Indoor cycling

Indoor cycling, as an organized activity, is a form of exercise with classes focusing on endurance, strength, intervals, high intensity (race days) and recovery, and involves using a special stationary exercise bicycle with a weighted flywheel in a classroom setting. It is commonly called spinning.

Classes generally use specialized stationary bicycles. Features include a mechanical device to modify the difficulty of pedalling, specially shaped handlebars, and multiple adjustment points to fit the bicycle to a range of riders. Many have a weighted flywheel, which simulates the effects of inertia and momentum when riding a real bicycle. The pedals are equipped with toe clips as on sports bicycles to allow one foot to pull up when the other is pushing down. They may alternatively have clipless receptacles for use with cleated cycling shoes. Padded shorts aid comfort and avoid the chafing caused by the sewn seams in underwear.

If the exercise is not done correctly or the rider's position is bad, injuries can occur; problems with the lower back and knees are most common. To avoid injury and aid comfort it is important to make sure the bio-mechanical position of the rider is correct. Group cycling bikes have a wide range of adjustment, and it is essential to obtain the correct setup prior to riding. The seat position must be right for the participant's height. The height of the seat should be in level with the hip when the participant is standing next to the cycle. Horizontally, the seat should be set in order for the front of the knee to be directly in vertical line with the ball of the foot when the pedal is pointing forward. This results in a position where the knee is slightly bent at an angle between 25% and 35% when the leg is extended with the foot resting flat at the bottom of the pedal stroke. Handlebar height can be adjusted for comfort; less experienced riders may want to set them higher to ease lower back discomfort. A reasonable reference point is to set it in level with the seat.

A typical class involves a single instructor at the front of the class who leads the participants through routines that are designed to simulate terrain and situations similar to riding a bike outdoors. Some of the movements and positions include hill climbs, sprints and interval training. A well-trained instructor uses music, motivation, visualization and enthusiastic coaching to lead students through a ride that best suits their fitness level and goals. Most instructors will lead what is called an interval ride, where students will sprint, run, climb, and jump all in the same ride, but there will not be definable pattern to the exercises. In the early 2000s, "terrain-based" classes that simulate outdoor conditions (e.g., wind resistance) were introduced. Terrain-based classes are designed to improve a rider's outdoor skill set and increase endurance while providing an intense cardio-based workout.

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