It’s important to keep the muscle both strong and supple – especially if you’re working on completing a running goal. Over time, tightness in the iliacus can lead to an ‘anterior pelvic tilt’, Daurat says. That’s when the pelvis is tilted forwards, creating an arch in the back. “Imagine the pelvis as a bucket of water – an anterior pelvic tilt would be as if the bucket was angled to tip water out of the front,” she says.

If tightness in the iliacus causes this tilt, you may begin to experience back pain in the long term too. Here are some tips to help strengthen and lengthen your iliacus and banish hip tightness for good:

Get up and move

“Making a point to break up episodes of prolonged sitting can go a long way to decrease the likelihood of muscles becoming shortened and irritating during a run,” suggests Daurat. “After 30 minutes of sitting it is important to stand up and move around for a few minutes.”

Stretch after a run

Stretch, stretch, stretch. Before and after a run, try incorporating stretches like lunges and bridges into your routine. “While it is important to make sure the iliacus and other muscles are strong, it is vitally important to promote good flexibility to reduce the risk of injury and pain,” Daurat says.

“Many simple stretches can be done in the comfort of your home, including hanging leg and knee to chest stretches,” says Arnold. “But,” she adds, “always consult a professional before doing any intensive stretching to prevent further injury.”

Hip pain when running? You may need to strengthen your iliacus muscle