Normalization of early isometric force production as a percentage of peak force during multijoint isometric assessment

Comfort, P; Dos’Santos, T; Jones, PA; McMahon, JJ; Suchomel, TJ; Bazyler, C; Stone, MH

Abstract

Purpose: To determine the reliability of early force production (50-, 100-, 150-, 200-, 250 ms) relative to peak force (PF) during an isometric mid-thigh pull (IMTP) and assess the relationships between these variables. Methods: Male collegiate athletes (n = 29; age: 21.1 ± 2.9 years; height: 1.71 ± 0.07 m; body mass: 71.3 ± 13.6 kg) performed IMTPs during two separate testing sessions. Net PF and net force produced at each epoch were calculated. Within- and between-session reliability were determined by using intraclass correlation coefficients (ICC) and coefficient of variation (CV%). Additionally, Pearson’s correlation coefficients and coefficient of determination, were calculated to examine the relationships between PF and time-specific force production. Results: Net PF and time-specific force demonstrated very high to almost perfect reliability both within- and between-sessions (ICCs 0.82-0.97; CV% 0.35-1.23%). Similarly, time-specific force expressed as a percentage of PF demonstrated very high to almost perfect reliability both within- and between-sessions (ICCs 0.76-0.86; CV% 0.32-2.51%). Strong to nearly perfect relationships (r = 0.615-0.881) exist between net PF and time-specific net force, with relationships improving over longer epochs. Conclusion: Based on the smallest detectable difference, a change in force at 50 ms expressed relative to PF >10% and early force production (100-, 150-, 200- and 250 ms) expressed relative to PF of >2% should be considered meaningful. Expressing early force production as a percentage of PF is reliable and may provide greater insight into the adaptations to the previous training phase than PF alone.

Citation

Comfort, P., Dos’Santos, T., Jones, P., McMahon, J., Suchomel, T., Bazyler, C., & Stone, M. (2020). Normalization of early isometric force production as a percentage of peak force during multijoint isometric assessment. International Journal of Sports Physiology and Performance, 15(4), 478-482. https://doi.org/10.1123/ijspp.2019-0217

• Journal Article Type: Article
• Acceptance Date: Jul 8, 2019
• Online Publication Date: Oct 8, 2019
• Publication Date: Apr 1, 2020
• Deposit Date: Jun 3, 2020
• Publicly Available Date: Jun 3, 2020
• Journal: International Journal of Sports Physiology and Performance
• Print ISSN: 1555-0265
• Electronic ISSN: 1555-0273
• Publisher: Human Kinetics
• Volume: 15
• Issue: 4
• Pages: 478-482
• DOI: https://doi.org/10.1123/ijspp.2019-0217
• Publisher URL: https://doi.org/10.1123/ijspp.2019-0217
• Related Public URLs: http://journals.humankinetics.com/ijspp
• Additional Information: Access Information : Accepted author manuscript version reprinted, by permission, from International Journal of Sports Physiology and Performance, 2020, 15 (4): pp.478-pp. 482, https://doi-org.salford.idm.oclc.org/10.1123/ijspp.2019-0217. © Human Kinetics, Inc.