The Effects of Caffeine on Vertical Jump Height and Execution in Collegiate Athletes.

Bloms, LP, Fitzgerald, JS, Short, MW, and Whitehead, JR. The effects of caffeine on vertical jump height and execution in collegiate athletes. J Strength Cond Res 30(7): 1855-1861, 2016-Caffeine ingestion elicits a variety of physiological effects that may be beneficial to maximal-intensity exercise performance, although its effectiveness and physical mechanism of action enhancing ballistic task performance are unclear. The purpose of this study was to examine the effects of caffeine ingestion on vertical jump height and jump execution in Division I collegiate athletes. The study used a single-blind, randomized, crossover design. Athletes (n = 25) consumed either caffeine (5 mg·kg) or placebo. After a 60-minute waiting period, athletes performed 3 squat jumps (SJ) and 3 countermovement jumps (CMJ) while standing on a force platform. Jump height and execution variables were calculated from mechanography data. In comparison with placebo, caffeine increased SJ height (32.8 ± 6.2 vs. 34.5 ± 6.7 cm; p = 0.001) and CMJ height (36.4 ± 6.9 vs. 37.9 ± 7.4 cm; p = 0.001). Peak force (p = 0.032) and average rate of force development (p = 0.037) were increased during the CMJ in the caffeine trail compared with the control. Time to half peak force was the only execution variable improved with caffeine (p = 0.019) during the SJ. It seems that caffeine affects both height and execution of jumping. Our data indicate that the physical mechanism of jump enhancement is increased peak force production or rate of force development during jumping depending on technique. The physical mechanism of jump enhancement suggests that the ergogenic effects of caffeine may transfer to other ballistic tasks involving the lower-body musculature in collegiate athletes.

Coaches' assessment of their coaching efficacy compared to athletes' perceptions.

This study compared coaches' assessments of their own coaching efficacy with their athletes' perceptions of the coaches' efficacy. Coaching efficacy was measured with the Coaching Efficacy Scale. Participants were 9 football coaches and 76 football players from the same team. Analysis indicated coaches were confident in their coaching abilities (range 6.5 to 9.0 on a 9-point scale). For 7 of the 9 coaches the coaches' ratings of themselves were higher than the athletes' ratings. For the other 2 coaches, athletes' ratings of coaches' efficacy were higher than the coaches' ratings of themselves. All coaches' ratings fell within the 95% confidence interval based on the athletes' ratings of the coaches' efficacy. Results are discussed in terms of the interplay between athletes and coaches efficacy beliefs and its influence on behavior.