Even before he celebrated his 40th birthday with a home run last Monday, Alex Rodriguez was being viewed as A-mazing by the baseball world.

He entered Saturday night's game against the White Sox hitting .282 with 24 home runs and 61 RBIs in 95 games. He was 11-for-27 with four homers, two doubles and seven walks on the current road trip.

All this after sitting out a year under suspension for alleged involvement with performance-enhancing drugs.

"I can't tell you what people are thinking but I am [clean] and I'm happy about it," he said after his birthday homer against the Rangers in Texas.

Many Hall of Famers, including Carlton Fisk, Stan Musial, Craig Biggio and Carl Yastrzemski, to name a few, have played well beyond that milestone 40th birthday.

But Rodriguez -- the second-oldest batsman in the majors behind Ichiro Suzuki, 41 -- is keenly aware that some still scrutinize his statistics.

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Major league players who have been suspected of PED use are tested more regularly than others as part of the Joint Drug Agreement, an industry source said.

"If you play clean and you work hard, then good things can happen," Rodriguez said.

What about the possibility of a residual effect of past PED use? "It's nothing that just sticks around in the system and so you're [not] going to have long-term benefits from it," said Dr. Eric Cheheb, an orthopedist specializing in sports medicine and aging at the Illinois Bone and Joint Institute. "There's nothing I would point to suggest that it's anything other than him playing well."

Rodriguez, through his publicist, emailed answers to some questions about his season.

What did he anticipate?

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"I had no idea what to expect," he said. "I'm finding that one of the advantages of age is it gives you the experience to read pitches carefully and know the difference between pitches. I have a lot more patience and discipline at the plate."

THE DH FACTOR

Asked if being a designated hitter has helped, Rodriguez said, "It's been huge. It lets me focus 100 percent on my swing and gives my body time to rest. I really credit Joe [Girardi] with seeing how smart this would be for me."

White Sox coach Harold Baines, known primarily as a DH, was productive until the age of 40. "I thought I'd be done at 30. My knee problems started at the age of 26," he said this past week. "I was fortunate that I was in the American League. You don't have the work you would do if you were playing both sides. You get more rest for sure when you're not running out to the field 18 times a day."

Rodriguez said he added yoga to his exercise regimen, saying, "A lot of the stretching and yoga moves are proving really helpful. Things I never did before -- but helps me keep limber."

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Hitting guru Walt Hriniak, who worked with Yastrzemski and Fisk, said, "What A-Rod is doing is phenomenal, particularly if he's clean. I'm sure he is. When this all started, I wasn't an A-Rod fan, but I have all the respect in the world for him, what he's going through and the abuse that he took from everybody."

PLAN AHEAD

Fitness is a key for older players, said former Yankee Raul Ibañez, who hit 44 home runs after reaching age 40.

"If you train for 40 when you're 38, it's too late," said Ibañez, who retired after the 2014 season and works as an MLB analyst for Fox Sports 1.

"If you train for 35 when you're 33, it's too late. But when you're training since age 24, 23, that's when you really reap the rewards on the back end of your career. Alex looks like he has his old swing from his younger days. He's finishing more balanced instead of hanging back on his back leg. He's hitting more out front of his body and he's driving the ball to the opposite field. That requires coordination, the ability to lag your bat a little bit, a better technique of hitting."

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Merv Rettenmund, another former hitting coach, has been wowed by Rodriguez's performance. "Unbelievable," he said. "I can't explain Alex Rodriguez. He's not just having a good year, he's having an MVP type of year."

In spring training, some scouts thought Rodriguez's bat speed seemed to be slowing down. "Bat speed is way overrated," Rettenmund said. "I've seen more guys with quote unquote bat speed who can't control it. They are always in trouble. [Rodriguez] was a freak of nature since his first year with Seattle. At 19, you don't get inside the ball like that. I can't explain how he could do that or he can do this. It's beyond me."

Rodriguez, fourth on the all-time home run list with 679, is chasing Babe Ruth (714), Hank Aaron (755) and Barry Bonds (762). Aaron hit 42 homers after turning 40.

"I prepared the same way every year," Aaron, 81, told Newsday earlier this year. "I don't know that there was any secret to it but to stay in shape."

It's not unusual for pitchers to extend their careers into their 40s. The Mets' Bartolo Colon, 42, is baseball's second-oldest active player behind LaTroy Hawkins, also 42.

BUT EVENTUALLY . . .

For Rodriguez, the resurgence won't last forever, of course. "In general, the aging athlete starts declining in their performance," said Cheheb, the anti-aging specialist.

"That's because the blood flow to the tendons typically tends to go down in the fourth and fifth decades of life. There are people whose blood flow will start diminishing in the fifth decade as opposed to the fourth, so there's obviously some variability there. In general, that's why we think performance tends to decline."

Christopher Minson, a professor in the department of human physiology at Oregon State University, has studied athletes and aging. He said a baseball player's power surely will decline.

"The hand-eye coordination, those aspects of baseball that are going to require a high level of skill, are all going to be fairly well maintained . . . Power, as he continues to age in the first years after 40, it begins to really drop off," he said. "That's because, for some reason that's not fully understood, the type of muscle fibers are not as powerful. They're just going to slow someone like A-Rod down eventually."

But not yet.