The Science of Running

Stretching your muscles – or neurons; Time dilation in running; Recovery for older athletes; Whither the Knees; FODMAPs for runners

Does stretching reduce your injury risk or help you run more efficiently? The vast majority of elite runners swear by it, but the scientific consensus after decades of research and hundreds of studies remains a resounding “We’re not sure.” Part of the challenge is that it’s not clear what stretching actually does to your muscles and tendons. There’s no doubt that a consistent stretching program increases your f lexibility and range of motion – but it’s less clear whether that change happens in your muscles or your brain.

Researchers from the University of Lisbon recently tackled that question by pooling the results of 26 previous studies to compare the predictions of two rival theories. The “mechanical theory” argues that regular stretching literally stretches your muscles and tendons, making them longer or less stiff. The “sensory theory,” on the other hand, argues that stretching simply accustoms you to the feeling of tension when you stretch, allowing you to reach or bend further without actually changing the properties of your tissues.

The results, which were published in the Scandinavian Journal of Science & Medicine in Sports, tend to support the sensory theory: most studies saw an increase in the tension subjects were willing to endure at the extreme end of their range of motion, with minimal changes in the actual muscle and tendon properties. Still, the question is far from settled. The pooled studies lasted between three and eight weeks, which leaves open the possibility that early gains in f lexibility are mostly neuromuscular while structural changes take longer. After all, it’s clear that the extreme f lexibility of lifelong gymnasts and dancers isn’t just mental. For now, the clearest conclusion is that if you want to include stretching in your routine, you need to make a long-term commitment to it – because the benefits of a month of stretching appear to be mostly in your head.