Tiger Woods' former caddie doesn't believe all the weightlifting the golfer did has done him much good, but was adamant that he wasn't aided by performing-enhancing drugs.

Steve Williams, who caddied for Woods from 1999 to 2011 and was on the bag for 13 of Woods' 14 majors, said as much during a long "My Shot" interview for Golf Digest's July issue.

Steve Williams has faith that Tiger Woods has never used PEDs, saying "Love him or hate him, Tiger always respected the game." Scott Halleran/Getty Images

"Did Tiger do PEDs? There's no chance," Williams said. "Love him or hate him, Tiger always respected the game. He knows its history and people, its standing in sports and the world. He always knew what golf did for him personally.

"Whether PEDs have been used by other people is a good question, because it's occurred in every other sport. So why would golf be any different? The PGA Tour tries so hard to promote a squeaky-clean image, and we all know that's not the case, certainly with recreational drugs and probably the other stuff. I saw no specific cases and was never particularly interested in the subject. But, yeah, I'm sure it's gone on."

The PGA Tour began random urine tests for PEDs on July 1, 2008, and so far there have been just two violations of the policy, and none from name players. The tour does not announce positive tests for recreational drugs.

Woods has never been linked to PEDs, though he did receive legal medical treatment from Dr. Anthony Galea, who pleaded guilty in 2011 in U.S. District Court in Buffalo, New York, to bringing unapproved drugs, including human growth hormone, into the United States.

Williams, who most recently caddied for Adam Scott and is coming out of retirement to work for the 2013 Masters champion at the remaining major championships and the WGC-Bridgestone Invitational this summer, parted ways with Woods in the summer of 2011.

Their breakup remains a sore spot for Williams, who said he was given the news over the phone; Woods was in the midst of a four-month injury layoff.

"Not hearing it from him face-to-face really bothered me," Williams said. "The suddenness of it, the way it was done, him coming out of the hardest time of his life and me having been loyal to him for so many years was worth some consideration. Caddies get fired all the time -- hey, Greg [Norman] fired me in 1989 -- but when you have what you believe is a friendship, it's going to leave a mark."

As for Woods' much-discussed workout routine, Williams said: "Tiger bulked up over the years. I spent the majority of my time with him on the course, so I'd only notice when I went months without seeing him. He always liked working out, and to a point it helped him, maybe more mentally than physically because of what exercise does to help your confidence and your thinking.

"As for his game, I'm not sure it helped him much, especially working with weights. Certainly he hit the ball farther when I first saw him than he did later."

Woods is playing this week's Memorial Tournament, where he has won five times. Williams will be back at work for Scott in two weeks at the U.S. Open at Chambers Bay.