If you are struggling to sculpt a six pack or shave time off your personal best, take heart, there could be a saboteur close at hand: your genes.

       Researchers at Anglia Ruskin University found that even when people put in the same level of effort, there are large differences in performance outcomes – and up to 72 per cent of the variation is down to underlying genetics.

       Put simply, you might work as hard as the next man, but if they have better DNA, you are unlikely to achieve the same results.

       Henry Chung, the report’s lead author and a postgraduate researcher at Anglia Ruskin University, said: “We know that exercise is good for us, but we all improve at different rates, even when following identical training regimes. This means there are other factors at play. Because everyone’s genetic make-up is different, our bodies respond slightly differently to the same exercises.”

       To find out the impact of genetics on sports performance, the scientists analysed results from 3,012 adults aged between 18 and 55 who had been asked to train in muscle strength, cardiovascular fitness and anaerobic power exercises for at least two weeks.

       Better genetic make-up behind better strength

       Their fitness levels were measured before and after exercise regimes and participants were grouped into genotypes based on their DNA.

       Each gene possesses alleles, and the allele type can influence how effective that gene is. The researchers believe it is these alleles that cause people’s bodies to respond differently to the same exercises.

       In total, the study identified 13 genes, and associated alleles, as being responsible for how well the body reacts to cardiovascular fitness, muscular strength, and anaerobic power exercises.

       On average, everyone saw a 10.97 per cent improvement in cardiovascular fitness, a 22 per cent increase in strength and 12 per cent increase in power, after the training.

       However, some genotypes saw greater improvements and some less. There was a 3.8 per cent difference between the best and worst cardiovascular scores, and 10 per cent between the strength scores. There was also a 4.4 per cent difference in top and bottom power results.

       The team determined that about 72 per cent of the difference in strength ability was due to genetics. For cardiovascular, it was 44 per cent, and strength 10 per cent.

       The remaining variations are influenced by other factors such as diet and nutrition, recovery, and injuries, according to the scientists.

       Tailor-made fitness regimes

       Although some of the differences seem small, the researchers say the information could help to personalise training regimes for athletes or people undergoing rehabilitation.

       “Our study found 13 genes that have a role in exercise outcomes, and we found that specific alleles contained within these genes are more suited to certain aspects of fitness,” said Mr Chung.

       “For example, with repetition exercises designed to boost muscular strength, genetic differences explained 72 per cent of the variation in outcomes between people following the same training.

       “It should be possible to improve the effectiveness of an exercise regime by identifying someone’s genotype and then tailoring a specific training programme just for them.

       “This could particularly benefit those who need to see improvements in a short period of time, such as hospital patients or elite sportspeople, where marginal improvements could mean the difference between success and failure.”

       The research was published in the journal PLOS One.