2013 年 37 巻 3 号 p. 927-929
Background: The objective of this study was to analyze the rotator cuff muscles and other 7 muscles activity simultaneously during shoulder abduction by utilizing electromyographic (EMG) analysis.
Methods: Measurements were compared between full can and empty can exercise. Non-dominant shoulders of five asymptomatic male volunteers (21-34 y.o.) were investigated. Fine-wire EMG electrodes were inserted into supraspinatus (SSP), infraspinatus (ISP), teres minor (TM), and upper and lower part of subscapularis (SSCU and SSCL). Surface electrode EMG were collected from lattisimus dorsi(LD), deltoid anterior(DA), middle(DM), posterior(DP), pectralis major upper(PMU), lower(PML), and trapezius(TRAP). The EMG data were collected during abduction exercises on the scapula plane while holding 1kg dumbbell. The EMG value was expressed as a percentage of MVC (maximum voluntary contraction) of the corresponding muscle to standardize.
Results: %MVC of DM was significantly higher with empty can exercise. DP and TRAP showed a trend that %MVC was higher with empty can exercise (P=0.07,0.08) than with full can exercise. In the cuff muscle, we could not see any statistically significant difference, however, %MVC was higher in the ISP, SSCU, SSCL, TM with empty can exercise. It is reported that contraction of SSP is not different between full and empty can position.
Conclusion: In this study, the other cuff muscles (ISP,SSC,TM) showed higher %MVC with empty can exercise. The empty can exercise may be a good exercise to recruit the all cuff muscles.