I woked with this guy for years and he never worked out and he had some of the biggest calfs I've ever seen. He was my height and about myt weight but his calfs were about 18.5 inches. All he did was wrastle at local shows on the weekends and he said jumping on that mat made his calfs grow...it was frustrating as hell cause I was working my balls off at the time to get my calfs to grow.