The Effects of Gender and Limb Dominance on Critical Tracking Tasks Involving Neuromuscular Control of the Shoulder

Abstract

0840 A new commercially-available, computerized testing system has enabled the administration of critical tracking tasks (CTT) that involve visual acuity and perception, fine motor control, and neuromuscular reactivity of the shoulder. No previous studies with this device have examined the effects of gender or limb dominance on the performance of these tasks. PURPOSE: To determine the influence of gender and limb dominance on the performance of CTT using a new, commercially-available measurement system. METHODS: Twenty aged-matched subjects (10 women, 23.6 + 6.9 yrs; 10 men, 24.6 + 4.7 yrs) with no history of visual or vestibular disability, or upper limb impairment participated in this study. Subjects stood 180 cm from the system's laptop computer screen positioned at eye-level. The computerized CTT required the subjects to perform rapid, subtle shoulder internal and external rotation movements in the scapular plane in attempt to continuously correct the changing position of an object on a computer screen. Our experimental protocol involved administration of 2 of the 3 levels of CTT difficulty: the intermediate (Level 2) and advanced (Level 3) were evaluated in this study. The dominant and non-dominant limbs of each subject were tested. Gender (2) × Limb (2) repeated measures ANOVAs were performed on two dependent variables, coordination and concentration at Level 2 and Level 3. RESULTS: At the Level 2 (intermediate) CTT difficulty, no significant differences were present between men and women for coordination or concentration, or between dominant and non-dominant limbs (p > 0.05). All Level 2 CTT group means were higher than Level 3 means, reflecting the increased difficulty of the Level 3 CTT. At the Level 3 (advanced) CTT difficulty, men scored significantly higher than women on the coordination variable (p < 0.05). No interactions were observed for any variable at any level of difficulty. CONCLUSION: We observed bilateral symmetry with respect to the performance of the CTT in the dominant and non-dominant shoulders of our healthy subjects. The only significant difference between genders was present at the Level 3 (advanced) CTT, with male subjects (36.2 + 1.7 SEM) demonstrating significantly higher coordination scores than female subjects (29.5 + 1.7 SEM). One explanation for this result is the greater level of experience with computer/video games by the male subjects in our study that may have rendered the critical tracking tasks less novel. Supported by Northwest Health Foundation Grant #2002–220