Int J Sports Med 2011; 32(4): 254-258
DOI: 10.1055/s-0030-1270487
Training & Testing

© Georg Thieme Verlag KG Stuttgart · New York

Validating Two Systems for Estimating Force and Power

B. T. Crewther1 , L. P. Kilduff2 , D. J. Cunningham2 , C. Cook3 , N. Owen2 , G.-Z. Yang1
  • 1Imperial College, Institute of Biomedical Engineering, London, United Kingdom
  • 2Swansea University, Sport and Exercise Science, School of Engineering, Swansea, United Kingdom
  • 3UK Sport, Research, London, United Kingdom
Further Information

Publication History

accepted after revision December 17, 2010

Publication Date:
04 March 2011 (online)

Abstract

This study examined the validity of 2 kinematic systems for estimating force and power during squat jumps. 12 weight-trained males each performed single repetition squat jumps with a 20-kg, 40-kg, 60-kg and 80-kg load on a Kistler portable force plate. A commercial linear position transducer (Gymaware [GYM]) and accelerometer (Myotest® [MYO]) were attached to the bar to assess concentric peak force (PF) and peak power (PP). Across all loads tested, the GYM and MYO estimates of PF and PP were moderately to strongly correlated (P≤0.05–0.001) with the force plate measurements (r=0.59–0.87 and r=0.66–0.97), respectively. The mean PF and PP values were not significantly different between the 2 kinematic systems and the force plate, but the estimates did produce some systematic bias and relatively large random errors, especially with the 20-kg load (PF bias >170 N, PF error >335 N, PP bias >400 W, PP error >878 W). Some proportional bias was also identified. In summary, the estimation of PF and PP by a linear position transducer and accelerometer showed moderate to strong relative validity and equivalent absolute validity, but these estimates are limited by the presence of bias and large random errors.

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Correspondence

Dr. Blair Tehira CrewtherPhD 

Imperial College

Institute of Biomedical

Engineering

South Kensington

SW7 2AZ London

United Kingdom

Phone: +44/20/7594 0701

Fax: +44/20/7594 0704

Email: bcrewthe@imperial.ac.uk