The 50th anniversary of the first four-minute mile has led to a renewed interest in the question “Have we reached the limit of human performance?”

It is generally believed we have not yet done so, but record breaking-performances are slowing and questions are being asked about the involvement of drugs and other factors in records set today.

When Roger Bannister broke the four-minute mile in 1954 it was generally considered that not only was it impossible for a human to run that fast, but that it might be dangerous to do so. Research suggests, however, that the four-minute mile might have been broken in 1770 and on a number of occasions between 1770 and 1850 by professional runners.

Following the foundation of the Amateur Athletic Association in the Victorian era, professional athletes were excluded from competing and all previous non-ratified times were erased from the record books. The world waited 100 years before the four-minute mile was broken by an amateur athlete. Though at the time it was believed we had reached the limit to human performance, the record was broken a number of times in the same year and now stands at 3:43.2.

The current world record holder, Hicham Elgarouj, broke the two-mile world record running below the four-minute mile pace, with the second mile equal to Roger Bannister’s 3:59.4. Indeed, Elgarouj would have finished 117 metres ahead of Roger Bannister over the mile had they have been in the same race.

With a colleague, Professor Alan Nevill of the University of Wolverhampton, I have mathematically modelled the progress of the world mile record (see above). It appears that the rate at which the record is being broken is not slowing. Indeed, the reduction in the world record from 1913 to Roger Bannister’s 1954 record was 15 seconds, and from 1954 to today 16.2 seconds. It would appear from this that we have not reached the limit of human performance.

In contrast, however, let us examine another sporting discipline. In 1972 the great Eddy Merckx (pictured below, second from right) set the world one-hour cycling record of 49.431km. Twenty eight years later, the equally great Chris Boardman (below, extreme right) set about challenging the record using the same bike. Despite 28 years of training advancement, Boardman managed to beat Merckx’s record by only 11 metres. Surely, this is evidence that the limit to human performance has been reached, at least in certain events.

Human performance is based on a complex interaction of physiological systems. In general, however, the fundamental limitation is that of energy production. Irrespective of the sporting discipline, the physiological limitation will be the ability to produce energy, sustain it and deal with the production of waste-products resulting from it.

The mechanisms of energy production are too complex to go into here, however the key factor is to do with adenosine triphosphate (ATP) production and subsequent hydrolysis. Factors limiting the rate of ATP production and hydrolysis include temperature and acidity, the two key waste-products of energy production. Humans use only 26 per cent of energy production for work (ie 26 per cent efficiency), the remaining energy is dissipated as heat. This is detrimental not only to performance, but also health. In addition to metabolic heat, ambient temperature plays a key role in performance. The optimal ambient temperature is about 10 centigrade, and the high temperatures at this year’s Athens Olympics (up to 43C) will undoubtedly lead to poor performance by poorly prepared athletes.

Are athletes born or are they made? The answer is both. Recent evidence supports the contention that genetics are, in part, responsible for human performance. Physiological factors determining performance include height, number and type of muscle fibres and heart size.

Can we breed the super athlete? This may at first seem a bizarre concept, however, we have bred other species such as horses and dogs for centuries with the aim of optimising performance. It is interesting to note that we may have reached the limit of equine performance. Professor Craig Sharp, a leading figure in animal-human comparative physiology, explains how the horse lung is now at breaking point, literally. When watching horse racing we frequently see jockeys spattered in what looks like mud. In fact it is blood exhaled from the lung due to the breakdown of the blood-gas barrier in the alveoli. Breading may have resulted in the peak of equine performance but we are yet to seriously examine its role in humans. Recent advances in genetic engineering, however, have raised concern regarding its potential to enhance performance. At present the technology is in its infancy but watch this space...

While genetics plays a role, environmental factors such as availability of facilities, coaching, sports science and medicine effect performance. The relative importance of nature and nurture may be difficult to discern, but it is those with both nature and nurture who have the potential for sporting immortality.

It is from the world of cycling that we see technology in the advancement of human performance. Using a specially-designed bike, Chris Boardman holds the world one-hour best of 56.375 km, nearly 7km farther than with the standard bike. The primary reason for this is the optimal use of energy.

Approximately 80 per cent of the resistance on a cyclist is air resistance created by the body. In reducing this by altering his position, the cyclists optimises his energy production.

New technologies at this year’s Olympics will make it difficult to differentiate between human performance and technology-assisted gains in setting new records. But does it matter? Technology is to today’s athlete, what training was when Roger Bannister broke the four-minute mile. Experts attribute Bannister’s achievement to his state-of-the-art training programme. Sports science has moved training closer to its optimum so athletes now search for performance gains from technological advancement.

Public thirst for record-breaking, combined with the fame and fortune associated with winning, have led some to believe that pharmacology plays an integral part in the super-human performances of today. It is clear that pharmacology can enhance performance. For example, recombinant erythropoietin (EPO) has been the focus of attention in endurance athletes in recent years. EPO is a hormone that leads to the production of red blood cells. An increase in red blood cells leads to an enhanced oxygen carrying capacity, increase in energy production and resultant performance enhancement.

But is the use of pharmacologic performance enhancement widespread in sport? At a time when positive drug tests appear to be on the increase is it any wonder that some believe humans have reached the limit to “natural” performance? On the other hand, however, athletes have never been subject to greater levels of scrutiny than today. The frequency and sophistication of drug testing suggests it is now less likely that athletes could manipulate performance with pharmacological aids. While it is clear that drugs may enhance performance, it would appear that pharmacological aids may not play a central role in the advancement of human performance.

Athletes continue to set new records, living up to the Olympic moto - “Citius, Altius, Fortius” (swifter, higher, stronger) and it appears that we have not yet reached the limit to human performance. The rate at which new records are set may be slowing, but we continue to be amazed by the extraordinary performances of today’s athletes and will continue to wonder “have we reached the limit to human performance?”

* Dr Greg Whyte is director of science and research, English Institute of Sport