Jimmie Johnson: Being fit has improved my quality of life

Jeff Gluck | USA TODAY Sports

If Jimmie Johnson isn't in the best shape of his life now, he's close.

The peak of Johnson's physical fitness came in January, when he completed a 70.3-mile triathlon — a half-Ironman — in just over 4.5 hours (this despite missing a turn and adding two extra miles to his route).

Johnson told USA TODAY Sports on Wednesday he's "maintained really well since then" and doesn't anticipate slowing down anytime soon despite his 40th birthday approaching in September.

"I can only judge off my times I've set in the last five years, and I continue to get faster," Johnson said. "At some point there will be a taper off, but I'm still getting stronger. From hearing what coaches say, your body naturally starts producing less human growth hormone and testosterone at some point, but I haven't seen it yet."

That's probably not very good news for competitors of the six-time NASCAR champion, especially heading to Martinsville Speedway, which Johnson said is in the top five or seven most physically demanding tracks. Johnson's won there eight times — most recently in April of 2013 — and has an average finish of 6.2 at NASCAR's smallest track — the best among active drivers.

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Part of Johnson's ability to stay in shape is due to his increased understanding of nutrition and hydration. He didn't know — or care — much about that type of thing in his 20s and throughout most of his 30s before getting on a fitness kick about five years ago.

"It's really opened my mind to being fit and having some long-term fitness goals, into my 50s and 60s, even," he said. "I also know the impact it has on me today, the fatigue and dehydration I deal with, I'm able to manage all that. So the end result is my quality of life is so much better."

Johnson, a spokesman for Gatorade, was doing interviews on behalf of the sports drink's upcoming "Sweat with the Best" promotion, which launches this spring. By entering a code available under the cap of Gatorade bottles (sweatwiththebest.com), participants can win a contest to train with Johnson's pit crew and take laps with the driver at Darlington Raceway.

"I think it's going to be an eye-opening, mind-blowing experience," Johnson said. "I know a lot of people want to question the athleticism required in our sport, but I think it'll open eyes if the person is not in the belief of drivers being athletes."

Gatorade is also offering a similar experience with Matt Kenseth. Other athletes participating in the contest include Peyton Manning, Serena Williams, Dwyane Wade and Bryce Harper.

Follow Gluck on Twitter @jeff_gluck

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