Longitudinal assessments of balance and jump-landing performance before and after anterior cruciate ligament injuries in collegiate athletes.

The purpose was to quantify the effect of an anterior cruciate ligament (ACL) injury on balance and jump-landing performance and bilateral asymmetries. Among 500 collegiate athletes who performed a reaching test and a double-leg counter-movement jump-landing test at baseline, 8 male and 6 female athletes suffered ACL injuries. In the follow-up, they performed the reaching test 3 and 6 months after ACL reconstruction (ACLR) and the jump-landing test 6 months after ACLR. Less reaching distances for the injured leg and increased reaching distance asymmetries were observed 3 and 6 months after ACLR compared to baseline. Less peak jumping and landing forces for the injured leg and increased jumping and landing force asymmetries were found 6 months after ACLR compared to baseline. The decreased performance of the injured leg and increased asymmetries may contribute to the high ACL re-injury rates. Baseline assessments would be useful for establishing an individual's pre-injury performance.

Using trunk kinematics to predict kinetic asymmetries during double-leg jump-landings in collegiate athletes following anterior cruciate ligament reconstruction.

BACKGROUND: Bilateral vertical ground reaction force (VGRF) and knee extension moment asymmetries are commonly observed during jumping and landing tasks following anterior cruciate ligament (ACL) reconstructions (ACLR) in collegiate athletes. Kinetic asymmetries during landings are associated with increased ACL re-injury risk. Efforts have been made to predict bilateral kinetic asymmetries using trunk kinematics during squats but not during jump-landings. RESEARCH QUESTION: To determine the correlations between trunk kinematics (medial-lateral shoulder positions, medial-lateral hip positions, and lateral trunk bending angles) and bilateral kinetic asymmetries (VGRF and knee extension moments) during double-leg jump-landings in collegiate athletes following ACLR. METHODS: Fifteen National Collegiate Athletic Association Division I athletes who had ACLR in the past 24 months participated. Eleven of them performed two assessments over the study period for a total of 26 assessments for data analyses. Athletes performed three double-leg countermovement jumps. Kinematics and kinetics data were collected. Medial-lateral shoulder and hip positions relative to ankle positions, lateral trunk bending angles, and kinetic asymmetries were calculated during the jumping (the lowest hip position until takeoff) and landing (the first 100 ms after initial contact) phases. RESULTS: Medial-lateral shoulder positions correlated with VGRF (r = 0.63, p < 0.001) and knee moment asymmetries (r = 0.53, p = 0.006) in the jumping phase. Medial-lateral hip positions correlated with VGRF (r = 0.61, p < 0.001; r = 0.52, p = 0.006) and knee moment asymmetries (r = 0.55, p = 0.004; r = 0.61, p < 0.001) in both jumping and landing phases. SIGNIFICANCE: Medial-lateral hip positions correlated with kinetic asymmetries during double-leg jump-landings in collegiate athletes following ACLR. A 2D assessment using a standard video camera might be used as a low-cost and clinically applicable tool to assess bilateral kinetic asymmetries by quantifying medial-lateral hip positions during jump-landings following ACLR.

Jump-landing kinetic asymmetries persisted despite symmetric squat kinetics in collegiate athletes following anterior cruciate ligament reconstruction.

