Heart rate, pace, and power are the metrics every endurance athlete tracks, but they're all proxies for what's really happening inside the body. In this episode, Brady sits down with Arnar Larusson, co-founder of Tymewear and the mind behind the VitalPro device. Arnar makes the case for ventilation as a more direct, more stable window into internal workload and fitness.

Custom insoles made with supershoe foam: visit kilarun.com and use code “RLRH” to get $50 off your first order.

Carb loading before a marathon is one of the most "accepted" rituals in distance running, but does it actually improve race performance?

In this episode of Run Long Run Healthy, Thomas Watson and Brady Holmer break down a brand-new meta-analysis that finally asks the question nobody had rigorously tested: does carbohydrate loading work if you're already fueling properly during the race?

If you've ever wondered whether you really need to stuff yourself with pasta the night before your marathon, this episode has the answer.

00:00 Introduction: Revisiting the Carb Loading Orthodoxy
00:32 What Is Carbohydrate Loading? (Glycogen Science Explained)
03:27 The Original Protocol & Old-School Traditions (Pasta Parties, Grandma's Marathon)
06:10 The New Meta-Analysis: Does Carb Loading Even Work?
08:00 Placebo, "Nocebo," and the Study's Limitations
13:32 Sponsor: Kila Insoles
15:55 What This Means for Everyday Marathon Runners
19:49 Brady's Recommended Carb Loading Protocol
28:19 Race-Day Fueling & the Breakfast Debate
32:30 Final Takeaways: Do You Actually Need to Carb Load?

Wahoo Fitness spent 15–20 years becoming the data leader in indoor cycling and now they're bringing that same obsession with precision to running. In this episode of Run Long Run Healthy, Thomas Watson and Brady Holmer sit down with Joe Justice and Mac Cassin of Wahoo Fitness to break down the KICKR RUN treadmill, a machine they rebuilt from the ground up instead of just copying what already existed.

We get into why cycling data (power, cadence, FTP) doesn't translate cleanly to running, how Wahoo is tackling grade-adjusted pace, vertical oscillation, and ground contact time, and why "durability" and physiological resilience are the next frontier in runner data. Joe and Mac also walk through the three non-negotiable design principles behind KICKR RUN (run feel, speed/acceleration control, and simplified controls), the treadmill's 4-minute-mile top speed, Run-Free adaptive pacing mode, terrain mode, and the Bluetooth headwind fan. Plus, how thermoregulation changes when you take a run indoors.

Chapters:
0:00 Introduction: Wahoo enters the treadmill game
1:04 Why Wahoo built a treadmill from scratch
2:03 The cycling-to-running data gap
4:00 GPS accuracy & grade-adjusted pace
6:20 Individualized metrics vs. population averages
7:55 Physiological durability & resilience scoring
10:24 Sponsored by Kila custom insoles
12:37 Turning treadmill data into actionable feedback
14:43 Inside KICKR RUN's 6–7 year development story
16:39 The 3 non-negotiable design principles
19:35 Why treadmill speed limits held runners back
21:24 Run-Free mode, terrain mode & the headwind fan
26:16 The case for precision in indoor training
27:33 Reframing the treadmill as a tool, not a fallback
29:58 Thermoregulation, sweat & heat adaptation indoors
33:57 Reducing mental load to stay motivated
38:13 The next 10 years: AI, wearables & training data
44:07 Explaining Wahoo's 3DP/4DP performance models
50:09 Will AI ever replace a running coach?
55:42 Integrating cycling into your run training
58:53 Where to demo the Wahoo KICKR RUN

Custom insoles made with supershoe foam: visit kilarun.com and use code “RLRH” to get $50 off your first order.

Check out the KICKR RUN Treadmill:
https://www.wahoofitness.com/devices/running/treadmills/kickr-run-buy

Could the best runners of the 1960s have beaten the sub 2-hr marathon if they had 2026 level sports science, gear, and training protocols? That’s what Thomas is looking to answer today - and why our understanding of Marginal Gains is, at times, flawed.

