METHODOLOGICAL CONCERNS FOR DETERMINING POWER OUTPUT IN THE JUMP SQUAT

• Published in: Journal of strength and conditioning research 2007-05, Vol.21 (2), p.424-430
• Main Authors: CORMIE, PRUE, DEANE, RUSSELL, MCBRIDE, JEFFREY M
• Format: Article
• Language: English
• Subjects: Adult; Case studies; Data Collection - instrumentation; Data Collection - methods; Humans; Leg - physiology; Linear Models; Male; Measurement techniques; Methods; Movement; Muscle Strength - physiology; Muscle, Skeletal - physiology; Physical Education and Training; Physical fitness; Space life sciences; Transducers
• ISSN: 1064-8011; 1533-4287
• DOI: 10.1519/00124278-200705000-00024

The purpose of this study was to investigate the validity of power measurement techniques during the jump squat (JS) utilizing various combinations of a force plate and linear position transducer (LPT) devices. Nine men with at least 6 months of prior resistance training experience participated in this acute investigation. One repetition maximums (1RM) in the squat were determined, followed by JS testing under 2 loading conditions (30% of 1RM [JS30] and 90% of 1RM [JS90]). Three different techniques were used simultaneously in data collection(a) 1 linear position transducer (1-LPT); (b) 1 linear position transducer and a force plate (1-LPT + FP); and (c) 2 linear position transducers and a force place (2-LPT + FP). Vertical velocity-, force-, and power-time curves were calculated for each lift using these methodologies and were compared. Peak force and peak power were overestimated by 1-LPT in both JS30 and JS90 compared with 2-LPT + FP and 1-LPT + FP (p ≤ 0.05). Peak power determined by 2-LPT + FP was significantly higher than that determined by 1-LPT + FP under the JS90 loading condition. Peak vertical velocity determined by 2-LPT + FP was significantly lower than that determined by either 1-LPT and 1-LPT + FP in JS90. This investigation indicates that peak power and the timing of power output in the jump squat varies according to the measurement technique utilized. The 1-LPT methodology is not a valid means of determining power output in the jump squat. Furthermore, the 1-LPT + FP method may not accurately represent power output in free weight movements that involve a significant amount of horizontal motion.