Shilletha Curtis‘s lungs were screaming, and her legs were cramping. “I was like, I’m not ready for this!” she remembers. She’d just arrived in Georgia to hike the roughly 2,190-mile long Appalachian Trail, and even though she’d been training on her local Pennsylvania trails with a full backpack six days a week, the much steeper 5,000-foot climbs at the southern start of the Appalachians left her struggling. “I didn’t have the muscle tone. I didn’t have my abs,” she says.

Fast-forward six months to the White Mountains of New Hampshire: “My legs were like rocks,” recalls Curtis. “My arms were fit from using my poles to push me up the hill. I was carrying maybe 25 pounds on my back, and it felt like nothing. And instead of needing a break at every blaze, it was more like every 10 or 20 blazes.” (Blazes are trail markers, FYI.)

It’s no surprise that embarking on a thru-hike—an end-to-end backpacking trip on a long-distance trail—changes your body. The health effects are both physical and mental, with results that last long after thru-hikers return home. “Being in nature and doing something that challenging for that long helps you learn to be in the moment more,” says Cory Nyamora, PsyD, a sports psychologist and the founder of Endurance—A Sports & Psychology Center. “It helps you develop a sense of confidence in yourself and resilience—and the capacity to endure suffering or pain.”

Hikers gain “trail legs”

No matter how much hikers train, nothing truly preps the body for the day-in and day-out of carrying your life on your back other than simply doing it. “You’ll feel a lot of soreness at first,” says Kristi Foxx, DPT, a physical therapist at Hospital for Special Surgery in New York City. “It’s called ‘getting your trail legs,’ and it typically takes five to seven days, depending on the person.” The calf muscles, quads, glutes, and the smaller support muscles in the feet and ankles take a beating until they get used to all the hiking.

“It also challenges your core and spinal control, because you’re controlling a heavy pack on your back,” adds Foxx.

This was the struggle Curtis faced when she landed in Georgia in February 2021 and felt her muscles and stamina lacking. Gail Storey, who attempted the 2,663-mile Pacific Crest Trail with her husband Porter when she was 55 (and wrote about it in her memoir I Promise Not to Suffer), says it took two weeks of hiking 20-mile days before she got her trail legs. She’d trained by hiking six miles with a full backpack daily, plus strength-training and sometimes taking two Jazzercize classes back-to-back. “But I didn’t have much experience in the way of long-distance hiking,” she says. “I had to figure it out on the trail.”

Eventually, the muscles adapt and grow far stronger. “All the girls I hiked with on the trail, we looked built by the end,” Curits says. “The men looked like bearded skeletors.”

Although the muscles typically fade back to normal after the hike is over, the intense physicality lasts. “Even now I’m in the best shape I’ve ever been,” says Storey, now 74. “The trail taught me about the mind-body connection. And gave me a leg up in embracing the vicissitudes of growing older. I love having that kinesthetic relationship with my body as a woman.”

The appetite amps up—and becomes essential

Because thru-hikers have to haul several days’ worth of meals, and need to eat far more than usual, food can pose a challenge.

“My appetite from the jump was ravenous,” says Curtis. “I was eating 15 to 20 snacks a day.” She also experienced weird cravings, like raw lemons and candy. “I’m usually very wary of sugar just because diabetes runs in my family, but in the forest I got a serious sour gummy bear thing.”

Sugar and fat cravings are typical because the body wants—and needs—that quick energy. But eating so much high-calorie, processed food causes its own problems. “Digestion is a big issue,” says Foxx. “You have to carry lightweight grab-and-go snacks. Only when you get off the trail can you get some healthy things with fiber like fresh fruits and vegetables.”

Foxx, who hiked Vermont’s 273-mile Long Trail in 2019, also felt the acute effects of not getting enough calories: At one point, she became so tired and miserable that she just “sat down on the trail and cried,” she says. She called her brother, an experienced thru-hiker, to tell him she was going to quit. “He said, ‘You need to get a Snickers at the next stop,'” she remembers. She listened, refueled, and kept going.

For Storey, however, not being able to eat enough ended her trek after three months. “I was so emaciated that I was losing muscle,” she says. At a resupply stop in the northern High Sierra, she decided the weight loss had grown too extreme; she didn’t want to slow down her husband, and potentially put them both at risk of getting stuck in dangerous conditions. So she returned home, regained the weight, and eventually met up with her husband again for brief hiking stints during the remainder of his two and a half months on the trail.

