Postactivation Potentiation, Sprint and Jump Performance 1 Manuscript Title: The Effects of Postactivation Potentiation on Sprint and Jump Performance of Male Academy Soccer Players Running Head: Postactivation Potentiation, Sprint and Jump Performance

The purpose of this investigation was to evaluate the postactivation potentiation (PAP) effects of both dynamic and isometric maximum voluntary contractions (MVCs) on sprint and jump performance and establish whether PAP methods could be used effectively in warm up protocols for soccer players. Twelve male soccer players performed 4 warm up protocols in a cross over, randomised and counterbalanced design. In addition to a control warm up, subjects performed dead lift (5 repetitions at 5RM), tuck jump (5 repetitions) and isometric MVC knee extensions (3 repetitions for 3 seconds) as PAP treatments in an otherwise identical warm up protocol. After each treatment the subjects underwent three 10m and 20m sprints 4, 5 and 6 minutes post warm up and three vertical jumps (VJ) at 7, 8 and 9 minutes post warm up. Repeated measures ANOVA showed no significant differences in the first 10m (p=0.258), 20m (p=0.253) sprint and VJ (p=0.703) performance and the average 10m (p=0.215), 20m (p=0.388) and VJ (p=0.529) performance between conditions. There were also no significant differences in performance responses between the strongest and weakest subjects but large variations in individual responses were found between the subjects. The findings suggest that there was no significant group PAP effect on sprint and jump performance following dynamic and isometric maximum voluntary contractions compared to a control warm up protocol. However the large variation in individual responses (-7.1% to +8.2%) suggests PAP should be considered on an individual basis. Factors such as method, volume, load, recovery and interindividual variability of PAP must be considered in the practical application of PAP and the rigorous research design of future studies Postactivation Potentiation, Sprint and Jump Performance 4 to evaluate the potential for performance enhancement.