Jimmie Johnson is a beast in a car or on a bike

Not only is Jimmie Johnson a better stock car driver than any of us mere mortals will ever hope to be, he could probably kick most of our butts in a bike race too.

Need proof? The day after last Sunday's race at Dover, Johnson (along with fellow Sprint Cup Series drivers Landon Cassill and Josh Wise) took part in the Assault on Mount Mitchell bike ride. The 103-mile jaunt with a 10,000 foot climb starts in Spartanburg, South Carolina and ends at the summit at Mt. Mitchell State Park.

While Johnson said last week that he'd be in "survival mode" for the ride, he finished it in just over 6:11 and rode with former pro cyclist and Tour de France stage winner George Hincapie.

What Johnson calls survival mode on a bike would make a lot of us humans extinct.

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Johnson swam as a child and caught the fitness bug as an adult while he was in the midst of his run of five-straight Sprint Cup Series championships.

It was a hot summer day in Charlotte like it typically is and I wanted to get back in the water," Johnson told Yahoo Sports earlier this month. "So I got in the pool and swam and … after I was there a couple weeks someone asked me what triathlon I was getting ready for. It wasn’t even on my radar. A triathlon?"

"So I went home, thought about it, mentioned something to my wife and she said do it. Why don’t you pick one and do it. So the next thing you know I found one, I’m at the bike shop buying a bike and getting back into running and kind of started then."

He competed in his first sprint triathlon – a triathlon typically consisting of a swim under 1,000 meters, a 12-mile bike ride and a 3.1-mile run – in July 2008. Now, Johnson can probably do one of those without needing to take a drink.

Before he jumped into endurance sports, Johnson said he had been lifting weights to improve his conditioning both in and outside the car. The strength training helped rekindle his love of swimming, which then carried over to biking and running.

Now, Johnson commonly rides his bike throughout Sprint Cup Series weekends.

"I think it really keeps your senses sharp, like [a Friday] between the practice sessions and qualifying I’ll hop on the bike and go for a 20-30 mile ride just to stay loose and keep my senses alive and going," Johnson said. "Before I’d come back and just sit on the couch and veg out and brain shut down and not be as sharp."

"On Fridays that’s definitely part of it. I’d say the rest of the week there’s as much for me mentally to get out and have a release, to be out in the woods on my mountain bike to forget about the pressure and stress so there are a couple huge benefits out of the car more mentally than anything."

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As Johnson was tracking his exercise outside the car, he started tracking how his body performed inside the car too by wearing a heart rate monitor at occasional races.

"I wore it at the races where I felt the intensity was the highest to get a good understanding of what my average heart rate was and what the spikes were," Johnson said. "Bristol is definitely the one that spikes it."

Cup cars average approximately 15-second laps around Bristol's high-banked concrete. How high was Johnson's heart rate?

"Upper 150s sustained once we get into a green flag run which is mindblowing to me because that’s kind of a 10K race effort for me on my aerobic scale," Johnson said. "That’s right of the border to transitioning to anaerobic for me"

Yes, that's 150 beats per minute. The average heart rate for an untrained individual is between 60-100 beats per minute according to the American Heart Association while someone like Johnson has a resting heart rate of between 40-60 beats per minute.

If you're unfamiliar with the difference between anaerobic and aerobic training, simply think of the contrast between an all-out sprint and jogging slow enough to carry on a detailed conversation with a friend. The former is anaerobic.

"I didn’t think it was that high," Johnson said about the readings. "I thought it’d be mid-aerobic level, not high."

The high marks help make fitness even more important. While anaerobic thresholds vary from person to person, it's higher in fit individuals.

Throughout his use of the monitor in car, Johnson said he also noticed a pattern on the graphs it produced. When his heart rate spiked, especially over the course of a long run, his car was loose. As the car was tighter, his heart rate wasn't as high.

"It was interesting to see," Johnson said. "And it makes sense because when you’re loose and sideways you’re puckered up and really tense

"You’re still not comfortable when the car’s tight but I guess your hands and feet aren’t as busy driving it so it drives your heart rate down. When you’re tight you just turn the wheel and you’re like ‘come on, come on, turn, turn.' And of course you see the wall and you’re nervous about not hitting your marks. But it brings the heart rate down."

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Johnson's fallen in love with fitness and endurance sports so much that he's started spreading the word to others. He has an iOS app titled "Jimmie Johnson's Workout Challenge" and serves as a cheerleader and mentor of sorts in a group in another fitness app that includes many in and around NASCAR.

He even encouraged media members before the Daytona 500 to be more active and said he was available as a resource if they needed any help.

"If you want to get fit, you want to focus on wellness. I'm a resource. I'm here," Johnson said in February.

Sunday also marked the 10th anniversary of the Jimmie Johnson Foundation 5K race.

Many people who spent the late night working the All-Star Race made it up early to run or walk. Or in Johnson's case, run really fast despite not setting a record.

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Nick Bromberg is the editor of From The Marbles on Yahoo Sports. Have a tip? Email him at nickbromberg@yahoo.com or follow him on Twitter!

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