[Research Review] Fluid Dynamics of the Flip Turn in Swimming Pools and Analysis of the Underwater Dolphin Kick Effect: A Biomechanical Quantification Experiment Report (No. 768)

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

This article explores the fluid dynamic characteristics of underwater glide length 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 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 the moment of push-off and the gliding posture are the keys to determining 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 surface wave drag, while too deep incurs additional distance and time costs for ascending. 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 the cruise pace will actually slow down overall speed due to the drag generated by the kicking motion itself; the high-frequency, low-amplitude dolphin kick should be initiated only after the glide speed has dropped to near the normal pace to sustain underwater momentum.

Time Allocation Comparison Across Turn Phases (Illustrative)

Core Research Conclusions and Practical Recommendations

• Push-off strength training: Land-based training targeting lower-body explosive power (e.g., jump 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 deserves dedicated technical training sessions
• Individualized glide distance: Longer glide distance is not necessarily better; the optimal transition point must be found based on individual push-off strength and dolphin kick ability—excessively prolonging the glide can cause 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 will actually lower the average speed. The key is to find the critical point where “gliding is still faster than pace” and transition to 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 quite significant and warrants dedicated practice time.

References and Academic Citations

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

Related Topic Reading

• Research Review: Fluid Dynamics of the Flip Turn in Swimming Pools and Analysis of the Underwater Dolphin Kick Effect: A Biomechanical Quantification Experiment Report (No. 468)
• Research Review: Fluid Dynamics of the Flip Turn in Swimming Pools and Analysis of the Underwater Dolphin Kick Effect: A Biomechanical Quantification Experiment Report (No. 231)
• Research Review: Fluid Dynamics of the Flip Turn in Swimming Pools and Analysis of the Underwater Dolphin Kick Effect: A Biomechanical Quantification Experiment Report (No. 111)
• Research Review: Fluid Dynamics of the Flip Turn in Swimming Pools and Analysis of the Underwater Dolphin Kick Effect: A Biomechanical Quantification Experiment Report (No. 81)