Validity and reliability of two field-based leg stiffness devices:Implications for practical use

Ruggiero, Luca and Dewhurst, Susan and Bampouras, Theodoros M. (2016) Validity and reliability of two field-based leg stiffness devices:Implications for practical use. Journal of Applied Biomechanics, 32 (4). pp. 415-419. ISSN 1065-8483

[thumbnail of Validity and reliability of two field-based leg stiffness devices_implic.._]
PDF (Validity and reliability of two field-based leg stiffness devices_implic.._)
Validity_and_reliability_of_two_field_based_leg_stiffness_devices_implic.._.pdf - Accepted Version
Available under License Creative Commons Attribution-NonCommercial.

Download (589kB)


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.

Item Type:
Journal Article
Journal or Publication Title:
Journal of Applied Biomechanics
Additional Information:
Copyright Human Kinetics
Uncontrolled Keywords:
ID Code:
Deposited By:
Deposited On:
09 Oct 2018 13:06
Last Modified:
18 Sep 2023 01:25