Xtreme Hike to Cure CF enlists two U of A physicians in Grand Canyon fundraiser

A husband-and-wife team at the University of Arizona College of Medicine – Tucson will hike the Grand Canyon rim to rim this October to raise money for the Cystic Fibrosis Foundation.

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James Knepler, MD, and Holli Horak, MD, are part of a cohort of 25 hikers and three teams collecting funds for the CF Foundation as part of its Grand Canyon Fall Xtreme Hike 2026, which takes place on Oct. 2-4. Each hiker is trying to raise a minimum of $4,000 as their goal. The actual hike is on Saturday, Oct. 3.

Contributions can be made at this link. Scroll down to see the hikers and click on Dr. Knepler or Dr. Horak by name to make a donation. Their individual pages to donate to with their stories on why they’ve joined the Hike to End CF can be found here (for Dr. Knepler) and here (for Dr. Horak).

Cystic fibrosis is a genetic, life-shortening disease that causes the body to make thick, sticky mucus instead of thin, watery fluids, devastating the lungs, pancreas and other vital organs. CF prevents key enzymes from breaking down food and makes it difficult to breathe or fight life-threatening infections, often leading to lung damage and respiratory failure.

About 40,000 people in the U.S. and more than 100,000 globally live with CF. Roughly 1,000 new cases are diagnosed annually — 75% by age 2. Driven by advanced therapies, the median predicted survival for a child born with CF today reaches into the mid-60s, an improvement of about 30 years since 2000 and more than 50 since the 1960s, according to the National Heart, Lung, and Blood Institute.

UPDATE: Tragic Grand Canyon flash flood may delay CF Foundation hike

Monday, Aug. 31, 2026 — Over the weekend, devastating flash floods surged through Bright Angel Canyon in the Grand Canyon National Park causing the tragic death of at least two people, possibly more. Fifteen people were reported missing and more than 60 people were evacuated and are being assisted by the American Red Cross.

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Drs. Knepler and Horak wish to express their sorrow and acknowledge the grief of those affected. They’re awaiting an update from the Cystic Fibrosis Foundation as to the status of their hike.

The floodwaters also caused destruction of nearly all trails and footbridges, utility buildings, facilities and other infrastructure in the canyon. Also suffering extensive damage was the Transcanyon Waterline, the only water pipeline that provided water to tourists and residents at the canyon.

Thus, there’s unfortunately a very real chance the CF Foundation will cancel the entire hike, or postpone it until the spring, Drs. Horak and Knepler said. Further updates will be posted here as they become available.

Dr. Knepler, a pulmonologist, professor of medicine and Division of Pulmonary, Allergy, Critical Care & Sleep Medicine associate chief at the College of Medicine – Tucson and Banner – University Medicine Tucson, had been medical director of the CF Clinic here from 2019 to 2023. As respiratory therapy medical director and Pulmonary & Critical Care Medicine Fellowship director, he continues to work with CF patients in the multidisciplinary clinic.

“It’s my experience caring for these patients that led us to want to do this hike. The advances in the care of CF have made huge strides with new medications that really have altered the trajectory of the disease. The CF Foundation has played a big role in that. So, the combination of hiking the Grand Canyon and helping the CF Foundation just made sense.” Dr. Knepler said.

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“We’ve hiked the Grand Canyon once before down to Phantom Ranch and then, hiked back up the next day,” he added. “We’ve never hiked rim to rim, so we are excited to do that. We have many shorter hikes in the Grand Canyon as well as a rafting trip. It’s a special magical place for us.”

Dr. Horak is a Department of Neurology professor and director of the Clinical Neurophysiology Fellowship and Neurology Clerkship. She and he met at Ohio State University where they earned their medical degrees and completed their residency training before their fellowships at Indiana University. They came to Tucson in late 2009 and 2010, with her joining the College of Medicine – Tucson faculty then, and him being a staff physician at the Southern Arizona VA Health Care System until June 2011, when he joined the U of A faculty.

“Previously, I’ve helped to raise money for patients with neuromuscular disease, including running the New York City Marathon for the American Neuromuscular Foundation,” Dr. Horak said. “I’m looking forward to the challenge of hiking the Grand Canyon and helping raise money to end cystic fibrosis.”

Drs. Knepler and Horak will arrive at the CF Foundation’s Arizona Chapter office in Phoenix on Friday, Oct. 2, before heading out with other hikers via motor coach to the Marble Canyon Lodge next to the Vermilion Cliffs National Monument off Arizona Highway 89A between Page, Arizona — home of the Glen Canyon Dam at Lake Powell — and the Grand Canyon’s North Rim.

The North Rim is where the cross-canyon hike starts. On Saturday, the hikers will march 23.9 miles from the North Kaibab Trailhead to the Bright Angel Lodge on the South Rim, which is more familiar to Grand Canyon visitors as it’s where most of them come to look out at the amazing vistas. And, on Sunday, they’ll have a recognition celebration before returning to Phoenix.

Out of 5-to-6 million visitors a year, only about 5% of visitors ever hike below the rim and just 1% make it to the bottom and back, with rim-to-rim hikers even fewer. That’ll put them in rare company indeed.

EXTRA: ‘Xtreme Hikes to Cure CF’ across the country

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The Cystic Fibrosis Foundation also hosts multiple Xtreme Hike to Cure CF fundraising events nationwide, including two more in Arizona — a spring scenic trek through Sedona’s red rock country and Grand Canyon summer rim-to-rim hike. Others include hikes along the Appalachian Trail in North Carolina, Massachusetts’ Berkshire Mountains, as well as Zion National Park and Yosemite National Park, and dozens more. To find and plan yours, see hike.cff.org.