A Study of Antagonist/Agonist Isokinetic Work Ratios of Shoulder Rotators in Men Who Play Badminton

Patrick C. W. Lam, Gabriel Y. F. Ng, Gabriel Y. F. Ng

Study Design: Normative descriptive study.

Objectives: Exploring the isokinetic work ratios of eccentric antagonist/concentric agonist shoulder rotators in the late cocking and deceleration phases of a forehand overhead smash in badminton players. Comparing the work ratios between dominant and nondominant shoulders.

Background: The strength of shoulder muscles for badminton players has been studied but there is little information on the work output of these muscles for a specific range of movement.

Methods and Measures: Twenty-five skilled men who play badminton at club level with a mean age of 29.4 years (SD = 6.1) were measured for concentric and eccentric isokinetic work (joules) of shoulder internal (IR) and external (ER) rotators on both upper extremities at 120°/s. Bilateral isokinetic work ratios for eccentric IR/concentric ER between 60° and 90° of shoulder external rotation were calculated to denote strength profile in the late cocking phase of the badminton smash. Work ratios for eccentric ER/concentric IR between 10° external rotation and 30° internal rotation were calculated to denote strength profile in the deceleration phase of the badminton smash. The respective work ratios were compared between both shoulders.

Result: The eccentric IR/concentric ER work ratios in late cocking were 1.9:1 and 1.3:1 (P = 0.001) for the dominant and nondominant shoulders, respectively. The eccentric ER/concentric IR work ratios in the deceleration phase were 1.1:1 and 1.3:1 (P = 0.003) for the dominant and nondominant shoulders, respectively.

Conclusion: The work ratios of eccentric antagonist/concentric agonist are different between dominant and nondominant shoulders of skilled badminton players. Rehabilitation for injuries of these athletes should aim at developing the optimal antagonist/agonist work ratios to return them to this sport.

J Orthop Sports Phys Ther. 2002; 32(8):399–404.

Key Words: concentric contraction, eccentric contraction, muscle assessment, sports, strength profile

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