Performance and Neuromuscular Adaptations to Heavy Resistance and Ballistic Training

Abstract

The purpose of this investigation was to compare performance and neuromuscular adaptations following ballistic and heavy resistance training. Twenty male university students were divided into a training (n=10) or control group (n=10). Each subject in the training group, by random assignment, trained the elbow extensors of one arm with heavy resistance (HR.) [(5 sets of the maximal weight that could be lifted for 5-7 repetitions (reps.)]; the other with ballistic (BL) actions (5 sets of 6 reps. at 10% of their isometric MVC). Training was done 3 times per week for 17 weeks. Following training, both training HR. and BL regimens produced significant (p≤0.05), but not significantly different increases in ballistic performance peak torque (2.5 vs. 2.7 N·m, peak velocity (1.0 vs. 1.3 rad·s⁻¹), and peak power (32.8 vs. 48.4 W). Similarly, elbow extension movement time decreased to the same extent (-12.5 vs. -6.3 ms; p≤0.05). In contrast, HR training produced significantly greater increases in maximal weight lifting (I RM) (15.8 vs. -0.1 N·m; p≤0.001) and isometric (MVC) strength (8.1 vs. 0.8 N·m; p≤0.01). Electromyography (EMG) recordings of the agonist (AG) triceps brachii indicated significant (p≤0.05) increases in average EMG (AEMG) during I RM, MVC, and ballistic tests (collapsed across training conditions). The only difference between training regimens was the greater 1 RM AEMG after HR. training. Ballistic training resulted in significantly (p≤0.05) greater antagonist ballistic/MVC, and antagonist coactivation (ballistic/MVC) EMG ratios compared to HR. training. Evoked isometric twitch torque and torque-time integral increased only after HR training. Fiber (needle biopsies of triceps) area increases were also significantly (p≤0.001) larger in the HR than the BL arm after training in type I (28.0% vs. -4.7%), type IIa (43.0% vs. 8.3%), and type IIb (41.4% vs. 3.0%) fibers. Dual photon x-ray absorptiometry regional arm analysis revealed that only the HR. arm significantly (p≤0.05) increased in lean mass following training. Heavy resistance training resulted in a significant (p≤0.05) decrease in the percentage of type IIb fibers with a corresponding increase in IIa; whereas ballistic training did not result in any fiber type conversion. These data suggest that although neuromuscular adaptations may differ, either form of training can increase ballistic performance, but only HR. training is effective in increasing muscle size and maximal force during I RM and MVC single joint actions. Heavy Resistance, Ballistic, Torque, Velocity, Power, Electromyography, Evoked Contractile Properties, Fiber Type, and Fiber Area