Ankle weights are one of the best ways in which to add resistance to your lower body training, by targeting certain muscle groups. The leg and hip joint are like a lever and fulcrum. With the hip being the fulcrum, the farther away the weight, the harder it is to lift and balance. The same can be said for the knee joint. By adding a minimum amount of weight, the leg muscles must exert considerable effort to lift and balance the weights, which provides maximum results.