Heavy and Explosive Training Differentially Affect Modeled Cyclic Muscle Power.

Introduction/purpose: Muscular power is important in applications ranging from elite sport to activities of daily living. Results for improvements in power after resistance training have been mixed, possibly because of changes in muscle activation and deactivation rates. Our purpose was to determine the effects of heavy and explosive training programs on maximal power across a range of frequencies during cyclical contractions using a mathematical model.

Methods: Maximal force production and time constants for muscle activation and deactivation after heavy and explosive training programs were determined using previously reported data. A muscle-tendon model was subjected to sinusoidal length change, and activation and deactivation were set to maximize power for a range of cycle frequencies (0.5-3.0 Hz). Power for shortening/lengthening cycles was modeled for each training program and for a hypothetical periodized program with the best results from each program.

Results: The heavy training program increased strength by 26.8%, and increased time required for activation (20%) and deactivation (48%). The explosive training program increased strength by 10.8%, but decreased time required for activation (24%) and deactivation (10%). Increases in maximal power were similar after heavy (13.6%) and explosive (13.8%) training, but with different power-frequency relationships (optimal frequencies of 1.56 and 1.94 Hz for heavy and explosive, respectively). The hypothetical periodized program increased power by 30.3% (optimal frequency at 1.94 Hz).

Conclusion: Power during low-frequency movements (e.g., swimming) improved more after heavy training, whereas power during high-frequency movements (e.g., running) improved more after explosive training. These findings suggest that changes in time required for activation and deactivation in response to training are highly influential for maximal power across a range of functional frequencies, ultimately altering the ideal training regimen for specific activities.