Neuromuscular Timing during Drop Jumps Between Healthy Women And Women With Semitendinosus-gracilis ACL Reconstruction

Abstract

Anterior Cruciate Ligament (ACL) reconstruction with hamstring-gracilis (SG) autograft is one of the preferred surgical options in women advocating the return of knee stability. These women have shown neuromuscular compensatory strategies to maintain knee stability during landing tasks. PURPOSE: To identify neuromuscular timing imbalances of the quadriceps and hamstrings muscle groups during landing from a bilateral and single-legged drop jumps between women 1-5 years post SG ACL reconstruction and non-injured women. METHODS: Twenty-nine young women (non-injured = 15, SG = 14) performed five trials of a double-legged and single-legged drop jumps from a 60-cm and 40-cm height box, respectively. Participants had five bipolar Ag pre-amplified surface electromyography (EMG) electrodes attached on the skin over the vastus medialis, vastus lateralis, rectus femoris, medial and lateral hamstrings on the dominant leg for the non-injured women and in the reconstructed leg for women with ACL surgery. EMG data was collected at 1kHz. Data from all the quadriceps and hamstring muscles were averaged to represent each muscle group in its entirety. The time taken in seconds to reach peak EMG activity (latency) during the ground contact phase after landing was the variable of interest. Data was screened for normality and outliers previous to analyses. After data screening, independent t-tests were used to compare latency of the quadriceps and hamstrings between groups for both tasks. RESULTS: Twenty-seven participants were included for the double drop jump comparisons; a total of 26 participants were included in single-leg drop jump comparisons. No statistically significant differences during the double drop jump for latency of the quadriceps (control:.1709 ±.11805, SG:.1498 ±.17775; p = 0.734) and hamstrings (control:.2233 ±.13017, SG:.1990 ±.21555; p = 0.744) were found. Neither quadriceps (control:.3204 ±.16475, SG:.2175 ±.14024; p = 0.098) or hamstrings (control:.3692 ±.21629, SG:.2373 ±.16549; p = 0.091) latency comparisons reached statistical significance during the single leg drop jump. CONCLUSIONS: It appears that women with SG ACL reconstruction possess similar neuromuscular timing patterns for the quadriceps and hamstrings than women without knee surgery during double and single legged landings.