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The Effects of Variable Resistance Training and Dynamic Constant External Resistance Training on Force and Neuromuscular Adaptations as a Result of Four Weeks of Leg Press Training

Cory M Smith, University of Nebraska - Lincoln

Abstract

The purpose of the present study was to examine the changes in force, electromyographic amplitude, electromyographic frequency, mechanomyographic amplitude, mechanomyographic frequency, electromechanical delay, relaxation-electromechanical delay, reflex-electromechanical delay, and the motor unit activation strategies used during the time course of fatigue as a result of four weeks of either variable resistance training or dynamic constant external resistance leg press training. The findings indicated that four weeks of variable resistance training or dynamic constant external resistance leg press training was sufficient to elicit increases in muscular strength and muscular endurance as well as various neuromuscular adaptations. Specifically, the dynamic constant external resistance and variable resistance training groups increased one-repetition maximum strength from baseline at week-2 and week-4. The variable resistance training group increased the total repetitions to failure at week-2 which was earlier than the dynamic constant external resistance group who increased at week-4. The dynamic constant external resistance and variable resistance training groups exhibited training-induced changes in neuromuscular responses associated with decreases in motor unit recruitment thresholds and increases in neural plasticity. The dynamic constant external resistance and Control groups patterns could generally be explained by the Muscle Wisdom theory or Onion Skin Scheme at baseline, week-2, and week-4. The initial 20 to 30% of the time course of neuromuscular responses for the variable resistance training group could be explained by the After-Hyperpolarization theory. After the first 20 to 30% of the repetitions to failure, the remainder of the variable resistance training groups neuromuscular responses could be explained by the Muscle Wisdom theory or Onion Skin Scheme. There were training-induced decreases in reflex-electromechanical delay for the dynamic constant external resistance and variable resistance training groups at week-2 and week-4. Thus, the findings of the current study indicated that four weeks of dynamic constant external resistance or variable resistance training resulted in similar muscular strength and muscular endurance adaptations as well as similar changes in neuromuscular responses, electromechanical delay, relaxation-electromechanical delay, and reflex-electromechanical delay measures.

Subject Area

Physiology

Recommended Citation

Smith, Cory M, "The Effects of Variable Resistance Training and Dynamic Constant External Resistance Training on Force and Neuromuscular Adaptations as a Result of Four Weeks of Leg Press Training" (2019). ETD collection for University of Nebraska - Lincoln. AAI13813595.
https://digitalcommons.unl.edu/dissertations/AAI13813595

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