Below is a short presentation I made on leg training for athletes. The slides go over topics such as squats versus leg presses in terms of safety and muscle activation, different types of squats such as back squats versus front squats, leg presses versus squats, and whether we should back squat at all and also how low people can and should squat based on their hip structure.
Leg strength is a prerequisite for acceleration fast and jumping high off of two legs. I think all soccer players should have a good understanding of how to train to get stronger legs in a safe way that suits them as individuals. This slideshow and the links provided in it will help with that.