The Endurance Lab Podcast is a long-form conversation series exploring training, nutrition, performance, recovery, and endurance sport through the lens of long-term health and longevity.
Designed for midlife runners and endurance athletes who care about improving performance without sacrificing long-term well-being, each episode features thoughtful, evidence-based conversations with experts across endurance sport, including researchers, coaches, and specialists in specific areas of performance, alongside midlife athletes who’ve achieved meaningful performance breakthroughs later in life.
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Run Elite Coach: Brutal Advice for A Sub-3 Hour Marathon After 40
Episode 31
Friday, October 2, 2026 • Duration 01:38:25
How do you run a faster marathon after 40?
Whether your goal is to break 4 hours, run a sub-3:30 marathon, qualify for Boston, or eventually run a sub-3 hour marathon, Andrew Snow argues that the answer may have far less to do with adding harder workouts—and far more to do with building the foundation required to support them.
Andrew Snow is a running coach and author of Run Elite, a book that takes training principles used by elite runners and translates them for recreational athletes. In this conversation, we explore how runners in their 40s, 50s and beyond can apply those principles to marathon training while dealing with limited training time, recovery capacity, work, family and the realities of getting older.
We break down Andrew’s base → support → specific approach to marathon training, why he prioritizes training frequency and mileage before harder workouts, how much running you may actually need to reach your marathon potential, the role of strides and hill sprints, marathon-pace training, long runs, nutrition, recovery and race specificity.
Andrew also explains why a runner trying to go from a 4-hour marathon toward sub-3 may need to think in terms of years rather than another 12- or 16-week marathon training plan—and why building a much bigger aerobic foundation could ultimately be the key to running your fastest marathon.
If you’re trying to figure out how to run a faster marathon, how to break 4 hours, how to run a sub-3:30 marathon, how to run a sub-3 marathon, or how to keep improving as a masters runner, this conversation offers a very different way of thinking about long-term marathon performance.
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HRV Scientist: The NEW HRV Metric That Could Help Runners Over 40 Keep Improving
Episode 30
Friday, September 25, 2026 • Duration 01:14:12
In this episode of The Endurance Lab, I sit down with Dr. Greg Grosicki, Staff Research Scientist at WHOOP, to explore the science of HRV and HRV-CV and, more importantly, how runners can actually use these metrics to make smarter training decisions.
We break down why higher HRV is generally better while lower HRV-CV is generally better, why your seven-day HRV trend can tell you something very different from today's reading, and what different combinations of HRV and HRV-CV may reveal about recovery, adaptation and accumulated training stress.
We also get practical. What should you do when today's HRV is suppressed but you feel great? When should HRV actually cause you to change a planned interval workout? What happens to HRV-CV during a hard training block or taper? And can these metrics help runners recognize when they're adapting well versus drifting toward excessive fatigue?
For runners over 40, we also explore an especially interesting question: how do HRV and autonomic stability change as we age? Greg discusses research showing age- and sex-related differences in HRV-CV, what may happen after around age 40, and whether exercise and fitness could help attenuate some of the age-related decline in HRV.
In this episode, we cover: what HRV-CV actually measures; HRV vs HRV-CV; why HRV should be compared to your own baseline; whether wearable HRV measurements can be trusted; heat stress and HRV; daily HRV vs seven-day trends; four HRV/HRV-CV training scenarios; when to train hard versus back off; HRV-CV as a marker of adaptation; what happens during overload and tapering; HRV recovery and resilience; how HRV-CV changes with age; autonomic aging; and how Zone 2 and high-intensity training affect HRV.
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Fat Adapted Athlete: From PREDIABETES to PEAK Performance at 50
Episode 29
Friday, September 18, 2026 • Duration 01:15:57
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.
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Brain Performance Scientist: How Runners Over 40 Run Faster For Longer With Brain Training
Episode 28
Friday, September 11, 2026 • Duration 01:22:05
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.
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Sports Dietitian: The Nutrition Mistake Destroying Performance In Runners Over 40
Episode 27
Friday, September 4, 2026 • Duration 54:00
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.
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➡️ Endurance Lab listeners SAVE $100 OFF the Tymewear Pro Training membership
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Endurance Scientist: The Fastest Way to Become a Fat Adapted Runner After 40
Episode 29
Friday, August 28, 2026 • Duration 01:25:18
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.
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World Record Ultra Runner: The Proven Way to Build Extraordinary Endurance After 40
Aleksandr 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 km
He 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.
