A Biomechanical Analysis of Four Sprint Start Positions

Abstract

The sprint starts of 12 skilled collegiate sprinter/hurdlers were filmed for four different sprint start conditions. Ground reaction forces were collected for the first step out of the blocks and velocities through a 2-m speed trap immediately following the first support phase were recorded. The subjects employed their preferred right-left leg placement in the blocks, while the anterior-posterior spacing of the front block with respect to the starting line and the amount of forward lean in the set position were varied. Four positions were constructed that accounted for anthropometric differences. The four positions consisted of combinations of two arm orientations (forward lean and perpendicular to ground) and two front block to starting line distances (bunched and elongated). Kinematic data were reduced to provide center of mass position and velocity measures and analyzed for critical periods throughout the starting action. Selected critical events from the first step kinetic records were also analyzed. The results indicated that the elongated starting positions resulted in greater horizontal displacement, greater propelling impulse, increased first step toe-off velocity, and greater average velocity through a 2-m speed trap. Arm orientation effects were less well defined. Forward lean tended to result in greater vertical velocity at block clearance and horizontal velocity at first step toe-off, whereas perpendicular arm positioning resulted in greater 2-m speed trap velocity.

Biomechanical structure of sprint start and effect of biological feedback methods on sprint start performance

“…It is seen that different sprint start positions were suggested in each different study (5,16,27,28,41). These studies were conducted on highly different study samples (male, female, young, adult, amateur, elite athletes), accordingly results of the studies showed variations depending on the biomechanical, morphological and anthropometric characteristics of these athletes.…”

“…Moreover, maximal and mean horizontal propulsive force generation capacities are said to be the main factor that seperates talented athletes from others (7). Therefore, ideal sprint start position that leads to maximal and mean propulsive forces should be assessed precisely considering inter-individual differences since this position is greatly affected by anthropometric measures of athletes (8,41).…”

“…It was found that sprint start position and kinetic variables of the onset of the sprint start had effects on acceleration measures during the sprint. Schot and Knutzen (41) concluded that propulsive force applied onto the front starting block, reaction time and block velocity were the most crucial variables that should be developed to acquire an effective and efficient sprint start. It was also shown that significant differences were existed in set positions relative hip height and knee joint angle between males and females.…”

“…Coh et al (5) suggested athletes to adjust their sprint start position according to reference points identified in the study of Schot and Knutzen (41). According to Schot and Knutzen (41) vertical distance between running track and center of body mass should be 54.4 ± 6.2 cm in males and 53.2 ± 2.0 cm in females; horizontal distance between projection of center of mass and starting line should be 18.8 ± 5.1 cm in males and 15.7 ± 3.0 cm in females; knee joint angle of rear leg should be 112° ± 13.3° in males and 115° ± 13.8° in females.…”

“…Hence, many investigators studied the biomechanical components of these two phases to clarify the determinants of sprint velocity (13,16,29,30,33,41,45).…”