The Endurance Lab

Can you become a fat-adapted endurance athlete while still using carbohydrates to race fast?In this episode, I sit down with Sami Inkinen, endurance athlete, age-group triathlon world champion and co-founder and CEO of Virta Health, to explore how he went from discovering he had prediabetes despite being extremely lean and fit to dramatically increasing his fat oxidation and, at age 50, producing some of the best endurance performances of his life.Sami explains how changing his nutrition increased his measured maximum fat oxidation from roughly 200 to 800 calories per hour, why he describes becoming highly fat-adapted as becoming “bonk proof,” and how he combines a low-carbohydrate lifestyle with strategic carbohydrate intake during hard training and racing.We go deep into fat adaptation, metabolic health, low-carb and ketogenic diets for endurance athletes, carbohydrate periodization, fat oxidation, training after 40 and 50, prediabetes in athletes, recovery, longevity and endurance performance.Sami also breaks down his “live low, race high” approach: eating mostly real foods and minimizing carbohydrates outside training while deliberately using carbohydrates during demanding workouts and competition.Importantly, Sami repeatedly distinguishes his personal N=1 experience as an athlete from established scientific evidence and from his professional work at Virta Health. Low-carbohydrate and ketogenic approaches to endurance performance remain an actively debated area of sports nutrition research, and individual responses can vary.➡️ Join The Endurance Lab Inner Circle on Telegram👉 https://t.me/TheEnduranceLabInnerCircle🔥 FIND YOUR TRUE ZONE 2 WITH TYMEWEARTymewear Vita Pro measures your breathing in real time to identify your individual physiological thresholds and help you train at the intensity you actually intend to train at.➡️ Endurance Lab listeners SAVE $100 OFF the Tymewear Pro Training membership Code: E-LABTW26👉 https://www.tymewear.com/E-LABTW26➡️ Listen to my conversation with TimeWear founder Anar Larson: 👉 https://open.spotify.com/episode/5sz25EZjGUHoGSaA38nHwM➡️ Virta Health👉 https://www.virtahealth.com/TIMESTAMPS00:00 Can midlife athletes have metabolic health AND peak performance?01:22 How did an elite endurance athlete discover he was prediabetic?09:01 Why are endurance athletes developing prediabetes?16:29 What did Sami change after discovering he was prediabetic?22:01 How he increased fat oxidation from ~200 to ~800 calories/hour25:08 How low-carb does Sami actually go?37:47 What does Sami eat day to day?44:18 How does he use carbohydrates during hard training and racing?52:11 Is Sami really performing better at 50 than when he was younger?56:27 How has recovery changed with age?58:20 Why Sami founded Virta Health1:08:52 Sami’s training and nutrition framework for midlife endurance athletesABOUT THIS EPISODEThis conversation is for educational and informational purposes only and is not medical or individualized nutrition advice. Speak with an appropriately qualified healthcare professional before making significant dietary changes, particularly if you have diabetes, prediabetes, take glucose-lowering medication, or have another medical condition.

Can training your brain help you run faster for longer after 40 — without actually getting fitter?Brain performance scientist Dr. Scott Frey joins The Endurance Lab to explain the science of Brain Endurance Training (BET) and why the brain may be one of the most overlooked determinants of endurance performance.We explore how the brain regulates perceived exertion, pacing and fatigue; how neuroplasticity could help aging athletes compensate for physiological decline; why mental fatigue can make an easy run feel hard; and what happens when cognitive training is combined with physical training.Scott also explains how he uses brain endurance training with elite and Olympic athletes, how much training is required, which cognitive tasks may work, and why mental tapering before a race could be one of the easiest performance gains available to runners.If you're a runner over 40 looking for ways to maintain performance as your physiology changes, this conversation offers a fascinating new perspective on what might be limiting you.Dr. Scott Frey is Professor Emeritus of Cognitive Neuroscience and founder of Cerebral Performance. With more than 30 years at the cutting edge of cognitive neuroscience research — and a lifetime in endurance sports — he works with athletes to apply neuroscience and psychology to performance, cognitive resilience and fatigue resistance.Scott has authored more than 100 peer-reviewed publications and books, with his research cited approximately 10,000 times. He has received more than $10 million in federal research funding and has consulted for organizations including the NIH and USA Triathlon. He is also an accomplished endurance athlete, competing in trail running, triathlon and cross-country skiing.➡️ Join The Endurance Lab Inner Circle on Telegram👉 https://t.me/TheEnduranceLabInnerCircle🔥 FIND YOUR TRUE ZONE 2 WITH TYMEWEARTymewear Vita Pro measures your breathing in real time to identify your individual physiological thresholds and help you train at the intensity you actually intend to train at.➡️ Endurance Lab listeners SAVE $100 OFF the Tymewear Pro Training membership Code: E-LABTW26👉 https://www.tymewear.com/E-LABTW26➡️ Listen to my conversation with TimeWear founder Anar Larson: 👉 https://open.spotify.com/episode/5sz25EZjGUHoGSaA38nHwM➡️ Scott Frey / Cerebral Performance:👉 https://cerebralperformance.com/Chapters:0:00 Can Brain Training Make You Faster?4:34 How the Brain Controls Performance10:08 Age, Experience and Endurance16:40 Scott’s Journey Into Brain Science23:22 What Is Brain Endurance Training?28:58 How Much Can Performance Improve?41:35 Mental Tapering Before Racing46:36 How to Start Brain Training1:01:27 Mental Fatigue and Running1:13:31 Exercise and the Aging Brain

