With its low impact on the joints and high caloric burn rate, cycling is a great choice for anyone wanting to get (and stay) in shape. It is accessible to all fitness levels and allows for easy progression. At all levels, cycling demands extreme physical effort and stamina to power the bicycle and to maintain correct form and speed, especially if for an extended time. Most of the work is in pushing down on the pedal, which uses all of the muscles in the leg. Equally important are the supporting muscles, which support the upper body, provide balance, reduce fatigue and increase endurance.