The purpose of the study was to determine whether a submaximal loading protocol or a super maximal loading protocol was the most effective postactivation potentiation method for improving a vertical jump test with Division II football and volleyball players. If there was a significant increase in vertical jump performance following the super maximal loading or submaximal loading protocol, it may be assumed that one of the protocols causes a greater postactivation potentiation effect. The researcher hypothesized that the heavy spinal load created by the rack squat may produce a higher anaerobic output result through the vertical jump in comparison to the submaximal spinal load from the jump squat. The participants underwent a four week protocol including maximal back squat testing, baseline vertical jump testing, vertical jump testing after the submaximal loading protocol, and vertical jump testing after the super maximal loading protocol. Each intervention was completed on a separate week to ensure adequate rest from the movements. The dependent variables of the study were the vertical jump performances and the EMG peak amplitude measured after each intervention. The results were analyzed using a mixed ANOV A design since the research included two independent variables, which were the sport played and the specific intervention. All data was run through SPSS (Version 22, 2013) and the significance level was set at p < 0.05 for all variables. The football players observed an insignificant increase in average vertical jump performance following the jump squat intervention (27.71 inches) and rack squat intervention (27.62 inches) in comparison to the pretest performance (27.31 inches). The volleyball players observed an insignificant decrease in average vertical jump performance following the rack squat intervention (18.38 inches) and the jump squat intervention (18.45 inches) in comparison to the pretest performance (19.56 inches). There was not a significant difference within groups between the vertical jump heights after the rack squat and jump squat interventions (p > .05). The results show that there was a significant effect of the sport played in relation to the increase or decrease in vertical jump performance during the rack squat and jump squat interventions (p < 0.05). The results from the study indicate no significant difference between the super maximal and submaximal loading protocols for postactivation potentiation prior to vertical jump testing in these specific athletic groups. Therefore, the hypothesis posed by the researcher was rejected.
