title: Mechanical Differences between Barbell and Body Optimum Power Loads in the Jump Squat Exercise.
abstract: This study compared the values of bar-peak force (PFBar) and power (PPBar), body-peak force (PFBody) and power (PPBody) and bar-mean propulsive power (MPPBar) in different jump-squat (JS) conditions: unloaded condition (UC); bar-loaded condition (BLC) and optimum bar-MPP condition (OBC). Twenty-five soccer players performed the JS using a bar with negligible mass (UC), using the Smith-machine bar (BLC) and using the load capable of maximizing the bar-MPP (OBC). The PFBodywas significantly higher in the UC (2847.9 ± 489.1 N) than in the OBC (2655.4 ± 444.3 N). The UC presented greater PPBody (3775.9 ± 631.5 W) than the BLC (3359.7 ± 664.3 W) and OBC (3357.8 ± 625.3 W). The OBC presented higher values of PFBar, PPBarand MPPBar(676.2 ± 109.4 W) than the BLC (MPPBar= 425.8 ± 53.7 W) (all p < 0.05). In the OBC (compared to the UC), the body peak-power presented a reduction of ≈ 11%, while generating bar-power output from ≈ 59 to 73% higher than the BLC. While the fact that the body-peak power is maximized in the UC denotes a mechanical phenomenon, the bar-optimum load represents an intensity at which both components of the power equation (force and velocity) are optimized. This has important implications for sports training.
authors.affiliation: NAR - Nucleus of High Performance in Sport, São Paulo, SP, Brazil; Department of Mechatronics Engineering, University of São Paulo, SP, Brazil.
authors.forename: Irineu
authors.initials: I
authors.lastname: Loturco
authors.affiliation: NAR - Nucleus of High Performance in Sport, São Paulo, SP, Brazil.
authors.forename: Lucas A
authors.initials: LA
authors.lastname: Pereira
authors.affiliation: Red Bull Brazil Football, SP, Brazil.
authors.forename: Vinicius
authors.initials: V
authors.lastname: Zanetti
authors.affiliation: NAR - Nucleus of High Performance in Sport, São Paulo, SP, Brazil.
authors.forename: Katia
authors.initials: K
authors.lastname: Kitamura
authors.affiliation: NAR - Nucleus of High Performance in Sport, São Paulo, SP, Brazil.
authors.forename: César C Cal
authors.initials: CC
authors.lastname: Abad
authors.affiliation: NAR - Nucleus of High Performance in Sport, São Paulo, SP, Brazil.
authors.forename: Ronaldo
authors.initials: R
authors.lastname: Kobal
authors.affiliation: NAR - Nucleus of High Performance in Sport, São Paulo, SP, Brazil; State University of Londrina, Londrina, PR, Brazil.
authors.forename: Fabio Y
authors.initials: FY
authors.lastname: Nakamura
keywords: ballistic; muscle power; neuromuscular; optimal loads; plyometrics