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Stroking characteristics during time to exhaustion tests
Morgan Alberty1, Michel Sidney, Patrick Pelayo
1Laboratory of Human Movement Studies, Faculty of Sport Sciences, University of Lille, Ronchin, France.
Medicine and Science in Sports and Exercise
|February 11, 2009
Summary
As swimmers fatigue, stroke rate (SR) increases and stroke length (SL) decreases to maintain propulsion. Arm coordination improves, optimizing propulsive actions during front crawl swimming.
Area of Science:
- Biomechanics of swimming
- Exercise physiology
Background:
- Swimming performance relies on the interplay between stroke rate (SR) and stroke length (SL).
- Understanding motor organization during fatiguing exercise is crucial for optimizing swimming technique.
Purpose of the Study:
- To investigate the changes in stroke length (SL) and stroke rate (SR) during fatiguing front crawl swimming.
- To analyze intracycle motor organization and its effect on propulsive parameters.
Main Methods:
- Ten trained swimmers performed time-to-exhaustion (TTE) tests at supramaximal intensities (95%, 100%, 110% of 400-m race velocity).
- Measurements included stroke rate (SR), stroke length (SL), phase durations, and index of coordination (IdC).
- Time allotted to propulsion per distance unit (T prop) was calculated.
Main Results:
- Fatigue led to increased SR and decreased SL across all speeds.
- Propulsive phase duration per stroke remained constant, while non-propulsive phases shortened.
- Increased IdC indicated reduced lag time between propulsive actions, increasing T prop.
Conclusions:
- Increased SR compensates for reduced propulsive impulse per stroke due to fatigue.
- Improved arm coordination enhances propulsive action chaining and time per distance.
- Motor adaptations maintain overall propulsive impulse despite reduced force per arm stroke.
