NEW YORK -- If there's one iron-law in the Yankee clubhouse, it's that you won't find Roger Clemens at his locker days between starts. He's not signing autographs, he's not making TV appearances and he's certainly not in the players' lounge eating pizza.

Instead, the Rocket is in the weight room, consumed by a four-day ritual that he's convinced has kept his elite-caliber fastball in the mid to upper 90s, and has actually prolonged his career.

	Andy Pettitte, left, has adopted much of the Rocket's routine.

When Andy Pettitte says Clemens, "a freak of nature" it not meant as a joke or even a figure of speech. That's because, Clemens doesn't just work out; he's obsessed with exercise, and proudly says, "my only day off is the day I pitch."

But unlike most major-league pitchers, who run (a little) or lift weights (even less), Clemens has devised a system that keeps him both strong and quick, combining power-lifting for the lower body, light-dumbbell work for his rotator cuff and agility drills that would probably make more sense for an NFL linebacker.

Clemens admits his philosophy may be unorthodox, but he believes in the development for side-to-side strength, as well as balancing skills that a pitcher requires to keep his fastball intact.

Watch the Rocket's delivery. Watch how much torque he generates with his legs. Watch how far forward his torso leans upon the release of the ball and little he actually taxes his arm as it's whipped across his body. That's no coincidence. Clemens' mechanics are the bi-product of that intense regimen -- so successful for the Rocket, Pettitte copied it two years ago.

"Roger's the one who taught me that the better shape you're in, the better you'll throw the ball," Pettitte said. "If I've had four good workouts between my starts, I take that confidence to the mound with me. How can it not help me to think that way?"

Like a chef protecting a secret recipe, Clemens refuses to discuss too many details of his regimen. But the bones of the workout consist of two days of lower-body lifting, one day for the upper body work and four cardio sessions. All four workouts are framed by abdominal drills, he says, the equivalent of 750 sit-ups.

The intensity of the drills decrease as Clemens gets closer to his next start. In other words, his toughest session is the day after he pitches; the easiest is on the eve of taking the mound.

"That's the day when you break a light sweat, maybe a half-hour of cardio, do some abs. That's about it," Clemens said. "By the last day, you've got most of your work in, so you're set."

Before that, however, Clemens and Pettitte, who work together when the Yankees are on the road, will concentrate their heavy lifting on the lower body, including multiple sets of squats and leg-presses.

	“	If it's 90 degrees with 80 percent humidity, Roger is able to say, 'so what, I've trained in that. I've trained for that.' ”
		— Jeff Mangold, Yankees' strength coach.

But instead of making the session entirely anaerobic, the two will intersperse side-to-side agility drills, or sometimes run a quarter mile. The combination of strength and conditioning in the same drill reproduces the challenges a pitcher faces in later innings -- the need to still throw hard without getting winded.

As Yankees strength coach Jeff Mangold put it, "if it's 90 degrees with 80 percent humidity, Roger is able to say, 'so what, I've trained in that. I've trained for that.' Actually, his program is harder than the games themselves."

When he was younger, Clemens would rely on long-distance running to keep his legs strong and his lungs healthy. It wasn't unusual for him to run 4-5 miles a day, and when he was with the Red Sox, would even jog three miles in the afternoon before he took the mound.

Even as recently as three years ago, Clemens could still churn out three miles in under 21 minutes, no small achievement for a man approaching 40 and weighing 225 pounds.

DID YOU KNOW?

Things you need to know about Roger Clemens: Clemens will become the 21st member of 300-Win Club. Clemens could be the fourth-fastest (in terms of decisions) to reach 300 wins. Clemens is 24 strikeouts shy of becoming the third pitcher with 4,000. Clemens won his first game on May 20, 1984 vs. the Twins. Clemens could be the second pitcher to win 300 games in a Yankee uniform (Phil Niekro). In 1997, Clemens won his 200th career game at Yankee Stadium (while with Blue Jays).

The Rocket has now substituted those long runs for shorter, more intense bursts of aerobic exercises, convinced it better trains him for actually pitching. And Clemens also believes in throwing twice between starts, unlike most pitchers who require only one bullpen session.

The Rocket will throw a normal session two days after his start, as is baseball's custom, usually 35-40 pitches at 75-80 percent velocity. But Clemens will follow up the next day with a "short" session -- throwing from 55 feet instead of 60 feet, six inches.

The reason for that, said Yankee pitching coach Mel Stottlemyre, is that by throwing at a reduced distance, Clemens is better able to concentrate on keeping the ball down.

"To throw low, that close, means you really have to really concentrate on that trajectory," Stottlemyre said. "It usually carries over for Roger when he goes back to 60 feet."

The Yankees were so impressed with Clemens' idea, they instituted it throughout the minor-league system. Today, virtually every Triple-A pitcher now uses a "short" day as a between-start drill.

Still, there's no one in pinstripes who trains or behaves quite like Clemens. By the time he throws his first pitch, the Rocket has burned thousands of calories, churned out thousands of sit-ups and pushed all the heavy metal his legs could withstand.

Smiling, but certainly not kidding, Pettitte says, "Roger's in such great shape, I have no doubt he could keep pitching for four, five more years if he wanted to."

Bob Klapisch of The Record (Bergen County, N.J.) covers baseball for ESPN.com.