Hmm...interesting mix of opinions already.
I'd agree that the fear of losing muscle is probably the biggest factor stopping me (and probably most lifters) from cutting that low. After all, who wants to see all their hard work being used as fuel. I wonder though at what level the body starts to break down muscle? 10%? 8%? 4%? Why break down muscle, if theres fat available to burn.
I'm following a low carb approch to my diet anyway, i'm losing about 2 pounds a week at the moment, not had icecream or beer for months. I actually don't like beer anymore.
I've never seen the point in eating extra and then just running it off. Surely thats like filling my car full of fuel, then making a hole in the tank because i'm concerned I put too much in for the journey ahead!
But why wouldn't you be able to get to 9% without cardio? I would think there are a huge amount of people that have achieved this and that 95%+ of people can do so.
So far, no-one here has said they have done it.
The only benifit of cardio, must be time related. i.e. 12 weeks prep for a competition. It would be interseting to see what % pro bodybuilders average out at off-season.
I have been as low as 8% without doing any cardio, cardio really has little effect on getting to low body fat, it's mostly calories/hormonal manipulation and/or drugs for some people.
You should read up on leptin, it's the hormone that is the biggest determinant, from what I understand, of being able to get down to single digit body fat.
That's why most experts these days recommend a high carbohydrate refeed (Over maintenance) fairy often as you get leaner, to reset leptin levels and make the body feel like it's fed.
Also, it's really hard to lose muscle if you're continually lifting correctly and protein is high - look up the minnesota semi-starvation study, even while essentially being starved, not having adequate protein and not weight training ( I think that's how it was, anyways) they only lost about a 50/50 fat/LBM ratio - and that's assuming EVERYTHING is wrong with your diet/training.
Meaning, if you have diet/training in check, muscle loss is not a big issue.