Muscle Fibre Types of World-Class Cyclists

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“We’re all individuals” shouted the mob outside Brian’s window in the Monty Python classic ‘Life of Brian’. We’re also all individuals in our response to training, and that may be due to our muscle fibre typing.

Dr. Stephen Cheung not getting his pulse up

I well remember my year spent on a development squad in British Columbia in the early 1990s. It was my first time working with a coach, at the same time as I was first diving into the world of exercise physiology as a graduate student. One workout I was prescribed was based on intervals where heart rate should reach 180 bpm. Despite my best efforts over weeks, there was simply no way I could get my HR above 160, to which I was simply told that I had to try harder.

Through years of heart rate and now power monitoring, along with access to regular fitness testing within my lab, I have a pretty good knowledge of my capacity, and one of my quirks is that my maximal heart rate has always been much lower than that predicted by the 220 – age formula (which actually has zero scientific basis, but that’s another story). Even in my early 20s, my max HR was in the high 160s, and now in my early 50s it’s at 160 bpm or so. So planning generic workouts based on arbitrary values is pretty meaningless.

The above is all to remind you that we are all individuals, and that we need to train to our own individual characteristics. That limitation of basing training on a single parameter applies to our current obsession with threshold power as a singular focus. While a higher threshold is rarely a bad thing, it alone doesn’t identify our individual abilities, and therefore basing training solely on it can be quite inaccurate.

Look at it this way. Two riders can be the same weight and have the same threshold power. Yet one can be a diesel time trialist, while another might be more of a surging, attacking style rider. If you gave the two an identical workout, how they respond to it will likely be quite different.

I’ve written previously about different athlete types and how software like Xert can identify these athlete types and also build unique workouts for different athletes.

In this article, I will first talk about different muscle fibre types across different cyclists. In a future article, I will show how athletes with different fibre types respond differently to the same training, and have different risks for overtraining.

‘BMX racing shows up in having even greater fast muscle typology than what is seen in huge track sprinters’

Lievens 2020

Muscle fibre typing is traditionally not the most fun, involving taking a muscle biopsy, staining it, then counting the relative proportion of Type 1 (“slow twitch” and relatively more aerobic and fatigue-resistant) versus Type 2 (“fast twitch” and relative more forceful but more prone to fatigue). As you might imagine, while useful as a research technique, you’re not really going to find elite athletes lining up for this kind of testing.

In a study in Medicine & Science in Sports & Exercise, a group from Ghent University in Belgium used a new and noninvasive (though still expensive) technique to indirectly quantify muscle fibre composition in world-class cyclists across a range of disciplines (Lievens et al. 2020).

The technique involves proton magnetic resonance spectroscopy of muscle carnosine content. Carnosine act as a buffering agent to maintain muscle pH, and it has been correlated to be much higher in Type 2 fibres and associated with the relative cross-sectional area of these fibres.

• In this study, 80 professional cyclists (57 men, 23 women) were tested. All were either World Tour (n=18) or Pro Conti (6) road cyclists, or competing at continental/world champs level in other disciplines. Overall, this group included 4 Olympic medalists and 24 World Champ medalists.
• UCI rankings were used to categorize participants across a range of cycling disciplines: BMX (4), XC MTB (11), Cyclocross (8), track (33).
• Road cyclists were further analyzed as being single-stage, multi-stage, or time trialists, and also as preference for flat, uphill, or all-terrain riders.
• Track riders were analyzed as sprint and endurance riders.
• Imaging took place on the soleus and gastrocnemius muscles. Both are part of the calf muscle area.
• The carnosine content was compared to a control population matched for age and sex (201 men, 142 women).

What Are The Pros Made Of?

Courtesy of @TeamDerave Twitter October 27, 2020

The above infographic summarizes the results from this study. In keeping with direct muscle biopsy literature, particular muscle fibre typing does seem to be required for elite performance in different disciplines. Some observations.

• Despite their relatively smaller size, the massive power outputs off the start ramp in BMX racing shows up in having even greater fast muscle typology than what is seen in huge track sprinters.
• Road sprinters and track endurance riders have very similar typology, which might explain why road sprinters such as Elia Viviani and Mark Cavendish were able to do so well in the Omnium at the Rio Olympics.
• Cyclocross distribution falls within the middle of all-terrain road distribution, which might explain the road dominance of riders like van Aert and van der Poel.
• Similarly, the large overlap of mountain bikers and all-terrain road riders might explain the successful transfer of many mountain bikers to the road.

With any analysis like this, the nature versus nurture question always arises. Given that there is minimal evidence that muscle typology significantly changes with training, along with the world-class nature of these cyclists, it is likely that these muscle typing is largely genetics, and that these athletes ended up self-selecting themselves for these particular cycling disciplines from a young age. That is, they found success in these particular types of racing, and were continually streamed towards more and more development and success in them.

Horses for courses

Summary

While we may not have access to either this noninvasive testing or muscle biopsies, such studies reinforce the unique individual characteristics that each of us bring to our training and racing.

In the next article later this month, we’ll explore how different muscle typology affects our response to, and recovery from, high-intensity training, along with how it might affect our risk for overtraining.

Ride fast and have fun!

References

Lievens E, Bellinger P, Van Vossel K, et al (2020) Muscle Typology of World-Class Cyclists across Various Disciplines and Events. Med Sci Sports Exerc Publish Ahead of Print: https://doi.org/10.1249/MSS.0000000000002518

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