title: Postactivation potentiation biases maximal isometric strength assessment.
abstract: Postactivation potentiation (PAP) is known to enhance force production. Maximal isometric strength assessment protocols usually consist of two or more maximal voluntary isometric contractions (MVCs). The objective of this study was to determine if PAP would influence isometric strength assessment. Healthy male volunteers (n = 23) performed two five-second MVCs separated by a 180-seconds interval. Changes in isometric peak torque (IPT), time to achieve it (tPTI), contractile impulse (CI), root mean square of the electromyographic signal during PTI (RMS), and rate of torque development (RTD), in different intervals, were measured. Significant increases in IPT (240.6 ± 55.7 N·m versus 248.9 ± 55.1 N·m), RTD (746 ± 152 N·m·s(-1) versus 727 ± 158 N·m·s(-1)), and RMS (59.1 ± 12.2% RMSMAX  versus 54.8 ± 9.4% RMSMAX) were found on the second MVC. tPTI decreased significantly on the second MVC (2373 ± 1200 ms versus 2784 ± 1226 ms). We conclude that a first MVC leads to PAP that elicits significant enhancements in strength-related variables of a second MVC performed 180 seconds later. If disconsidered, this phenomenon might bias maximal isometric strength assessment, overestimating some of these variables.
authors.affiliation: Human Performance Laboratory, Physical Education Department, São Paulo State University, Rio Claro, SP, Brazil.
authors.forename: Leonardo Coelho Rabello
authors.initials: LC
authors.lastname: Lima
authors.affiliation: Human Performance Laboratory, Physical Education Department, São Paulo State University, Rio Claro, SP, Brazil.
authors.forename: Felipe Bruno Dias
authors.initials: FB
authors.lastname: Oliveira
authors.affiliation: Human Performance Laboratory, Physical Education Department, São Paulo State University, Rio Claro, SP, Brazil.
authors.forename: Thiago Pires
authors.initials: TP
authors.lastname: Oliveira
authors.affiliation: Human Performance Laboratory, Physical Education Department, São Paulo State University, Rio Claro, SP, Brazil.
authors.forename: Claudio de Oliveira
authors.initials: Cde O
authors.lastname: Assumpção
authors.affiliation: Human Performance Laboratory, Physical Education Department, São Paulo State University, Rio Claro, SP, Brazil.
authors.forename: Camila Coelho
authors.initials: CC
authors.lastname: Greco
authors.affiliation: Biomechanics Laboratory, Physical Education Department, São Paulo State University, Rio Claro, SP, Brazil.
authors.forename: Adalgiso Croscato
authors.initials: AC
authors.lastname: Cardozo
authors.affiliation: Human Performance Laboratory, Physical Education Department, São Paulo State University, Rio Claro, SP, Brazil.
authors.forename: Benedito Sérgio
authors.initials: BS
authors.lastname: Denadai
mesh_terms: D006801:Humans; D007537:Isometric Contraction / Q000502:physiology*; D008297:Male; D053580:Muscle Strength / Q000502:physiology*; D013997:Time Factors; D019415:Torque; D055815:Young Adult