Uphill Athlete no longer recommends fasted training. Steve House explains why, then RD Alyssa Leib and host Alyssa Clark dig into fat oxidation, metabolic flexibility, low energy availability and RED-S, and what research says about low-carb, high-fat diets for endurance and altitude. The takeaway: aerobic training builds your fat-burning engine, carbs fuel performance and recovery, and there are no shortcuts. Originally released November 2024, with a new introduction.

Read more:
Fat adaptation: https://uphillathlete.com/nutrition/fat-adaptation/
Fasted training and performance: https://uphillathlete.com/nutrition/the-impact-of-fasted-training-on-performance/
Low-carb, high-fat diets: https://uphillathlete.com/nutrition/high-fat-low-carb-diet-ultra-endurance-performance/
Nutrition coaching with Alyssa Leib: https://uphillathlete.com/coaching/nutrition-coaching/

Full transcript: https://uphillathlete.com/podcast/fat-oxidation-fasted-training-and-low-carb-high-fat-diets/

Fat Oxidation, Fasted Training, and Low-Carb, High-Fat Diets (Replay)

Signed up for your first ultra? Coach Alexa Hasman, who has run 40+ ultras including seven 200-milers, joins Steve House to cover what first-timers need to know: why you don’t need a road marathon first, how much runway to give yourself, why hiking is part of the plan, the minimum strength training that works, fueling, poles, dress rehearsals, and the two keys she wants you to remember: consistency and adaptability.

Your First Ultra

Buzz Burrell coined the term "fastest known time," and he's spent his life honoring the athletes who never tell anyone what they did. Steve House talks with Buzz about his 1969 run to Lake Michigan with no food, no water, and no one to tell; pushing multi-day FKTs on the Colorado Trail and the John Muir Trail; surviving a "widowmaker" heart blockage his doctors kept missing; and why, once goals and expectations fall away, what's left is simple: keep moving.

No One to Tell with Buzz Burrell

Trail running, climbing, skiing, riding: can you train for all of them without getting worse at each? Steve House and Director of Coaching Chantelle Robitaille share the framework Uphill Athlete coaches use with multi-sport athletes. Pick one priority per season, run an honest gap analysis, and harmonize your sports instead of balancing them. They also cover the interference effect, layering sports through the year, when to set one aside, and why strength training is non-negotiable.

 Multi-Sport and Seasonal Planning

Steve House talks with Dr. Eliza Sampey, a Doctor of Physical Therapy specializing in brain injury rehab, former professional endurance athlete, and concussion survivor herself about why mountain and endurance athletes so often underestimate head injuries, and what science-backed recovery actually looks like.

Dr. Sampey explains that concussions are especially easy to dismiss in the backcountry because the injury is invisible and athletes are conditioned to push through pain. She walks through the neurometabolic cascade that occurs after a head or body impact — how stretched axons flood the brain with misplaced neurochemicals, disrupt blood flow, and trigger an "energy crisis" that takes three to six weeks to resolve, regardless of how mild or severe the initial injury seemed. She stresses why getting hit again during that window is dangerous, even life-threatening in rare cases of second impact syndrome, and can turn a six-week recovery into six to nine months.

The conversation covers red-flag symptoms that warrant emergency evacuation, why "rest in a dark room" is outdated and harmful advice, the real role of relative rest and sleep in the first 48 hours, and why low-intensity, sub-symptom-threshold exercise (not standard heart-rate training zones) is the cornerstone of active rehab. Dr. Sampey introduces the seven systems affected by concussion (autonomic, metabolic, visual, vestibular, cervical, cognitive, and affective) and explains why treating them in isolation fails — recovery requires integrating them back together. She also discusses the Buffalo Concussion Bike/Treadmill Test for gauging exercise tolerance, common mistakes endurance athletes make in returning to training too fast, how old, "resolved" concussions can resurface under new training stress, and how to vet a qualified concussion provider. The episode closes with practical guidance on symptom tracking, supporting a partner or teammate through recovery, and her core message: concussion is a treatable injury — most long-term problems come from how it's managed, not how bad it was to begin with.

