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Derek Maddy

December 10, 2019 @ 2:00 pm - 3:00 pm MST

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Thesis Information

Title: Analyzing Change-of-Direction and the Laterally Resisted Split Squat: Incorporating a Lateral Vector into the Single Leg Squat

Program: Master of Science in Kinesiology

Advisor: Dr. Shawn Simonson, Kinesiology

Committee Members: Dr. Tyler Brown, Kinesiology and Dr. Dave Hammons, Kinesiology


Improving change of direction (COD) with the use of strength training has seen 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 45-75º frontal plane angle; however, the MSLS and BS are performed at a 90º 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 screening test to minimize the motor learning effect. Participant’s weight and 1RM (using Bryzcki formula/technique) for the LRSS, MSLS, and BS were measured. After rest, 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, vector angle, and eccentric-concentric (ECC-CON) magnitude. Peak GRF magnitude was significantly larger in COD (47.32±8.32) than the LRSS (25.65±2.34; p < 0.001), MSLS (29.66±2.34; p = 0.001), and BS (20.96±2.51; p < 0.001). COD (66.70±4.98) revealed no significant difference in vector angle to 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). ECC-CON magnitude revealed no significant difference between COD (13.24±6.77), LRSS (7.54±2.19; p = 0.262), MSLS (5.66±1.18; p = 0.072) and BS (9.50±3.22; p = 0.621). In an application of the force vector theory, the LRSS more closely matches COD than the MSLS or BS.