. %MED at slight and moderate flow intensities was significantly greater in the flexed standing posture than in the upright and extended standing postures in the trunk extensors, although there was no difference in the trunk flexors. In the trunk flexors, %MED of IO was greater than that of EO and RA at slight flow intensity in each posture. In the trunk extensors, %MED of LO and MF were greater than that of IC at slight and moderate flow intensities in the flexed standing posture. The results indicate that the relationship between trunk muscle activity and forced expiratory flow has high specificity in different standing postures and flow intensities.