Acute neuromuscular and hormonal responses and recovery from velocity-based strength loading sessions : effects of velocity based training in men

Abstract

Velocity based training has been an important topic of research, especially in recent years, with interest serving sport scientists and coaches aiming to improve performance in athletes, in the scope of maximal strength, hypertrophy and explosive power. The emergence of training based on mean propulsive velocity rather than fixed repetition training has gained attention including investigations around the world as a possible alternative to traditional forms of resistance training for athletes. The purpose of the thesis was to study acute exercise profiles in 20 to 30-year-old men based on a single VBT full squat loading pre and post training intervention. Subjects trained over 8 weeks for a total of 16 training sessions. The study investigated effects of VBT on isometric bilateral leg press (including rate of force development and maximum power) countermovement jump (impulse and height), changes in mean propulsive velocity, mean propulsive power, and muscle activation using electromyographic measurements. The study also investigated acute hormonal responses to VBT loading before and after the training period in testosterone, cortisol, growth hormone, and creatine kinase concentrations. The results indicated that rate of force development in VL40 (p<0.01) and VL20 (p<0.05) remained decreased in post 24 hours loading, but recovered to basal levels after the training intervention. Training effect showed an increase in mean propulsive power measurements at 60% of 1RM in VL20 (p<0.05) and VL20 (p<0.05). The training period also led to increases in mean propulsive power at 70% 1RM in VL40 (p<0.01) and VL20 (p<0.01), while mean propulsive velocity showed an increase in VL20 (p<0.05) at 70% 1 RM. Serum testosterone concentration showed an acute increase at pre training intervention in VL40 (p<0.05). Serum cortisol showed a significant decrease in the next morning samples in VL20 (p<0.05) from before to after the study. Growth hormone showed significant increases in post loading in VL40 (p<0.01) and VL20 (p<0.05), while only in VL40 (p<0.05) after the training intervention. Creatine kinase levels were elevated significantly more in the next morning samples in VL40 (p<0.05) compared to immediately post loading before and after the study. The primary findings showed that training in the group of VL40, in which subjects performed a higher average amount of reps over the training period, resulted in similar significant effects related to the development of power and velocity compared to VL20 before and after the training intervention. Therefore, performing an additional amount of fatiguing repetitions (VL40 vs. VL20) may be unnecessary for developing power, strength, and facilitating recovery in men.