Analyzing Change-of-Direction and the Laterally Resisted Split Squat

Improving change of direction (COD) with the use of strength training has led to mixed results. To date, the modified single leg squat (MSLS) and the bilateral squat (BS) have been successfully used to improve COD, with equal improvement. COD is primarily performed at a 45-75° frontal plane angle; however, the MSLS and BS are performed at a 90° frontal plane angle. Based on the force vector theory, it is proposed that a more mechanically similar strength training exercise, the Laterally Resisted Split Squat (LRSS), be used. The purpose of this study is to compare COD with the LRSS, MSLS, and the BS via kinetic measurements. Ten healthy and recreationally active female individuals volunteered for this study. Participants were pre-screened using a COD test to verify proper mechanics. Participant's weight was measured and 1RM (using Bryzcki formula/technique) for the LRSS, MSLS, and BS calculated. Peak ground reaction force (GRF) of participant's dominant leg in the frontal plane for COD and the three exercises at 70% 1RM was collected and used to calculate peak magnitude and vector angle. Peak GRF magnitude was significantly larger in COD (2.13 ± 0.52 bodyweight: BW) than the LRSS (0.85 ± 0.07 BW; p < 0.001), MSLS (0.99 ± 0.10 BW; p = 0.001), and BS (0.52 ± 0.07 BW; p < 0.001). COD (66.70° ± 4.98°) vector angle was not significantly difference than the LRSS (74.94° ± 4.11°; p = 0.057) as compared to the MSLS (89.04° ± 0.48°; p < 0.001) and BS (82.69° ± 4.30°; p < 0.001). In an application of the force vector theory, the LRSS more closely matches COD than the MSLS or BS.