Here is a post by SOS Athletic Excellence Personal Trainer Candice Weymouth (see photo) on the king of leg exercises the squat.
We all know the squat is a full body, compound exercise that engages a persons abdominals, obliques, lower back muscles, with hamstrings, quads, glutes and groin acting as prime movers, even the shoulders and arms are working holding the bar in position.
Contrary to popular belief squats are not bad for your knees or back however squatting with bad form can cause very bad knee & other related injuries. Good technique consists of standing with feet shoulder width apart from heel to heel, not too narrow as you would struggle to hit parallel which can cause stress upon the knees and not too wide either as you would risk hurting your groin and will struggle to keep knees outward.
The most common mistake people make when squatting is the squatters knees pointing forward this is done because people mistake squatting to be a quadricep exercise however to do it this way is completely incorrect because you will struggle to hit parallel, this can cause you to experience frontal hip pain because the femur will impinge the ilium. It would also cause you to squat less weight due to not engaging the acquiring muscles. You can also cause pain in the lower back by it rounding due to your hips not dropping to the required depth.
Another important thing to consider when squatting is knees must be pushed out to the side and thighs must be travelling in the same direction as the way your feet are turned, which are outwards approximately 30° so there’s no twisting in the knees. If knees ‘cave’ or drop inwards when you squat you’ll experience all the previously talked about problems plus twisting of the knee ligaments and ACL tears if this happens during heavy squats. This can happen when you do a half or quarter squat as all the weight is put forward onto the knees instead of using the hip muscles, and this is why it is essential to break parallel when squatting.
Breaking parallel is when you hit a depth where the hip creases go below the top of your knees. When quarter squads are performed they are mostly working the quadriceps, quarter squats can cause weak, imbalanced gluteus and hamstring muscles which will result in knee injuries and stress added onto them. Therefore squatting deep, breaking parallel on every rep is totally safe for your knees.
So make sure the next time you squat your hitting depth and maintaining that strong and balanced posture.