Genes and Endurance Performance

By Prof. Rohan W. Jayasekara

Published in the Sri Lanka Sports Medicine, NEWSLETTER 1994
(The author is the Vice President of the Sri Lanka Sports Medicine Association)

The human body, be it male or female is composed of trillions of independent functional units called cells, in various forms shapes and sizes, each adapted to perform a particular function, be it as muscle cells in movement or nerve cells in the analysis and conduction of nerve impulses. All activities of cells are controlled by a structure found within the cell, called the nucleus(command centre). Inside this nucleus is a network of 46 thread like structures called chromosomes. Each of these chromosomes is the vehicle which carries a long thread of a chemical called Deoxyribonucleic Acid (DNA). This DNA is demarcated into definitive segments of varying lengths called Genes. It is very easy to understand the relationship of genes to DNA if one remembers the statement, ” Genes are to DNA what words are to a sentence”. The genes are called Exons and the intervening spaces which are also made up of DNA are called introns. The exons, are the words in a sentence and introns the spaces between the words. For this passage to make any sense, the words need to be spelt correctly and placed in a proper sequence and certainly spaced out. Likewise, the exons(genes) need to be of a definite structure and the intervening intron regions or spaces need to support the expression of exons.

In addition to the nucleus, the cytoplasm, or that area of a cell which surrounds the nucleus, has its component of DNA (mitochondrial DNA) packed into certain structures or organelles called mitochondria. Mitochondria are the power units that generate energy for cellular functions. The basic function of nearly 100,000 genes found within each cell is to produce proteins, and if one considers a simple motor task in everyday life or a complex sport skill executed with great finesse by an elite performer, the contractile, transport, enzymatic, immune, hormonal, cytoskeletal (structural) and other components of that maneuver are the products of genes, firmly under their control.

The fundamental question today is not whether genes are important determinants of the potential to perform endurance activities, which is true, but rather whether inherited differences in the gene complement account for some of the commonly observed variations in endurance performances. For example, a person may have inherited a gene which produces a vital enzyme involved in endurance with above average activity, placing him in a certainly advantageous position, or he may inherit a change in the intron regions flanking genes. This would result not in any alteration of the structure of the protein but in the expression of the gene in a specific tissue. For example, myocardial (heart muscle) genes may enhance training hypertrophy of cardiac muscle in an individual producing a considerable impact on endurance. Research into DNA at a molecular level with regard to sports in general and endurance performance in particular is yet in its infancy but definitely on the ascent.

Numerous research studies have convinced us that with regard to prolonged endurance training, there are non-responders, low responders and high responders and that this status runs in families and that it is probably determined by genetic characteristics. While the nature of these genetic influences remain unknown, one will certainly have to await the outcome of several years of research to determine the genetic basis. This line of research, the identification of candidate genes using gene probes, will assist in the identification and precise location of genes, responsible for particular functions in endurance performance. This field of molecular biology, with its gene seeking probes, augmented by other research methodologies like epidemiology, family studies and twin studies will offer great opportunities for the understanding of endurance performance and trainability.

What impact the preparation of such gene maps pertaining to the varied functions of a performer will have on sports in general and the Olympic movement in particular, will certainly be awesome to say the least. While the benefits will be tremendous to the performer and the coaches, as has been in the other subspecialties of genetics, where it has helped in the diagnosis, prevention and treatment of genetic(inherited) disorders, ethical questions and long and complex debates are bound to surface. No doubt, once armed with the ideal gene recipe for a super athlete, future sports scientists or should I say sport geneticists will begin screening programmes targeting infants and other prospective groups. Their subsequent close surveillance, up through the sports pyramid to the elite level at its summit will bring about a complete upheaval in the organizational structure. The very concept of sports will be undermined, this time, not by the use of banned drugs and doping, a problem which would appear trivial in comparison to the magnitude of this emerging new threat.

Here in Sri Lanka, in view of the social, cultural and religious factors at play, this might seem a distant dream, but genetic engineering or recombinant DNA studies on animals, plants and humans is very much here to stay. It has beyond doubt enriched the quality of our lives and to entertain a few fears on the selfish, smothering effects of science is in no way premature, when one considers the many skirmishes science has had with society on subjects of ethical value.

It is now time for positive steps to be taken by coaches, sports administrators, members of sports bodies, sports scientists and sports physicians, to acquaint themselves with the basics of genetics, molecular biology and biosocial ethics. Such a step will assist these categories of personnel involved in the administration of sports to stay informed of any new development in the international arena, and if the need arises, to make the necessary amendments in sports law to control it. This will no doubt prevent a socially and ethically costly confrontation, that is today, the burning issue in genetic engineering in many a developed country, caught in a deep slumber, in the face of a merciless onslaught by science.