[Research Review] Fluid Dynamics of the Flip Turn and the Effect of the Underwater Dolphin Kick in Swimming Pools: Advances in Sports Physiology Research (Article 1461)

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

This article examines the fluid dynamic characteristics of glide distance and the dolphin kick effect in the swimming 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 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 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 recommend an optimal glide depth in the 0.5–0.9 m range below the surface. The timing of dolphin kick initiation is equally critical—kicking while the glide speed is still faster than cruise pace will actually slow overall speed due to the drag created by the kicking motion itself; the high-frequency, low-amplitude dolphin kick should be initiated only after the glide speed drops to near normal pace to sustain underwater momentum.

Time Allocation Across Turn Phases (Schematic)

Core Research Conclusions and Practical Recommendations

• Push-off strength training: Dry-land 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 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 depends on individual push-off strength and dolphin kick ability—overextending the glide 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 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 the dolphin kick.

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

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

References and Academic Citations

1. Sports Biomechanics — Research 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.

Related Reading

• Research Review: Fluid Dynamics of the Flip Turn and the Effect of the Underwater Dolphin Kick in Swimming Pools: Advances in Sports Physiology Research (Article 1443)
• Research Review: Fluid Dynamics of the Flip Turn and the Effect of the Underwater Dolphin Kick in Swimming Pools: Advances in Sports Physiology Research (Article 1428)
• Research Review: Fluid Dynamics of the Flip Turn and the Effect of the Underwater Dolphin Kick in Swimming Pools: Advances in Sports Physiology Research (Article 1470)
• Research Review: Fluid Dynamics of the Flip Turn and the Effect of the Underwater Dolphin Kick in Swimming Pools: Advances in Sports Physiology Research (Article 1449)