Abstract
The aim of this study was to test the influence of 3 different horizontal distances
between the blocks (bunched, medium and elongated) on the velocity of the centre of
mass (VCM) and the kinetic energy (KE) of the body segments and of the whole body. 9 well-trained
sprinters performed 4 maximal 10 m sprints. An opto-electronic Motion Analysis® system (12 digital cameras 250 Hz) was used to collect the 3D trajectories of 63
markers during the starting block phase. The results demonstrated that the elongated
start, compared to the bunched or medium start, induced an increase of VCM at block clearing (2.89±0.13; 2.76±0.11; 2.84±0.14 m.s − 1) and a decrease of the performance at 5 and 10 m. Both results were explained by
a greater pushing time on the blocks in the elongated condition. During the starting
block phase, the KE of the whole body was greater in the elongated start (324.3±48.0 J
vs. 317.4±57.2 J, bunched and 302.1±53.2 J, medium). This greater KE of the whole
body was mainly explained by the KE of the head-trunk segments. Thus, to improve the
efficiency of the starting block phase, the athlete must produce greater KE of the
head and trunk segments in the shortest time.
Key words
sprint - running - performance - start - biomechanics
