Upper Extremity Activity And Strenght Characteristics Between Thrower And Non-trower During Isokinetic Shoulder Muscle Action

Abstract

PURPOSE: To examine the patterns of electromyography(EMG) activity and torque values during maximal, isokinetic muscle action with shoulder flexion (FlexCon/FlexEcc), abduction (AbdCon/AbdEcc) and diagonal activities (DiaCon/DiaEcc), and to determine whether concentric or eccentric contractions or any of the obtained values were correlated with thrower and non-throwers at 60 and 180°/s on the dynamometer. METHODS: The participants for this investigation were 18 males who assigned to two groups, thrower group of 9 male subjects (mean age, 21.9±1.2 years; mean height, 177.2±4.2 cm; mean body mass, 74.8±4.7 kg) that volunteered from university students who participate in overhead sports at least three days a week and non-thrower group of 9 healthy male subjects (mean age, 24.3±1.7 years; mean height, 175.9±2.5 cm; mean body mass, 65.1±6.4 kg). We assessed muscle activation of the anterior deltoid, middle deltoid, posterior deltoid, upper trapezius, middle trapezius, lower trapezius, pectoralis major, and biceps brachii muscles by surface electromyography. RESULTS: The anterior deltoid and biceps bracii muscle activities were significantly greater for thrower group than non-thrower group during AbdCon/AbdEcc, at 60 (both, P<0.05) and 180°/s (both, P<0.001). The middle and posterior deltoid muscle activities were significantly greater for thrower group than non-thrower group during FlexCon/FlexEcc (both, P<0.05) and AbdCon/AbdEcc (both, P<0.001) at 180°/s. The middle trpezius muscle activity was significantly greater for thrower group than non-thrower group during all tasks at 60°/s (FlexCon, DiaCon, and AbdEcc, P<0.05; the other tasks, P<0.001). In the upper trapezius and pectoralis major muscle activities were not found to be dependent on all tasks of the velocity (60 or 180°/s) and the mode (Con or Ecc). The muscle strength value on thrower group was significantly higher for eccentric than concentric contraction in all the tasks (Abd, P<0.05; the other tasks, P<0.001). CONCLUSIONS: This study has provided evidence that isokinetic eccentric muscle strength testing of the posterior upper extremity muscle is effective to develop of a proper program for overhead athlete requires forceful stability during throwing phases.