Muscle strength, cardiovascular fitness, and anaerobic power are all key factors in shaping an individual's fitness, wellbeing, and quality of life, and all participants showed improvements following their exercise training, but to varying degrees, even when performing exactly the same exercise training.
By combining data from 24 separate studies, the researchers discovered that genetic differences are responsible for 72 per cent of the variation in outcomes for people following identical exercises designed to improve muscle strength.
Meanwhile, genetic variations caused 44 per cent of the differences seen following cardiovascular fitness exercises, measured through “VO2max tests”, and 10 per cent of the differences in outcomes following exercises to improve anaerobic power, which is the key for movement and agility. The remaining variations are influenced by other factors such as diet and nutrition, recovery, and injuries.
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.
The researchers suggest that genetic testing could allow exercises to be tailored so they are more effective for each individual, rather than general exercise for all. This could benefit everyone from hospital patients undergoing rehabilitation to elite sportspeople.
Lead author Henry Chung, a postgraduate researcher at Anglia Ruskin University (ARU), 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.
"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. 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.
"Because everyone's genetic make-up is different, our bodies respond slightly differently to the same exercises. Therefore, 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."