Persian athletes, to increase strength and stamina, may have used the earliest medicine ball types. These early types, used at least 3000 years ago, were often animal bladders stuffed with sand. You find later references to the medicine ball about 2500 years ago as advocated for use by the father of medicine, Hippocrates. He recommended the use of animal skins in rounded form, also stuffed with sand as a way to train athletes or to help rehabilitate injuries to athletes.
Today the medicine ball serves much the same function as mentioned by Hippocrates. They are weighted balls, weighing anywhere from a couple of pounds to up to 25 pounds (11.34kg). They can be used as a part of athletic training or in rehabilitative ways to help people recover from or prevent injuries.
Unlike a standard air-filled ball, the weight of a medicine ball is important. Extra weight can help take exercises to a new level, and also helps to absorb impact if a ball is spiked, or caught. Some would assume that the best medicine ball choice would be the heaviest one you can find. Actually, that’s not always the case, particularly if you’re just beginning an exercise regimen. People normally start with lower weighted balls, which they might hold while they do squats, sit-ups, or leg lifts, and then work their way up to heavier weights. Using a ball that is too heavy can be a path to injury.
Heavier medicine balls do have a function. When an athlete wishes to train to exert more force in kicking and throwing, heavier balls absorb a certain amount of the impact. This means you have to work harder to get a heavier ball as far as you need it to go. Over time use of a heavy medicine ball may increase the force at which an athlete can throw or kick.
For people who are not professional athletes, weights of the medicine ball tend not to exceed about 8 pounds (3.63 kg). The extra weight does contribute to strength training, providing just enough to more thoroughly work muscles during a variety of exercises. Medicine balls may be used in a variety of different exercise methods, such as Pilates, sometimes modernized forms of yoga, and various aerobic classes like spinning or aerobic dance.
Lighter balls are used for athletes who have been injured. They can be part of groups of exercises designed by sports medicine experts or physical therapists to help increase strength and maximize range of motion without risking injury. You can purchase medicine balls in many stores (sometimes even in grocery stores) but you might want to wait until you get a specific recommendation from a trainer or physical therapist, to be certain you don’t get the wrong weight or type for the exercises you will do.
Lastly don’t confuse the medicine ball with the larger, inflatable balls used to increase core stability. These may be used in rehabilitative exercises too, especially for those with low or mid back pain. They are distinct from the medicine ball, and serve a completely different purpose. Some exercises may combine use of both but one cannot be substituted for the others.