photo by David N. Seelig

VO2 & you

new technology can create personalized workouts for fitness or weight loss

by Greg Moore

Whether they are serious triathlon competitors or just recreational athletes, local residents and visitors can benefit from a more scientific approach to their workouts.

“A lot of people are putting in the time, but they’re not making good use of their time,” says Bill Nurge, director of human performance testing at Zenergy in Ketchum.

Most people, he says, do workouts that regularly involve a consistent, “pretty hard” level of exertion. That, he says, is a mistake.

Nurge, who holds a master’s degree in exercise physiology, advocates a varied training program for anyone interested in improving aerobic fitness. The program should include at least three workouts per week, each of a different level of intensity. Each type of workout prompts the body to respond in different ways, all of which contribute to overall fitness.

The first is an easy workout of long duration, such as a two- to three-hour hike or easy Nordic ski trip.

The second involves a 20-minute warm-up, then 20 to 30 minutes of exertion near one’s anaerobic threshold, followed by a 20-minute cool-down. The anaerobic threshold is the highest level of exertion that can be sustained for 30 to 60 minutes without significant lactic acid buildup. Examples of this kind of workout are fairly strenuous skate skiing, or, in the summer, riding on a biking trail up part of Bald Mountain, Sun Valley’s premiere ski area that continues its recreational offerings after the snow melts.

The third involves high-intensity bursts of energy for short duration, only one to a few minutes at a time, with a minute or two at a relaxed level of output in between.

“Most people don’t go easy enough on their long workouts, and they don’t go hard enough on their short ones,” Nurge says.

Those who want to dial their training in to the maximum efficiency can do so via new technology called New Leaf that recently became available at Zenergy. For decades, top-level athletes have been tested for their capacity to process oxygen. Combined with heart rate monitoring, that information can be used to tailor a training regimen to each athlete.

But, until about two years ago, the machines used were bulky and expensive. Now, modern micro-technology has made such analysis available to health clubs.

“It’s helping people make better use of their training time,” Nurge says, “training smarter and not necessarily harder.”

To get tested, the athlete walks on a treadmill moving at a fairly rapid rate. As the 10- to 15-minute test proceeds, the treadmill is tilted upward, increasing the amount of exertion required.

A neoprene mask with a plastic tube, through which the person inhales and exhales, is placed over his or her face. The machinery measures the volume of air used, as well as the amounts of oxygen and carbon dioxide in the exhaled air. Oxygen in minus oxygen out equals volume of oxygen processed by the body.

The test measures both the volume of oxygen the person can process (called VO2) and his or her anaerobic threshold, stated as a percentage of the VO2. One’s VO2 can be thought of as the size of one’s “engine,” and the anaerobic threshold as the amount of exertion that can be sustained without blowing the engine up.

Throughout the test, a heart monitor measures the increase in the person’s heart rate. When training later, the athlete can wear a monitor to correlate heart rate with the level of exertion he or she is seeking in that particular workout.

Once a person’s level of fitness is pinpointed, Nurge can combine that data with his client’s goals and time schedule to design the most efficient workout regimen, with the intent of increasing both one’s VO2 and anaerobic threshold.

“Without training, we’re all pretty similar,” Nurge says. “You don’t know how fit you can get unless you apply yourself. Different people can adapt to different degrees,”

At a low level of exertion, the body obtains some of its energy from burning fat. But that’s a slow way to produce energy. When the level reaches a certain point—about 150 heart beats per minute, depending on the person—the main source of energy shifts from burning fat to burning sugars stored in the muscles.

From that point on, the level of exertion cannot be sustained for long. Byproducts of burning those sugars are lactic acid and carbon dioxide. Lactic acid buildup fatigues muscles, and carbon dioxide buildup in the blood crowds out oxygen there. The athlete starts panting hard, partly to bring oxygen in, but mainly to force carbon dioxide out.

“The goal of the endurance athlete,” Nurge says, “is to do as much work with as little acid buildup as possible.”

The way to get there, he contends, is an efficient, scientifically designed workout schedule.

Such an approach not only helps endurance athletes, it’s also an effective way to lose weight. When your body is at rest, it actually obtains a higher percentage of its energy from fat than it does while it’s exercising. The point at which it burns the most fat (though not the most calories) is just before it reaches its anaerobic threshold. So a person who for any reason cannot do strenuous exercise can still lose weight. With the help of a VO2 analysis and a heart monitor, he or she can pinpoint the level of exertion that will burn the most fat.

On the other hand, the more strenuously you exercise, the more calories you burn. The more calories you burn, the more you can eat afterward before your food starts being converted to fat.

And what is particularly important is the more fit you are, the more calories your body burns at a given level of exertion.

“Your muscles get more efficient at burning fat when you’re aerobically conditioned,” Nurge says.

That’s bad news for people who are overweight and out of shape—they will have trouble losing weight at first. But it’s good news in the sense that anyone can speed up their rate of weight loss by increasing their level of fitness.

It’s also good news for older people who presume their days of being able to get into good shape are long gone. Nurge, who is 41, has won the Baldy Hill Climb race four times in the last several years. He placed third this fall. Nurge says that by taking a committed and scientific approach to his workouts, he is now in better shape than he was when he was training for triathlons at age 23. He’s increased his VO2, as measured in milliliters of oxygen consumed per minute for each kilogram of his body weight, from 70 to 84.

One of Nurge’s clients is a woman in her 70s who, he says, is now more than three times as strong as she was when he began to work with her.

For those who either want to lose weight or increase their fitness level, Nurge advocates a workout program that combines both aerobic exercise and strength training. The stronger you are, the more work your body’s going to be able to do at a given level of exertion.

He also emphasizes that people should pay as much attention to conditioning their upper bodies as they do their legs. Studies have shown that Nordic ski racers burn almost as many calories with their poling as they do with their skating.

For visitors who are wondering if training at the fairly high altitude here will condition them better than training at sea level does, the answer is no. Your body conditions itself best when it’s getting as much oxygen as possible.

“You get the positive altitude adaptations by living at altitude, not by training at altitude,” Nurge says.

Athletes who plan to compete at high altitude try to sleep high and train low. Anyone who will be traveling from a low elevation to compete at high elevation, Nurge advises, should either arrive within 24 hours, before the body has time to react, or be there for at least a week.

Whatever your elevation, a methodical approach to working out should have you skiing smoother, biking farther and looking sleeker.