[Research Review] Fluid Dynamics of the Flip Turn and the Effect of Underwater Dolphin Kicks in the Pool: A Study of Elite Swimmers’ Physiological Characteristics (Article 1131)

Reference Journal Source: Sports Biomechanics • International Scientific Research Review Series

This article explores the fluid dynamics characteristics of glide distance and dolphin kick effect in the pool flip turn.

Mechanical Phase Breakdown of the Flip Turn

The flip turn can be broken down into four mechanical phases: the final stroke approaching the wall, the somersault motion, the explosive power output at the moment of wall push-off, and the underwater glide with dolphin kick transition after push-off. Among these, the explosive power at push-off and the gliding posture are key to maintaining speed after the turn—the faster the initial push-off velocity and the better the body’s streamline, the longer the high-speed distance that can be maintained during the underwater glide.

Underwater Glide Depth and Dolphin Kick Initiation Timing

There is an optimal range for underwater glide depth after push-off: too shallow (near the surface) is affected by wave drag at the water surface, while too deep requires additional distance and time costs to ascend. Most studies suggest the optimal glide depth falls within the 0.5–0.9 m range below the surface. The timing of dolphin kick initiation is equally critical—if you begin kicking while the glide speed is still faster than your cruise pace, the drag from the kicking motion itself will slow you down overall; you should wait until the glide speed drops close to your normal pace before initiating high-frequency, low-amplitude dolphin kicks to sustain underwater momentum.

Time Allocation Comparison Across Turn Phases (Schematic)

Core Research Conclusions and Practical Recommendations

• Push-off strength training: Land-based explosive lower-body training (e.g., jump training) helps improve initial velocity at the moment of wall push-off
• Streamline posture practice: Body posture during the underwater glide phase (arms pressed against ears, body extended) directly affects glide resistance and deserves dedicated technical training sets
• Individualized glide distance: Longer glide distance is not always better; the optimal transition point depends on individual push-off strength and dolphin kick ability—excessively extending the glide causes excessive speed decay
• Integrating turn rhythm into pace training: Long-distance training sets should incorporate actual turn practice rather than only straight-line swimming; the cumulative effect of turn quality is considerable in long-distance races

Common Research Q&A (FAQ)

Q: Is a longer underwater glide always better?

A: No. Glide speed continuously decays with distance, and gliding too long will actually lower average speed. The key is finding the critical point where “gliding is still faster than pace” to transition into dolphin kicks.

Q: Do amateur swimmers also need to practice flip turn technique?

A: Yes. Even for amateur-level long-distance swimmers, the cumulative time benefit of optimized turn technique across an entire race or training session is significant and worth dedicated practice time.

References and Academic Citations

1. Sports Biomechanics — Research direction on mechanical phase analysis of swimming turn movements.
2. Journal of Sports Sciences — Literature related to quantitative research on underwater glide depth and dolphin kick efficiency.

Related Reading

• Research Review: Fluid Dynamics of the Flip Turn and the Effect of Underwater Dolphin Kicks in the Pool: A Study of Elite Swimmers’ Physiological Characteristics (Article 891)
• Research Review: Fluid Dynamics of the Flip Turn and the Effect of Underwater Dolphin Kicks in the Pool: A Study of Elite Swimmers’ Physiological Characteristics (Article 396)
• Research Review: Fluid Dynamics of the Flip Turn and the Effect of Underwater Dolphin Kicks in the Pool: A Study of Elite Swimmers’ Physiological Characteristics (Article 1224)
• Research Review: Fluid Dynamics of the Flip Turn and the Effect of Underwater Dolphin Kicks in the Pool: A Study of Elite Swimmers’ Physiological Characteristics (Article 612)