Construct Validity and Test-Retest Reliability of Hip Load Compared With Playerload During Football-Specific Running , Kicking, and Jumping Tasks

Purpose: To determine the test-retest reliability of the recently developed Hip Load metric, evaluate its construct validity, and assess the differences with Playerload during football-specific short-distance shuttle runs.Methods: Eleven amateur football players participated in 2 identical experimental sessions. Each session included 3 different shuttle runs that were performed at 2 pace-controlled running intensities. The runs consisted of only running, running combined with kicks, and running combined with jumps. Cumulative Playerload and Hip Loads of the preferred and nonpreferred kicking leg were collected for each shuttle run. Test-retest reliability was determined using intraclass correlations, coefficients of variation, and Bland-Altman analyses. To compare the load metrics with each other, they were normalized to their respective values obtained during a 54-m run at 9 km/h. Sensitivity of each load metric to running intensity, kicks, and jumps was assessed using separate linear mixed models.Results: Intraclass correlations were high for the Hip Loads of the preferred kicking leg (.91) and the nonpreferred kicking leg (.96) and moderate for the Playerload (.87). The effects (95% CIs) of intensity and kicks on the normalized Hip Load of the kicking leg (intensity: 0.95 to 1.50, kicks: 0.36 to 1.59) and nonkicking leg (intensity: 0.96 to 1.53, kicks: 0.06 to 1.34) were larger than on the normalized Playerload (intensity: 0.12 to 0.25, kicks: 0.22 to 0.53).Conclusions: The inclusion of Hip Load in training load quantification may help sport practitioners to better balance load and recovery.

Automated summary

The purpose of this study was to determine the test-retest reliability and construct validity of the Hip Load metric, as well as compare it with Playerload during football-specific short-distance shuttle runs. The results showed high intraclass correlations for Hip Loads and moderate correlations for Playerload. The study also found that Hip Load was more sensitive to running intensity, kicks, and jumps compared to Playerload.