A medicine ball is a weighted ball used for exercise. Modern balls are made of rubber or soft plastic, but they used to be made out of leather and stuffed with felt or horsehair.

If your treadmill doesn't start, you will need to troubleshoot the possible cause. Depending on the make, model, age and condition of your machine, the problem might be something you can repair yourself.

If you flip on the switch, set the speed and nothing happens, your treadmill is an unhappy camper. Troubleshooting involves putting on your inspector hat and taking a tour of the belt. You may have to proceed to the console if that doesn't solve the matter.

The Iron Gym is a piece of exercise equipment that you can use to complete strength training workouts in your home. With the Iron Gym unit, you can complete an array of upper body strength exercises, including pullups with a variety of grips, pushups, dips and abdominal crunches.

Pulldown exercises are used to strengthen muscles in your upper body. You will know if you are performing a pulldown because your arms will be pulling down toward your body against a resistance.

If your treadmill belt starts running closer to either foot rail -- either right after you buy the treadmill or after steady use -- it's usually not a big deal. On almost all treadmills, you can fix the problem yourself by using an Allen wrench to adjust the tension on the rear rollers.

Raising the incline on your treadmill is a way to make your workout a calorie-scorching, heart-pumping challenge. Running or hiking uphill increases muscle activation in many of the muscles of the lower body, which also leads to muscle gain.

Exercise is a critical part of successful recovery after knee replacement surgery. Your treatment should include regular visits to a physical therapist, which will include exercises that serve to extend your range of motion and strength in your recovering leg.

Working out is one of the best habits to have, but even a small injury can set back months of progress. The iliotibial band, or IT band, can be difficult to address. Rather than thinking about what exercises can be done, focusing on proper healing and progression of exercises should be the focus.

The barbell is an essential strength-building tool, both for the serious powerlifter training for competition and the beginner performing squats at his local gym. While simple in design, barbells can hold more weight than any other piece of workout equipment -- sometimes up to 1,200 pounds.

Weight loss occurs when you burn more calories than you consume. This can be done through aerobic exercise, strength training and eating a healthy, low-calorie diet. Increasing the work you do while exercising can help you lose weight in a shorter amount of time; this can be achieved by wearing a weighted vest.

No weight lifted on any machine is the same as using free weights. In all cases, less effort is required to stabilize the weight, making the lift easier. In some cases, the Smith machine itself has a counterweight that reduces the weight of the bar, and often there is no way to know by how much.