title: Influence of towing force magnitude on the kinematics of supramaximal sprinting.
abstract: 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.
authors.affiliation: Center for Orthopaedic and Biomechanics Research, Boise State University, Boise, Idaho, USA. davz289@yahoo.com
authors.forename: David A
authors.initials: DA
authors.lastname: Clark
authors.forename: Michelle B
authors.initials: MB
authors.lastname: Sabick
authors.forename: Ronald P
authors.initials: RP
authors.lastname: Pfeiffer
authors.forename: Seth M
authors.initials: SM
authors.lastname: Kuhlman
authors.forename: Nicole A
authors.initials: NA
authors.lastname: Knigge
authors.forename: Kevin G
authors.initials: KG
authors.lastname: Shea
mesh_terms: D000293:Adolescent; D000704:Analysis of Variance; D001696:Biomechanical Phenomena; D001835:Body Weight; D005260:Female; D006801:Humans; D008297:Male; D010806:Physical Education and Training / Q000379:methods; D012420:Running / Q000502:physiology*; D016474:Weight-Bearing / Q000502:physiology*; D055815:Young Adult