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Genetics and Sport
There have been two people that have really shaped the public debate about the role of genetics in sport over the last few years. David Epstein and Malcom Gladwell: The sports gene vs. 10 000 hours debate.

Framing the debate in a way that uses “vs.” is always going to create controversy but what role do these differing perspectives play in sports performance?

In this case superior genetics might refer to a predetermined aptitude to a task, an increased likelihood that you will be good at a certain activity be it marathon running, basketball or the 100m sprint. Genetics has an influence over a wide range of areas including gender, anatomy, ethnicity, strength, biomechanics, muscle size, muscle fibre composition, VO2 max, lung capacity and flexibility.

If this were the case then it would indicate that your ability to perform is already predetermined before you even start, right?

Well not always.

Performance also depends on a wide range on environmental factors some of which can be influenced by the athlete and others which are outside their control. Variables that are under the athletes control might include, training and conditioning, rest and recovery, hydration and nutrition. Variables outside of an athlete’s control: climate, altitude, event timing.

It is the interaction between genetic and environmental factors that determine an athlete’s development and performance.

Genetics + Environment = Performance

To achieve peak performance then we need the right combination of both genetics and environmental factors and if either of these is found to be lacking then performance at the elite level is unlikely. What is also true is that certain types of performance require various expressions and interactions between the two variables and what might be a favourable genetic expression for one type of performance may be detrimental to another.

Can we determine how much of performance is genetics and how much is environment?


A range of studies have been completed but perhaps the most famous of which was data collected in the HERITAGE study and analysed by Bouchard et al. 1995. Heritability in this study ranged widely from 25-75% over a variety of factors from oxygen consumption, stroke volume, cardiac output and power output at submaximal workloads.

The proportion of skeletal muscle fibre type variation due to genetics has also been place at 30-40 % (Bouchard 1995). On a separate note the heritability of IQ has be placed at around 50%.

So which genetic expressions are beneficial for what sport and should we test for them?


To date much of the research has been associated with individual single nucleotide polymorphisms (SNP), however, it is likely that to account for large inter individual differences then combinations of SNP’s will prove more effective. Perhaps the two widely recognised SNP’s are ACTN3 (sprint) and HIFIA (endurance).

According to the Human Genetics Society of Australasia the most commonly tested gene is ACTN3. However, they note, “having the “sprint” genotype does not equate to having any talent as a sprinter or preclude an individual from participating in and enjoying endurance sports”

The evidence points to perhaps a 50% contribution for genes in sports performance and as such the role of genetics in sport is likely to grow significantly over the next decade, however at the moment the ability to identify and isolate genetic variations which predispose for performance has considerable limitations.

So if 50% is nature then 50% must be nurture.

And if you can’t change nature.

Then in my opinion “practice makes perfect” still rings true.