Finding the Signal in the Noise-Interday Reliability and Seasonal Sensitivity of 84 Countermovement Jump Variables in Professional Basketball Players

Mercer, RAJ, Russell, JL, McGuigan, LC, Coutts, AJ, Strack, DS, and McLean, BD. Finding the signal in the noise-interday reliability and seasonal sensitivity of 84 countermovement jump variables in professional basketball players. J Strength Cond Res 37(2): 394-402, 2023-This study examined the measurement characteristics of countermovement jump (CMJ) variables in basketball athletes using different variable selection criteria. Test-retest reliability (noise) and seasonal variability (signal) CMJ data were collected from 13 professional basketball athletes playing for the same club throughout 1 competitive season. Interday reliability (coefficient of variation [CV] and intraclass correlation coefficients) were calculated over 3 preseason tests conducted on 3 consecutive days. To evaluate sensitivity, signal-to-noise ratio (SNR) was calculated by dividing seasonal variability (CV) from 8 in-season CMJ tests (collected from November to February) by preseason reliability (CV). Players performed 3 CMJs each testing day, and 3 data analysis techniques were applied: a single variable from the trial with either the best jump height (Best(JH;) calculated by flight time) or the best flight time to contraction time (Best(FT:CT)) and mean output across 3 jumps (Mean(3)). Mean(3) was the most reliable data analysis technique, with 79 and 82 of 84 variables displaying lower interday CVs compared with Best(JH) and Best(FT:CT), respectively. Overall, many CMJ measures display seasonal changes that are greater than the inherent noise, with 77 variables producing SNR of >1.00 for Mean(3) compared with 65 and 58 variables for Best(JH) and Best(FT:CT), respectively. To improve reliability and sensitivity, it is recommended that practitioners use the average of multiple CMJ trials and regularly reassess measurement characteristics specific to their cohort and environment.

Automated summary

This study aimed to assess the measurement characteristics of countermovement jump (CMJ) variables in basketball athletes using different variable selection criteria. Results showed that averaging across multiple tests provided more reliable data for CMJ variables. Furthermore, many CMJ measures displayed seasonal changes that were greater than the measurement noise, suggesting the importance of regularly assessing and improving the reliability and sensitivity of CMJ measurement in athletes.