Validity and Reliability of Two Field-Based Leg Stiffness Devices: Implications for Practical Use

in Journal of Applied Biomechanics

Click name to view affiliation

Luca RuggieroUniversity of Cumbria
University of British Columbia

Search for other papers by Luca Ruggiero in
Current site
Google Scholar
PubMed
Close
,
Susan DewhurstUniversity of Cumbria

Search for other papers by Susan Dewhurst in
Current site
Google Scholar
PubMed
Close
, and
Theodoros M. BampourasUniversity of Cumbria

Search for other papers by Theodoros M. Bampouras in
Current site
Google Scholar
PubMed
Close
Restricted access

Leg stiffness is an important performance determinant in several sporting activities. This study evaluated the criterion-related validity and reliability of 2 field-based leg stiffness devices, Optojump Next® (Optojump) and Myotest Pro® (Myotest) in different testing approaches. Thirty-four males performed, on 2 separate sessions, 3 trials of 7 maximal hops, synchronously recorded from a force platform (FP), Optojump and Myotest. Validity (Pearson’s correlation coefficient, r; relative mean bias; 95% limits of agreement, 95%LoA) and reliability (coefficient of variation, CV; intraclass correlation coefficient, ICC; standard error of measurement, SEM) were calculated for first attempt, maximal attempt, and average across 3 trials. For all 3 methods, Optojump correlated highly to the FP (range r = .98–.99) with small bias (range 0.91–0.92, 95%LoA 0.86–0.98). Myotest demonstrated high correlation to FP (range r = .81–.86) with larger bias (range 1.92–1.93, 95%LoA 1.63–2.23). Optojump yielded a low CV (range 5.9% to 6.8%), high ICC (range 0.82–0.86), and SEM ranging 1.8–2.1 kN/m. Myotest had a larger CV (range 8.9% to 13.0%), moderate ICC (range 0.64–0.79), and SEM ranging from 6.3 to 8.9 kN/m. The findings present important information for these devices and support the use of a time-efficient single trial to assess leg stiffness in the field.

Luca Ruggiero, Susan Dewhurst, and Theodoros M. Bampouras are with the Department of Medical and Sport Sciences, University of Cumbria, Lancaster, United Kingdom. Luca Ruggiero is also with the School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada.

Address author correspondence to Theodoros M. Bampouras at theodoros.bampouras@cumbria.ac.uk.
  • Collapse
  • Expand
All Time Past Year Past 30 Days
Abstract Views 3552 1140 198
Full Text Views 26 9 0
PDF Downloads 41 20 0