Muscle Fiber Composition, Pro Cyclist Data, Crashing and More – Ask a Cycling Coach 316

What muscle fiber type is best for cycling, how do you influence it, and how much of it is genetic? We’ll cover this as well as pro cyclist data and why many athletes don’t share it, how to race in dangerous circumstances and manage crashes and much more in Episode 316 of the Ask a Cycling Coach Podcast!

Tune in for the YouTube Live Stream this Thursday at 8:00am Pacific!

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Topics Covered in This Episode

  • Intro 0:13
  • Jonathan’s learnings from National MTB National Championships 5:41
  • Nate is racing again! 39:04
  • Why pro cyclists don’t share data 42:47
  • A deep dive on muscle fiber composition for cyclists 54:11
  • Race-day focus tips 1:20:33
  • Publishing data insights from TrainerRoad’s data-set 1:23:52
  • Do gels replace aid stations? 1:29:16
  • Do recovery shakes get nullified by post-ride meals? 1:31:55
  • How to mitigate risk in criterium racing 1:46:08
  • How to avoid crashes in a criterium 1:52:23
  • Why are cyclists so susceptible to broken collarbones? 1:55:21
  • How to learn to crash safely 1:57:46

Resources Mentioned in This Episode

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why are cyclists so susceptible to broken collarbones - because we have no upper body muscle and fall on our collarbones?

It’s not about muscle mass (probably bigger shoulder muscles and pectorals could decrease the impact, albeit slightly). Your collarbones are practically the only connection between your shoulderblades / shoulder sockets and sternum. There is no other bone connecting them, and this bone is about as thick as your middle finger. When you land part of your body weight on one of your shoulders sideways (so not on your back or on your chest mainly), this small bone should “compress” lengthwise, which it doesn’t do. Instead, it cracks. Even if you’d have bigger muscle mass on shoulders and pectorals, it would be 0.5-1kg mass, which wouldn’t really change the impact.

My point wasn’t about muscle mass so much as strength training increases the strength of bones. Maybe that doesn’t matter all that much either for young people. Nonetheless - when we crash we often land on our shoulders which is usually how collarbones break.

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I only wish I could live to see the human body of the distant future, after 100,000 years of crit racing pushes evolution to develop a more compressive and resilient collarbone.


Sorry, misunderstood the question :face_with_hand_over_mouth:

I believe that the forces are so sudden and big, that increased bone density wouldn’t really impact the stats. But I have to agree there could be cases where it could have been avoided if the bone strength would be higher. Maybe the cracked (not thoroughly broken) cases could be avoided somewhat :thinking:

Collarbones are designed to break, one of the many wonders of the human body.


We may never discover the PhD consultant, but my dream is it turns out to be Andrew Gelman.

@Jonathan I thought the Pol plans weren’t part of AT yet.

I don’t have any interest in following one, but found your comment at odds with what some have said.

You can’t directly add the POL plans, but you can hack to apply them after the fact, so it is possible.


Great podcast.


Muscle fiber tests are now non-invasive. They can now be done in an MRI machine.

Here’s the results of a recent study across many cycling disciplines, using this new testing.

Interestingly, as Chad pointed out, you can shift. However, it’s only to a small degree. If you really are predominately fast twitch, then focus on disciplines where this helps. Equally, if you’re all slow twitch. Go long.

A study was done on recent top performing 100m athletes with the result being. It wasn’t training. It was virtually all genetic. Meaning they excelled at it naturally and found their way into their best discipline at middle and high school.

This is why I very much maintain that athlete testing should not just be a simple FTP test. It needs a full spectrum of power profiling. This is needed to better understand what kind of athlete you are attempting to prescribe training too.


Hope your testing with the cardiologist turns out OK @Jonathan

For those in the UK under 35 there is a charity called Cardiac Risk in the Young who will perform an ECG for free and look for undiagnosed heart conditions. It is well worth getting checked out for the 10 minutes it takes to have the test.

I’m a cardiac electrophysiologist here in the UK - not offering medical advice but would strongly recommend @Jonathan get something like an AliveCor/Kardia device (Portable Single-Lead Heart Monitor | KardiaMobile | Kardia) to get decent ECG traces if and when things recur. Easy to take with you everywhere.

It is really really hard to treat/advise without some sort of documentation of what the arrhythmia might be as treatments vary so much. Hope nothing too serious anyway!


Almost 10,000 in beta… There’s goes my stretch goal of reaching top 10,000th place!

TR user for 3+ years, signed up for beta same day as announcement, do indoor and outside workouts (both scheduled workouts and races), training 6 days a week consistently using Plan Builder (HV plans) and almost never miss a training day? What? What don’t I have that TR beta wants :frowning_face:. And I don’t want to here the “it’s not you, it’s me” reasoning.


I’ve talked to other PhDs and they are pretty sure this isn’t an accurate way to do it. :man_shrugging:

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I am pretty confused about the section on strength training.

When Coach Chad says concurrent training is counterproductive, does he mean immediate juxtaposition of strength and endurance workout vs. spreading out through the day or on different days?

I could take the discussion to mean endurance athletes shouldn‘t strength train, ever. But I am sure that‘s not what Choad Chad meant (?), as that contradicts many previous discussions?

I’m not sure if your post is rhetoric, but I suspect that the recent additions are people mostly training indoors (at least I am).

If it makes you feel better, Nate said recently they are close to moving to open beta. That’s a great step.

From Chad!

“This refers more to hypertrophy training than strength training, i.e., getting big vs increasing muscle activation, recruitment, coordination, etc. Big fibers will never be the fibers with the greatest endurance/oxidative capacity and small fibers will never be the strongest fibers, they simply aren’t big enough. But it is possible, and realistic and attainable and encouraged and recommended and necessary , to be strong as an endurance athlete–everything we’ve touched on regarding strength training, timing of strength training in a largely endurance routine, the types of lifts/exercises, the recommend rep ranges, our recommendations on levels of strength, etc., all still applies.
And yes, the greatest strength athletes will never have the endurance of the greatest endurance athletes, and vice versa.”


I can’t believe you guys have never had a fluffernutter @Nate_Pearson @Jonathan

Coming from a born and raised New Englander, I’d put them up against the classic PB&J. I think they’re perfect for long endurance rides to change up from the everyday fuel.

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