Research Review: Fluid Dynamics of Flip Turns and Underwater Dolphin Kick Effects in Swimming Pools: Latest Academic Literature Review and Training Practice (Article 1293)

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

This article explores the fluid dynamic characteristics of underwater glide length and dolphin kick effects in swimming pool flip turns.

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 somersaulting motion, the explosive force output at the moment of wall push-off, and the underwater glide with dolphin kick transition after push-off. Among these, the explosive force at push-off and the gliding posture are key determinants of speed continuation 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-making drag at the water surface, while too deep incurs additional distance and time costs for ascending. Most studies recommend an optimal glide depth in the 0.5–0.9 meter range below the surface. The timing of dolphin kick initiation is equally critical—if kicking starts while the glide speed is still faster than the cruise pace, the drag generated by the kicking motion itself will slow down overall speed; instead, high-frequency, low-amplitude dolphin kicks should be initiated only when the glide speed drops to near the normal pace to sustain underwater momentum.

Time Allocation Comparison Across Turn Phases (Schematic)

Core Research Conclusions and Practical Recommendations

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

Common Research Q&A (FAQ)

Q: Is a longer underwater glide always better?

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

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

A: Yes. Even for recreational-level long-distance swimmers, the cumulative time benefits of optimized turn technique across an entire race or training session are quite significant and warrant dedicated practice time.

References and Academic Citations

1. Sports Biomechanics — Research directions related to 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.

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