Chris Stanton, PT at Third Space Moorgate and the hand behind the machine gun, explains that it’s all do with a little muscle known as the psoas. “The psoas muscle contracts as you lift your knee and relaxes as your leg swings back, and along with the core muscles, the psoas also helps to stabilise your hips. In fact, every time you stand, walk or run, you’re engaging the psoas.”

Tightness in the psoas, Stanton explains, can indicate various issues. “Inevitably, tight psoas compromises your ability to run and move effectively. It can also misalign your posture and reduce movement efficiency.”

In other words, if you want to run pain-free, are struggling with a sore lower back or don’t feel that comfortable when you walk or hike, then it’s worth testing how tight your psoas is.

Not sure if you should run or rest? Try this simple hack to see if you’re close to injury