Ironman ability: is it in your genes?

Is your endurance capacity in your genes? A new study by Australian researchers attempts to uncover whether there’s a perfect Ironman genotype…

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What it takes to be an elite athlete or top age-grouper is something coaches and sports scientists have been trying to uncover for years, but it’s a complicated answer due to the myriad of interactions. There’s clearly the environmental factor, which includes training, nutrition and the gear you use. But then there’s what you were born with in the first place, namely your DNA. 


Your DNA provides a natural ceiling to your blood lactate threshold, maximal oxygen capacity, glucose and lipid metabolism, and muscular strength, all associated with how fast or slow you can race. And it’s your genetic side that a group of Australian researchers set about studying to see if there was the perfect genetic code to excel at Ironman racing.  

“We examined the genetic profile of 196 men and women who raced the 2008 Ironman Worlds to distinguish whether there were significant genetic differences between the faster athletes and the slower ones,” explains professor Lyn Griffiths of Queensland University. “We did this by isolating seven genes that have favourable alleles that are important to endurance performance.”

Alleles are different versions of the same gene and can be dominant or recessive. Griffiths focused on the following seven that, with the right allele combination, exhibit positive endurance traits: ACE – blood pressure; ACTN3 – anaerobic and aerobic energy production; AMPD1 – fatigue; CKMM – aerobic capacity; GDF8 – muscle-fibre strength; HFE – iron absorption; and PPARGC1A – energy availability.

After taking swabs and examining the seven genotypes, the researchers tallied up a total genotype score (TGS), which represents the percentage of ‘optimal’ alleles for a particular phenotype, in this case an endurance athlete. 

Firstly, they found that age-groupers in Hawaii really are the best in the world. Despite the heat, humidity and wind, mean finishing time came in at 11:44hrs with the fastest at 9:53hrs and slowest just making the 17hr cut-off (16:55hrs). And was this reflected in genotype?

“It was but only the endurance combination for the AMPD1 gene,” says Griffiths. “It shows the importance of training and that much work needs to be done to identify further genes involved in endurance performance.” 

It might be an underwhelming conclusion but it does have connotations to performance…

Taking a DNA test may be a waste of money. “I don’t think we know enough about all the genes involved in performance yet and feel that, at present, DNA testing is too early,” says Griffiths.

The researchers also showed that high-intensity training, was vital to improve muscle glycogen levels and increase mitochondrial capacity, both key to endurance performance.


 Research by Ironman has shown an average 15hrs-a-week training is the minimum needed to be a top age-group performer.