Bilateral Symmetry Analysis Of Tibial Accelerations During Single Leg Hop For Distance In Healthy Collegiate Soccer Players

Abstract

Bilateral comparative analysis has commonly been used to aid return-to-sport (RTS) decision making during functional testing. Different symmetry thresholds have been used as a criteria to determine RTS, however, knowledge of normative symmetries are prerequisite to establishing any criterion. Normative bilateral symmetry of tibial acceleration metrics during the single leg hop for distance (SLH) have never been reported. PURPOSE: To determine if bilateral differences exist in tibial acceleration metrics (PA: peak acceleration, TPA: time to peak acceleration, AS: acceleration slope) during the SLH and to report normative symmetry within a healthy group of collegiate soccer players. METHODS: Twenty-four collegiate soccer players (4F, 20 M; 19.5 ± 1.2 yrs) granted informed consent and performed three SLH trials with both legs (D = dominant, ND = non-dominant) while wearing inertial measurement units (IMU; 9.5 g, 1500 Hz) fixated with a silicon strap 3-cm proximal to both medial malleoli. A Matlab script processed triaxial acceleration data for the SLH of greatest distance with a 60-Hz, fourth-order, dual-pass Butterworth filter before resultant acceleration was computed. Bilateral PA, TPTA and AS were tested for significant differences between legs with a series of paired t-tests. Significance level was set apriori at 0.05. Symmetry angle % was then computed for hop distance and all tibial acceleration metrics. RESULTS: Hop distance (D: 53.8 ± 7.6 cm, ND: 54.4 ± 7.3 cm, p = 0.42), PTA (D: 35.5 ± 5.4 g, ND: 38.3 ± 10.1 g, p = 0.06), TPTA (D: 15.9 ± 5.2 ms, ND: 16.5 ± 6.1 ms) and AS (D: 3233.0 ± 1222.2 g/ms, ND: 2990.3 ± 1233.9 g/ms) did not significantly differ between legs. All average symmetry angle %s were < 10% (hop distance: 1.6 ± 1.5%; PTA: 4.0 ± 3.8%; TPTA: 8.0 ± 7.5%; AS 9.1 ± 5.9%). CONCLUSIONS: Within a group of healthy collegiate soccer players, no significant differences in either hop distance or tibial acceleration metrics existed when comparing dominant and non-dominant legs. Seven of the participants (29.2%) displayed bilateral differences in peak tibial acceleration greater than the MDC95 level indicating a meaningful difference. Clinicians are encouraged to perform baseline testing to establish player-specific symmetry angle %s for establishing RTS criteria in tibial acceleration metrics during the SLH.