Abstract: This study investigated the maximal sprint velocity kinematics of the fastest 100 m sprinter, Usain Bolt. Two high-speed video cameras recorded kinematics from 60 to 90 m during the men 100 m final at the IAAF World Challenge Zagreb 2011, Croatia. Despite a relatively slow reaction time (194 ms), Bolt won in 9.85 s (mean velocity: 10.15 m/s). His fastest 20-m section velocity was 12.14 m/s, reached between 70 and 90 m, by 2.70-m long strides and 4.36 strides/s frequency. At the maximal velocity, his contact and flight times were 86 and 145 ms, respectively, and vertical ground reaction force generated equalled 4.2 times his body weight (3932 N). The braking and propulsion phase represented 37% and 63% of ground contact, respectively, with his centre of mass (CoM) exhibiting minor reductions in horizontal velocity (2.7%) and minimal vertical displacement (4.9 cm). Emerged Bolt’s maximal sprint velocity and international predominance from coordinated motor abilities, power generation capacities, and effective technique. This study confirms that his maximal velocity was achieved by means of relatively long strides, minimal braking phase, high vertical ground reaction force, and minimal vertical displacement of CoM. This study is the first in-depth bio-mechanical analysis of Bolt’s maximal sprinting velocity with the segmental reconstruction.
These findings reinforce those of numerous other studies that highlighted the key factors in determining the maximum mph speed of athletes: proper form to make certain that the maximum amount of available GRF (ground reaction force) is applied at the right time, in the right direction, and in the the shortest possible GCT (ground contact time). At maximum speed, nearly 100 percent of ground force requirements are in a vertical direction to quickly minimize braking forces at ground contact, overcome the force of gravity, and propel the body back up into the air. For elite sprint performance, this requires a vertically-directed ground reaction force of over four times the body weight of athletes. Training to improve form and technique and maximum power generation (vertically-directed ground reaction force) is the key to a higher top-end speed for athletes in all sports.
Milan Čoh, Kim Hébert-Losier, Stanko Štuhec, and Vesna Babić. 2018. Kinemartics of Usain Bolt’s Maximal Sprint Velocity. Kinesiology Vol. 50, No.2 Prosinac.