Every 4 years we get to see one of the greatest and shortest sporting events on TV. The world stops to see 8 of the fastest sprinters come together as they race to determine who the fastest man on Earth is. Usain Bolt has dominated the last 2 Olympics running 9.69 & 9.63 and now just days ago wins his 3rd Olympic 100m gold medal running a 9.81sec. Not to mention his fastest time and World Record of 9.58 in 2009. But what makes Usain Bolt the fastest man on Earth?

A paper by Taylor & Beneke, [1] set out to model the characteristics of the three fastest sprinters on the planet, Usain Bolt, Tyson Gay and Asafa Powell. The data used was from the 2009 World Championships where Usain Bolt set his World Record. The authors of this paper adopted the spring mass model to identify what characteristics make these athletes so talented.

Anthropometric Data

Estimated Spring Mass Model Characteristics

The above parameters of the spring mass model may not make any sense now but bear with us. All will be explained throughout this article. The first characteristics that stands out is the body mass and stature of Usain Bolt compared to his competitors.

Body Mass & Height

From the data above it is clear that Usain Bolt has impressive body stats in regards to body mass and height, that literally dwarf his competition. In a previous article we discussed the physics of force production, where force = mass x acceleration (F=ma).

Before even lining up at the starting blocks, Usain Bolt’s body mass has already given him a hefty weight advantage to generate more force over his smaller competitors. This additional body mass naturally gives Usain Bolt the ability to generate significantly greater forces than his competitors. The key here is being able to harness the additional mass and transfer this into additional force production and not slow down acceleration.

Centre of Mass Height: ΔYc (m)

Studies have shown that world record holders in the 100m sprint are becoming taller and heavier and these are becoming significant factors of success when characterising athletic success [2, 3]. It has been suggested that it is the height from which the centre of mass falls from, which is indicative of sprinting performance. The results of this study provide further evidence to this theory, with Usain Bolt having a greater maximal downward displacement of his centre of mass during ground contact over Tyson Gay and Asafa Powell.

Ground Contact Time: Tc (s)

The data derived from this study [1] has highlighted Usain Bolts running technique produces longer ground contact times, 0.021 seconds and 0.011 seconds longer than Tyson Gay and Asafa Powell respectively. This is contrary to the commonly held premise that shorter ground contact times generated larger vertical forces and in turn faster runners. In scientific speak, Usain Bolt is generating a larger impulse (Force x Time), due to the longer ground contact period. This longer contact time reduces the peak force loading and allows Usain Bolt to generate greater speed and acceleration at lower forces per unit of bodyweight.

Leg Stiffness: Kleg (kN.m-1)

The estimated leg stiffness of Usain Bolt, Asafa Powell and Tyson Gay from this study is 3.8-5.7 times larger than for slower sprinters [4]. The most interesting finding from this data was that Usain Bolt had a significantly lower leg stiffness than his two competitors. This decrease in lower leg stiffness of Usain Bolt is attributed to the larger ground contact times.

Force production: Fmax (kN) & Kvert (kN.m-1)

Of the three athletes analysed Usain Bolt produced the largest force of 3.6kN during the race. When we compare the athletes force production vs body weight, Usain Bolts maximum force per body weight is actually lower. However, this where the larger body mass comes into play of naturally generating more force over a smaller individual. So due to the share size of Usain Bolt, he is able to produce significantly more force than his competitors.

Why is this important? A recent paper by Slawinski et al., [5] analysed multiple international 100m races and athletes from 1987 through to 2012 including Usain Bolts 2009 World Record Performance. They state “The ability to maintain maximal speed until crossing the finish line during sprint running depends on the capability to maintain a high level of force production or power output despite the fatigue induced physiological and/or neural alterations.” This is backed up by their analysis as maximal sprinting velocity (Vmax) and mean power (W/kg) produced over the 100m significantly influenced 100m sprint performance. Meaning, the ability to produce force at high speeds. World class performances require a maximal velocity for men that reach more than 41.5km/h and 37.4km/h for women. Usain Bolt reached 43.9km/h in his World Record performance in 2009.

Here are the split times and velocities for Usain Bolt and Asafa Powell from Usain’s 9.58sec world record performance in 2009 taken from Applied Sprint Training by James Smith [6].

Split Times (sec)

Velocities (m/s)

Reaching a higher Vmax later in the race requires the ability to keep accelerating despite the increase in running velocity. Therefore, athletes need the capability to produce horizontal force onto the ground at very high velocities. This is considered a crucial factor in 100m race performance [5]. An increase in the acceleration phase duration allows athletes to reach Vmax later in the race reducing the effect of fatigue on performance.

Usain Bolt possesses all of these traits. He is able to reach a higher maximal velocity later in the race compared to other sprinters. As you can see above, Bolt reaches is maximum velocity at 70m (12.35m/s) while Powell reaches his at 60m (11.90m/s). Hence he accelerates longer than anyone else to a speed faster than anyone else, showcasing the ability to keep producing high amounts of horizontal force at very high velocities. Which is why you often see him cruising to the finish line as other sprinters have started decelerating much earlier in the race compared to him.

All of the characteristics listed above culminate to make Usain Bolt the greatest outlier of elite sprinters to date. Ranging from the stature and body mass of the man, to the kinetics (forces) and kinematics (motions) of his sprint performances, Usain Bolt seems to fly against the characteristics of high level sprinters which generally possess short ground contact times, high leg stiffness and the ability to produce force in a short amount of time. The findings from the study by Taylor & Beneke [1] open a number of questions for further research as to how to we should be best training our sprinters. Would training sprinters to sprint like Usain Bolt create more world-class sprinters or is it the fact his anthropometric characteristics are so different to his competitors? We can’t be sure, but we can be sure the 3x 100m Olympic gold medalist is the fastest man on Earth.

HERE is an awesome little interactive graphic showing the whole 100m final at the Rio 2016 Olympics.