Classes are usually performed in small to medium sized groups which are led by an instructor. Depending on the type of Pilates, you will either be performing movements on a mat or using specialist equipment.
For floor-based classes you will be shown a series of movements by the instructor, which require you to hold you body in certain positions whilst resisting the force of gravity (or other equipment such as resistance bands) against the movement. While mat-based Pilate can look similar to yoga (and share some similar elements) it focuses much more on continuous flowing movement rather than holding static positions.
Classes which utilise equipment such as the Reformer or Cadillac will require you to perform similar movements. However, the resistance will be provided by ropes and pulleys.
Classes typically last 45-60 mins