Body Of A Backpacker

It's lean, it's mean, and it can last forever.
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It's lean, it's mean, and it can last forever.

Backpackers get no respect as athletes.

Truth be told, the term athlete is rarely applied to us, and we're seldom mentioned in the same breath as the ultrafit devotees of cycling, distance running, or adventure racing. Perhaps it's our own fault--no one lists exercise as the reason to hit the trail, we don't shave our legs and wear Lycra, and we're way too busy fraternizing with Mother Nature to parade our tanned hard bodies around the local gym.

But that doesn't change the facts: Backpacking is great exercise. No other sport combines endurance training, weight-bearing workouts, and a low injury rate in such an enticing package. When properly trained, a hiker's body is just as honed and fit as those of other athletes. The problem is, our sport never gets compared to these pursuits.

Until now. We decided it was time to put our money where are mouths are, and fund an ambitious physiological study of the backpacking body. To that end, we rounded up eight hardcore hikers and sent them to the Human Performance Lab at the Boulder Center for Sports Medicine (BCSM) in Colorado. Not surprisingly, our trail rats aced the tests--but even we were shocked at just how superfit they are. In fact, the results offer compelling evidence that backpacking might be the very best thing you can do for your long-term health.

So here's a well-deserved (and well-substantiated) dose of fitness hype that offers an exercise in inspiration.

The Guinea Pigs

We began by recruiting a captain for our all-star team: 41-year-old Triple Crown King Brian Robinson. "Flyin' Brian" is the only guy we know who has lived on the trail 24/7 for nearly a year. Next, we selected two long-haul specialists: two-time Appalachian Trail thru-hiker Terry Norton, 39, and world-famous mountaineer "Big Wall Pete" Takeda, 38, who does more backpacking just approaching his climbs than most people do in a lifetime. We also signed up two ultralighters whose exploits toe the line between hiking and trail running: 51-year-old Colorado Trail speed record holder Buzz Burrell and Hong Kong Trailwalker winner Stephanie Ehret, 40. For a little family drama, we added Buzz's 23-year-old son, Galen Burrell, who recently returned from a multicontinent backpacking trek. We rounded out the group with 38-year-old Cathy Chittum, an avid dayhiker, backpacker, and cross-country skier, and self-proclaimed "mellow" backpacker Eileen Lambert, 29.

The Lab

We sent our group to BCSM for a serious, scientific gut check. The lab, packed with state-of-the-art diagnostic equipment, offers physiologic, biomechanic, and nutrition consultations to recreational athletes and Olympians alike. There, Neal Henderson, the center's coordinator of sport science, joined fellow exercise physiologist Paul Kammermeier and certified athletic trainer Denise Knutson in subjecting our volunteers to a seven-test protocol designed to measure aerobic capacity, cardiovascular health, body composition, and flexibility.

The Science

Hiking is stressful--in a good way. "Backpacking provides the body with a stress, and it adapts," says Paige Holm, a sports physiologist at the U.S. Olympic Training Center in Colorado Springs. For instance, to cope with increased energy needs, muscle cells produce and expand existing mitochondria, an organelle that powers the cell. "You also get an increase in oxidative enzymes that help your cells use oxygen, and a protein called myoglobin that helps with oxygen metabolism," says Holm. Backpacking demands extra work of your muscles, so they grow more capillaries. It may sound complex, but the bottom line is simply empowering: The more you backpack, the more your body can produce energy.

Hiking also helps your heart. When you're humping over steep trails, your muscle cells hunger for more oxygen, which prompts your heart to beat faster. Over time, that extra work enables that organ to pump more blood with each stroke.

Other benefits are more obvious. Long, low-intensity workouts-like an 8-mile day with a 40-pound pack--build endurance and lean muscle mass. Moderate to high intensity workouts-that same 8-mile day with 5,000 feet of elevation gain and loss thrown in--give you a fifth gear. And all those hours of full-body exertion burn fat faster than Jenny Craig. But only scientific testing will reveal the scope of these benefits.

The Tests

Backpackers have serious heart

Galen Burrell marches to a different beat than most folks--a much slower beat. Burrell, who calls himself "naturally relaxed," had an astoundingly low resting heart rate (RHR) of 42 beats per minute (bpm). While the other participants weren't quite so slow thumping, the group's average RHR was just 59 bpm, far better than the 72 bpm average of the general population.

Experts like Henderson and Holm say those slower heartbeats speak volumes. That's because RHR is typically lower in athletes and is a good measure of fitness. "A low resting heart rate indicates that your heart is very efficient--it's pumping more blood per beat," says Holm.

Interestingly, the RHR test highlighted one factor that can mess with your ticker: altitude. A day after arriving in Boulder, Robinson's pulse measured about 15 beats per minute higher in the lab than in his sea-level home in Mountain View, CA. Henderson was hardly surprised. "Your resting heart rate, especially initially, will be higher at altitude," he says. That's because at altitude, the oxygen-carrying capacity of your blood drops (see "Why Do We Bonk At 14,000 Feet?" on page 59).

Exercise is also known to lower blood pressure, and our backpackers scored well here, too. A reading of 120 over 80 or lower is considered optimal; our group averaged 119 over 76. "Overall, we found good numbers," says Henderson. "Everyone's values were in the healthy range."

A bunch of hard workers

To hell with aging gracefully. By manhandling the big, bad VO2 max test, Buzz Burrell shows you can still be kicking ass when your coworkers are considering retirement. The 51-year-old put up numbers that amazed the BCSM crew.

