Altitude sickness: the warning signs you shouldn't ignore with Monica Piris
What actually happens to your body on a high-altitude expedition, and how much do genetics, experience, or fitness matter when the summit is in the “death zone”? In this episode of The Progress Theory, I’m joined by Dr Monica Piris, a medical doctor and veteran of dozens of Himalayan expeditions, to understand the physiological and practical challenges of climbing above 5,000 metres.We explore how the body adapts (or fails to adapt) to extreme altitude, why altitude illnesses can escalate rapidly, and what individual, genetic and cultural differences mean for mountaineers. Monica describes the day-to-day realities of her role as an expedition doctor, from remote preparation through managing clients at base camp, and offers clear advice for anyone considering a serious mountain challenge. Along the way, we discuss why technical difficulty and fitness interact with altitude risk, the realities of using supplemental oxygen, and what motivates climbers to keep pushing despite the hazards.Whether you’re preparing for an expedition or fascinated by how humans cope in extreme environments, Monica’s experience and practical insights will help you understand the real trade-offs behind altitude performance.In this episode, we discuss:00:00 – The risks of extreme altitude and Monica’s background as an expedition doctor03:28 – Common illnesses on expeditions and the realities of “glamorous” mountain medicine04:46 – How Monica works with clients before and during expeditions07:17 – Why doctors stay at base camp and the impact of altitude on decision-making08:39 – What altitude does to the body: definitions and oxygen availability10:26 – Adaptation limits above 6,000 metres and the variability in acclimatisation12:16 – Genetics, cultural adaptation, and why some populations perform better at altitude14:10 – Recognising and responding to high-altitude illnesses (AMS, HACE, HAPE)18:28 – How quickly altitude illnesses can progress and the importance of self-awareness20:14 – Managing motivation, communication and decision-making on expeditions23:35 – Why Monica rarely faces dramatic resistance from clients24:29 – Differences between commercial clients and professional athletes28:22 – The distinction between elite performance and guided expedition support30:24 – Using and not using supplemental oxygen: safety, ethics, and challenges33:58 – Is Everest technical, or just high? What makes mountains dangerous36:45 – How technical difficulty, fitness, and exertion affect risk at altitude39:53 – Preparing physically and practically for mountaineering challenges41:35 – The rise of extreme challenges and social media influence42:11 – FKTs and what elite athletes actually need from doctors44:29 – The reality of appetite, nutrition and fuelling at serious altitude49:51 – Monica’s personal altitude symptoms and inter-individual differences52:30 – Why even professionals sometimes turn around on major climbs53:38 – Variability in individual response and the role of trip factors55:51 – Why concurrent illness increases risk at altitude57:07 – How to contact Monica and find out more about safe expeditionsTakeawaysAltitude adaptation and risk are highly individual and context-dependent: Monica explains that physiological responses to altitude differ greatly due to genetics, previous exposure and training, and even the presence of minor illnesses or fatigue.Recognising and acting on altitude illness early is crucial: Symptoms such as headache, nausea, reduced exercise capacity and cough may seem minor at first but can escalate rapidly. Education and honest self-monitoring are key to safety on expeditions above 5,000 metres.Preparation goes beyond fitness — practical mountain experience matters: Monica emphasises that good preparation includes time spent moving in mountainous terrain, carrying loads, dealing with cold and logistical discomforts, and not just aerobic fitness. Those with practical exposure are much less likely to be overwhelmed when conditions become extreme.FOLLOW OUR PODCASTThe Progress Theory: @theprogresstheoryDr Phil Price: @drphilpriceResources mentionedMonica on Instagram: https://www.instagram.com/monica_piris/Alpenglow Expeditions: alpenglowexpeditions.comExplore more episodes at: https://www.theprogresstheory.com/For all our other episodes and to get in touch, please visit www.theprogresstheory.com.Thanks for listening!This podcast is hosted by Captivate, try it yourself for free.KULT Media 2026Mentioned in this episode:Progress Theory NewsletterDo you want the latest information on how to optimise human physical and mental performance sent straight to your email? Subscribe to the free Progress Theory newsletter on Substack where you will receive the latest research and recommendations on how to optimise your performance each week.
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