The feet get particularly beat up

Few hikers make it through a trail unscathed. Hiking up mountains with a heavy pack puts a lot of load on the body—particularly during downhill climbs. “You have to make sure to stretch out the muscles, keep them moving with a gentle range of motion,” says Foxx. Injuries from slips and falls are not uncommon. “Everybody on the trail takes a ton of Ibuprofen. We call it ‘vitamin I,'” says Storey.

Probably the most common body part to take a beating is the feet. “My thighs got stronger, my arms got toned—and my feet got weaker,” says Curtis. Wearing the wrong shoes left her with plantar fasciitis, or inflammation of the foot, and by the time she got to Pennsylvania, her ankles also started locking up. Without access to ice, she improvised by plunging her feet into cold water whenever she camped near a river or lake.

Blisters from sweaty socks and rigid shoes are more likely than not. “You have to protect your feet,” says Foxx. “Wash your feet, look for skin breakdown, and let them breathe.” (Though that can admittedly be harder in colder weather—Storey recalls waking up in the icy mountains with her socks frozen.)

Skin can both chafe and glow

If hikers can avoid sunburn, they might find nature to be their best skincare regimen. “I usually struggle with acne but my skin was glowing on the trail,” says Curtis. She credits that to the fact that she wasn’t touching her face as often as usual, and only showering every three to seven days. “I also put a lot of mud on my body to shield it from the sun and mosquitos.” Not only did the tactic help prevent burns and bug bites, but she believes not washing off the good bacteria had therapeutic effects.

Not all skin fares so well. In addition to blisters on the feet, chafing can be a problem where hikers’ pack hits their chest and back (particularly for women with larger chests who have a hard time finding a good fit). “It can be a lot of skin rubbing and wear,” says Foxx. “You have to be sure to get the right fit.” Looking for a pack with an adjustable chest strap, as well one around your waist can offer extra support and allow you to customize the fit to your body shape and size.

Mental strength gets majorly challenged

There’s a common saying on the trail: “Embrace the suck.” Although those stuck behind computers may romanticize the idea of being in nature 24/7, the constant churn and fight against the elements can be both physically and emotionally exhausting. “It gets heavy sometimes to be out there,” says Foxx.

Hikers have to come to terms with giving up control over things like weather conditions and injuries, says Storey. “Being that vulnerable grew my resilience, resourcefulness, and confidence,” she says. “I learned how to be happy even in intense discomfort.”

Dr. Nyamora suggests hikers make a plan ahead of time for when things don’t go well. “Be prepared to want to quit,” he says. “And be clear with yourself—these are the reasons I will quit.” The temptation will happen, he says, so it’s essential to prep for it (and also for hikers to not let perfectionism push them past healthy limits).

Yet the constant exercise and exposure to nature also has its mental health benefits. Curtis, who lives with depression, ADHD, and panic disorder, found her thru-hike gave her a chance to practice more mindfulness. “Being out on the trail was the best I’d ever been able to cope,” she says.

Social bonds accelerate

Dr. Nyamora points out that not only do hikers have to learn to rely on themselves, they’re forced to rely on others sometimes—whether for a ride to town, advice for the next pass, or simply someone to talk to. “You’re pushed to connect with strangers,” he says.

The emotional experience makes everyone very raw, and many open up to each other in ways we don’t typically experience in day-to-day life. Some hikers end up sticking together as a “tramily.” “It’s like a socialist society in the forest—we help each other out,” says Curtis.

The biggest challenge can come after the finish line

After spending so much time focused on one goal—and getting used to a steady stream of endorphins from regular physical activity—going back into “real life” can be the hardest part. “Transitioning out of a space that was so meditative, where you got a break from the juggling all the details of our normal lives, can be jarring,” says Dr. Nyamora.

Post-trail depression can hit hard. Storey missed hiking so much that she found herself backpacking to the grocery store two miles each way in her shorts and hiking shirt. Curtis says she “felt like a puppy thrown out into the world,” and didn’t leave the house for a month, and explains she was unable to relate to other people who hadn’t experienced what she’d just been through.

“I don’t think you ever really are the same after doing something like that,” she says. One coping mechanism: to just keep hiking. Today, Curtis is in the middle of the 3,028-mile Continental Divide.

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