Greg Oden might be too pumped up for his eventual NBA debut.

Oden is doing what most people with too much idle time tend to do: gain weight. Only Oden is bulking up instead of fattening up, and the No. 1 overall pick may be too buff, too fast.

"We don't want him to get bigger. That's going to come," Portland coach Nate McMillan said on Friday night. "It's very easy for him to put a lot of weight on having a year off. We've really got to be careful about the weight training with him."

Oden, who will miss this season after he had knee surgery, was in the weight room Friday night before the Trail Blazers played the Philadelphia 76ers, sculpting his upper body. The 7-footer looked chiseled and has gained nearly 30 pounds of muscle -- all in the upper body -- since he was drafted. He is up to 280 pounds.

That's too much weight to carry on a surgically repaired knee, and McMillan is mildly concerned.

"I would much rather have him be wiry strong than bulky, especially coming off a surgery," McMillan said. "When you're talking about putting on extra weight and having to carry that weight on a surgically repaired leg, that's not good. We want to be really careful with the weight training with him."