Last night we went to see "Sheffield's own" Martin Simpson and that's why I didn't do the circuit class. I did go this evening however. On the little jog there I wondered if it was wise as I could feel my left patellar ligament but didn't suffer with it once there. The class was quite hard work and I included some single leg squats and very small number of lunges. During the squats I noticed a bit of irritation in my left knee but was avoided by improving form.
Alice thought I'd be going to have sore abdominal muscles from 3 minutes planks - with alternate leg raises, twice. We'll see. Overall I don't think it's a great exercise once you've mastered over a minute. Moving the legs does at least change the centre of gravity and add the need for more stabilisation.
At one station I'd done heel kicks and high knees so I really didn't think it wise to jog home.