GENETICS & ENVIRONMENT
It is well-established that a high percentage of the variance observed in athletic status can be explained by genetic factors. The ratio of response to aerobic and strength training should vary between individuals, even those training towards the same goal. We cannot all compete in the Grand Tours, nor can we all achieve the same perfection as Arnold 'The Terminator' did. We can however, use our inherited strengths to our best advantage, and focus on improving any weakness.
There is no question that environmental factors such as training and nutrition are essential for the development of an elite athlete, but without the inherited genes associated with elite performance, we cannot all achieve the same status.
There are of course, other factors influencing sports performance such as individual determination and desire to succeed, and multiple physiological factors.
There are multiple candidate genes involved in sports performance. There is also, an element of gene-gene interaction, as well as gene-environment interaction, and we would also look at the genetics of human resilience to get a full genetic blueprint of the individual athlete.
In this article we are looking in isolation at the SNP (single nucleotide polymorphism) - ACE ID.
ENDURANCE & POWER PERFORMANCE
Besides regulating blood pressure, The ACE I/D gene (angiotensin 1 converting enzyme), is a candidate gene for elite sports performance.
The human ACE gene has two alleles ( I or D) An individual may be homozygous (same)for II or DD, or heterozygous (opposite) and have the ID genotype.
The I allele is associated with endurance ability and the D allele is associated with sprint or power performance. So if you carry the ID genotype this would be a mix between the two disciplines, and it could go either way with a moderate ability for both endurance or power.
ACE II or ACE DD
This is where is gets a little more interesting.
Being homozygous for the I allele (II) is associated with significantly greater improvements in muscle endurance and muscle contractile efficiency, which translates to endurance capability. These individuals will have a higher proportion of type 1 (slow twitch) muscle fibres.
So, if you are homozygous for ACE II, you should have the potential to excel at ultra-endurance events. This would possibly be the bulk of the Tour de France peloton!
ACE II and ACE ID individuals are also more salt-sensitive and may experience hypertension when there is a very high intake of salt.
Thompson et al (2007) conducted a study on ACE I/D using elite high altitude mountaineers. This fascinating study revealed that there was an association between individuals carrying the II genotype and the ability to successfully summit to over 8000m!
Another group of researchers (Tsianos et al.) examined the effects of acute mountain sickness (AMS) on individuals climbing Mt Blanc. These authors found that the successful climbers that summitted without experiencing AMS was genotype dependent. The results were 87.7% for DD genotypes; 94.9% for ID genotypes and 100% for II genotypes.
ACE DD carriers have higher ACE activity and show enhanced muscle growth in response to weight training. These individuals are also prone to visceral fat deposition in the absence of exercise, and may gain fat if they are too sedentary during the off-season.
D allele carriers may also benefit from increased muscle strength and excel at sprint/power activities, rather than endurance sports.
Being either homozygous for the II or DD genotypes, does NOT mean that you should be changing your sport, but rather, using your genetic information to enhance your training and performance. By utilising training techniques to increase your lower power or endurance potential, and boosting your natural talent, you can improve your performance and understand your potential more clearly.
In the following article we will take a look at another gene, ACTN 3 and consider the implications of a combination of ACE I/D and ACTN3 R/X genotypes.