Concussion Fundamentals with Dr. Eliza Sampey

Steve House sits down with elite mountain athlete Kílian Jornet, calling in from his home in Norway, for a wide-ranging conversation about what draws people to high-risk mountain pursuits. They explore mountains not as a destination but as a sense of home and identity, the fine line between earned confidence and dangerous complacency, and how fear and euphoria can each distort decision-making in exposed terrain. Jornet reflects on his upbringing; being "born into the mountains," his mother's nighttime forest walks, a family trek across the Pyrenees; and how he's now passing that connection to nature on to his own children with his wife, Emily. The two discuss the blurred lines between mountaineering, alpinism, and running as labels; the philosophy behind going fast and light versus slow and immersive; and the particular psychology of "accepting" mortal risk versus fighting to survive an emergency. The conversation turns deeply personal as Kílian opens up about the loss of his friend and climbing partner Stefane Brosse and how grief and loss reshapes friendships, risk tolerance, and one's relationship with death across cultures. They close on parenthood, legacy, and the freeing realization that, ultimately, no one will be remembered. What matters is being present, honest, and good to the people around you now.

Voice of the Mountains: Who Says Yes? with Kílian Jornet

Steve House sits down with client René Morkos to unpack his Everest summit and the profound, almost spiritual experience he had on the summit ridge. René describes the physical transformation five and a half years of structured training brought him — from a non-athlete to one of the fittest climbers on the mountain — and how that fitness "buffer" let him fully experience rather than merely survive the climb. The conversation moves through his systems-thinking background (a Stanford PhD in AI applied to construction), his formative years surviving war in Beirut and rebuilding infrastructure in Afghanistan, his personal framework for risk-taking, and the mysterious, overwhelming sensation he felt above 8,600 meters that he still can't fully explain. They close by comparing mountaineering to other transcendent experiences (Burning Man, live music) and reflecting on why the training itself — not just the summit — is the lasting reward.

Endurance and Enlightenment on Everest

Steve House sits down with Hunter Allen — cycling coach, co-creator of TrainingPeaks, and co-author of Training and Racing with a Power Meter — for a wide-ranging conversation on training technology through the lens of the hype-adoption-disillusionment cycle. They trace the power meter's unusual "trickle-up" adoption (from data-driven amateurs to pros around 2008-2009) before working through today's landscape: HRV as a life-stress signal, the limits of wrist-based sleep tracking, the untapped promise of respiration and minute ventilation monitoring for mountain athletes, pulse oximetry's highly individual response to altitude exposure, heat/core-temperature training for hot events, skepticism around substrate utilization metrics, and the current bottlenecks holding back continuous lactate monitoring. The back half is a deep dive into continuous glucose monitors (CGMs), where Allen unpacks why endurance athletes run naturally higher glucose than the general population, why CGMs are both a performance and behavior-change tool, practical strategies like "food stacking" at meals, and why he recommends six months of wear time before drawing conclusions — closing with his take on where CGM technology is headed over the next decade.

The Evolution of Training Technology with Hunter Allen

Max King is the only American ever to win both the World Mountain Running Championship and the World 100K Championship. He joins Steve House for a wide-ranging conversation about identity, competition, and longevity in endurance sport. Max traces his path from a chemical engineering degree and Cornell track team to Olympic Trials appearances in both the steeplechase and marathon, his accidental first ultra the week after a disappointing Trials prelim, and his eventual move into trail and mountain ultrarunning, including a recent attempt at the Barkley Marathons. The two dig into the tension between elite competitiveness and the collaborative, adventure-driven ethos of trail culture, how aging athletes renegotiate identity as performance declines, and why Max is drawn to races defined by history and mythology (Barkley, Dipsea, Mount Marathon) rather than media hype. The conversation closes on Max's diversified career (coaching, race directing, youth camps, a new sponsorship with the Chinese brand Kailas) and his hope to be remembered for what he gave back to the sport, especially through youth development.

Voice of the Mountains: Legacy is Not the Measure with Max King

Steve House talks with legendary coach and author Joe Friel, now 82, about the newly released second edition of Fast After 50. Friel reflects on how a serious 2014 cycling crash reshaped his own training, and explains why the book's focus shifted from encouraging older athletes to add intensity (2012) to now urging them to build a much larger aerobic base, since he's observed most masters athletes over-doing high intensity and under-doing low intensity work. The conversation covers his "5+2" and "9-day" training patterns, how strength training is periodized across a season, the concept of durability (maintaining output late in long events) and how it's trained through fatigue-then-specificity workouts, muscular/strength endurance versus durability, adapting training around perimenopause, and the two key metrics Friel prioritizes with athletes: efficiency factor (EF) in base training and heart-rate/power decoupling in build periods. The episode closes on themes of patience, lifestyle identity, coaching athletes toward self-sufficiency, and Friel's core message: build the aerobic base first.

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Training Considerations for Master Athletes with Joe Friel

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Uphill Athlete Podcast