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Different Lower-Limb Setup Positions Do Not Consistently Change Backstroke Start Time to 10 m
Gordon E Barkwell1, James P Dickey1
1School of Kinesiology, University of Western Ontario, London, ON N6A 3K7, Canada.
Sports (Basel, Switzerland)
|April 5, 2020
Summary
The optimal knee flexion angle for backstroke starts is individualized. While maximal knee flexion increases takeoff velocity, less flexion improves head entry distance, with no overall impact on 10m start times.
Area of Science:
- Biomechanics of swimming starts
- Sports performance analysis
Background:
- Backstroke starts require athletes to push off the wall from a flexed position.
- Swimmers utilize varying knee angles in the setup position, potentially impacting performance.
Purpose of the Study:
- To investigate the performance effects of different knee extension angles during the backstroke start setup.
- To determine if specific knee angles optimize distinct components of the start phase.
Main Methods:
- Ten competitive backstroke swimmers performed maximal effort starts.
- Two setup positions were tested: maximal knee flexion and less knee flexion.
- Data collected included force sensing on start handles/touchpad, surface electromyography of extensor muscles, and high-speed sagittal plane kinematics.
Main Results:
- No significant overall difference in 10-meter time was observed between the two knee flexion conditions (p = 0.36).
- Starts with less knee flexion resulted in a greater head entry distance (0.07 m, p = 0.07).
- Starts with maximal knee flexion yielded a higher takeoff velocity (0.2 m/s, p = 0.02).
Conclusions:
- Different knee flexion angles in the backstroke start setup may optimize distinct performance parameters (takeoff velocity vs. head entry distance).
- Individual assessment by coaches is recommended to identify the optimal start position for each swimmer.
- Further research could explore the combined effects of these parameters on overall race performance.
