Fabulous knee strengthener. As I have said before, the weak knee muscle is the tear drop shaped one on the inside of the knee. Sending the knees forwards like this will really give it some welly. Placing the hands on the front of the hips will ensure that the upwards movement starts at the hips and not at the chest. Once it is mastered with the heels on a heel lift, then I recommend losing the heel lift and letting the heels lift naturally as the body lowers. You may need to hold onto something with one hand at first to keep balanced. Don’t forget to do a balancing hamstring exercise.
I do not recommend trying this exercise if you are a regular wheat eater since you will not have the core strength to do it safely. Also do not do this exercise if it causes any pain. Use the pain as a red flag and see someone to sort it out before it becomes an injury.