NYT: Personal Best: Short Layoff, Long Comeback

[centralpa]

November 22, 2007 By GINA KOLATA

http://www.nytimes.com/2007/11/22/he...on/22best.html

WHEN Helen Betancourt, an assistant coach at Princeton, was preparing for the World Championships in rowing in 1998, she suffered an overuse injury: stress fractures of her ribs. She competed anyway, but then had to take five months off.

Like most athletes, she did her best to maintain her fitness, spending hours cycling. Finally, she returned to her sport.

“I lost half my strength,” she said. And rowing just felt weird. “It was like I had stepped off another planet.”

Yet a couple of months later, much faster than it takes to get that strong to begin with, Ms. Betancourt felt like her old self on the water. Four months of rowing and she was in top form.

It shows, exercise physiologists say, that training is exquisitely specific: you can acquire and maintain cardiovascular fitness with many activities, but if you want to keep your ability to row, or run, or swim, you have to do that exact activity.

It also shows, they say, that people who work out sporadically, running on weekends, for instance, will never reach their potential.

This is a time of year when many people who exercised religiously for months cannot maintain their exercise schedules because they are traveling, or they have a severe cold, or simply because they are celebrating holidays with family.

That may not matter if you do not want to compete, and there is no reason why everyone who works out would want to race. But if competition or a new personal record is your goal, exercise physiologists have some lessons to impart.

Training has a pronounced effect on the heart, says Matthew Hickey, the director of a human performance laboratory at Colorado State University. Athletes develop a lower resting heart rate, their hearts beat slower during exercise, and their hearts are larger than they were before training began.

They also have a greater blood plasma volume, which allows the heart to pump more blood with each beat. One of the first and most noticeable effects of detraining is that that plasma volume is lost.

“It’s water in your plasma,” said Joseph Houmard, the director of the Human Performance Laboratory at East Carolina State University. “You just lose it. There’s no reason to keep it.”

Plasma water is lost amazingly fast, said Dr. Paul Thompson, a marathon runner and cardiologist at Hartford Hospital in Connecticut.

“We once paid distance runners $10 a day not to run,” Dr. Thompson recalled. “They spent a lot of time in the men’s room urinating.” Two days into their running fast, he said, the men lost a little more than two pounds from water weight as their plasma volume fell 8 percent.

But if runners keep running, even if they cover many fewer miles than at their peak, they can maintain their plasma volume, Dr. Thompson said.

When athletes stop training, the heart also pumps less blood to their muscles with each beat. Both changes are so pronounced, says Edward Coyle, an exercise physiologist at the University of Texas, Austin, that within three months of detraining, athletes are no different in these measures than people who had been sedentary all their lives.

But athletes, like Ms. Betancourt who do alternative activities still find that they lose a lot of conditioning.

It makes sense, Dr. Coyle said, because each activity trains specific muscles and the muscles change biochemically as a result.

He compares bicycling and running: Fast runners propel themselves forward, using their calves and ankles. With bicycling, the ankles barely move and the calves play little role. Instead, the quadriceps muscles at the front of the thigh power the bike.

Even exercises that seem similar are rarely similar enough, Dr. Coyle added. Some injured runners run in a pool, wearing a vest. That, Dr. Coyle said, is not the same as running on land. In fact, it is more like bicycling because it uses the quadriceps muscles to push against the water.

Training is especially challenging for people who want to compete in more than one sport, like triathletes, and have to divide their training time among different activities, exercise physiologists say. It’s also hard for people who reduce their exercise time because they are traveling or busy at work.

When training time is limited, Dr. Coyle said, “you have to decide where you will get the biggest performance bang for the hour you spend.”

The key, he found in his research, is to substitute intensity of effort for time. “A runner who’s been running doesn’t need much time to maintain his performance,” Dr. Coyle said. “But the training needs to be almost like racing.”

Dr. Rafael Escandon, a medical researcher in San Francisco, did it all wrong this summer when he trained for a September triathlon in Cancún, Mexico.

Dr. Escandon said he was a natural runner who completed 43 marathons. But he spent most of the summer cycling. When he ran, he did not push himself and he averaged at most 15 miles a week. He normally runs a half marathon in about 90 minutes.

When race day came, Dr. Escandon did great in the swimming and bicycling segments, even averaging almost 25 miles an hour when he was riding.

But running was another story. He ran the half marathon segment in 2 hours 17 minutes, “my worst ever, by far, far, far under any conditions,” he said. “I completely fell apart.”

But the good news is that it takes much less time to regain fitness for a specific sport than it did to become fit in the first place.

Even exercise physiologists are surprised at how quickly the body can readapt when training resumes. Almost immediately, blood volume goes up, heartbeats become more powerful, and muscle mitochondria come back.

Of course, researchers say, individuals respond differently and young people may bounce back faster than older athletes. But, they say, speed and strength and endurance do return, even in deconditioned athletes, some of whose lab test results look like those of a sedentary person.

Part of the reason, researchers say, is that training may elicit lasting effects that are very hard to measure, like changes in nerve-firing patterns and blood vessels. Dr. Coyle, who has measured muscle mitochondria, said that even though muscles lose mitochondria when athletes stop training, they retain more of them than are found in muscles of a person who has always been sedentary.

But another reason may be that athletes, unlike most inactive people, know how to train and how to push themselves.

Dr. Michael Joyner, an exercise researcher at the Mayo Clinic, saw the effects of detraining and retraining firsthand. He was a young man at the time (he’s now 49), a college athlete, and had been training continuously for several years, running an average of 80 miles a week.

“It was all very macho and I had a bunch of buddies to run with,” Dr. Joyner said. “Someone was always prepared to pick up the pace.”

Then he agreed to be a subject in one of Dr. Coyle’s deconditioning studies, which required him to stop running entirely for 12 weeks.

When he started running again, Dr. Joyner could hardly believe it. Running was so hard, he was so slow, he became tired so fast. But he persevered, running 30 miles a week for the first couple of weeks and then increasing his mileage.

“I just sort of got back with the group and started pushing it,” he said. Which, of course, is the key.

“A lot of coming back is knowing how to read your body and how to manage your suffering,” Dr. Joyner said.

But there are real rewards.

“I was back to normal again in about a month,” Dr. Joyner said.