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Changes in dynamic exercise performance following a sequence of preconditioning isometric muscle actions
Duncan N French1, William J Kraemer, Carlton B Cooke
1Human Performance Laboratory, Department of Kinesiology, University of Connecticut, Storrs, Connecticut 06269, USA. Duncan.French@uconn.edu
Journal of Strength and Conditioning Research
|November 26, 2003
Summary
Complex training, using maximal isometric knee extensions before dynamic exercise, can enhance performance. A specific protocol of 3 repetitions of 3-second maximal voluntary contractions improved drop jump performance and knee extension torque.
Area of Science:
- Sports Science
- Exercise Physiology
- Biomechanics
Background:
- Complex training, combining heavy and light loads, aims to enhance postactivation potentiation.
- Limited research exists on sequencing isometric loads with dynamic muscle actions.
Purpose of the Study:
- To investigate the effects of preconditioning with maximal isometric knee extensions on dynamic exercise performance.
- To assess the impact of different maximal voluntary contraction (MVC) protocols on athletic performance.
Main Methods:
- Fourteen track and field athletes performed dynamic exercises (drop jump, countermovement jump, cycle sprint, knee extension) after MVC protocols (3x3s or 3x5s) or a control condition.
- Electromyographic (EMG) activity was recorded during knee extension assessments.
Main Results:
- Significant improvements in drop jump height (5.03%), maximal force (4.94%), and acceleration impulse (9.49%) were observed after 3 repetitions of 3-second MVC.
- Maximal knee extension torque increased by 6.12% following the 3-second MVC protocol.
- No significant changes were found for countermovement jumps or cycle sprints; EMG activity did not differ significantly.
Conclusions:
- A sequence of 3 repetitions of 3-second maximal isometric knee extensions may favorably impact performance in short-duration dynamic exercises.
- This specific preconditioning protocol shows potential for enhancing explosive power beyond unconditioned performance.