The VO2 max test is many things. For one, it can be the longest 10 to 30 minutes of your life. Test subjects, outfitted with a nose plug and a mouthpiece, hit the treadmill. The pace and grade are slowly jacked up until the tester can't continue. From a scientific point of view, all that suffering reveals exactly how much oxygen your body uses in a minute given your body weight. Put simply, it's the gold standard of exercise tests because it measures your aerobic capacity for work-in other words, the size of your engine. About 80 percent of your VO2 max is written in your genes, says Henderson; the rest comes from training.

As a group, our backpackers produced excellent VO2 max values, with the men averaging 61 and the women 46-scores similar to what Henderson finds in other serious endurance athletes. (By comparison, a typical man in his 20s or 30s scores around 40, while the average woman performs in the low 30s.) Buzz was the team's VO2 superstar, scoring a 64-an astonishing 200 percent of the results predicted by his age and weight. What makes the elder Burrell's mark even more phenomenal, says Henderson, is that it is nearly identical to his son Galen's VO2 max of 64.7, despite a 28-year age difference. VO2 max is known to fall with age, but Buzz's result is proof that training can slow this decrease.

The group's numbers also show that backpacking can increase your aerobic capacity without the need for lung-busting sprints, says Henderson. "These people aren't doing lots of interval training, yet their VO2 max values are all exceptional-probably because they do a lot of high-volume training at a moderate intensity."

Lean, mean, and hungry

No doubt about it, long days on the trail burn some serious calories, so it's no surpise our testers are low-fat specimens. "It doesn't sound like much, but if you need 3,000 calories per day just to maintain your weight, you'll need 21,000 calories for a week," says Henderson. "And that's a lot of energy bars."

To get the skinny on just how lean our athletes are, Henderson and Knutson measured both body mass index (BMI), which analyzes the ratio between your height and weight, and body fat percentage, using a skin fold caliper test that measures the thickness of the subcutaneous fat layer at seven places on the body. "For the latter test, 10 to 12 percent body fat is an ideal level for guys," says Henderson. "For women, closer to 18 percent is best for sustained endurance." The men in the group averaged 9.8 percent body fat, the women 17.3 percent.

Most hikers consider weight loss spurred by backpacking a bonus, but Henderson warns that lower fat levels than our athletes carry could spell trouble. "There are no health benefits from extremely low body fat," he says, "and there may be detrimental effects." For women, 10 to 12 percent is the lower end of the essential body fat; for men, it's 3 to 4 percent.

Henderson also advises people embarking on thru-hikes or expedition-length travel to aim for the higher end of the fat spectrum so they have fuel in reserve. "Terry is extremely lean--5.6 percent body fat," notes Henderson. "I told him I wouldn't plan on doing any really long trips right now, because he doesn't have much stored energy."

Pete Takeda already follows this advice. The climber was plumper than normal when he hit the lab, as he was preparing for a mountaineering trip to Canada. "I go in fat, and plan on losing it," says Takeda. "In cold conditions, you're not eating as well as you should. I've come back from Himalayan trips 25 pounds lighter than I went in."

Not at the top of their lungs

Kammermeier administered three tests of lung function, and as a group, our backpackers' pulmonary scores were unremarkable. That's not surprising to the experts: Contrary to popular notion, says Holm, what determines lung capacity is mostly how big you are. "Underwater sports like swimming or deep diving, where you're breathing against resistance, can increase lung capacity," says Henderson, "but general aerobic training does not."

But that's no reason to fret. "Lung volume is not a big predictor of performance or fitness," says Henderson.

Still, the maximum volume ventilation (MVV) test, which measures the ability to get air in and out of the lungs, can help predict performance at high altitude where the air

pressure is lower. "The better you can get air in and out, the better you'll adapt," says Henderson. Here, Buzz, Pete, and Cathy scored above-average values.

Flexibility-not!

It's no accident that backpacking is rarely compared to yoga. When it came to their lower calves and ankles, our testers resembled robots more than yogis. Knutson assessed our backpackers' flexibility by testing their performance with back, hamstring, quad, hip, chest, shoulder, calf, ankle, and shin stretches. "Overall, hip, low back, and hamstring flexibility was good, but several people admitted that at the end of a long hike, the tests would likely have shown less flexibility in these areas," says Henderson.

Of course, it's not easy to avoid this stiffness. "The lower leg muscles provide stabilization during hiking on rugged terrain," says Henderson. And while backpacking strengthens these muscles, it can also tighten them. To counteract this effect, Holm suggests adding a few stretches to your routine.

The Bottom Line

Backpackers are very fit athletes--every bit as fit as marathoners or cyclists. "These folks are not like run of the mill joggers," says Henderson. "They are serious endurance athletes."

The backpacker bodies we tested were lean and strong with powerful, healthy hearts and high-endurance capacities. "Their fitness level makes them very similar in nature to distance runners," says Holm. For his part, Henderson admitted he would be hard-pressed to distinguish their results from those of serious cross-country skiers, cyclists, or runners.

And the icing on the cake: Despite backpacking's noncompetitive nature, its fitness benefits rival those of more intense, high-impact activities. "For the recreational athlete, the results confirm that hard is not always better," says Henderson. "Long, steady aerobic workouts like backpacking will also significantly improve fitness without a high chance of getting ill, injured, or burned out."