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Reliability of and relationship between flight time to contraction time ratio and reactive strength index modified

McMahon, JJ; Lake, JP; Comfort, P

Reliability of and relationship between flight time to contraction time ratio and reactive strength index modified Thumbnail


Authors

JP Lake



Abstract

Countermovement jump (CMJ) force-time testing is commonly used to monitor seasonal alterations in athletes’ CMJ strategy (to infer alterations in neuromuscular function). The flight time to contraction time (FT:CT) ratio and reactive strength index modified (RSImod) are considered to be two primary CMJ variables of interest. Due to similar calculations, it is likely that the FT:CT ratio and RSImod share similar reliability and an almost perfect relationship. Consequently, there may be no requirement to include both variables in CMJ monitoring reports. This study aimed to investigate this by recruiting twenty-five males to perform three CMJs on a force platform across two sessions that were separated by one week. The FT:CT ratio and two calculations of RSImod (based on the jump height from either flight time or take-off velocity) were then calculated using robust methods. The between-day reliability was good-excellent for all of the variables (95% confidence interval range of the coefficient of variation = 2.02–9.22%) with no significant between-day differences noted (p ≥ 0.231). There was an almost perfect positive relationship between the FT:CT ratio and RSImod regardless of the calculation method (r = 0.944–0.947, p < 0.001). As the FT:CT ratio and RSImod yield similar absolute reliability and share 90% of common variance, there is little reason to include both variables in CMJ monitoring reports.

Citation

McMahon, J., Lake, J., & Comfort, P. (2018). Reliability of and relationship between flight time to contraction time ratio and reactive strength index modified. Sports, 6(3), 81. https://doi.org/10.3390/sports6030081

Journal Article Type Article
Acceptance Date Aug 14, 2018
Online Publication Date Aug 15, 2018
Publication Date Aug 15, 2018
Deposit Date Aug 21, 2018
Publicly Available Date Aug 21, 2018
Journal Sports
Publisher MDPI
Volume 6
Issue 3
Pages 81
DOI https://doi.org/10.3390/sports6030081
Publisher URL https://doi.org/10.3390/sports6030081
Related Public URLs http://www.mdpi.com/journal/sports