A medicine ball is a weighted ball used for strength training and conditioning exercises. It typically comes in various weights, ranging from 4 to 25 pounds, with a soft outer surface that provides a good grip. Medicine balls are designed to be thrown or caught, incorporating elements of cardiovascular exercise as well as building muscular strength and endurance. They can also be used for core exercises such as sit-ups, leg raises, and planks. The term "medicine ball" is believed to have originated in the early 20th century when gym instructors would use them along with other equipment like barbells and dumbbells to create personalized workout programs for patients recovering from injuries or illnesses, hence the name.