Sports Nutrition Scientist: Lactate Gels Are the Next Generation of Sports Fuel
Episode 26
Friday, August 21, 2026 • Duration 01:09:57
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In this episode, I sit down with Dr. Aitor Viribay, co-founder of FLF (From Lab to Field), to discuss the science behind exogenous lactate—why elite cycling teams are suddenly interested in it, how it compares with carbohydrates and ketones, and whether drinking lactate could become the next major breakthrough in endurance fueling.
We discuss:
• Why lactate is no longer considered the "bad guy"
• How exogenous lactate works inside the body
• Whether lactate is actually a preferred fuel over glucose
• How it compares with ketones
• Whether it could improve endurance performance
• Possible effects on the brain, recovery and fatigue
• Why the science is still in its early stages
• What athletes should realistically expect today
If you've been hearing rumours about pro cycling teams using lactate during races, this episode explains the science directly from one of the researchers developing the technology.
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Muscle Cramp Scientist: The Best Way for Runners to Prevent Cramps
Episode 25
Friday, August 14, 2026 • Duration 01:26:15
In this episode of The Endurance Lab Podcast, I sit down with Dr. Kevin Miller, one of the world's leading researchers on exercise-associated muscle cramps. We dive into the latest science behind muscle cramping, why the traditional dehydration theory doesn't fully explain what happens, and Dr. Miller's new Multifactorial Theory of Muscle Cramping.
Dr. Kevin Miller is a Professor and Athletic Trainer at Texas State University. He is the Director of the Heat Emergency Assessment and Treatment (H.E.A.T) Lab in the Department of Health and Human Performance. His research expertise includes the causes, treatments, and prevention of exertional heat illnesses with a specific emphasis on exercise-associated muscle cramping and exertional heatstroke. He has published over 75 peer-reviewed manuscripts and given over 120 presentations on exertional heat illnesses. He has Chaired or co-authored 5 different official heat illness position statements including the 2021 NATA Roundtable on the Prehospital Care of Exertional Heatstroke and the 2015 NATA Position Statement on Exertional Heat Illness. He is a Fellow of the NATA, Associate Editor for the Journal of Athletic Training, member of the Korey Stringer Institute’s Medical and Science Advisory Board, and consultant to schools, hospitals, Universities, and companies for his expertise in heat-related illness.
➡️ Dr. Kevin Miller:
For consultancy-related assistance on heat or muscle cramping, you can contact Dr. Miller at kmconsultingtx@gmail.com.
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Endurance Scientist: How Runners Over 40 Get Faster With Less Oxygen
Episode 24
Friday, August 7, 2026 • Duration 01:28:26
Can training in low oxygen actually make you a faster runner without adding more training hours?
In this episode of The Endurance Lab, I speak with Dr. Barney Wainwright, Senior Research Fellow at Leeds Beckett University, about the science of hypoxic (altitude) training and why many elite endurance athletes now use it to break through performance plateaus.
We discuss how hypoxic training works, whether it actually improves sea-level performance, the physiological adaptations behind altitude training, and whether an altitude generator is worth the investment for recreational runners and cyclists.
If you've reached a plateau despite consistent training, this episode explains why hypoxic training may be one of the few remaining tools capable of producing meaningful physiological adaptations that traditional training cannot.
Discover shows related to The Endurance Lab, based on actual content similarities. Explore podcasts with similar topics, themes, and formats, backed by real data.
➡️ Previous Endurance Lab HRV episode with Dr. Marco Altini
👉 https://youtu.be/D6ZPuaMaEgs
➡️ HRV-CV research discussed in the episode:
Grosicki et al. — “Heart rate variability coefficient of variation during sleep as a digital biomarker that reflects behavior and varies by age and sex”
👉 https://pubmed.ncbi.nlm.nih.gov/41309064/
Chapters
00:00 Higher HRV vs lower HRV-CV
00:30 Using HRV to guide running training
02:21 What is HRV-CV?
08:57 The science behind HRV-CV
12:03 How new is HRV-CV?
13:48 Dr. Greg Grosicki’s journey to WHOOP
19:31 What is WHOOP?
20:43 Sleep, recovery and strain
27:42 How WHOOP uses recovery data
31:04 Inner Circle: Can you trust HRV from sports watches?
35:15 How heat stress affects HRV
37:06 Daily HRV vs 7-day HRV vs HRV-CV
39:59 Two runners with the same HRV — but very different recovery
44:09 Four HRV + HRV-CV training scenarios
47:47 The HRV-CV warning sign
49:55 How to use HRV to decide whether to train hard
53:28 When good HRV can still be misleading
54:14 Is HRV-CV a measure of adaptation?
