After Rory McIlroy's hilarious "exchange" with Brandel Chamblee on Twitter earlier this week, it was inevitable that he would be asked about his fitness routine. He was on Wednesday, and he revealed something I didn't know about: McIlroy had back problems as a late teenager.

"The end of 2010 is when it started because I had back problems and as a 19-, 20-year-old having back problems isn't really ... you're just at the start of your career, and you don't want to have to keep managing that for the rest of your career," he explained.

"I realized that this isn't going to get any better unless I start to take care of myself better. So getting in the gym, eating better, and I think from the start of 2011, the direct correlation between leading a healthier lifestyle and my performance on the course was the same. I won my first major in 2011. I got to the best World Ranking I had ever been in 2011, and then it just continued from there."

You can see why he would think this. 

McIlroy also seemed annoyed by the semi-criticism of his fitness routine.

On Wednesday, he revealed why he gets frustrated with the criticism. 

"Stay injury-free," McIlroy said of his goal with working out. "That's really it. Obviously I'm trying to be strong but the whole reason I started this is because I was injured. I had a degenerative disk in my back that sort of stayed the same. It has not got any worse, for example. It's always been there. 

"You think of the golf swing and the torque and the load that you're putting on your spine. The spine does two things: It flexes and it rotates. And it doesn't like to flex and rotate at the same time, which is what a golf swing does. So if anything, the golf swing is way worse for your back than anything I do in the gym.

"So I'm trying to make my back as strong as I possibly can so that when I come out here and swing a golf club at 120 miles an hour, I'm robust enough to take that 200 times a day when I hit shots and when I practice and when I play golf."

Interesting stuff from McIlroy. I understand where he's coming from. He's trying to be strong and fit and prepare his body for the violence of the golf swing. He's not trying to squat 700 pounds. 

Rory McIlroy is a fitness machine. (USATSI)
Rory McIlroy is a fitness machine. (USATSI)