Fastest man in the world

A short while ago I posed the question as to who really is the fastest man in the world. One of the comments made by a reader was that just because Usain Bolt is the fastest 100m runner in the world it does not necessarily follow that he has the greatest top speed in the world. This reader went on to make the point that the reason why Bolts superior sprint performance is particularly apparent in the second half of his races may be primarily due to his ability to hold his top speed for a greater length of time than his competitors. Is it possible that Bolt does not reach greater top speeds than his rivals, but once having reached his maximum speed he maintains it for longer?

The official analysis from the 2009 World Championships Mens 100m Final shows that Bolt took 1.61 seconds to cover the distance between the 60m and 80m points in the race. This was the fastest 20 segment recorded in the race (0.2 seconds faster than Tyson Gay ran for the same section). With regard to the ability to maintain this maximum speed, Bolt slowed down by 0.5 seconds in the final 20m section whereas Gay slowed down by 0.6 seconds. This suggests that the ability to achieve a greater maximum speed as well as a greater ability to maintain this speed contributes to Usain Bolts superior performance in the second half of 100m races.

However, I would like to draw your attention to another point that was made. The readers comment highlighted the fact that there are two distinct factors to consider: speed whilst the athlete is in contact with the ground and speed whilst the athlete is in full flight.

In actual fact, even during the so called maximum speed phase of sprinting there will be a constant fluctuation in running velocity. This is because it is only possible for an athlete to accelerate his centre of mass forward whilst he is in contact with the ground. As soon as the flight phase of the running stride begins the athlete will start to decelerate. Deceleration during the flight phase occurs due to the effect of wind resistance (along with the absense of any propulsive forces).

An athlete may be able to maintain maximum speed, from stride to stride, for around 15 metres. But during this maximum speed phase his running speed will actually fluctuate within each stride. This adds another dimension that must be considered when determining the identity of the fastest man in the world.

If two athletes are able to achieve the same 'stride to stride maximum speed', the athlete who truely achieves the greatest maximum speed will be the one with the greatest variability in speed within each stride. The main factor that will contribute to a large variability in speed within each stride is the duration of the flight phase. A longer flight phase results in a greater decrease in speed. If two athletes achieve the same 'stride to stride maximum speed', the athlete who has a greater decrease in speed during the flight phase will have to compensate for this by achieving a greater speed at the point of take off (at the end of the ground contact phase).

STRENGTH AND CONDITIONING CONSULTANCY - TIM EGERTON HIGH PERFORMANCE COACHING SERVICES