It’s all very well to explain that you should keep your feet straight, and that there are correct positions and postures to adopt with your body during exercises, but this instructions become much more meaningful when you understand exactly why these positions should be adopted. The following test will help demonstrate, with your own body, the impact your foot angle has on your hip joints and lower back:
To see the influence of your foot angle on your hips, sit on a chair or box and assume the bottom position of a wide stance squat. When in this position, instead of having your feet correctly placed straight or near straight, turn them out heavily so the toes are turned out at least 45 degrees. Next, keep your toes where they are and pivot on them, turning your heels out wider until the feet get to straight. As you do this, observe the effect the movement of the heel and lower leg has on your upper leg. You will notice the lower leg acts like a lever which winds the upper leg, internally rotating your femur.
During this action, you may feel a tightness in your hip joints. If you feel so much tightness in your hip joints that the only way to tolerate the position is to release the slight natural arch in your lower back, by posteriorly tilting your pelvis and rounding out your lower back, then this could mean that you lack sufficient range of motion for the internal rotation of your hip. Those who struggle to keep the slight natural arch in their lower backs at the bottom of a wide stance squat are likely to fall into this category, with your body seeking out the rounded lower back position to escape the locked in, tight position which challenges your inflexible hips.
The common culprits which restrict hip internal rotation are the ligaments which make up the hip joint capsule. The tissues of the hip joint capsule are not easy to mobilise, but improvements can be made. Those experiencing hip joint restrictions from the test outlined are advised to research how to improve their hip capsule internal rotation capacity.