As with most exercise, it's best to stick with what you were doing pre-pregnancy. If you're jumping into spin for the first time, let the instructor know, and start easy. If you haven't exercised in a while, begin by building as little as 5 minutes a day until you feel comfortable enough to join a 30-minute class.
Especially if you're not showing yet, says Ziel. "It's easy to push yourself too hard when an instructor is yelling at you," she says. By letting him/her know you're pregnant ahead of time, you won't need to worry about being singled out if you need a break.
The ability to carry a light conversation is the age-old indicator that you're working out at a safe level of effort, but few spinning classes are convo-friendly. Your new rule-of-thumb: If you're panting or gasping for breath, take it down a notch.
As anyone—pregnant or not—can attest, standing up during a spin class is way more intense than sitting down, which may be overdoing it when you're pregnant. Plus, standing may add pressure to extra-flexible joints.
Relieve lower back stress: Sit back more, instead of leaning forward, which means you'll need to bring the handlebars closer to you.
"An hour is plenty when you're pregnant," says Ziel. But that may be too much for some women, especially if you're new to spinning. A good compromise is a spin class that devotes the first part of the hour to spinning and the second to strength training or yoga.
Some spin classes have introduced un-stationary machines like RealRyder bikes that move with spinners as they lean right or left to engage smaller, stabilizing muscles. If you find yourself feeling unstable toward the end of your pregnancy, stick to the old-fashioned bikes that stay put.
During class, engage your pelvic floor to support the weight of the baby. "I tell my clients that it should feel like you're giving your baby a light hug," says Ziel. That extra support will protect your low back, and if you're doing it right, Ziel says you'll avoid any soreness in that area afterward.
It's the number one rule when attempting any sort of exercise, says Ziel. Trust your body. There will be days when you can go harder and days when a light walk will do the trick.