Abdominal/Core exercises

[MeghanG]

What is the rule of thumb on abdominal and core strengthening exercises in pregnancy? My last pregnancy, i went to the gym a lot, but mostly did the elliptical and arm/leg/back strength training on the machines.
This time around I find myself doing a lot more spinning and group strength classes, which focus a lot on abs and core. Are exercises like planks and crunches ok so long as they feel ok to me? Obviously if anything is giving me discomfort I will stop immediately.
Thanks!

[Lyss]

I had bleeding, but my OB said (and I used to be a certified group exercise instructor and I learned) no core exercises and no twisting.

[Maprilynne]

My midwife told me to let my body be my guide. I've stopped doing crunches and upper ab excercises, but I still like doing lower ab strengtheners. I don't do much twisting, but plank is really great for me, though I do do it on my knees now. I LOVE spin and never really thought of it as a core training thing . . . but I would say listen to your body. What I do and do not do has DEF changed the further along I've gotten.

[AZgirl2207]

Listening to your body should be your primary concern. That being said, my yoga instructor (who has training in prenatal yoga) says no plank and no twisting after 20 weeks. No plank because it's too much strain on your lower back/internal ligaments and can lead to seperation of ab muscles.

[MeghanG]

Thanks for your responses! I'm only 13 weeks right now so it's easy for me to fight the rules b/c I don't have a huge belly yet.
Maprilynne - spinning isn't total core but the instructors are always telling us to be aware of our core/abs and keep them sucked in during class. I want to say "honey you're lucky I'm even here let alone sucking in my stomach!"