This Boxing Workout Will Get You in the Best Shape of Your Life
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"Boxing is the ultimate challenge," Sugar Ray Leonard said. "There's nothing that can compare to testing yourself the way you do every time you step in the ring." The welterweight legend wasn't just talking about throwing and taking punches. Boxing involves near constant movement. You have to be agile and precise and play a mental game of  action-reaction. A three-minute round can feel like the longest three hours of your life.

Which might be why, in this intensity-crazed fitness age, the sport has enjoyed a renaissance (in the gym if not in the actual ring). It combines all the biggest fitness trends: functional training, intervals, total-body routines. Plus, a recent spate of watch-this-guy-get-jacked films (Creed, Southpaw, The Fighter) has made its body-transforming powers undeniable. Hence, a new generation of boutique boxing gyms has cropped up nationwide — Title Boxing Club and UFC Boxing, among them — offering group classes to work a heavy bag and get in a ring. Even major gyms like Equinox, Crunch, and LA Fitness now have classes structured around boxing.

What fuels this popularity? Boxing's particular training combo. First, it delivers body-weight strength training. Every punch requires the legs, core, and arms to flex, explains kinesiologist Stuart Phillips of McMaster University. "You step into it, brace, and bam," he says. "It's a contraction from top to bottom and a big demand on the cardio system."

Which leads to the second benefit: anaerobic exercise. That's the reason you're sucking wind 10 minutes into a boxing class. While activities like cycling or running rely on rhythmic, repetitive motions that allow heart rate to stay stable, boxing is a ceaseless sequence of ballistic, full-body movements. You jab, cross, duck, and weave, and your heart rate spikes — then you shuffle away from your opponent just long enough for your breathing to recover, and punch again. A study last spring from the European Journal of Applied Physiology found that these intervals increase the body's fat-burning capacity, creating an afterburn that torches an additional 140 calories in the 24 hours post-workout.

All of that takes work, and it can come with a steep learning curve. But that's not such a bad thing. Because unlike a repetitive boot camp class or a tired gym routine, with boxing there's always a way to be better, stronger, and faster, says Khaled Zeidan, a coach at Equinox Soho and founder of Warrior Style. "No matter how good or hard you hit, you're never going to beat that bag."

There's one other major benefit — the psychological one, says Alicia Napoleon, head of training at the new Overthrow Boxing Club in New York City: "Everyone wants to hit something sometimes."

The workout that transformed Miles Teller for Bleed for This:

Miles Teller hadn't boxed a day in his life before training to play champion Vinny Paz in the new biopic Bleed for This. But by day one of filming, the 188-pound actor had dropped 20 pounds, shed 12 percent of his body fat, and had Paz's legendary knockout cross down pat. The actor has boxing coach Darrell Foster to thank for it. In five-day-a-week sessions, Foster drilled Teller on how to "dance through the punches" and strengthened his legs, arms, core, and lungs. After three months, "he wasn't just a playing a role — he became a boxer," says Foster. Try the 45-minute bout below, inspired by Teller's routine. (Fair warning: It's tough. If you're a novice, take a couple of boxing classes first.) Done two to three times a week, it will burn fat and get you in fighting shape.