Fitness balls come in various sizes. For most exercises, you'll want a ball that allows your knees to be at a right angle when you sit on the ball with your feet on the floor. The firmer the ball, the more difficult the exercise will be. So if you're just starting out, you might want to slightly deflate the ball. You can add more air as you gain strength and confidence.

Last Updated: 03-26-2019
content provided by
© 1998-2020 Mayo Foundation for Medical Education and Research (MFMER). All rights reserved. A single copy of these materials may be reprinted for noncommercial personal use only. "Mayo," "Mayo Clinic," "," "Mayo Clinic Health Information," "Reliable information for a healthier life" and the triple-shield Mayo logo are trademarks of Mayo Foundation for Medical Education and Research.