Comparative Effects of Dolphin Kick Streamline Training Versus Flutter Kick Training on Core Stability and Sprint Performance in Competitive Swimmers

实验性的：Dolphin Kick Streamline Training

Healthy male competitive swimmers aged 16-30 years with a minimum of 2 years of competitive swimming experience will be allocated to the experimental group. Participants will undergo an 8-week progressive dolphin kick streamline training protocol. Assessments will be performed at Week 0 (baseline), Week 4 (mid-assessment), and Week 8 (final assessment). The training program progresses from basic body undulation and flutter-to-dolphin transition to kickboard and underwater dolphin kick sets, race-pace butterfly training, sprint intervals, technique refinement, and race simulation. Participants will also receive an identical land-based core conditioning program consisting of forearm plank, side plank, bird-dog, and dead bug exercises throughout the 8-week study period.

行为的：Dolphin Kick Streamline Training

An 8-week progressive dolphin kick streamline training program for healthy male competitive swimmers aged 16-30 years with a minimum of 2 years of competitive swimming experience. Training frequency progresses from 3 sessions per week during Weeks 1-2 to 5 sessions per week during Weeks 6-8, with session duration progressively increasing. The training progresses from basic body undulation and flutter-to-dolphin transition to kickboard and underwater dolphin kick sets, race-pace butterfly training, sprint intervals, technique refinement, and race simulation. Participants also receive an identical land-based core conditioning program consisting of forearm plank, side plank, bird-dog, and dead bug exercises throughout the 8-week study period.

有源比较器：Flutter Kick Training

Healthy male competitive swimmers aged 16-30 years with a minimum of 2 years of competitive swimming experience will be allocated to the active comparator group. Participants will undergo an 8-week progressive flutter kick training protocol with 2 sessions per week. Training intensity and exercise duration will progress across the 8 weeks, with medicine-ball resistance introduced during Weeks 7-8. Assessments will be performed at Week 0 (baseline), Week 4 (mid-assessment), and Week 8 (final assessment). Participants will also receive an identical land-based core conditioning program consisting of forearm plank, side plank, bird-dog, and dead bug exercises throughout the 8-week study period.

行为的：Flutter Kick Training

An 8-week progressive flutter kick training program for healthy male competitive swimmers aged 16-30 years with a minimum of 2 years of competitive swimming experience. Training is conducted 2 times per week. Weeks 1-2 consist of low-intensity training, Weeks 3-4 low-moderate intensity, Weeks 5-6 moderate intensity, Week 7 moderate-high intensity, and Week 8 high-intensity training. Exercise duration, rest intervals, and resistance are progressively modified, with light medicine-ball resistance introduced during Weeks 7-8. Participants also receive an identical land-based core conditioning program consisting of forearm plank, side plank, bird-dog, and dead bug exercises throughout the 8-week study period.

Horizontal Streamline Hold Test

Time (seconds) that the swimmer can maintain a rigid horizontal streamline position in the water, used to assess aquatic core stability.

15 m Freestyle Sprint Test

Time (seconds) required to complete a 15-meter freestyle sprint from a push-off start. The best performance from two trials will be recorded.

25 m Freestyle Sprint Test

Time (seconds) required to complete a 25-meter freestyle sprint, used to assess sprint swimming performance and sustained swimming speed. The best performance from two trials will be recorded.