Though extremely similar to medicine (med) balls, slam balls have one important difference: their surfaces are thicker, making them excellent for high-impact throwing workouts. Med balls, on the other hand, have significantly thinner rubber, leather, or plastic surfaces and are therefore unsuitable for severe workouts. However, both types of balls are designed to be tossed back and forth in order to best utilize gravity's influence on their movement. There is no standard size for a medicine ball, but they usually range from 20 to 30 inches in diameter. The weight of a medicine ball depends on how thick its surface is; the heavier the ball, the more force it can withstand before breaking. People have been using medicine balls since at least 300 B.C., when ancient Chinese writings described a ball made out of goatskin that was used for training in martial arts. Today, medicine balls are employed by athletes of all disciplines - not only do they help build strength and stamina, they also serve as an effective tool for practice throws. In terms of athletics, a medicine ball can be used by health professionals who need to maintain muscle tone and balance skills, such as physiotherapists and physical therapists. In addition, medicine balls are popular among athletes who want to improve their punching, kicking, and blocking techniques - after all, you cannot hit or block with a dummy!