Is it true that … doing pilates can lengthen your muscles?

Pilates has been hailed as something of a wonder exercise in recent years. Some fans claim the low-impact conditioning workouts can lengthen muscles, leaving participants with longer, leaner physiques. But is that true?

Absolutely not, says Dr Christopher Morse, reader in exercise physiology at Manchester Metropolitan University Institute of Sport. For a start, he says, there’s little evidence to show human muscle fibres can be lengthened by stretching – and if it were possible, it would require putting the muscle under great strain, which pilates doesn’t do. “There is some data that shows you can lengthen muscles,” he says, “but it was performed on the wings of quails with a weight hanging off them for 16 days of continuous stretch.”

Morse says muscles can appear longer when flexibility increases, which can be achieved when people do stretches with light resistance, such as some of the movements in weighted or reformer pilates. This isn’t a result of an increase in the length of the muscle, it’s because of an increase in the range of motion: the body has simply got better at dealing with the discomfort of being in a stretch position. “From one day to the next, if I attempt to touch my toes and get progressively closer to the floor, the hamstring will elongate further, but not because it has grown longer,” says Morse. “You’re going to be able to stretch further because the muscle can tolerate the stretch better, rather than because it has increased in length.”

So what does that mean for the “long, lean” physique influencers promise pilates gives you? “Long and lean is essentially lean,” says Morse. “And you don’t burn many calories doing pilates. They’re not getting lean from doing pilates.” Morse does think pilates is a great form of exercise, though. “There’s a lot of core control,” he says. “This improves core muscle strength, which is one of the most effective mechanisms for preventing back pain.”