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.
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.”