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.

-------

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."

-------

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.

Story continues