KINEMATIC DIFFERENCES IN THE SPRINT START AND INITIAL ACCELERATION PHASE ON THE STRAIGHT AND BEND

Abstract

The study aimed to investigate differences in the kinematics of the sprint start and initial acceleration phase on the straight and a banked indoor-bend running track. The sprint start and initial acceleration phase has been thoroughly investigated in previous research. However, a limited insight into the biomechanics of the sprint start and initial acceleration phase on the bend has been achieved. Three participants were tested (mean ± sd: age 19.7 ± 1 yr; body mass 74.7 ± 9.0 kg; height 1.81 ± 0.03 m; 100/200 m personal best time: 11.64/22.95 s). Data was collected using an automatic motion analysis system during a typical sprint training session. Active markers were located lateral to the fifth metatarsal-phalangeal (MTP) joint, lateral malleolus, lateral condyle of the tibia, greater trochanter, greater tubercle, olecranon process of the ulna and proximal to the hand (for the wrist). Data was collected for step characteristics and joint kinematics on two separate occasions, during which participants completed four maximal effort sprints over 15 m from blocks on the straight (session one) and on the bend (session two). Normality of residuals was confirmed for selected variables using the Anderson-Darling test ensuring the appropriateness of parametric tests. A paired samples t-test was used to assess differences and Pearson’s product moment correlation was used to assess the relationship between selected variables, using an α priori of 0.05. An absolute performance differential of 0.07 s was found between time to 10 m on the straight and bend, participant 2 was quicker on the bend. Ankle, knee and hip extension patterns were consistent with previous research on the straight and bend but peak values were consistently higher on the bend than on the straight (up to 10°). Mean horizontal velocity at the 10 m mark was significantly different on the straight and bend (p <0.05) (7.36 m/s on the straight versus 7.08 m/s on the bend). Block velocity was significantly lower (p <0.05) on the bend than on the straight (3.15 m/s on the straight versus 2.99 m/s on the bend). Although differences in step characteristics and joint kinematics were observed in the sprint start and initial acceleration phase between conditions, the research design could not distinguish between the bend or coach interventions as the cause of difference. Future research could aim to measure the underlying forces behind the movement, in an attempt to better understand the biomechanical differences in the start and initial acceleration phase on the straight and bend.