physiology.bike
From the bike to the cell. And back.
Yarin riding a bicycle in the mountains
Same curiosity.
Further.
The science behind the ride

20 years riding. Still asking why.

I'm Yarin, 40. I've raced road, gravel and track, and when the numbers on my screen stopped answering "why," I went and read the physiology instead.

Free, research-backed videos and short explanations for the questions endurance riders ask, from the watts on the screen to the cells doing the work.

Explore free videos
FREE VIDEOS AND EXPLANATIONS

Questions from the road. Answers from the science.

Each one is something riders feel on the bike, answered with the physiology and the experiment behind it: a short video, a Short, and a few minutes’ read with the sources.

Browse by topic Made with coaches 1 Fueling 4 Zones & thresholds 6 Lactate & energy systems 6 Fatigue & durability 4 Training & adaptation 7
Browse all 20 questions

One or two new questions every week. Get them by email

Have a question I haven’t answered yet? Ask your question

Ask a question

Ask what you want.

Every ride raises questions. Tell me what you're curious about. Your question might inspire a future physiology.bike video.

Questions stay private: they're never shown on the site, and no account is needed.

Science questions, not personal medical or training advice. Please leave out health details.

How your details are kept

For coaches

Free cycling science resources for your athletes.

Share research-backed videos, Shorts and explanations with your athletes. Free, easy to share, and without obligation.

  • Every question has a ready-made message for WhatsApp and email, and a link to copy.
  • No registration, for you or your athletes.
  • Link to them, forward them, embed the videos. To re-post one on your own channels, just ask.
  • Complimentary access to the audio course, on request.
Browse questions Request course access
THE AUDIO COURSE

Go deeper: the complete audio course.

The free library answers individual questions. The audio course connects them into a deeper, structured journey: 7 episodes so far, about 6 hours, each one following something you feel on the bike down to the cell and back.

See the course Episode 1 is free in full
  1. 1 What a Watt Actually Costs 42 min
  2. 2 What the Numbers Actually Mean 62 min
  3. 3 Why You’re Gasping Before Your Legs Give Out 58 min
  4. 4 The First Ten Seconds 58 min
  5. 5 Where the Lactate Goes 43 min
  6. 6 The Fuel Mix 42 min
  7. 7 Inside the Furnace 42 min
WITH SUPPORT FROM Training 4 Success
LET'S CONNECT

Reach out. Ride together.

Questions, thoughts, or just want to say hi? You can reach me on LinkedIn, or find me on Zwift and let's ride together.

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