WHY DOES MY KNEE ACHE?

FORM FLAWS

Willy says hip adduction – when the thigh moves inward from the hip midstride, causing a knock-kneed effect – is one of the most common sources of biomechanical-related knee pain. Overstriding is another.

MUSCLE IMBALANCES

This is related to biomechanics, since muscle imbalances can cause poor biomechanics and, conversely, poor biomechanics can result in imbalanced muscle development. If you can’t do a single-leg squat without wobbling or having your knee dive in or out at a steep angle, you may have some glute or hip weaknesses, says Keith Spain, a sports medicine specialist.

GENETICS

Spain says that arthritis has a genetic component. ‘If your parents had arthritis, you’re more likely to have it,’ he says. And while age is a factor, Spain says that getting old doesn't necessarily mean you’ll get arthritis.

GENDER

Women are twice as likely to report knee pain as men, says Willy. But researchers aren’t sure why. ‘The hypothesis has been that women’s lower extremity alignment places the knee in a position where it’s more susceptible to injury,’ says Paquette. ‘I think there’s more to it than that.’ He points out that subtle differences in women’s connective-tissue makeup may also play a role.

UNKNOWN FACTORS

Pain is something researchers are still working to better understand, says Willy, adding that joint-related pain seems to be individual. ‘Two runners with the same biomechanics can go through the same training programme, and one gets injured but the other does not,’ he says. ‘ We really don’t know exactly why that happens.’ He says that variables such as sleep quality, nutrition and even psychosocial factors – such as fear of getting injured – may contribute.