# Effect of Post-Activation Potentiation on Weightlifting Performance and Endocrinological Responses
## 1 Introduction  
The manifestation of post-activation potentiation (PAP) occurs based on the muscles' acute contractile history following a conditioning stimulus [1, 2, 3, 4]. The optimal elicitation of PAP is heavily dependent upon individual characteristics' with the primary determinant of onset, degree, and duration of PAP being an individual's relative strength and their ability to dissipate fatigue [5, 6]. The majority of studies investigating lower body PAP have utilised conditioning stimuli consisting of ballistic or high-load resistance exercises, such as power cleans [6], snatch pulls [7] and back squats [6, 8]. These stimuli have been found to have significant positive effects on performance measures such as jump height (\(p=0.01\)) [8], sprint time (\(p=0.001\), \(d=-0.66\)--\(0.92\)) [6], acceleration (\(p=0.001\), ES = 0.70-1.00) [6] and power output [8]. While there is a breadth of research on lower body PAP and its effect ongeneral measures of athletic performance, very little information exists on the use of PAP and its effect on weightlifting performance. Research from [PERSON] et al. [4] on national level weightlifters utilised mid-thigh clean pulls (MTCPs) at absolute loads of 60, 80, 100 and 120 kg for females and 60, 140, 180 and 220 kg for males, with a fifth set performed at the 80 and 140 kg loads, respectively. Their findings demonstrated significant increases in barbell vertical peak velocity (vPV) between the second and fifth set (\(p\) = 0.023, \(\eta^{2}\) = 0.61), with a strong correlation to peak rate of force development (RFD) (\(r\) = 0.92, \(r^{2}\) = 0.85, \(p\) = 0.003), although peak RFD did not reach significance with respect to the fifth vs. second set. This suggests that MTCP may be an effective PAP stimulus in increasing the chance of weightlifting success, as barbell vPV has previously been associated with successful and effective lifts [9; 10]. It should be noted that since the relative strength of an individual has been shown to determine the degree to which PAP is induced as well as the onset and duration of its effects, the absolute loads used in [PERSON]'s study may have affected the PAP response. The maximal loads used were 120 and 220 kg for females and males, respectively, with their average 1 RM's presented as 117.5 \(\pm\) 6.6 kg (female) and 211.9 \(\pm\) 18.3 kg (male) equating to \(\sim\)113-96% of clean and jerk 1 RM. This means that the intensity of the conditioning stimulus would have been higher for some athletes compared to others and would potentially affect the magnitude of effect. Secondly, the fifth set following the heaviest MTCP was not based on a percentage of the individuals 1 RM but instead based on prior observations where barbell vPV, relative peak power (PP), and peak force (PF) were produced. Since absolute loads may have individual effects due to their relative intensity, utilising percentages to prescribe PAP-inducing loads may make the load specific to the individual. More recent research from [PERSON] et al. [11] investigated the use of mid-thigh clean pulls (MTCPs) with loads up to 140% of power clean 1 RM. The results from this study showed that vPV (1.69 \(\pm\) 0.042 m\(\cdot\)s\({}^{-1}\)) and PP (3712.82 \(\pm\) 254.38 W) occurred at 40% 1 RM, with peak RFD occurring at 120% (26,224.2 \(\pm\) 2461.6 N\(\cdot\)s\({}^{-1}\)) and peak force significantly increasing at 140% compared to 120% (\(p\) < 0.02). The same study also showed a linear increase in impulse, as the loads increased, with the highest total impulse (1129.86 \(\pm\) 534.86 N\(\cdot\)s) occurring at 140%. When implementing supramaximal pulls, factors such as impulse, RFD, peak power, and velocity have been shown to change significantly as the load increases [6; 11; 12]. It could be stipulated that a greater impulse developed during the second pull phase of a clean would increase the systems' velocity and subsequently the velocity of the barbell.