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Influence of Towing Force Magnitude on the Kinematics of Supramaximal Sprinting

Clark, David A1; Sabick, Michelle B1,2; Pfeiffer, Ronald P1,3; Kuhlman, Seth M1; Knigge, Nicole A1; Shea, Kevin G4

Journal of Strength & Conditioning Research: July 2009 - Volume 23 - Issue 4 - pp 1162-1168
doi: 10.1519/JSC.0b013e318194df84
Original Research

Clark, DA, Sabick, MB, Pfeiffer, RP, Kuhlman, SM, Knigge, NA, and Shea, KG. Influence of towing force magnitude on the kinematics of supramaximal sprinting. J Strength Cond Res 23(4): 1162-1168, 2009-The purpose of this study was to determine the influence of towing force magnitude on the kinematics of supramaximal sprinting. Ten high school and college-age track and field athletes (6 men, 4 women) ran 60-m maximal sprints under 5 different conditions: Nontowed, Tow A (2.0% body weight [BW]), Tow B (2.8% BW), Tow C (3.8% BW), and Tow D (4.7% BW). Three-dimensional kinematics of a 4-segment model of the right side of the body were collected starting at the 35-m point of the trial using high-speed (250 Hz) optical cameras. Significant differences (p < 0.05) were observed in stride length and horizontal velocity of the center of mass during Tow C and Tow D. For Tow D, a significant increase (p = 0.046) in the distance from the center of mass to the foot at touchdown was also observed. Contact time decreased significantly in all towing conditions (p < 0.01), whereas stride rate increased only slightly (<2.0%) under towed conditions. There were no significant changes in joint or segment angles at touchdown, with the exception of a significant decrease (p = 0.044) in the flexion/extension angle at the hip during the Tow D condition. We conclude that towing force magnitude does influence the kinematics of supramaximal running and that potentially negative training effects may arise from towing individuals with a force in excess of 3.8% BW. Therefore, we suggest that coaches and practitioners adjust towing force magnitude for each individual and avoid using towing forces in excess of 3.8% of the athlete's BW.

1Center for Orthopaedic and Biomechanics Research, 2Department of Mechanical and Biomedical Engineering, and 3Department of Kinesiology, Boise State University, Boise, Idaho; and 4Intermountain Orthopaedics, Boise, Idaho

Address correspondence to David Clark, davz289@yahoo.com.

© 2009 National Strength and Conditioning Association