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Dr Cailbhe Doherty

Dr Cailbhe Doherty

12,000 subscribers

👁 173,606 views

The Physiology of Endurance Running: Energy Systems, VO₂max, and Fatigue

Video Overview & Insights

This lecture examines the physiological foundations of human endurance running. It introduces the body’s primary energy systems—from ATP turnover and phosphocreatine to glycolytic and aerobic metabolism—and explains how oxygen uptake (VO₂max), lactate threshold, and running economy interact to shape endurance performance.

content quality at it's peak! thanks!

— @user-vu7jt3jx1d

Using the classic thought experiment proposed by Michael Joyner, the lecture revisits the long-standing “man as machine” model of fatigue and highlights its limitations. The session concludes by motivating a shift from purely mechanical explanations toward regulatory models of fatigue that integrate physiology, perception, and control.

00:00 The body as a machine: early models of fatigue

Since it is all normalized by weight, wouldn't extra body fat affect the VO2max number rather than the running economy number?

— @Sgrunterundt

00:19 Joyner’s thought experiment and the sub-2-hour marathon

01:23 From engines to batteries: ATP and cellular energy

Interesting, when the video was posted, the sub-2 hours marathon was still a goal, few months later, 2 men in a same day did it

— @elmeraguileratreminio8988

03:10 Immediate energy systems: phosphagen and glycolysis

04:25 Lactate, acidity, and the sensation of fatigue

I read the title as the psychology of endurance - I was wtf had this all to do with mental strength? 😂

— @DwaynettaD

05:34 Aerobic metabolism and mitochondrial energy supply

06:44 VO₂max: measuring aerobic limits

Lovely to see and hear human speaking 👍

— @okiok2535

08:06 Lactate threshold, running economy, and endurance performance

14:33 Beyond machines: regulation, fatigue, and the brain

Athlete or Academic, HELP!

— @Tigu76

Reference list:

https://doi.org/10.2165/00007256-200737040-00011

Unrealistic and unacceptable and unnecessary for life 💯

— @aaronwhite3298

https://doi.org/10.1371/journal.pone.0064319

https://doi.org/10.1249/mss.0000000000000777

Excellent webinar- Joyner was a genius.

— @gretskycompton

https://doi.org/10.1152/jappl.1991.70.2.683

PMID: 16446673 (https://pubmed.ncbi.nlm.nih.gov/16446673/)

This is how someone who absolutely understands his subjects teaches. This is the only video you need to watch on this topic. Kudos and envious of your teaching ability

— @barbadosobstaclerace115

More User Perspectives

@

Well I think the London Marathon just proved him right. 2 runners just broke 2 hours for the first time in history

@Jm-Gonz
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those VO2 max examples seems to be extremely high

@thewen
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creatine supplementation should help with ADP recycling to ATP

@thewen
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Good 👍🏽 Dr. Thanks 🙏🏽!! 🏃‍♀️💣🩸🩸🧨🧨📈🏇🏼🏇🏼🫜🫜🏃🏻🏃🏻💨💨🏃🏽‍♂️🏃🏽‍♂️🏃🏽‍♂️⚡️⚡️⚡️🦶🏼🦶🏼

@JungleSoundzperc
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I appreciate the lack of ads. Thank you for the quality content as well

@enzosv7510
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Fatigue is housed in the CNS. The doping of the future(and possibly now), is the delay, or shutting down of the process producing the "signals" of fatigue. The release of adrenaline or something that mimics adrenaline is probably one such area of continued exploration. Neuro blockers, another area. For the natural performers it is simplified to genetics, educated training methods, hard work, and dialed recovery.

@EndurancePerformanceOptimized
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One of the best explanations! Wish I had you teaching me in university for physiology haha

@dannybeeh6332
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Your mind is the strongest muscle.

@Automattie
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This is pure gold, thanks a lot for providing such content.

@Night9Walker
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I have never seen data listing an average VO2 max in the 50s for a 80kg male of any age. I think that is way to high. Mid 40s for young men, <30, and decreasing from there.

@davidpauff302
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why don't they blame the abuser instead of victim shaming?

@vrd555
@

Gold standard explanation! 🙌

@EnzoMayser
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11:00 Bigger brains require more oxygen - explains that graph.

@Jena_Tools
@

Great video!

@Kimefitness
@

This is a fantastic explanation.

@Exendin
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It hurts, keep moving, nobody cares...LOL!

@Adventurejunkie78
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My mind moves me 😊

@Steve-hu7jf
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Perfect for my current degree course this!

@ianjames3078
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A fascinating description, thanks. During the presentation, I was repeatedly reminded of my experience doing martial arts then transitioning to a field sport. The different definition discussed after 15:00 brings home my experience with regulation. Specifically, the martial arts conditioning with mind over matter focus lead to my surprising success playing that field sport.

@jaymacpherson8167
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Excellent!

@JohnSmith-zy1ur
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so ein Blödsinn!! natürlich ist der Körper einem Verbrennungsmotor ähnlich, nicht einem Elektromotor. !!!

@gerwichemerstorfer6980
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great production. very good overview, great visuals

@moglin15
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Never mind!

@RichardGeekie
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What about weight of the body? Those with more fat will be at a disadvantage. How does weight figure in?

@RichardGeekie
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👏👏👏👏

@universitycollegedublin
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Excellent

@munyaradzidamson2214
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When mountain climbing, I once was descending a steep ice slope on the north face of a large peak. It was extremely dangerous and I did not notice any fatigue. When I reached the bottom and stepped onto a moraine (safe terrain) I suddenly collapsed and felt incredibly fatigued and not able to move another step. I literally transitioned from no fatigue to collapse within minutes. This makes me think that our body keeps a safe cushion from dangerous limits and as we get near to the cushion overwhelming fatigue takes over. That is unless our lives depend on exceeding that cushion. Then it is allowed to exceed the cushion and keep going. However, exceeding that limit can be dangerous as we can see with the climbers who die from exhaustion descending big mountains like Mt. Everest. My guess is that the reason people seldom die on foot races is that the motivation is not great enough to exceed the cushion by very much and that keeps us safe.

@Tony-m5t
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Great summary. Looking to the lecture on CGT.

@Good13man
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Great explanation. To be clear:

H+ is the product of using up ATP, regardless of whether that ATP came from aerobic or anaerobic metabolism, so the accumulation of H+ says little about whether activity is aerobic or anaerobic.



Lactate does come from anaerobic metabolism, but the lactate threshold is simply a point where its production rate tips over its clearance rate. It doesn't mean that anaerobic metabolism suddenly rises there. Assuming activity is relatively long and the aerobic system is fully engaged, the activity remains predominantly aerobic also after the lactate threshold. (Which is why it really shouldn't be called the "anaerobic threshold".)

@Fielmann55
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Excellent 🎉.

@herbertbloch4167
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Many thanks - love the Born to Run 2026 lectures!

@svenfokkema3440
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Brilliant video.

@RobertNaik
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This gold explanation

@TheMafiaflix