^^^^^
lol, I don't think those are good for his core strength.
Just wanna comment that he would have been better off if his gym was less 'equipped' with modern stuff. He would walk around the running track and talk with his buddies- not power walk or anything but that toe-dragging, shuffle walk he did - then go to the steam room. He would do this 5 days a week for years. Never thought that he would be dangerously out of shape while going to the gym. All those years of going to the steam room and funky walking, if he only put aside 15 minutes doing body weight squats and sit ups he would still be in OK shape.
Had his gym been an old school one with machines, weights and a mat, he would have been forced to learn the floor exercises and a few weighted ones and kept the muscles in check. Hell, those exercises I'm having him do are all basic and don't need to be in a gym. I think the gyms should be some what responsible for informing seniors on what is important for them to work on, not to awe them with all the fancy amenities and implicitly give them a false sense of security that as long as they show up, they would be OK. My dad has been showing up and he wasn't OK. Alright, rant off

. It shows that the tried and true the low tech and the often forgotten things about working out are still the best.