I do aqua aerobics twice a week. My regular instructor is a 93 year old woman, who is in great shape. She drives herself to the gym and teaches 6 classes per week, and she is in the water doing the exercises. It's a mixture of cardio, intervals, resistance and flexibility. Very in line with Primal. There is another instructor who is probably about 80 and takes a similar approach. There are various other instructors on Saturday. I don't usually go on Saturday but I did go today. There was a sub instructor.
This guy is probably about 50. He teaches P.E. for his day job and moonlights at athletic clubs. He does the exercises we are doing but he does them at the side of the pool. And he does them very hard core (but tells us to do them at our own speed.) It was pretty much all aerobics class speed. A little bit of resistance. Several times, the guy mentioned how many calories we were burning.
OK, here's the point. This guy does chronic cardio for a living. He is overweight with a beer belly and puffy face.