PURPOSE: This study compared the activities of the trunk muscles during crutch walking to determine which of the crutch length measurements is most beneficial.
METHODS: Twenty young women volunteered to participate in this study. After adjusting crutch length, the participants performed a three-point walking with nondominant leg limited in weight bearing. This study used six crutch length measurements: (1) Height-40.6cm, (2) Height´.77, (3) Olecranon-to-finger length, (4) Axillary-toheel length, (5) Arm-span length-40.6cm, and (6) Arm-span length´.77. The EMG activities of the internal oblique (IO), rectus abdominis (RA), multifidus (MF), and erector spinae (ES), muscles on the weight bearing side were monitored using wireless surface EMG.
RESULTS: The EMG activities of the RA and ES appeared to be significantly different among the crutch length measurements (p<.05). The post-hoc test showed that the ‘Arm-span length-40.6cm’ was significantly greater in the RA activity when compared to the ‘Height´.77’ and ‘Axillary-to-heel length’ measurements, and in the ES activity when compared to ‘Height´.77’ measurements. Furthermore, IO/RA and MF/ES ratios showed significant differences among the crutch length measurements (p<.05). In the post-hoc test, significant difference was observed between ‘Olecranon-to-finger length’ and ‘Arm-span length-40.6cm’ for the IO/RA ratio, and between ‘Height´.77’ and ‘Olecranon-to-finger length’ and between ‘Height´.77’ and ‘Arm-span length-40.6cm’ measurement for the MF/ES ratio.
CONCLUSION: These findings suggest that the ‘Height´.77’ measurement is relatively advantageous to optimize the activities of trunk muscles during the crutch walking, and allow simple measurements of the crutch length.