Is DNA key to an ideal workout? Scientists say genes determine fitness and create test to identify if someone is suited to sprints or marathons If you gamely go to the gym or perpetually pound the pavements but don't seem to be getting any fitter, the answer could lie in your genes. Scientists say DNA is key to sporting ability - and they have created a genetic test that tells someone if they are better-suited to marathons or to the 100 metres. Billed as "the end of workouts that don't work," the £249 kit reads around 20 genes involved in how the body reacts to exercise, the risk of injury and how long it takes muscles to recover from exertion. Customers receive a read-out that tells them whether they'd be best focusing on sports that require short, sharp bursts of power, such as sprinting and weight lifting, or whether their talents lie in endurance efforts, such as long, slow runs or back-to-back aerobics classes. The test capitalises on the fact that many of those who begin exercise give up simply don't feel they are getting results A third group will hover between the two and will benefit from following a varied routine. The three-month bespoke fitness programme also contains information on diet and recovery. The Berkshire-based makers of the DNAFit test, the first of its kind the world, haven't run formal trial to prove it works. However, they say that elite athletes, including cyclists, who have used it, have been impressed with the results. Genes analysed include ACTN3, which exists in ¿sprint¿ and ¿endurance¿ versions But other experts have said the science simply isn't this advanced - and advised people not to waste their money. The test capitalises on the fact that many of those who begin exercise give up simply don't feel they are getting results. A survey of 1,000 gym-goers by DNAFit found that only half thought their workouts were working. Those who take the test begin by sending in a swab of cells from the inside of their mouth. Scientists in DNAFit's labs then read the cells" genetic code, focusing on around 20 genes known to be linked to muscle composition blood pressure, how hard the heart works, and other traits key to fitness. Genes analysed include ACTN3, which exists in "sprint" and "endurance" versions. Dr Daniel Meyersfeld (CORR), a molecular biologist who oversaw the test's development, said: "The beauty of DNAFit is that it's not a one-size-fits-all approach. Each plan is tailored to a person's individual ability to cope with exercise, assess the risk of potential energy and how much time their body needs to recover. Celebrity personal trainer Matt Roberts said genetics could help amateur athletes reach their "true sporting potential." However, others said that although we can tell some specific things about fitness from a person's genes, we don't have the know-how to make such sweeping predictions. Professor Jamie Timmons, a Loughborough University expert in the links between genes and fitness, said people would be better off simply guessing the best exercise programme for them. He added that simple factors such as whether there hills near their house are likely to have a greater effect on their fitness than on the information from the genetic test.