An examination of motor unit firing rates during steady torque of maximal efforts with either an explosive or slower rate of torque development

Effect of Verbal Encouragement on Performance and Affective Responses in Male Sport Science Students during Sprint Modalities

This investigation aimed to examine the effect of verbal encouragement teacher to student (VETS) versus verbal encouragement student to student (VESS) on physical performance and affective responses during different modalities of sprint tests in active male students. In a randomized crossover design, twenty-two male sport science students (age: 21 ± 1.2 years, body height: 1.77 ± 0.3 m, body mass: 76.6 ± 2.1 kg, BMI: 22.9 ± 1.3 kg·m-2) performed linear and change-of-direction sprint tests under one of three conditions: (1) VETS; (2) VETS; (3) no verbal encouragement. In each condition, participants performed the 20 m sprint test, the 10 × 2 sprint test, and the L sprint test. The assessed parameters comprised physical performance, rating of perceived exertion (RPE), and a feeling scale. Post hoc test analysis indicates a significant increase in physical performance during VETS and VESS conditions compared to the control condition due to a decrease in sprint in line 20 m (VETS: p < 0.001, d = 0.55; VESS: p = 0.016, d = 0.41), sprint 10*2 (VETS: p < 0.001, d = 0.64; VESS: p = 0.05, d = 0.36), and sprint L (VETS: p = 0.001, d = 1.19) times compared to the control condition. Moreover, the feeling score was greater after VETS compared to other conditions (p = [<0.001-0.001], d = [0.77-1.18]). In addition, the RPE had no effect on sprint performance between the different conditions. It is indicated that VETS, rather than VESS, is a more significant and effective way to increase effort intensity and positive feelings during sprinting modalities.

Resistance exercise training and the motor unit

Resistance exercise training (RET) is a key modality to enhance sports performance, injury prevention and rehabilitation, and improving overall health via increases in muscular strength. Yet, the contribution of neural mechanisms to increases in muscular strength are highly debated. This is particularly true for the involvement of the motor unit, which is the link between neural (activation) and mechanical (muscle fiber twitch forces) mechanisms. A plethora of literature that examines the effects of RET on skeletal muscle speculate the role of motor units, such as increases in firing rates partially explains muscular strength gains. Results, however, are mixed regarding changes in firing rates in studies that utilize single motor unit recordings. The lack of clarity could be related to vast or subtle differences in RET programs, methods to record motor units, muscles tested, types of contractions and intensities used to record motor units, etc. Yet to be discussed, mixed findings could be the result of non-uniform MU behavior that is not typically accounted for in RET research. The purpose of this narration is to discuss the effects of acute resistance exercise training studies on MU behavior and to provide guidance for future research.