【Research Review】Fluid Dynamics of the Flip Turn and the Effects of the Underwater Dolphin Kick: Exploring the Relationship Between Clinical Medicine and Athletic Performance (Article 150)

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

This article explores the fluid dynamics characteristics of underwater glide length and dolphin kick effects 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 and dolphin kick transition after push-off. Among these, the explosive power at the moment of wall push-off and the gliding posture are key to determining the continuation of 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-making drag at the water surface, while too deep requires additional distance and time costs for ascending. Most studies recommend the optimal glide depth to fall within the 0.5-0.9 meter range below the surface. The timing of dolphin kick initiation is equally critical—if you kick while the glide speed is still faster than your cruise pace, the drag from the kicking motion itself will actually slow down your overall speed; you should wait until the glide speed drops to near your normal pace before initiating high-frequency, low-amplitude dolphin kicks to sustain underwater momentum.

Time Allocation Comparison Across Turn Phases (Illustrative)

Core Research Conclusions and Practical Recommendations

• Push-off strength training: On-land training targeting lower-body explosive power (such as 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 drag and deserves dedicated technical training sessions
• Individualized glide distance: A 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 prolonging the glide can cause too much 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 for too long will actually lower your average speed. The key is to find the critical point where “the glide is still faster than your pace” to 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 benefits of optimized turn technique across an entire race or training session are quite significant and deserve 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.

Related Reading

• 【Research Review】Fluid Dynamics of the Flip Turn and the Effects of the Underwater Dolphin Kick: Exploring the Relationship Between Clinical Medicine and Athletic Performance (Article 168)
• 【Research Review】Fluid Dynamics of the Flip Turn and the Effects of the Underwater Dolphin Kick: Exploring the Relationship Between Clinical Medicine and Athletic Performance (Article 1185)
• 【Research Review】Fluid Dynamics of the Flip Turn and the Effects of the Underwater Dolphin Kick: Exploring the Relationship Between Clinical Medicine and Athletic Performance (Article 459)
• 【Research Review】Fluid Dynamics of the Flip Turn and the Effects of the Underwater Dolphin Kick: Exploring the Relationship Between Clinical Medicine and Athletic Performance (Article 402)