An Aerobic Workout That Really Packs a Punch : * Enthusiasts regularly tape their hands and jab at targets in an Irvine gymnasium to practice a pugilistic alternative to dance-based exercise.

The buzzer sounded and Round 6 began. Keith Sorensen, still panting after only 60 seconds of rest from Round 5, got up slowly from his chair. Sweat soaked through his T-shirt and bounced from his face as he raised his leather gloves and jabbed left, left, then a quick left-right-left combination.

Although Sorensen’s opponent in Round 6 was a vertical string of tennis balls laced with bungee cord, the Irvine resident locked his focus on his targets, weaving and dodging as the elastic cord sprang back at him after each punch. His boxing trainer shouted from the sidelines: “Don’t think power. Think number of punches.”

At age 55 and 230 pounds, Sorensen isn’t looking to give up his computer businesses to step into the ring with Thomas (Hit Man) Hearns. But he and about 10 other Orange County residents regularly tape their hands, lace on boxing gloves and punch at targets in an Irvine gymnasium to practice what former amateur boxer John O’Brien calls the manly aerobic exercise of the ‘90s.

O’Brien, who has trained in boxing since he was 14 and fought in more than 60 amateur bouts, also teaches traditional boxing at his own exercise studio in Costa Mesa and a Westminster gymnasium, at which he is also on the board of directors.

Students in the all-male class, ranging in age from teens to seniors, go through the same circuit training used by professional boxers, getting the heart pumping just as fast as dance-type aerobics, O’Brien said.

“When those guys put the gloves on, it’s like putting ducks in water,” O’Brien said. “They just don’t want to stop.”

O’Brien said he got the idea for the class after suffering through an aerobics class. He didn’t like the movements, and worse, he said, he had trouble doing them. So he began the boxing workouts in the fall at the Irvine Jazzercise center with a small group of students. Today, between six and 10 students regularly attend each class.

“Men have a hard time going to aerobics classes,” Sorensen said. “I tried to do that and just . . . no way.”

O’Brien’s students prefer to ball their fists, lean forward and punch something with all of their might. He capitalizes on that urge by teaching proper stretching and toning as well as how to deliver solid punches to the stomach, sternum and head.

A big attraction for students is that they learn real boxing techniques--balance, form, hand-eye coordination--without ever having to step in the ring.

“Professional boxing is an ugly, brutal game,” O’Brien said. “The boxing workout allows a person to go through the same professional training, but he doesn’t have to pay the consequences at the end of the month.”

Sorensen signed up for the boxing workout classes while looking for a low-impact aerobics workout. He realized he needed more exercise, he said, after looking down and seeing his growing gut and finding that his strength wasn’t what it used to be.

“From an exercise standpoint, it’s excellent,” Sorensen said. “Boxing is a very natural movement. We all swing our arms. A left hook. An uppercut. And it’s easy to do because no one is hitting back at you.”

In each of O’Brien’s twice-a-week workouts, students spend 10 rounds rotating through nine punching-bag stations set up on a padded mat. One round is spent one-on-one with O’Brien, who uses catcher-mitt-like “focus gloves” to present targets to the students. He tells them what kind of punches to deliver and presents the gloves as a target, correcting or reinforcing their technique.

The punching stations contain three maze bags (which resemble footballs swinging from a length of cord) at different heights, the vertical string of three tennis balls and five punching bags ranging from tiny to sumo-wrestler size.

The trick, O’Brien demonstrates with the bags, is to practice form and technique. The power behind the punch is less important. Students should go easy on the heavy bags until proper technique is mastered, he stresses. It is still possible to injure a wrist if a bad punch has too much force behind it.

The maze bag and tennis balls, in fact, require soft, well-aimed punches.

The maze bag swings in wide arcs after each punch and allows footwork practice as it swings back at you, O’Brien said. A good practice is to duck and weave as the bag approaches, then duck again just before it hits you from behind. Learning to avoid the bag teaches timing as well as how to dodge punches, he said, which would be important in a real fight.

The workout is intensive, students said.

“It’s equal to doing two or three aerobics classes,” said Erik Lunde, 29, of Newport Beach. “I think this is more fun, and the reason you sweat more than in aerobics is you have something coming back at you.”

Fun is also an important reason David DiRienzo, 33, of Irvine, keeps coming to the boxing workout. He regularly works out four days a week, including lifting weights and working out on a StairMaster.

An intense workout on that machine is equivalent to climbing 175 stories, he said, but the problem is boredom.

“It seems like an eternity. Here, it was over before I knew it,” DiRienzo said.

Hitting a bag also eases stress.

“It’s a real release,” Sorensen said. “If you’ve had a stressful day at work and you go through this, it’s gone. You go in and you hit the bags and they don’t hit back. And they don’t talk back. You’ve let your frustrations out in a very healthy way.”

Jay Westphal, 38, an Irvine physician, said he doesn’t step up to the bags saying, “I’m going to kill that bag. . . . But you do forget other anxieties and stresses because your mind is focused on what you’re doing. For the hour in here, I don’t think of anything else.”

Recruiting students for the boxing workout has its challenges because potential students feel hesitant about learning to box.

“It is intimidating at the beginning,” he said. “Students wonder, ‘Is someone going to try to hit me? Am I going to look bad?’ But once they come, they love it.”

So far, O’Brien seems to be one of the few Southern California boxing coaches using the sport as an aerobic workout for the general public. Calls to area fitness centers found no similar classes.

Whether the boxing workout could be considered equivalent to other forms of aerobic exercise is impossible to say without the students measuring their heart rates during the workout, said Sue Long, an exercise physiologist and assistant professor of physical education at Irvine Valley College.

The boxing workout by itself would not qualify as a good aerobic exercise for an individual because a good routine needs to be practiced three times a week for at least 20 minutes at a time, with the heart beating to roughly 60% to 75% of its maximum capacity, she said.

But the fact that the men are going through several rounds of intensive activity twice a week certainly qualifies the workout as a good form of exercise, Long said.

The concept of using boxing training as aerobic exercise is still relatively new, national fitness organizations said.

Officials with the Institute for Aerobics Research in Dallas and the Aerobics and Fitness Assn. of America in Sherman Oaks said they had heard of the boxing workout, but have yet to conduct any research on its popularity or use as aerobic exercise.

A woman from New York applied about two years ago to demonstrate a boxing workout regimen to a national convention of fitness professionals. But IDEA: The Assn. for Fitness Professionals in San Diego, determined at the time that there was insufficient interest in a boxing workout to warrant the demonstration, said Jennifer Jo Wilson, the association’s director of public relations.

“We didn’t see it as being a trend,” Wilson said.

However, if trainers such as O’Brien can succeed in sparking a wider interest, she said, boxing training might indeed become more widespread. A boxing workout could even help to attract more men to organized aerobic workouts, which now attracts mostly women, Wilson said.