Many endurance athletes think getting leaner automatically means getting faster. But for masters runners, cyclists, and endurance athletes, there is a hidden problem that can quietly destroy performance: underfueling and low energy availability.In this episode of The Endurance Lab, I speak with Rebecca McConville, MS, RD, LD, CSSD, CEDRD, a sports dietitian specializing in endurance nutrition, Relative Energy Deficiency in Sport (RED-S), athlete fueling, and eating disorder recovery.Rebecca explains why RED-S is not just a problem affecting young female athletes, why masters athletes are often overlooked, and how trying to lose weight while increasing training volume can leave athletes stuck in a cycle of poor recovery, declining performance, and increased injury risk.Rebecca shares her own experience as a masters athlete, mother, and endurance enthusiast, explaining why so many recreational athletes fall into the trap of trying to do more training while eating less.Rebecca McConville works with athletes ranging from recreational endurance athletes to elite competitors, helping them understand the connection between nutrition, performance, health, and long-term athletic development.➡️ Join The Endurance Lab Inner Circle on Telegram👉 https://t.me/TheEnduranceLabInnerCircle🔥 FIND YOUR TRUE ZONE 2 WITH TYMEWEARTymewear Vita Pro measures your breathing in real time to identify your individual physiological thresholds and help you train at the intensity you actually intend to train at.➡️ Endurance Lab listeners SAVE $100 OFF the Tymewear Pro Training membership Code: E-LABTW26👉 https://www.tymewear.com/E-LABTW26➡️ Listen to my conversation with TimeWear founder Anar Larson: 👉 https://open.spotify.com/episode/5sz25EZjGUHoGSaA38nHwM➡️ Rebecca’s Website:👉 https://beccamcconville.com➡️ Rebecca’s book: Finding Your Sweet Spot: How to Avoid RED-S and Fuel Your Athletic Performance👉 https://www.amazon.com/dp/1091089051?lv=shuf&channelId=500&plpRedirect=mhFallbackChapters00:00 The hidden problem affecting masters athletes02:30 What is low energy availability and RED-S?04:54 Why calories are not the whole story06:44 Are older athletes at risk of RED-S?08:26 How athletes accidentally fall into underfueling11:10 The long-term health consequences of chronic underfueling13:11 Why aging can hide RED-S symptoms14:20 Early warning signs you should not ignore17:35 Digestion, sleep, immunity and RED-S symptoms18:49 Can HRV and resting heart rate reveal underfueling?20:46 Can you have low energy availability without symptoms?21:52 Is fasted training actually beneficial?23:28 Fat oxidation vs endurance performance26:58 Keto diets, carbohydrates and RED-S risk31:33 Losing body fat without destroying performance35:03 How much energy do endurance athletes actually need?36:27 How to recover from RED-S39:07 Why carbohydrates matter during recovery40:30 How long does RED-S recovery take?44:37 Can you keep training while recovering from RED-S?47:44 Finding help and working with RED-S specialists50:41 The biggest nutrition mistake masters athletes make51:35 The one nutrition change athletes should make today52:24 What does endurance mean to Rebecca McConville?

