Knowledge of results during vertical jump testing: an effective method to increase the performance but not the consistency of vertical jumps

This study aimed to determine whether the provision of jump height feedback (knowledge of result; KR) can increase the performance and the consistency of output variables. In a randomised order, sixteen participants performed six squat or countermovement jumps (three from a 90o knee angle and three from a self-preferred knee angle) with or without KR over four sessions. The provision of KR significantly increased peak force (p = 0.046, 1.83%), mean force (p = 0.037, 1.45%), peak velocity (p < 0.001, 3.71%), mean velocity (p = 0.004, 3.44%), peak power (p < 0.001, 4.22%) and mean power (p = 0.001, 4.69%). A high within-session reliability was observed for all variables (coefficient of variation [CV] <= 5.62%, intraclass correlation coefficient [ICC] >= 0.95). No systematic differences in reliability were detected between the jumps performed without KR (CV = 3.00 +/- 1.38%, ICC = 0.97 +/- 0.03) and with KR (CV = 3.04 +/- 1.49%, ICC = 0.97 +/- 0.04). These results suggest that the provision of jump height feedback during vertical jump testing is effective to enhance vertical jump performance but it does not reduce the variability between jumps.

Automated summary

This study found that providing jump height feedback can effectively enhance vertical jump performance, but it does not reduce the variability between jumps.