In current rehabilitation practice, exercise selection is commonly based on the amount of muscle recruitment demonstrated by electromyographic (EMG) analysis. A preponderance of evidence supports the concept that EMG of a muscle and torque output are positively correlated. This study was designed to investigate the relationship between surface EMG activity of the infraspinatus and torque production during exercises involving shoulder external rotation (ER). A total of 30 participants (average age = 24.6 y) performed maximum voluntary isometric contraction of ER at 5 points within the range of motion of 3 shoulder exercise positions with concomitant surface EMG recording. As a maximal internally rotated position was approached, maximum ER torque and minimum or near-minimum EMG recruitment were demonstrated. Conversely, at maximally externally rotated positions, EMG activity was greatest and torque values were lowest. An inverse relationship between joint torque output and EMG activity was established in each of the 3 exercises. The inverse relationship between EMG activity and torque output during Shoulder ER suggests that there may be additional factors warranting consideration during exercise selection. Further research may be needed to determine the relative value of electrical activity versus torque output to optimize the selection of rehabilitative exercises.
Bill Stodart, Maria Cup and Curtis Kindel
Ronald E. Smith, Frank L. Smoll and Bill Curtis
Little League Baseball coaches were exposed to a preseason training program designed to assist them in relating more effectively to children. Empirically derived behavioral guidelines were presented and modeled, and behavioral feedback and self-monitoring were used to enhance self-awareness and to encourage compliance with the guidelines. Trained coaches differed from controls in both overt and player-perceived behaviors in a manner consistent with the behavioral guidelines. They were also evaluated more positively by their players, and a higher level of intrateam attraction was found on their teams despite the fact that they did not differ from controls in won-lost records. Children who played for the trained coaches exhibited a significant increase in general self-esteem compared with scores obtained a year earlier; control group children did not. The greatest differences in attitudes toward trained and control coaches were found among children low in self-esteem, and such children appeared most sensitive to variations in coaches' use of encouragement, punishment, and technical instruction.