Took it slow and easy - although it was still plenty hard (my heart rate was140 - 160.) I did most of the class seated and with low resistance, but tried standing a few times. I was so afraid I would pull something again.

I am pleased to report that I had no pain whatsoever during or after the class, so now next time I won't be so worried and can keep pushing a little harder each time.

Thanks again to everyone who responded to my post.