A workout that's fast, furious and not for the faint of heart

CrossFit takes basic, functional-fitness exercises -- squats, push-ups, pull-ups, dips, dead-lifts, medicine ball throws and more -- emphasizes full range of motion (i.e. on a squat, lowering your rear-end to within a foot of the ground, then fully straightening your legs as you explode to a standing position), and adds short bursts of cardio. Then it throws them into a blender and flips the switch to "puree."

The mix, different day to day, blasts every muscle in your body while providing adequate recovery time for growth. The fast pace provides metabolic benefits that have been supported by at least two small studies.

CrossFit success stories are legion. Petranek says that two months of doing only the three-days-on/one-day-off "Workouts of the Day" (WODs) regimen raised his maximum pull-up count from 15 to 42 and dropped his 5K run time from 23:50 to 21 flat.

"And the only running I did the whole time were the quarter-mile runs in the WODs," he says.

Ed Korb, 34, a loan broker from Tustin, says four months of CrossFit dropped his 5K time by 3 minutes, 29 seconds while it raised his body weight from 150 to 164 -- "all muscle," he says.

Monrovia trainer Eric LeClair, 28, who started CrossFit in 2004 and began teaching it last year, gained 14 pounds and got faster in all his running events, including four minutes in the Camp Pendleton 10K Mud Run last year.

In my class, every one of Petranek's clients -- triathletes, runners, tennis players and those just out for general fitness -- said CrossFit had helped them lose fat, add muscle and get significantly faster and fatigue-resistant on less time.

The regimen also apparently works for world-class athletes. Olympic skier Jonna Mendes credits her recovery from a poor 2004 season to CrossFit.

Ultimate Fighting world champion Chuck "The Iceman" Liddell has been undefeated since he added CrossFit to his training regimen two years ago. "Chuck dreads CrossFit because it's the hardest part of his workout," says his trainer John Hackelman, who forced it on him, "but it has raised his all-body fitness levels so high that no one can stay with him."

That was exactly what Greg Glassman, 49, had in mind when he developed CrossFit at several L.A.-area Gold's Gyms in the 1980s. A former high school gymnast with a manic, fact-spewing speaking style and a pronounced limp from an old rings injury, Glassman would experiment with new exercises in order to give his police and firefighter clientele an edge.