[Research Guide] Hydrodynamic Analysis of the Flip Turn and the Effect of Underwater Dolphin Kick: A Study on the Physical Characteristics of Elite Swimmers (Article 396)

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

This article explores the hydrodynamic 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 somersault action, 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 the instant of push-off and the streamlined posture are key to determining speed maintenance 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 sustained during the underwater glide.

Underwater Glide Depth and Dolphin Kick Initiation Timing

There is an optimal range for underwater glide depth after the wall push-off: too shallow (near the surface) will be affected by surface wave drag, while too deep incurs additional distance and time costs for surfacing. Most studies suggest the optimal glide depth falls within the 0.5-0.9 meter range underwater. The timing of dolphin kick initiation is equally critical—kicking while the glide speed is still faster than cruising pace will actually slow overall speed due to the drag generated by the kicking motion itself. One should wait until the glide speed drops close to normal pace before initiating high-frequency, small-amplitude dolphin kicks to sustain underwater propulsion.

Illustrative Time Allocation for Each Turn Phase

Core Scientific Conclusions and Practical Recommendations

• Wall Push-off Strength Training: Dryland training targeting lower body explosive power (e.g., plyometric training) helps improve the initial velocity at the moment of push-off.
• Streamlined Posture Practice: Body posture during the underwater glide phase (arms squeezing the ears, body fully extended) directly affects glide resistance and warrants dedicated technical drill sessions.
• Personalized Glide Distance: A 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 will cause too much speed decay.
• Integrating Turn Rhythm into Pace Training: Actual turn practice should be incorporated into long-distance training sets, not just straight-line swimming. The cumulative effect of turn quality is considerable in long-distance races.

Common Scientific Research Q&A (FAQ)

Q: Is a longer underwater glide always better?

A: No, glide speed continuously decays with distance. Gliding for too long will actually lower the average speed. The key is to find the critical point where “glide speed is still faster than race 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 over an entire race or training session are significant, making it worth investing dedicated practice time.

References and Academic Citations

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

Related Topic Reading

• 【Research Guide】Hydrodynamic Analysis of the Flip Turn and the Effect of Underwater Dolphin Kick: A Study on the Physical Characteristics of Elite Swimmers (Article 891)
• 【Research Guide】Hydrodynamic Analysis of the Flip Turn and the Effect of Underwater Dolphin Kick: A Study on the Physical Characteristics of Elite Swimmers (Article 1131)
• 【Research Guide】Hydrodynamic Analysis of the Flip Turn and the Effect of Underwater Dolphin Kick: A Study on the Physical Characteristics of Elite Swimmers (Article 942)
• 【Research Guide】Hydrodynamic Analysis of the Flip Turn and the Effect of Underwater Dolphin Kick: A Study on the Physical Characteristics of Elite Swimmers (Article 612)