Isokinetic evaluation of shoulder rotational strength between the plane of scapula and the frontal plane

The purpose of this study was to determine whether shoulder rotational strength was greater in the plane of the scapula or the frontal plane. Isokinetic shoulder rotational strength was evaluated in 20 subjects. Using the Merac (Universal Gym Equipment, Inc., Cedar Rapids, IA), test data was gathered in the right shoulders, in 45 degrees abduction, at a speed of 60 deg/sec, in the plane of the scapula and the frontal plane. Each subject returned within 1 week for retests to establish reliability. The average correlational coefficient across tests was 0.87. The Merac computer system was used to analyze data. Mean and standard deviations for peak torque to body weight were calculated. A paired t-test was used to examine the difference in the means for internal and external rotation between the two positions. The results indicated no significant difference between the two positions for shoulder internal rotational strength values. However, shoulder external rotational strength values in the plane of the scapula were statistically significantly higher than in the frontal plane (P less than 0.001). These preliminary results suggest isokinetic strength training and testing may be preferable in the plane of the scapula rather than the frontal plane.