The Biomechanical Breakdown of Bolt’s Race

August 8, 2012

Usain Bolt could run the 100m dash in 9.44s, given the right legal conditions, claims Cambridge mathematician, Professor John Barrow…if only he could get off the starting blocks a little bit quicker.

The Acceleration Phase (0-30m)

Unfortunately for Bolt, the sprint start and the acceleration phase account for 64% of the total result in the 100m dash. This creates a major disadvantage for taller sprinters, who are often poor starters.

Bolt’s reaction times are generally much slower than the 0.1s allowed and physics noticeably hampers him during the acceleration phase.

The Physics:

The acceleration is proportional to the force produced when pushing off the blocks but there is an inverse relationship between acceleration and body mass.

This means that height is a disadvantage because the force also has to overcome the drag produced by a bigger body.

Sprinters with well-developed, strong muscles attached to shorter limbs promote more rapid movements and a greater force, which gives them an initial advantage.

Maximum Velocity Phase (30-60m)

During this phase the runners are upright, well away from the blocks and are attempting to reach their top speed, which is achieved through a combination of stride length and stride rate.

This is where a taller sprinter has the potential to catch up – long limbs and good flexibility alone achieve half of the speed formula.

Bolt’s gangly limbs suddenly become an advantage, meaning he can reach 44km/h during this phase and can pull ahead, despite his poor start.

It also explains why Bolt does not achieve the same kind of success in the 60m dash as he does at longer sprint races: he is still catching up at the beginning of this phase!

Speed Maintenance Phase (60-100m)

The final phase is all about speed maintenance and Bolt himself has stated that if he is ahead at 60m, the other contenders simply don’t stand a chance.

Bolt is able to maintain his pace exceptionally well and in the Olympic 100m final Bolt completed the race in just 41 steps, compared to Blake’s 46 steps.

In the 200m final Bolt’s poor start will be even less of a factor…Thursday 9th at 8.55pm BBC1

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Posted by Jenny Gawley

What do frogs and archers have in common?

July 31, 2012

Elastic energy!  For those who’ve forgotten their school physics –or never paid attention!-  elastic energy is potential mechanical energy that can be stored when work is performed to stretch or compress an object or physical system.

How does the frog do it?

As a frog prepares to leap, the calf muscle shortens and pulls on the tendon, which is wrapped tightly around the ankle bone.  After a fraction of a second the calf muscle stops moving and the energy is fully loaded onto the stretched tendon. When the frog jumps, the elastic energy is released like a catapult, propelling the frog forward!

Frog fact: Frogs can jump amazing distances -in some cases up to 50 times their body length, which is the equivalent to a human jumping the length of a football field from a standing position!

How does the archer do it?

The archer creates the elastic potential by drawing the bowstring back, changing the configuration of the bow. The force is stored in the distorted shape until the archer decides to release the bowstring, just as the energy is stored in the frog’s tendon until it decides to leap! The arrow is then propelled at a much greater speed than muscles alone could achieve, projecting the arrow much further.

Archer fact: Archers competing in the London Olympics will be aiming their bows at targets approximately 70m away, a distance impossible to reach if they relied on the kinetic energy of the muscles.

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Posted by Jenny Gawley

Olympics Countdown: Why the dopers are heading for disaster

June 28, 2012

What is drug doping?

The International Olympic committee (IOC) define drug doping as the use of any method or substance that might harm the athlete, in a quest to gain an unfair advantage over their fellow competitors.

What methods are used?

Typically, cheats use performance enhancing drugs or blood doping. The performance enhancing drugs are usually stimulants, which increase alertness and physical activity, or steroids, which increase muscle mass. Blood doping involves undergoing a blood transfusion in order to acquire a higher red blood cell count, allowing extra oxygen to be carried to the muscles.

How are drug cheats caught?

Two urine samples are obtained from athletes and analysed using gas chromatography (which separates the contents of the sample) and mass spectrometry (which provides the exact molecular specification of the compound). If a banned substance is identified in both samples a positive result is declared.

Blood testing is also used to detect banned substances and to build a ‘blood profile’ over time for an individual athlete. This is used to determine average readings for the athlete and any significant changes that could indicate blood doping.

What’s so special about London 2012?

For the first time, a private sponsor -GlaxoSmithKline (GSK)- will be providing what are considered to be the most hi-tech laboratory facilities in Olympic history, at a cost of more than $30 million. GSK will test over 6,250 samples of blood and urine during the London Olympics, compared to 4,500 in Beijing, and 150 scientists will be on duty around the clock.

London 2012 could be the cleanest games ever. Keep Britain Tidy!

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Posted by Jenny Gawley

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