Technically, summer vacation ends tomorrow for Antoine Walker. He will sit down with personal trainer Tim Grover and devise an offseason conditioning program. He will begin weightlifting again. He will hit the court and practice shooting, particularly free throws. He will hear a lecture about the importance of a better diet. He will set a plan for losing weight and lowering his percentage of body fat. He will work toward strengthening his legs, particularly his injured and oft-abused knees.

To be sure, there will still be early-morning golf outings and late nights. Walker does have a charity golf tournament scheduled for mid-July at Mohegan Sun. But Grover expects the weekdays to be largely devoted to strength and conditioning work. A few weeks from now, Walker will start playing pickup games at Hoops the Gym. In general, it sounds a lot like the last couple of summers under Grover.

But there is one glaring difference. Walker wants to sign a four-year contract extension with the Celtics this summer. He wants to remain with Boston for the remainder of his career. The extension and the strength and conditioning routine are unavoidably linked. The prospect of one motivates the other, though a somewhat slimmer and certainly refreshed Walker said his commitment to the team will not change, regardless of whether he gets the extension.

''It's major,'' said Walker. ''It's like they gave [coach Jim] O'Brien. It's just the reassurance I'm going to be in Boston.