); [EMAIL_ADDRESS] (C.C.G. ); [EMAIL_ADDRESS] (R.V.B. ); [EMAIL_ADDRESS] (R.C.I. ); [EMAIL_ADDRESS] (G.B.M. ); [EMAIL_ADDRESS] (B.S.D. ); [EMAIL_ADDRESS] (C.C.G.) 2 School of Physical Education and Sport of Ribeirao Pereto, University of Sao Paulo,  
Ribeirao Preto 14040-907, Brazil  
2  
[PERSON]  
1 Human Performance Laboratory, Department of Physical Education, Institute of Biosciences, Sao Paulo State University, Rio Claro 13506-900, Brazil; [EMAIL_ADDRESS] (G.F.); [EMAIL_ADDRESS] (R.V.B. ); [EMAIL_ADDRESS] (R.C.I. ); [EMAIL_ADDRESS] (G.B.M. ); [EMAIL_ADDRESS] (B.S.D. ); [EMAIL_ADDRESS] (C.C.G. ); [EMAIL_ADDRESS] (R.V.B. ); [EMAIL_ADDRESS] (R.C.I. ); [EMAIL_ADDRESS] (G.B.M. ); [EMAIL_ADDRESS] (B.S.D. ); [EMAIL_ADDRESS] (C.C.G. ); [EMAIL_ADDRESS] (R.V.B. ); [EMAIL_ADDRESS] (C.C.G.) 2 School of Physical Education and Sport of Ribeirao Pereto, University of Sao Paulo,  
Ribeirao Preto 14040-907, Brazil  
2  
Canilla Coelho Greco  
1 Human Performance Laboratory, Department of Physical Education, Institute of Biosciences, Sao Paulo State University, Rio Claro 13506-900, Brazil; [EMAIL_ADDRESS] (G.F.); [EMAIL_ADDRESS] (R.V.B. ); [EMAIL_ADDRESS] (R.C.I. ); [EMAIL_ADDRESS] (G.B.M. ); [EMAIL_ADDRESS] (B.S.D. ); [EMAIL_ADDRESS] (C.C.G. ); [EMAIL_ADDRESS] (R.C.G. ); [EMAIL_ADDRESS] (R.V.B. ); [EMAIL_ADDRESS] (R.C.I. ); [EMAIL_ADDRESS] (G.B.M. ); [EMAIL_ADDRESS] (B.S.D. ); coelho.greco@unesp. to PAPE observed in trained individuals is a product of specific training adaptations is yet to be determined, but the phenotypical overexpression and development of type II muscle fibers in this population might play a role in this phenomenon [13; 14]. However, recent studies from our group presented conflicting evidence regarding the association between responsiveness to PAPE and indirect expression of type II muscle fibers or muscle strength. In [15] we showed that polymorphisms of the ACTN3 gene--which is associated with the expression of type II muscle fibers--do not influence responsiveness to PAPE in untrained individuals, who are less exposed to training-induced phenotypical adaptations in muscle fiber typology and strength. Furthermore, in [16] we showed, in untrained PAPE-responding men, that responsiveness to PAPE is compromised by glyumetric exercise-induced muscle damage probably due to fiber-type specific damage, since it is known that type II muscle fibers are predominantly damaged following eccentric biased exercise [17]. Interestingly, however, no association was observed between maximal knee extension strength loss and decreased responsiveness to PAPE during countermovement jumps (CMJ) followed by 5 RM of a barbell squat exercise [16]. These findings from our group contrast with those of [PERSON] et al. [11], which showed that type II muscle fibers are more responsive to post-activation potentiation. Even though the current body of literature suggests that resistance training experience favors responsiveness to PAPE, it is not yet clear--especially considering our recent findings [15; 16]--whether what makes an individual more responsive to PAPE is the expression and/or development of type II muscle fibers or other muscle characteristics, such as maximal strength and power (which does not rely entirely on fiber-type distribution, but also on neural parameters) and morphology. Furthermore, it is also not clear whether there are any easily assessable functional and/or morphological muscular parameters that might predict--in isolation or conjunctly--responsiveness to PAPE. The aim of this study was, therefore, to screen for morphological/functional muscular parameters that can predict, either in conjunction or in isolation, responsiveness to PAPE of CMJ, which is the most frequently investigated explosive muscle action in PAPE studies. Our hypothesis was that neither maximal and explosive strength nor vastus lateralis muscle thickness would be associated with responsiveness to PAPE following a frequently adopted pre-activation protocol.