[Research Review] Fluid Dynamics of the Flip Turn and the Effect of Underwater Dolphin Kicks in the Pool: A Study of Elite Swimmers’ Physical Characteristics (Article 1371)

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

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

Breakdown of the Mechanical Phases 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 and dolphin kick transition after push-off. Among these, the explosive power at push-off and the gliding posture are key to sustaining 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 for ascending. Most studies suggest the optimal glide depth falls within the 0.5–0.9 meter range below the surface. The timing of dolphin kick initiation is equally critical—if the kick is initiated while the glide speed is still faster than the cruising pace, the drag from the kicking motion itself will slow the overall speed; the high-frequency, low-amplitude dolphin kick should only be initiated when the glide speed drops to near the normal pace to sustain underwater momentum.

Time Allocation Across Turn Phases (Schematic)

Core Research Conclusions and Practical Recommendations

• Push-off strength training: Land-based training targeting lower-body explosive power (e.g., jump training) helps increase initial velocity at the moment of push-off
• Streamline posture practice: Body posture during the underwater glide phase (arms pressed against the ears, body extended) directly affects glide drag and deserves dedicated technical training sets
• Individualized glide distance: Longer glide distance is not necessarily better; the optimal transition point should be found 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 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 the average speed. The key is to find the critical point where “the glide is still faster than pace” and transition into the dolphin kick.

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 dedicating specific practice time to.

References and Academic Citations

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

Further Reading

• 【科研導讀】游泳池翻轉轉身 (Flip Turn) 的流體動力學與水下海豚腿效應分析：最新學術文獻回顧與訓練實務 (第 1293 篇)
• 【科研導讀】游泳池翻轉轉身 (Flip Turn) 的流體動力學與水下海豚腿效應分析：臨床醫學與運動表現關係探討 (第 1479 篇)
• 【科研導讀】游泳池翻轉轉身 (Flip Turn) 的流體動力學與水下海豚腿效應分析：前沿運動生理學研究進展 (第 1461 篇)
• 【科研導讀】游泳池翻轉轉身 (Flip Turn) 的流體動力學與水下海豚腿效應分析：前沿運動生理學研究進展 (第 1443 篇)