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Matt R. Cross, Farhan Tinwala, Seth Lenetsky, Scott R. Brown, Matt Brughelli, Jean-Benoit Morin and Pierre Samozino

. The greater the force (in this case F h ) expressed, the greater the acceleration for a given system mass (body mass plus any additional load; see Table  1 ). Any external resisting forces impede acceleration for a given F h output and must be overcome if the athlete is to accelerate. In a typical

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Prue Cormie, Jeffrey M. McBride and Grant O. McCaulley

The objective of this study was to investigate the validity of power measurement techniques utilizing various kinematic and kinetic devices during the jump squat (JS), squat (S) and power clean (PC). Ten Division I male athletes were assessed for power output across various intensities: 0, 12, 27, 42, 56, 71, and 85% of one repetition maximum strength (1RM) in the JS and S and 30, 40, 50, 60, 70, 80, and 90% of 1RM in the PC. During the execution of each lift, six different data collection systems were utilized; (1) one linear position transducer (1-LPT); (2) one linear position transducer with the system mass representing the force (1-LPT+MASS); (3) two linear position transducers (2-LPT); (4) the force plate (FP); (5) one linear position transducer and a force plate (1-LPT+FP); (6) two linear position transducers and a force place (2-LPT+FP). Kinetic and kinematic variables calculated using the six methodologies were compared. Vertical power, force, and velocity differed significantly between 2-LPT+FP and 1-LPT, 1-LPT+MASS, 2-LPT, and FP methodologies across various intensities throughout the JS, S, and PC. These differences affected the load–power relationship and resulted in the transfer of the optimal load to a number of different intensities. This examination clearly indicates that data collection and analysis procedures influence the power output calculated as well as the load–power relationship of dynamic lower body movements.

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Paul Comfort, Thomas Dos’Santos, Paul A. Jones, John J. McMahon, Timothy J. Suchomel, Caleb Bazyler and Michael H. Stone

pretension, determined as a force >50 N above the subjects’ system mass (body mass + bar mass), was not permitted prior to initiation of the pull. Subjects were instructed to pull against the bar “and push their feet into the ground as fast and hard as possible,” which has previously been reported to produce

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Seiichiro Takei, Kuniaki Hirayama and Junichi Okada

 × velocity). Because the present study investigated power output during the second pull phase of HPC, only the propulsion phase was analyzed, that is, the phase from the instance when the system velocity changed from negative to positive, to the instance when the force fell 10 N below the system mass. The

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Andrew D. Nordin and Janet S. Dufek

and colleagues 21 using the Load Accommodation Strategies Model, examining changes in ground reaction forces (GRFs) following modifications to an applied stressor, relative to a baseline condition (ie, increase system mass → increase GRF). 21 , 17 , 22 Newtonian predictions can also be assessed for