Measurement bias in estimates of system power during a vertical jump

Kym J. Williams, Dale W. Chapman, Elissa J. Phillips, Nick B. Ball

Research output: Contribution to journalArticle

Abstract

This investigation sought to quantify the level of measurement agreement in system force, velocity and power values derived across three commonly applied assessment techniques during a countermovement jump (CMJ). Twenty-five male national representative athletes completed three CMJs under unloaded (0%1RM) and loaded (40%1RM) jump conditions. Associated values of force, velocity and power were captured simultaneously from either a linear optical encoder (LOE) or force plate (FP) and then compared to the gold-standard reference values derived from a combined force plate and three-dimensional motion capture system (FPMC). The LOE significantly (p < 0.001) overestimated and failed to meet the minimum level of relatedness (<0.80) for measures of peak velocity, peak force, peak power and mean power across both conditions compared to the FPMC reference values. A reduction in measurement dispersion and bias was, however, evident during the loaded condition. The FP significantly (p < 0.05) underestimated mean and peak power across both conditions, yet measurement bias and dispersion remained consistent. These findings highlight a disparity in measurement agreement in force, velocity and power values across alternative assessment techniques and loads. Such variance in measurement agreement will uniquely alter derived force-velocity profiles, and thus the prescription of training loads to maximise system power during unrestricted CMJs.

Original languageEnglish
Article number1
Pages (from-to)1-13
Number of pages13
JournalSports Biomechanics
Volume18
Issue number6
Early online date1 Oct 2019
DOIs
Publication statusE-pub ahead of print - 1 Oct 2019

Keywords

  • force plate
  • force-velocity relationship
  • linear optical encoder
  • load-power relationship
  • Motion capture

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