Vertical Jump And Hop Performance In Professional Soccer Players With And Without Ankle Asymmetries

PURPOSE: Within soccer athletes, talocrural dorsiflexion range of motion (DFROM) has been shown as a risk factor for lower extremity injuries due to the necessary range of motion required for rapid jumping and cutting movements required in the sport. Further, bilateral asymmetries in DFROM may present a higher risk than reduced DFROM alone. Vertical jump and single leg hop tests have been previously recommended for use in identifying asymmetries linked to an increase in knee injuries and post-injury prognosis. However, it is unknown how DFROM asymmetries may affect these common screening tests. Thus, the purpose of this study was to examine the differences between those with and without DFROM asymmetries on hop and VJ assessments.

METHODS: 23 male United Soccer League players were tested for bilateral DFROM in cm at preseason using the Weight Bearing Lunge Test, and an asymmetry was defined as ≥2 cm between limbs. Hop testing consisted of bilateral single hop for distance (cm), triple hop for distance (cm), and 6-meter timed hop (s). VJ testing consisted of bilateral and unilateral countermovement jumps (in) using a jump mat. Max height and distance were calculated for VJ trials and distance hops, respectively. Fastest times were used in the analysis for timed hops. Statistical differences between groups were assessed with independent t-tests with significance set a priori at p ≤ 0.05.

RESULTS: Significant group differences were found for bilateral VJ testing in average height (t(21) = -2.6, p = 0.017 [with asymmetry = 21.7 ± 2.9 in, without asymmetry = 25.2 ± 2.7 in]), as well as max height (t(21) = -2.5, p = 0.019 [with asymmetry = 22.3 ± 3.1 in, without asymmetry = 25.7 ± 2.8 in]). No significant differences were found for unilateral VJ testing or hop testing (all p > 0.05).

CONCLUSIONS: Results from the current study suggest that professional soccer players with an asymmetry of 2 cm or greater in DFROM may have decreased bilateral VJ height, but not unilateral VJ or single leg hop test performance. These results suggest that DFROM asymmetries may affect performance on tasks that require power and coordination from both limbs to produce vertical motion, as opposed to single limb tasks.