A medicine ball (also known as an exercise ball, a med ball, or a fitness ball) is a weighted ball, roughly the diameter of the shoulders (approx. 14 inches). Often used for rehabilitation and strength training, it serves an important role in the field of sports medicine. It should not be confused with the larger, inflated Swiss ball.
Medicine balls are usually sold as 2–25 lb. balls and are used effectively in plyometric weight training to increase explosive power in athletes in all sports. Some medicine balls are in the form of weighted basketballs. It is possible to play basketball with a medicine ball, but it can be difficult, and has the potential to cause injury and property damage.
In the late nineteenth century and early twentieth century, the words "health" and "medicine" were synonymous. The so-called "Four Horseman of Fitness" were the dumbbell, the Indian club, the wand and the medicine ball. This is where the beginnings of the modern medicine ball originate.
Medicine balls throws are also implemented as part of the the SPARQ rating, a test of sport-specific athleticism, to assess core strength, total body power and coordination. Different tests involve an athlete throwing the ball behind them and over their head as far as they can, or kneeling and pushing the ball out from their chest for maximum distance.
They are also extensively used by secondary schools as a fitness aid. Example exercises include: lifting the ball or performing different exercises (such as sit-ups and leg raises) with the ball in order to increase the stress on a particular muscle.
A medicine ball is also commonly used by athletes who have sustained an injury and seek rehabilitation.
A basketball can be filled with sand, stitched shut, and used as an effective low-price medicine ball where resources are scarce, and is popular in, e.g.: home "garage" gymnasia.