Table 1.
Freestyle biomechanical parameters
| Stroke Phase | Correct Freestyle Biomechanics | Incorrect Freestyle Biomechanics | Relevance of Incorrect Biomechanics to Shoulder Pain |
|---|---|---|---|
| Hand entry | Hand enters water forward and lateral to the head, medial to the shoulder.6 Figure 2a | Hand enters further away from or crosses the midline of the long axis of the body.4,8,14 Figure 2b | Increases impingement to the anterior shoulder.4 Mimics Neer impingement testing position.14 |
| Little finger– or fingers-first hand entry.4 Figure 3a | Thumb-first hand entry.4 Figure 3b | Stresses the biceps attachment to the anterior labrum.4 | |
| Pull-through | Elbow kept higher than hand and points laterally throughout pull.2 Figure 4a | Dropped elbow during pull-through.15 Figure 4b | Increases external rotation, placing muscles of propulsion at mechanical disadvantage.7 |
| Swimmer should use a straight back pull-through.2 Figure 5a | S-shaped pull through or excessive horizontal adduction past body midline during pulling.4 Figure 5b | Increases time spent in the impingement position.4 Mimics Hawkins Kennedy impingement testing position of horizontal adduction, flexion, and internal rotation. | |
| Recovery | Elbow kept higher than the wrist throughout the recovery phase.4,15 Figure 6a | Dropped elbow during recovery phase.14Figure 6b | Leads to an improper entry position with the elbow entering the water before the hand. The water will cause an upward force on the dropped humerus, leading to its superior translation and subacromial impingement in the shoulder.14 |
| Body roll of ~45° along the longitudinal axis of the body.2,4 Figure 7a | Body roll that is greater or less than 45°.4 Figure 7b | Excessive roll can lead to crossover entry position during the hand entry and/or pull-through phase. A lack of roll during recovery can increase mechanical stress on the shoulder and lead to improper hand entry position.4 | |
| All phases | Head in neutral position. Imagine line through center of head and extending length of the spine.4 Figure 8a | Head carriage is in eyes-forward position.4 Figure 8b | Eyes-forward head position increases impingement by impeding normal scapulothoracic motion.4 |