Evaluating Properties Of The Supraspinatus Tendon Of D1 Collegiate Swimmers Using Ultrasonography, A Pilot Study

PURPOSE: The supraspinatus tendon increases in size to meet the demands of the training and repetitive biomechanics of the sport, as there are different biomechanical aspects of the sport that place varying tensile forces in varying planes on the muscles involved in producing the desired movement. Likewise, these differences in loading forces may express an angiofibroblastic response in a tendon, where many blood vessels are present because of pathological stresses and matrix disorganization. This pilot study aimed to investigate the differences in supraspinatus tendon characteristics and subacromial space among 15 female D1 collegiate swimmers of the same team with different stroke types. METHODS: Ultrasound imaging was used to evaluate supraspinatus tendon thickness, vascularity, and subacromial space. One-time measurements were performed in the Krass position from short-axis images at specific distances from the biceps brachii tendon junction. Vascularity was quantified using Power Doppler Index, and acromiohumeral distance was measured in a neutral arm position from edge of acromion to the greater tuberosity of the humerus. Descriptive statistics were used to analyze the collected data due to the small swim stroke group sizes. RESULTS: Supraspinatus thickness was lowest in breaststroke swimmers (mean = .58 cm) compared to the overhead stroke types (Butterfly mean = .74 cm, freestyle mean = .71, Backstroke mean = .69 cm). Butterfly swimmers displayed the highest vascularity score (mean = 0.170) while freestyle swimmers had the lowest vascularity (mean = 0.069), with breaststroke and backstroke means of .10 and .093 respectively. Subacromial space measurements were relatively equal (Backstroke mean = 2.09 cm, breaststroke mean = 2.19 cm, butterfly mean = 2.15 cm, freestyle mean = 2.23 cm). CONCLUSIONS: The relative higher supraspinatus tendon thickness found in overhead stroke type swimmers may be a response to increased loads resulting from those stroke types. Butterfly stroke especially loads the rotator cuff tendons, which may account for the highest vascularity. The swimmers in this sample did not have bony anatomical differences to the subacromial space. Future studies should include larger sample sizes and longitudinal follow-up to assess changes throughout the season.