Muscle fiber types, recovery and training adaptations

I was listening to the latest TTS podcast today. It covered a topic that I was thinking of lately, namely the differences between more “fast-twitch” fiber oriented athletes and “slow twitchers” in training.

Muscle fiber types, recovery and training adaptations, and overreaching with Phil Bellinger, PhD | EP#297

It is very much talked about the different training approaches like SweetSpot (Treshold), Polarized, Pyramidal and so on. What is often missed in those discussions is the individual variances between different athlete types. Of course, one will probably never be able to perfectly individualize ones training program, but the difference between “fast twitchers” and “slow twitchers” is perhaps the most obvious one to make and the reason why different training regimes lead to different adaptations from one athlete to the next one. Of course there may be subtle differences, but I would like to know from athletes that consider themselves to be more on the extreme end of the spectrum.

I consider myself to be a fast twitch athlete. Good at sprinting, punchy climbs, can react quickly, big anaerobic capacity. On the other hand I am bad at sustained efforts (time trialing), long climbs and so on.

What I found for my training:

  • Some type of Polarized (or pyramidal) training in general leads to less fatigue than treshold training.
  • Some periods of Threshold or SweetSpot training lead to good results, but too much of it leads to long fatigue (especially muscular fatigue).
  • A general limiter for me is muscular fatigue (not heart rate).
  • Endurance Pace needs to be lower (~60% FTP) than for other guys, otherwise it burns me out.
  • A higher cadence is preferred.
  • Shorter intervals are preferred.
  • Longer taper with almost no intensity needed before races.

Other aspects that can often be heard:

  • More subtle increases in volume are better than sudden big changes for Fast Twitchers.
  • HIT Training is easier to perform, but more recovery time in general needed in comparison to Slow Twitchers.
  • Fast Twitchers can not maintain peak form for a long time.

I would like to know, if others experienced the same or have some anecdotal findings on this topic.

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Good find @Tim_87 !!!

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I’d agree with all of the above. The information about this is starting to trickle down into cycling and I’m starting to learn about it. I wish I’d known it all 15 years ago.

Eat lots of carbs and never go low carb is another thing I wish I knew.

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Yes, I agree with the high carb approach. I experimented with low carb rides and never got used to it. It did more harm than good. I decided to always fuel appropriately and never looked back.

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I totally agree with your summary. After my junior cycling years, I switched to powerlifting where I was much more successful. This with my cycling powercurve make me believe I am more a fast twich.
Now a master, I start to ride my bike and I found that I am struggling with recovery compared to my teammates. From the literature, it says that the hybrid fibers could be converted to slow twitch. How could we (fast twichers) become more sliw twitch? What would be the best training? Lot of endurance ride?

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How could we (fast twichers) become more sliw twitch?

To be honest, I do not want to be slow-twitch dominant. Even though this is favourable for pure endurance, I like being the one that can respond to attacks and have (anaerobic) power left in the end for the final sprint. Especially in amateur cycling where races are often not that long.
For me the key is to have as much endurance and sustained power as possible without hurting my punch.

What would be the best training? Lot of endurance ride?

I would say so. Low intensity, high volume.

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You may find a metabolic test useful to help plan your training. The aerotune one is great value and gives some guidelines for training volume and types of sessions that suit your physiology.

What I would say is that in the quest of trying to improve FTP, I’ve broken down many times over years and unknowingly I’ve destroyed a lot of top end power.

I think the powermeter revolution, Zwift, sweetspot, FTP talk, etc, puts the fast twitcher on the back foot. But in the UK they win all the bike races.

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What I would say is that in the quest of trying to improve FTP, I’ve broken down many times over years and unknowingly I’ve destroyed a lot of top end power.

Did you, in the end, find a way to improve your “FTP” without destroying yourself? Or did you just stick to your top end power without actively trying to improve sustained power?

I’d say I’m in the process of that now, although have made a few mistakes in the last 12months, it’s looking promising.

Really consistent, avoiding group rides - especially longer ones where pace is too high, high carb in and out of training, correct training zones, so nothing fancy.
Also, traditional vo2 max 4-5 mins with equal recovery destroyed me.
40/20 with longer recovery between sets is working much better for me.

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I am happy that I found peoples with the same struggles than me!

Actually, you won’t as there is a limit to the conversion you can do. The issue I am facing is that at the end of the race my muscles are so dead than I cannot even sprint. I am also struggling with cramps likely caused by poor muscle endurance. I would like to increase my endurance so I can be fresher at the end of the race and still be able to do my best 30sec watts.

This year, I did a lot of long rides near AeT and it makes wonder. I was able to beat my 5min power without having done much intervals. However, as soon as I started to add some intensity in my training, I felt pretty tired and my performance declined.

Right now after about 1h45-2h of racing, I start to cramp. I feel that sustained power is my weak point. When doing hard group ride or 20min intervals, although I find it useful, I am dead for 10 days.

I agree consistency is key. If I increase volume or intensity, I usually stuggle. This is also one of the topics discussed in the podcast.

