What is it?
A class who sit on a special bike in a gym, following the instructions of their trainer.
The 'spinners' cycle for between 30 minutes and an hour on a special program to build up their fitness.
Who is it aimed at?
The spinning program is designed to help boost the fitness of people of all ages and fitness levels.
Radio One DJ Chris Moyles has used spinning as part of his quest to lose weight.
What equipment does it involve?
One bike for the instructor and up to eight bikes arranged in a semi-circle, facing the instructor's bike.
The instructor usually picks two teams who try to motivate each other to push themselves to the limit.
What is the difference between a normal exercise bike and a spinning bike?
They don't look hugely different. However, on closer inspection there is a lever on the handlebars which adjust the tension of the wheels.
When you are told to push the gear up it feels like you are riding up a hill. When you gear down it feels like you are going downhill.
And why do the bikes have strange handlebars?
There are three different riding positions. Normal riding position, a wide handlebars position and an extended riding position so you can stand up on the pedals.
Be prepared to sweat buckets during a spin class.