The one legged squat is a great movement as it
If you have never done a one legged squat before you should start just with your body-weight until you have mastered the balance and the strength that is needed. There are a few variations that one can do when training this movement.
For example one can first start with bending the knee of the leg that is not doing the work and then pushing your hips out and keeping your back straight lower yourself to parallel to the floor. This means that you upper leg muscle should be parallel to the floor.
When one has been able to master this movement you can then put the leg that you are not using in front of you. This will be using your hip flexors and abs a lot so it will be a bit more difficult to do it this way. Again make sure that you are lowering your leg slowly and keeping your foot flat on the ground.
One should concentrate on pressing up from your heel and not from your toes as you will then move left and right and lose balance. There are ways that you can increase the weight that you are using as you start to get stronger when doing this.
If you think that you are getting good at this you can carry a set of dumb-bells in each hand and do the same movement. It is important that you keep your style strict and concentrate on isolating the quads and gluteus of the leg that is bending and doing all the work,
When starting off doing this method one can do it by using something like a table to gently put your fingers on in order to help you from losing your balance. The idea would be to slowly remove the table so that you are working your leg without using any added balance.
You will immediately feel a big difference in the muscles that are being worked when you are doing the one legged squat without any help with your balance. The reason is that you are then using all the supporting muscles to do the movement correctly.