Methodological report: dynamic field tests used in an NFL combine setting to identify lower-extremity functional asymmetries.

Abstract

Side-to-side differences in lower-extremity biomechanics may be predictive of increased risk of lower-extremity injuries in athletes. The purpose of this report is to provide field testing methodology for tests designed to isolate lower-extremity asymmetry and to demonstrate the potential for these tests to provide reliable measures. Six athletes (3 females, 3 males) were tested on 2 consecutive days for activities incorporated into a replicated National Football League (NFL) combine setting. Vertical hop power (VHP) and jump height were measured on a portable force platform as athletes performed maximum effort hops for 10 seconds. The modified agility T-test (MAT) incorporates two 90-degree single-leg cuts during the trial and was measured as total time for completion. Intraclass correlations (within ICC [3,k], between ICC [3,1]) were calculated. The VHP test had good to excellent within-session reliability for peak power of both the right (ICC = 0.942) and left (ICC = 0.895) sides. Jump height showed excellent within-session reliability for both the right (ICC = 0.963) and left (ICC = 0.940) sides. The between-session reliability for peak power between jumps was good for the right (ICC = 0.748) and left (ICC = 0.834) sides. Jump height showed good to excellent between-session reliability on the right (ICC = 0.794) and left (ICC = 0.909) sides. The MAT also showed good reliability between days (ICC = 0.825).The results indicate that the VHP test provides reliable assessment of both within- and between-session jump height and power production. The MAT also provides good reliability between testing days. Both the VHP and the MAT may be useful for clinicians to identify the presence of lower-limb asymmetry and potential injury risk factors in athletic populations.