Chapters:
00:00 Could old-school runners have broken 2 hours?
01:31 Derek Clayton's old-school gear, diet & training
02:32 Stacking modern marginal gains onto Derek
05:42 Were old-school runners just tougher?
06:36 Origin of "marginal gains": Team Sky
07:30 The Team Sky doping controversy
08:29 Debunking the marginal gains myth
11:20 Ceiling effects and the Atomic Habits graph
13:04 Marginal gains = avoiding bad outcomes too
14:00 Back to Derek: what the real data says
18:05 Why Derek would still trail today's best
19:45 Verdict, and a message to Derek Clayton
22:03 Two real takeaways for your own training

Join Marathon Handbook’s RunClub for access to our members-only podcast, training plans, community rooms, merch and more: https://marathonhandbook.com/runclub

Shop Marathon Handbook merch: https://store.marathonhandbook.com

We do blood testing with RYTHM: Rythm is offering our listeners 15% off your first month and free shipping at https://RYTHM.HEALTH/RLRH

Brought to you by ProBio Nutrition - your all-in-one daily supplement for runners. Get 40% off with code RLRH (and an additional 10% off + free shipping with a subscription) ➡️https://bit.ly/ProBioRLRH

Brady and Thomas break down the new viewpoint paper on endurance whose co-authors include Michael Joyner: https://journals.physiology.org/doi/pdf/10.1152/japplphysiol.00343.20250:00 Introduction – The 4 Components of Fatigue Resistance0:39 What Is Durability? (The Joiner Model Revisited)4:00 Sponsor: ProBio Nutrition5:12 How to Use These 4 Terms to Find Your Weaknesses5:57 #1: Durability – Holding Your Physiology Together at Constant Pace8:32 How to Train for Better Durability11:30 #2: Fatiguability – Performance Loss Under Variable Intensity14:38 Sponsor: RYTHM Health (At-Home Blood Testing)17:11 #3: Repeatability – Can You Hit the Same Splits Every Interval?18:36 How to Train for Better Repeatability22:37 #4: Resilience – Performing Under Unexpected Conditions23:55 Amby Burfoot's 1968 Boston Win: A Case Study in Resilience26:47 How to Train for Resilience (Steve Magnus's Secret Tactic)28:31 The Danger of Being Over-Optimized on Race Day29:52 Thomas & Brady's Own Strengths and Weaknesses35:45 Resilience: The Last Unmeasurable Variable in Endurance Sport37:04 Wrap-Up

We do blood testing with RYTHM: Rythm is offering our listeners 15% off your first month and free shipping at https://RYTHM.HEALTH/RLRHBrought to you by ProBio Nutrition - your all-in-one daily supplement for runners. Get 40% off with code RLRH (and an additional 10% off + free shipping with a subscription) ➡️https://bit.ly/ProBioRLRHLegit or Grift returns! Thomas and Brady rank the most popular running trends of 2026 in terms of their legitimacy (how much evidence there is to support their safe use) and grifty-ness (lack of evidence / some profiteering going on).

0:00 Intro – What is "Legit or Grift"?

3:48 #1: NOM (Broccoli Sprout Juice) – LEGIT7:51 #2: BPC-157 Peptides – GRIFT

10:03 Why isn't BPC-157 better researched? + The Cam Haynes controversy

16:56 #3: Carb Maxing – GRIFT

21:01 Should carb intake be measured by distance, not time?26:41 #4: Bicarb for Marathon Running – GRIFT

29:14 #5: Protein Maxing (for runners) – LEGIT

33:00 #6: Downhill Training – LEGIT

37:03 #7: Sauna & Passive Heat Training – LEGIT

40:05 #8: Exogenous Ketones (post-workout) – LEGIT

44:06 #9: Eight Hours of Sleep – GRIFT

55:22 The Enhanced Games: Total Grift

58:20 Outro

Brady and Thomas discuss VO2 Max; why runners should be interested in training it, and how the best ways to improve it areWe do blood testing with RYTH: Rythm is offering our listeners 15% off your first month and free shipping at https://RYTHM.HEALTH/RLRHBrought to you by ProBio Nutrition - your all-in-one daily supplement for runners. Get 40% off with code RLRH (and an additional 10% off + free shipping with a subscription) ➡️https://bit.ly/ProBioRLRH00:00 Understanding VO2Max and Its Importance02:23 Genetics vs. Training: The VO2Max Debate05:51 Measuring VO2Max: Field Tests Explained11:46 Effective Training Methods to Improve VO2Max23:41 The Reality of Building and Losing VO2Max29:33 Additional Strategies for Enhancing VO2Max

We do blood testing with RYTH: Rythm is offering our listeners 15% off your first month and free shipping at https://RythmHealth.com/RLRHBrought to you by ProBio Nutrition - your all-in-one daily supplement for runners. Get 40% off with code RLRH (and an additional 10% off + free shipping with a subscription) ➡️https://bit.ly/ProBioRLRH00:00 Why The Biggest VO2 Max Doesn’t Win The Race03:44 The Pillars of Endurance Performance09:32 Performance VO2 vs. VO2 Max14:58 Physical Limits of VO2 Max17:24 Key Metrics for Runners' Health and Performance