614 - Motion Analysis of the Effects of Dolphin Stroke and Freestyle Swimming on Long-Distance Swimmers

In recent years, triathlon has gained global popularity, and swimming has once again become a widespread recreational and competitive activity. In long-distance swimming, elite athletes strive to complete the event using the most energy-efficient technique. This study applies a scientific motion analysis approach to provide swimmers with feedback during training, enabling them to examine their stroke mechanics and effectively adopt energy-saving techniques.

Design: This study employed an underwater action camera (GoPro Hero 13; specifications: 12-megapixel image sensor, 4K15 ultra-high-definition video, built-in Wi-Fi) to record swimming movements. The camera was positioned at a fixed location, perpendicular to the swimmer, at a distance of 3 meters. Video recordings were subsequently analyzed using Kinovea, an open-source motion analysis software. The analysis focused on movements of the head, elbow, and knee during dolphin stroke and freestyle swimming, performed by a certified level-3 dolphin stroke coach.

Results: Kinematic and motion analyses revealed that the dolphin stroke has lower stroke and kick frequencies, velocity, and acceleration than freestyle, making it slower but more energy-efficient. Specifically, the freestyle stroke cycle lasts about 1 second, whereas the dolphin stroke takes approximately 1.2 seconds. In terms of kicking, freestyle produces six kicks within a 3-second interval, compared with only two in the dolphin stroke (6:2).

Conclusions: Dolphin stroke emphasizes arm extension and coordinated body-axis control, enabling efficient propulsion at lower stroke frequencies. This conserves energy and supports stability over long distances. In contrast, freestyle prioritizes speed through rapid arm–leg alternations, making it better suited for short events (50–400 m). Overall, freestyle favors sprint performance, while dolphin stroke is more efficient for endurance swimming.