Effect of backstroke ledge on backstroke start technique for water entry

Area of Science:

• Sports Science
• Biomechanics
• Swimming Performance Analysis

Background:

• Optimizing the start is crucial for competitive swimming success.
• The backstroke start involves complex kinematic variables influencing performance.
• The backstroke ledge (BSL) is a potential aid for improving backstroke starts.

Purpose of the Study:

• To investigate the effect of a backstroke ledge (BSL) on backstroke start performance.
• To analyze kinematic variables including flight distance and water entry posture.
• To determine if BSL use enhances horizontal velocity post-water entry.

Main Methods:

• Ten male competitive swimmers performed backstroke starts with and without a BSL.
• High-speed video cameras (120 Hz and 60 Hz) captured kinematic data.
• Analysis included whole-body angular momentum, center of mass (CM) position, and entry angles.

Main Results:

• BSL use significantly reduced time to reach 5m and 15m (p < 0.04).
• BSL resulted in a higher CM at take-off, increased flight distance, and greater angular momentum (p < 0.02).
• BSL use led to a larger lower limb entry angle and smaller hole entry posture angle (p < 0.04).

Conclusions:

• A higher CM position and increased angular momentum with a BSL enhance flight distance and facilitate optimal water entry.
• Improved flight distance and post-entry horizontal velocity contribute to better backstroke start performance.
• The backstroke ledge is an effective tool for improving competitive backstroke start efficiency.