The purpose of this study was to examine the effects of increased self-efficacy on three separate jump tests. Forty-seven students (18 females & 29 males) from Utah State University were randomly assigned to a treatment or control group. Participants performed a vertical jump test, a standing broad jump test, and a 30-s Bosco test on three separate days over a span of 1 week. The treatment group (n = 24) were given false, positive feedback about their performance while the control group (n = 23) were told their true results. Self-efficacy was measured pre and post using the Physical Self-Efficacy scale (PSE) and was found to increase more for the treatment group than the control group. A 3 x 2 ANOVA showed a significant improvement for the Bosco test but no significance for the other two tests, suggesting that self-efficacy has an effect on power endurance but not explosive power.

The purpose of this study was to investigate the effect of various loads on the force-time characteristics associated with peak power during the hang high pull (HHP). Fourteen athletic men (age: 21.6 ± 1.3 years; height: 179.3 ± 5.6 cm; body mass: 81.5 ± 8.7 kg; 1 repetition maximum [1RM] hang power clean [HPC]: 104.9 ± 15.1 kg) performed sets of the HHP at 30, 45, 65, and 80% of their 1RM HPC. Peak force, peak velocity, peak power, force at peak power, and velocity at peak power were compared between loads. Statistical differences in peak force (p 0.001), peak velocity (p < 0.001), peak power (p 0.015), force at peak power (p < 0.001), and velocity at peak power (p < 0.001) existed, with the greatest values for each variable occurring at 80, 30, 45, 80, and 30% 1RM HPC, respectively. Effect sizes between loads indicated that larger differences in velocity at peak power existed as compared with those displayed by force at peak power. It seems that differences in velocity may contribute to a greater extent to differences in peak power production as compared with force during the HHP. Further investigation of both force and velocity at peak power during weightlifting variations is necessary to provide insight on the contributing factors of power production. Specific load ranges should be prescribed to optimally train the variables associated with power development during the HHP.

This study examined the impact of load on lower body performance variables during the hang power clean. Fourteen men performed the hang power clean at loads of 30%, 45%, 65%, and 80% 1RM. Peak force, velocity, power, force at peak power, velocity at peak power, and rate of force development were compared at each load. The greatest peak force occurred at 80% 1RM. Peak force at 30% 1RM was statistically lower than peak force at 45% (p = 0.022), 65% (p = 0.010), and 80% 1RM (p = 0.018). Force at peak power at 65% and 80% 1RM was statistically greater than force at peak power at 30% (p < 0.01) and 45% 1RM (p < 0.01). The greatest rate of force development occurred at 30% 1RM, but was not statistically different from the rate of force development at 45%, 65%, and 80% 1RM. The rate of force development at 65% 1RM was statistically greater than the rate of force development at 80% 1RM (p = 0.035). No other statistical differences existed in any variable existed. Changes in load affected the peak force, force at peak power, and rate of force development, but not the peak velocity, power, or velocity at peak power.

Jumping ability in volleyball players is crucial to a team's success. There are both muscular and neural components in jumping. Coaches often test jumping ability and body composition prior to the start of the competitive season, but many fail to monitor these important variables during the course of the season. Jumping ability can decrease over the course of the season as the focus moves from strength training in the weight room to skill development on the court. It is imperative that players maintain their jumping ability and body composition over the course of the season. Seasonal changes in elite-male volleyball players were determined by testing the players body composition, spike jump, block jump and lower body power index at three distinct time points: prior to the first game, during their bye-week, and at the end of their regular season. It was found that these players were able to maintain their vertical jump and lower body power index. Also, those who were deemed players (those who played throughout the course of the season) had lower body fat percentages and higher jump scores. These results will aid coaches in understanding the changes that occur over the course of the season in elite-male collegiate volleyball players.