STUDY DESIGN: Cross-sectional cohort study. OBJECTIVE: To investigate the differences in the level of activation of neck-shoulder muscles between elite swimmers with and without shoulder pain during a functional upper-limb task. BACKGROUND: Previous studies have reported altered motor control of the neck-shoulder muscles in patients with chronic neck-shoulder pain. Whether the activation of neck-shoulder muscles is altered among elite swimmers who have shoulder pain is unknown. METHODS: Surface electromyography from the sternocleidomastoid, upper trapezius, and anterior scalene (SCL) muscles was recorded bilaterally in 17 elite swimmers (9 men, 8 women; mean +/- SD age, 21 +/- 3 years) with unilateral shoulder pain, and 17 age- and sex-matched elite swimmers without pain. Root-mean-square values were calculated and normalized to assess the level of muscular activation 5 seconds before, 120 seconds into, 150 seconds into, and 10 seconds after a functional upper-limb task. RESULTS: The data revealed significant differences between groups for the root-mean-square of both SCL muscles (F = 3.733, P = .016) but not for the sternocleidomastoid and upper trapezius muscles. Swimmers with shoulder pain had higher normalized root-mean-square values in both SCL muscles at 120 seconds (78% on average) and 150 seconds (86% on average) into the task and at 10 seconds after the task (40% on average), as compared with swimmers without shoulder pain (P<.05). CONCLUSION: The elite swimmers with shoulder pain demonstrated greater activation of the SCL muscles during a functional task and a lower ability to relax the SCL muscles after completion of the task than elite swimmers without shoulder pain. The present findings suggest an altered pattern of cervical muscle activation in elite swimmers with shoulder pain during performance of a functional task. J Orthop Sports Phys Ther 2012;42(6):552-558, Epub 25 January 2012. doi:10.2519/jospt.2012.3875