# Effect of Post-Activation Potentiation on Weightlifting Performance and Endocrinological Responses
## 4 Discussion  
The aim of the present study was to investigate the PAP effect of supramaximal clean pulls executed at 120% of 1 RM CJ, on kinetic and kinematic clean performance. The purpose behind utilising the athletes' CJ 1 RM as apposed to their clean 1 RM was because the CJ was predetermined during a typical training session and is more indicative of competition success than using the clean alone. A further aim was to also investigate the effect PAP would have on salivary testosterone and cortisol and their ratio. The results demonstrate that the effects of PAP on kinetic and kinematic measures of the clean are subject-specific and therefore may positively affect some and not others. This is evidenced through the lack of statistical significance found between the control and experimental condition across all variables and loads (\(p\) = 0.140-0.803) but is highlighted when effect sizes are considered for each individual, as shown in Table 3. The most affected variable was UW impulse; however, the high variability (22%) suggests this metric has poor reliability, and therefore any changes elicited by PAP likely fall within its error. Peak force had the greatest positive change in five out of the eight participants, with effect sizes ranging from trivial to very large (ES = 0.14-2.51). The hormonal responses also suggested that no significant differences existed between the two conditions (\(p\) = 0.224-0.902), with the effect size of T:C (ES = \(-\)0.30) highlighting that there was a small increase in cortisol, therefore altering the T:C ratio. Unlike in the present study, heavy resistance loading has been shown to produce acute increases in serum testosterone, GH, and blood lactate [18]. Figure 4: Individual responses from the control compared to the PAP across kinetic, kinematic and hormonal variables. Mean \(\pm\) standard deviation group responses presented as bar graphs. Dashed lines represent percentage changes greater than the coefficient of variation (CV) solid lines represent percentage changes less than CV. (**a**) Vertical impulse during weighting 1, (**b**) vertical impulse during weighting 2, (**c**) peak force, (**d**) ratio of peak bar height relative to athlete height, (**e**) peak barbell power and (**f**) testosterone and cortisol ratio. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Subject** & **W1 vImpulse** & **UW vImpulse** & **W2 Impulse** & **PF** & **PBEHt** & **BPP** \\ \hline
1 & \(-\)0.14 & 0.32 & 1.42 & 0.14 & \(-\)2.21 & \(-\)2.03 \\
2 & 0.20 & 0.30 & \(-\)1.37 & 0.85 & \(-\)3.24 & \(-\)1.45 \\
3 & 0.10 & 0. These acute endocrine responses are critical for optimal force production during resistance exercise [19]. Within weightlifting, experience of more than two years has previously been associated with increased exercise-induced T responses [23]. However, other hormonal factors also have to be taken into consideration when it comes to competition-based factors, as increased cortisol concentrations can occur correspondingly, due to increased stress and arousal from the environment [21; 22]. The prescribed sets and reps are associated with hormonal responses, with three sets resulting in higher testosterone, hGH and cortisol responses [25; 26]. Within the present study, one set at different loads was used for the pulls, which may not have provided enough stimulus to generate adequate hormonal responses. The time between the stimulus (120% clean pull) and the performance measures was set at 3 min. The rationale behind this time frame was to replicate the time periods between clean attempts during competition. The athlete typically has 1 min from when the bar is loaded to perform the lift. Alternatively, should they follow themselves, there is a 2 min period between attempts. Although 3 min does not directly correspond with either of those competition times, it is highly likely that an athlete may perform their last warm up lift anywhere between 3 and 6 min prior to the competition lift.