Can you become a highly fat-adapted runner without going fully keto — and without sacrificing your ability to use carbohydrates when performance demands it?In this episode of The Endurance Lab, I sit down with exercise and nutritional physiology researcher Matt Carpenter to unpack the science of fat adaptation for endurance runners, including runners over 40.We explore what being “fat adapted” actually means, why fat adaptation is a spectrum rather than an on/off switch, and whether a ketogenic or low-carbohydrate diet is really necessary to increase fat oxidation.Matt explains how endurance training, mitochondrial capacity, carbohydrate availability and diet interact to determine how much fat you can oxidize during exercise. We also discuss how quickly fat oxidation can change, why becoming better at burning fat doesn’t automatically improve performance, and how going too far with carbohydrate restriction could reduce your metabolic flexibility and ability to perform at higher intensities.Most importantly, we get practical. Matt explains how recreational runners training around 5–7 hours per week can use carbohydrate periodization, low-carbohydrate meals and selected fasted training sessions to improve fat oxidation — while strategically using carbohydrates around hard training and racing.We also dive into Matt’s research on keto-adapted athletes and carbohydrate supplementation, including why strategically introducing carbohydrate around exercise may improve performance without necessarily undoing the adaptations developed through a low-carbohydrate diet.If you’re interested in becoming a more fat-adapted runner, ketogenic diets for endurance athletes, metabolic flexibility, fasted training, carbohydrate periodization, fat oxidation, endurance nutrition or how to fuel your running after 40, this conversation brings the science together without taking a dogmatic “high-carb vs keto” position.➡️ Join The Endurance Lab Inner Circle on Telegram👉 https://t.me/TheEnduranceLabInnerCircle🔥 FIND YOUR TRUE ZONE 2 WITH TYMEWEAR Tymewear Vita Pro measures your breathing in real time to identify your individual physiological thresholds and help you train at the intensity you actually intend to train at.➡️ Endurance Lab listeners SAVE $100 OFF the Tymewear Pro Training membership Code: E-LABTW26👉 https://www.tymewear.com/E-LABTW26➡️ Listen to my conversation with TimeWear founder Anar Larson: 👉 https://open.spotify.com/episode/5sz25EZjGUHoGSaA38nHwMCHAPTERS0:00 How to Become Fat Adapted1:23 Do You Need Keto?4:21 What Fat Adaptation Means5:52 Mitochondria and Fat Oxidation7:57 Fat Adaptation Is a Spectrum10:18 Do You Need Ketosis?15:31 Strategic Carbohydrate Use20:17 Do Carbs Undo Fat Adaptation?23:56 Long-Term Keto Adaptation30:59 Fueling Long Runs on Keto35:39 How Quickly Can You Adapt?40:01 Diet vs Endurance Training42:36 Fat Adaptation on 5–6 Hours45:04 Metabolic Flexibility49:11 Maximizing Fat AND Carbs54:58 Train Low, Race High57:17 Matt’s Carbohydrate Study1:00:20 When to Use Carbohydrates1:07:10 Keto vs High Carb: Who Wins?1:12:29 Does Fasted Training Work?1:16:19 Practical Fat-Adaptation Strategy1:18:36 Why a Hybrid Approach Works1:23:31 What Endurance Means to MattLINKS & RESEARCHMatt Carpenter — University of Northampton:https://www.northampton.ac.uk/directories/people/matt-carpenter/Matt Carpenter — Research Profile / Publications:https://pure.northampton.ac.uk/en/persons/matt-carpenter/Matt Carpenter — Instagram@mattendurancescientistCarpenter, Brouner & Spendiff (2024) — Carbohydrate Supplementation Improves Ultra-Endurance Performance in a Keto-Adapted Individual:https://hrcak.srce.hr/ojs/index.php/kinesiology/article/view/27167Volek et al. (2016) — Metabolic Characteristics of Keto-Adapted Ultra-Endurance Runners:https://pubmed.ncbi.nlm.nih.gov/26892521/

➡️ Join The Endurance Lab Inner Circle on Telegram👉 https://t.me/TheEnduranceLabInnerCircleAleksandr Sorokin went from weighing around 100 kilograms, smoking, drinking alcohol, and living an unhealthy lifestyle to becoming one of the greatest ultrarunners in the world.In this episode of The Endurance Lab, Aleksandr shares how he transformed his life, lost the weight, discovered ultrarunning, and eventually broke multiple world records in his 40s.His achievements include:🏃 100 km world record — 6:05:35🏃 100 mile world record — 10:51:39🏃 6-hour world record — 98.496 km🏃 12-hour world record — 177.410 km🏃 24-hour world record — 319.614 kmHe became the first runner to break the 11-hour barrier for 100 miles, and during that same race he also set the 12-hour world record.What makes Alexander’s story even more remarkable is that he did not begin running seriously until around age 32. Before that, after finishing his earlier sporting career in kayaking, he says his lifestyle became unhealthy — alcohol, cigarettes, poor food choices, and his body weight climbed to around 100 kg.Running initially started as a way to lose weight. Then he discovered ultra-running. A few years later, he was winning major races. By his early 40s, he was breaking world records.Alexander explains how his training evolved from roughly 60–80 km per week to peak weeks around 250–300 km, why long runs of 30–50 km became the foundation of his training, how he uses interval sessions to maintain speed as he gets older, and why recovery has become increasingly important in his mid-40s.We also discuss what runners over 40 can learn from his progression, why starting later does not necessarily mean your best running years are behind you, and how consistency, training variety, mileage and simply loving the process have shaped his career.For masters runners, recreational runners, marathoners and ultrarunners, Alexander’s journey is a powerful example of how dramatically running performance can change even when you start later in life.➡️ Save $100 on Tymewear Pro Training MembershipCode: E-LABTW26👉 https://www.tymewear.com/E-LABTW26➡️ Listen to my conversation with TimeWear founder Anar Larson:👉 https://open.spotify.com/episode/5sz25EZjGUHoGSaA38nHwM00:00 From 100 kg to running1:35 Alexander’s world records2:50 His life before running5:43 From weight loss to world records7:18 Did he ever expect to become elite?10:01 Strength training and cross-training11:03 Starting running in his 30s12:52 Can runners still improve after 40?16:54 How his training volume evolved20:56 How his speed training changed with age24:16 Mileage vs structured training25:29 When he reached his peak28:46 How runners over 40 can still improve29:39 What recreational runners can learn from him31:21 Heart rate vs pace33:08 What to do when your best years feel behind you