The purpose was to determine the differences/correlations in anterior cruciate ligament (ACL) loading variables and bilateral asymmetries between injured/uninjured legs and among ascending/descending phases of double-leg squats and jumping/landing phases of countermovement jumps (CMJ) in the collegiate athletes following ACL reconstruction (ACLR). Fourteen collegiate athletes performed squats and CMJ 6-14 months following ACLR. The bilateral knee/hip flexion angles, peak vertical ground reaction force (VGRF) and knee extension moments (KEM), and kinetic asymmetries were calculated. Squats showed the greatest knee/hip flexion angles, while the landing phase of CMJ showed the least (P<0.001). The uninjured leg demonstrated greater VGRF (P≤0.010) and KEM (P≤0.008) than the injured leg in CMJ. Kinetic asymmetries were less than 10% for squats but were greater for the jumping (P≤0.014, 12%-25%) and landing (P≤0.047, 16%-27%) phases of CMJ. Significant correlations were found for KEM asymmetries between phases of CMJ (P=0.050) and squats (P<0.001). Kinetic asymmetries persisted in CMJ, while kinetic symmetries were achieved in squats in collegiate athletes 6-14 months following ACLR. Therefore, the CMJ appears to be a more sensitive assessment to monitor the bilateral kinetic asymmetries compared to squats. It is suggested to assess and screen kinetic asymmetries in different phases and tasks.

Longitudinal assessments of strength and dynamic balance from pre-injury baseline to 3 and 4 months after labrum repairs in collegiate athletes.

BACKGROUND: There is a lack of quantitative assessments of athletes' functional strength and dynamic balance following labrum repairs. PURPOSE: To compare the upper extremity strength and dynamic balance among pre-injury baseline and approximately 3 and 4 months after labrum surgeries in collegiate athletes to identify critical values to inform rehabilitation. METHODS: Fifteen male and one female collegiate athletes between 18 and 22 years old were tested at pre-injury baseline (n = 14) and 2.7 (n = 16) and 3.8 months (n = 12) after labrum surgeries. Strength was assessed using the peak forces produced in a maximal push-up test. Dynamic balance was assessed using the reaching distances in a reaching test. RESULTS: The injured side's peak forces significantly decreased from the baseline to the 3-month post-surgery and then significantly increased between the 3-month and 4-month post-surgery assessments but remained significantly less at the 4-month post-surgery compared to the baseline (p ≤ 0.024; Cohen's dz ≥ 0.75). Peak force asymmetries were greater at the 3-month and 4-month post-surgery assessments than the baseline (p ≤ 0.005; Cohen's dz ≥ 1.02). CONCLUSION: With a relatively small sample size, the results support the use of objective functional assessments for rehabilitation and return-to-play decisions among collegiate athletes following labrum repairs.

Medial-lateral hip positions predicted kinetic asymmetries during double-leg squats in collegiate athletes following anterior cruciate ligament reconstruction.

ACL re-injury rates are high in collegiate athletes, and double-leg squats have been used as a functional weight-bearing exercise to strengthen the lower extremities and assess bilateral kinetic asymmetries. The primary purpose was to quantify the correlations between medial-lateral shoulder/hip positions and lateral bending angles and bilateral asymmetries in vertical ground reaction forces (VGRF) and knee extension moments during double-leg squats in collegiate athletes at two assessments following anterior cruciate ligament reconstruction (ACLR). Seventeen National Collegiate Athletic Association Division I athletes performed double-leg squats between 0 and 6 months and/or between 6 and 12 months following their ACLR while kinematic and kinetic data were collected. Medial-lateral shoulder positions strongly and significantly correlated with VGRF asymmetries at both assessments (p ≤ 0.007, r ≥ 0.68). Medial-lateral hip positions strongly and significantly correlated with VGRF asymmetries and knee moment asymmetries at both assessments (p ≤ 0.018, r ≥ 0.62). Additionally, participants demonstrated decreased VGRF asymmetries and knee moment asymmetries, more neutral shoulder and hip positions, and increased knee moments for the injured leg at the second assessment compared to the first assessment with large effect sizes (p ≤ 0.008, Cohen's d ≥ 1.06). In conclusion, medial-lateral hip positions correlated and predicted VGRF and knee moment asymmetries during double-leg squats in collegiate athletes at two assessments (0-6 and 6-12 months) following ACLR. The bilateral asymmetries support the need for an individual approach for kinetic asymmetry assessments. A commercially available camera can be utilized as a low-cost and convenient tool to monitor and potentially train bilateral kinetic symmetries during double-leg squats in patients following ACLR.