Knees Out Or Knees In When You Squat?

Out (left) versus in (right)

Here is a post that will perhaps change the way you squat. It depends on what area you want to work on. Previously, some physiotherapists and personal trainers hated me for saying that you can let your knees move forward when you squat. Most, if not all, personal trainers teach their clients that it is taboo to let your knees move forward while squatting, They get their patients or clients to stick their bums out instead.

Those same physiotherapists and trainers may be aghast if I suggest squatting with your knees pointing in (gasp!) or pointing out. 

The author recruited 14 males and 18 females for the squatting study (Chiu et al, 2024). Using 3D motion cameras and force platform meausures, normal squats required hip extensor, adductor and lateral rotator net joint movements (NJM). The gluteus maximus muscle exerts hip extensor and lateral rotator moments. The adductor magnus (pictured below) exerts hip extensor and adductor moments. Both muscles combine meet hip demands contributing to hip extensor NJM.

When squatting with hip in lateral rotation (feet pointing outwards), there was smaller hip extensor, lateral rotator and larger hip adductor NJM than normal squats. This loads the adductor magnus.

Medial rotation squats (feet pointing inwards) had smaller hip extensor and adductor NJM and larger hip lateral rotator NJM than normal squats. This loads the gluteus maximus.

Likewise if you stick your bum out when you squat, you are engaging more of your bum (Gluteus Maximus) muscles. If your let your knees move forward when you squat, you are definitely using your thigh (quadricep) muscles. If you want to increase hip adductor (adductor magnus) work, squat with your knees out. It just depends on what muscles you want to engage or work harder. Try it yourself.

There is definitely no real need to restrict forward knee movement when you squat. It's one of the biggest training myths ever. You can add squatting with your knees pointing inwards and outwards to the list of myths as well. 

This information should 'challenge' some old school "perfect squat" gurus.

Reference

Chiu LZF. "Knees Out" Or "Knees In"? Volitional Lateral Versus Medial Hip Rotation During Barbell Squats. J Str Cond Res. 38(3): 435-443. DOI: 10.1519/JSC.0000000000004655.