The imbalance of rotator muscles in the shoulder is evaluated in order to understand the biomechanical functioning of the shoulder. The study confirms that only a weak relation exists between the agonist/antagonist values of the extensor-flexor test and the values of rotator tests of the shoulder and glenohumeral joint. For the athletic wheelchair population tested, internal/external rotator strength and power ratios near the reference values of 1.5 is observed during the three speeds of work. For wheelchair athletes, who daily and intensively use all the musculo-articular components of the glenohumeral joint, the adaptation of the shoulder muscles must be monitored and a specific training program must be capable of preventing overuse and the subsequent interruption of physical activity.