Reliability and Utility of Load-Cell Derived Force–Time Variables Collected During a Constrained and Unconstrained Isometric Knee Extension Task on a Plinth

Juneau, CM
Oranchuk, DJ
Cahill, M
Forster, JW
Diewald, S
Cronin, JB
Neville, J
Item type
Journal Article
Degree name
Journal Title
Journal ISSN
Volume Title
Springer Science and Business Media LLC

Rate of force development (RFD) and impulse (IMP) are important mechanical measures of muscular performance but are relatively unused within the rehabilitation and performance community. Due principally to access to low-cost testing devices and understanding the utility of these measures. The aim of this study therefore was to quantify the reliability of various force–time variables using load-cell technology collected via isometric knee extension whilst constrained in an isokinetic device (CON90) or unconstrained on a physiotherapy plinth at 60 and 90 degree angles (UNCON60 and UNCON90). Thirty-two volunteers had their peak force (PF), RFD, peak RFD (PRFD), and IMP assessed across three protocols. For all variables, UNCON60 had the largest variability across all measures. PF and PRFD were found to have small variability (ICC > 0.67 and CV < 10%). With regards to RFD 2080 all three protocols were found to have moderate variability all ICCs above 0.75, however, all CVs were greater than 10% ranging from ~ 11%–22%. Finally, IMP 2080 was found to have moderate variability for both CON90 and UNCON90, the absolute consistency once more greater than 10% (~ 11%–25%). Using the constrained and unconstrained protocols, PF and PRFD can be measured reliably between trials with 90 degree knee position.

4201 Allied Health and Rehabilitation Science , 42 Health Sciences , 4207 Sports Science and Exercise , 4207 Sports science and exercise
Journal of Science in Sport and Exercise, ISSN: 2096-6709 (Print); 2662-1371 (Online), Springer Science and Business Media LLC, 6(1), 81-89. doi: 10.1007/s42978-022-00215-8
Rights statement
Open Access This article is licensed under a Creative Commons Attri bution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit