Bro,
not being funny, 225 is not big, and a 10 minute mile is pretty slow for someone who is 225. Bodyfat levels are a pretty good indicater of good aerobic conditioning. Just look at any marathon runner, or wrestler, or sprinter for that matter. Though they may not be hugely muscled beasts, they all have low bodyfat percentages, and high levels of aerobic conditioning. I'm not saying that this is always true, as there are people who walk around at 7% all year, eat like crap and couldnt run a sprint if they had to, but for the majority of us, it's a pretty good indicator.
I personally, have never seen a very large man, with a high percetage of bodyfat who is in good shape.