55:16 Why low HRV-CV isn't always good
57:19 What happens to HRV-CV during hard training?
58:25 How high is too high for HRV-CV?
1:00:49 What should happen to HRV-CV during a taper?
1:01:30 HRV recovery and resilience
1:03:30 What happens to HRV-CV as we age?
1:05:44 Autonomic aging and HRV
1:08:03 How training can improve HRV and HRV-CV
Code: E-LABTW26
👉 https://www.tymewear.com/E-LABTW26
➡️ Listen to my conversation with TimeWear founder Anar Larson:
00:00 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/hour
25:08 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 Health
1:08:52 Sami’s training and nutrition framework for midlife endurance athletes
ABOUT 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.
🔥 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:
00:00 The hidden problem affecting masters athletes
02:30 What is low energy availability and RED-S?
04:54 Why calories are not the whole story
06:44 Are older athletes at risk of RED-S?
08:26 How athletes accidentally fall into underfueling
11:10 The long-term health consequences of chronic underfueling
13:11 Why aging can hide RED-S symptoms
14:20 Early warning signs you should not ignore
17:35 Digestion, sleep, immunity and RED-S symptoms
18:49 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 performance
26:58 Keto diets, carbohydrates and RED-S risk
31:33 Losing body fat without destroying performance
35:03 How much energy do endurance athletes actually need?
36:27 How to recover from RED-S
39:07 Why carbohydrates matter during recovery
40:30 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 specialists
50:41 The biggest nutrition mistake masters athletes make
51:35 The one nutrition change athletes should make today
52:24 What does endurance mean to Rebecca McConville?
🔥 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:
00:00 From 100 kg to running 1:35 Alexander’s world records 2:50 His life before running 5:43 From weight loss to world records 7:18 Did he ever expect to become elite? 10:01 Strength training and cross-training 11:03 Starting running in his 30s 12:52 Can runners still improve after 40? 16:54 How his training volume evolved 20:56 How his speed training changed with age 24:16 Mileage vs structured training 25:29 When he reached his peak 28:46 How runners over 40 can still improve 29:39 What recreational runners can learn from him 31:21 Heart rate vs pace 33:08 What to do when your best years feel behind you
🏃 5K, 10K, Half & Full Marathon Training Plans
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🎓 Exclusive Discounts & Resources
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Exolactate
Learn more about Exolactate and FLF: https://flf.shop
Research website: https://exolactate.com
00:00 Why lactate may be the body's preferred fuel
01:00 Why elite athletes are suddenly interested in exogenous lactate
05:11 Is lactate where ketones were a few years ago?
08:08 How Aitor became interested in lactate research
10:17 How carbohydrates become lactate
12:14 Which organs actually use lactate?
14:12 Why lactate gets "VIP treatment" in the body
20:40 Is lactate a by-product of carbohydrate oxidation?
22:05 Where lactate fits among carbohydrates, fat and ketones
25:20 What happens after you drink exogenous lactate?
29:43 Is exogenous lactate different from natural lactate?
31:16 What's actually inside Exolactate?
38:04 Is exogenous lactate safe?
40:37 Does exogenous lactate bypass the cost of producing lactate?
42:26 Lactate, buffering and fatigue
45:40 Can lactate break through the carbohydrate ceiling?
47:25 Does lactate make carbohydrates work better?
49:51 Will lactate replace carbohydrates?
50:36 Lactate vs ketones
52:25 Training vs racing with exogenous lactate
55:07 Which athletes benefit the most?
57:38 Could lactate reduce central fatigue?
58:25 Recovery benefits
59:41 Why creating an exogenous lactate gel was so difficult
1:05:00 How much lactate do athletes actually need?
1:08:42 The biggest takeaway about exogenous lactate
1:09:33 What endurance means to Aitor
👉 https://theendurancelab.run/training-plans
🎓 Exclusive Discounts & Resources
👉 https://theendurancelab.run/exclusive-discounts
We also discuss:
• What actually causes muscle cramps
• Why stretching works immediately
• Why dehydration isn't the whole story
• Whether electrolytes actually matter
• Bananas, pickle juice, tonic water and salt tablets
• Heat vs cold environments
• Why elite athletes still cramp
• How to prevent cramps
• What to do when a cramp strikes
• The surprising science behind vinegar and pickle juice
• Practical advice every endurance athlete should know
00:00 Introduction
02:21 What actually causes muscle cramps?
06:02 Nervous system vs muscle — where do cramps start?
