Most glaringly, however, you've said nothing about the therapeutic effects of ab exercises on a middle aged lady's ego. It's done wonders for mine, since you've asked.
Wha? I don't think I asked did I?
I should clarify that that summary came straight out of the article. I didn't write it.
As for ab work. I do it at the end of every st workout. I've also incorporated 4-5 stability ball exercises, and a few plank exercises, into my routine, so I'm not against them by any means. My main beef, regardless of what the article concluded, comes when people try to expand beyond the commonsensical use of these exercise tools or concepts.
For balance exercises, and certain kinds of body weight exercises, sure, using a stability ball makes perfect sense, like the first one you described. I particularly like doing pikes, roll-ups, side-bends, and back extensions with one, and the 'stir the pot' plank exercise with a stability ball is great too, along with a few other plank exercises that don't involve a stability ball.
For most exercises involving weights, however, you need a stable platform to get maximum benefit. So when someone suggests, say, doing military presses sitting on a stability ball, I cringe. Not only is it dangerous, but, by working the 'balance muscles' (or more accurately, by working muscles outside of the targeted area, or in ways that take away one's ability to do the exercise with good form) while trying to lift a heavy object over your head, you simply won't be able to lift as much. If you can't lift as much, you won't get as strong.
So there's a trade-off, which a lot of functional fitness types don't seem to understand. It's usually best to work fitness components--strength, endurance, stamina, balance, agility--in isolation, if you got the time. A functional fitness program like Kemme Fitness tries to work everything at the same time, which may make sense if you have limited time, but you won't make as much progress over time in any given component. In that second exercise you described, it sounds like you're working everything at once, which is great, but you could probably do those same arm exercises (although I can't be sure because I don't know what they are) with more weight, and thus become stronger, if you did them with a stable platform, like standing up or sitting on a bench.
Both ways are fine, just depends on what you're after. Personally, I would rather just do the arm exercises, and then find exercises that really work my balance, without any weights. It would take more time, and won't be as hard as an all-in-one exercise, but I believe I would make more progress in each component over time. I just got a wobble board in fact, and am looking into some basic 'balance beam' type exercises too.
I've never had back pain so I can't really speak to what the article said about that. Apparently some core stability proponents have stated that strong abs will cure back pain, and the article gives evidence that that is not the case.
For me, the main point of the article is that there is no such thing as a 'core' or 'core muscles' that can somehow be separated from the rest of the trunk and targeted in a workout. This is what I've always wondered about, ever since I began hearing about
the core when I got back from Mozambique in 2010. I was like,
what? They discovered the core while I was gone? Why didn't anyone know about its existence before? There are abdominal muscles, certainly, and we can target them, and why wouldn't you, along with every other area, if you want good overall conditioning, right? I'm still going to do my crunches, bicycle sit-ups, side bends, bent-knee leg lifts, etc.