Prevalence of sleep disturbances and their association with quality of life among the general population in Qassim, Saudi Arabia.

Post-activation performance enhancement (PAPE) is the acute improvement in neuromuscular voluntary performance following conditioning activities (CAs) []; however, controversy exists regarding which CA leads to a higher PAPE response. Typical CAs include multiple sets of resistance exercises such as back squats (BS) at an intensity of more than 80% of one-repetition maximum (1-RM), or velocity-dependent exercises such as drop jumps (DJs) and loaded DJs [–]. CAs focusing on eccentric rather than concentric contractions have been reported to be more efficient in enhancing countermovement jump (CMJ) performance [,]. A systematic review demonstrated slightly superior PAPE effect induced by velocity-based exercises such as plyometrics, in comparison to high-intensity resistance exercises [], which is probably due to less motor pattern interference [,]. Additionally, some studies observed significant PAPE represented by an increase in jump height after loaded or eccentric overloaded velocity-based exercises [–]. It appears that different forms of CAs, considering the velocity-force spectrum and the phase of the movement (i.e., concentric vs eccentric) affect the magnitude of PAPE. However, no previous study has systematically evaluated the different PAPE responses between concentric or eccentric contractions in the BS and compared them with plyometric activities with or without additional load, to the best of our knowledge. This information can be important in the sports context when considering the best choice of CA to include in a training context like in contrast training. In many of the previous studies, PAPE was assessed after a general warm-up followed by a CA, and the CMJ height is one of the most described PAPE markers []. It has been documented that PAPE can be evoked by a warm-up routine, and its effect is similar to that evoked by a BS or loaded jump []. Xu et al. [] concluded in their review article that when a comprehensive warm-up including all RAMP [raise, activate, mobilize, and potentiate] phases was performed before a CA, the CA produced a trivial or small effect on PAPE. Therefore, if the aim is to investigate the PAPE effects of different CAs, a possible effect of warm-up exercise on PAPE before the CAs should be avoided by inserting sufficient time between them. Accordingly, Chen et al. [] showed that the time interval after which PAPE effects on jump performance were no longer observed was above 12–15 minutes.