People have been getting faster and faster over the last few decades. Usain Bolt shattered both the 100m and 200m world records at the World Championships in Berlin, knocking tenths of a second off each. Ethiopian Haile Gebrselassie’s world marathon (42km) record of two hours, three minutes and 59 seconds is nearly 23 per cent faster than it was in the 1920 marathon.
In all other competitive races, the running speed for men and women is significantly faster today than it was some years back, and as running performances continue to improve, the limits to human performance remain the subject of much debate.
Are there are absolute limits to the speed at which man can run? Legged locomotion is a complicated process. As it walks or runs, man or animal periodically accelerates both the limbs and centre of gravity. These accelerations require the co-ordinated application of forces by muscles and skeletal ‘springs,’ and the mechanical and co-ordination of these forces can be complex.
In turn, the acceleration of the body’s various masses and the contraction of muscles place stress on one’s skeleton that can be potentially harmful. The metabolic demands of locomotion vary with the shape, size, speed and gait of the individual.
Maximum running speeds have been predicted based on the mass of the body, the rate at which energy can be provided to the limbs, the ground force muscles can produce, the stiffness of the ‘spring’ formed by the muscles, ligaments and skeleton, the aerobic capacity of the lungs and circulatory system and the strength of bones, ligaments and tendons.
All of these factors vary with body size, limb shape and the distance over which speed is measured. Body size and limp structure, though with limits, can be worked on or ‘customised’ to increase running performance through substantial improvements in training, nutrition and equipment.
Competitive swimming provides an example of equipment potential effect: improvement in the design of full-body swimsuits, a breakthrough not contemplated 10 years ago, contributed to a rash of world records at the Beijing Olympics.
The subject of ‘legal’ artificial performance enhancement still surrounds the athletes’ world records and speed limits. For example, if a woman artificially enhances the concentration of testosterone in her body, a large number of changes accrue that make her physiologically more like a man and capable of higher speeds.
The speed or magnitude observed over the last century cannot continue indefinitely: for any given distance, any species of animal will eventually reach its limits. Female athletes will most likely to catch up or even run faster than men in middle and long distance events.
The consequences of reaching the limits of human athletic performance undoubtedly have social ramifications for both the athletic, scientific, and general populations. In a quest to attain faster times linked to commercial reward, the athletic and scientific community may continue to explore greater performance gains through the use of pharmacology and the evolving science of gene doping.
For spectators of athletic events, the impact of attaining the limits to human performance may be less profound. As was observed with the changes in javelin design in the 1990s and the subsequent reduction in the world record, spectators will continue to be thrilled by these gladiator-like contests between the world’s greatest athletes irrespective of performance in relation to world records.