Polarized works good for me to beat my PR on the local 5 min hill. However, I still miss that muscle endurance during long races. So, how would you increase muscle endurance for a fast twicher? Low cadence work, ~20 min intervals@ ftp, sweat spot? While these are hard to handle…

Another question I have is regarding weight lifting. I work on this over the winter to maintain muscle since I am getting older. The same happens there, as I cannot handle intensity on the bike if I lift 2 times a week

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More or less the same for me, except I prefer a lower cadence.

I haven’t had that problem, but I avoid threshold workouts. If I’m not training Z2 or HIIT, my preference is 3x20 SST at 85-88%. I pretty much avoid all training at 90-104% FTP.

If I do over-unders, I do the VO2max “float sets” like Pierce, which are a lot shorter and bounce between 88% and 125%.

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I started this topic a while back:

I’d call my self a fast-twitcher. I’m not track, sprint level 1800 watts but back when I raced, I was always a good sprinter and finisher and couldn’t climb worth crap.

The hard part of being a fast-twitcher is finding the events that you are training for. At 55 years old, I’m not going to ride crits anymore. I want to do fun group rides, fondos, gravel, etc. and these are not short fast twitch events. :frowning:

Still, I just hit a performance peak and have been riding with a new group at what feels like above my level.

This last fall/winter I just did a ton of Z2 and almost zero intensity. I’d mix in short tempo/SS intervals just for fun. In the spring I started with a SS block and got good gains (like +20 watts after all that Z2). Then I did a VO2max block and after three sessions I was dead. I rested for a couple weeks - back to Z2 and then tried VO2max again. It went a lot better. I played around with hard start, high cadence intervals. I think the high cadence works well for me because it induces a higher heart rate, more sucking wind, less torque, and less muscle fatigue.

What I found out is that I don’t need a lot of intervals over threshold or even a lot of SS. Above threshold is already my strength. Despite being a slow, old geezer, I have 3 pages of Strava KOMs all under 8 minutes with most even shorter in the 30 second to 3 minute range. My short power is relatively much better than my 20 minute power.

After the second VO2 block, I thought I’d try some sprint (10 second) intervals. The first session of 6x10sec crushed me and left me with DOMs for 3 days… I started doing those 10 second sprints at a lower power and then just sprinkling them in my rides (like 2-4 of them).

Like I said, I’m really happy with my performance lately. What would I do differently next year? I think I’d do a longer time in zone tempo/SS progression coming out of base. I seem to respond to 85% which also feels fairly easy.

It seems like raising my FTP is my Achilles heel. WKO5 says that my FTP is at 86% of my VO2max. The “raising the roof” part seems to be difficult.

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I am also struggling with cramps likely caused by poor muscle endurance. I would like to increase my endurance so I can be fresher at the end of the race and still be able to do my best 30sec watts.

It is almost funny how similar my experiences are. I also struggle with cramps and need to really focus on my power during racing not to overcook and still being able to “use” my sprint power in the end.

I feel that sustained power is my weak point. When doing hard group ride or 20min intervals, although I find it useful, I am dead for 10 days.

IMO, this is in general the key point in the dilemma of anaerobic oriented atheletes: Those type of workouts that are supposed to be the one that improve sustained power are at the same time the ones that can wear you down quite heavilly. So, for me the problem to solve is: How can fast-twitch dominant athletes improve sustained power without destroying themselves? Low SweetSpot (~85% FTP), no middle zone at all (only Polarized) or only a few threshold sessions sprinkled in?

I started this topic a while back

Great! Will check that out. (Edit: Checked it out. Great post.)

I played around with hard start, high cadence intervals. I think the high cadence works well for me because it induces a higher heart rate, more sucking wind, less torque, and less muscle fatigue.

Same here!

What I found out is that I don’t need a lot of intervals over threshold or even a lot of SS. Above threshold is already my strength.

I have a love/hate relationship with those. I feel that they really put the hurt on me (DOMS etc.) but in the past, when I managed to survive some threshold blocks, I felt that my sustained power really was improved. However, doing those all year round will just destroy me.

How are you setting your FTP for those sustained sessions? If you use the ramp test, you’ll likely overestimate it by probably quite a bit. I think often a hogh sprint power comes with a low FTP, so you might need to do those sustained efforts at much lower power.


This is from The Science of Running by Steve Magness. He talks a lot about fibre type and training and there are some big differences.
Dr Ferrari, on his old forum also said that sprinters should do shorter threshold training, of 2-3 mins mins with 1 mins recovery.

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You are right. I learned this the hard way when I just did the ramp test and tried to hit threshold workouts.

I still use the ramp test, because it is quick and convinient, but I reduce the result by 5%, which seems to put me to a realistic ftp number.

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Interesting chart. However, one sentence I do not fully understand:

“Lots of aerobic intervals at faster/moderate speeds to increase LT instead of Treshold runs. (Example: 400s at 10k pace with very short active rest)”

What would “10k pace” be in this example? Faster than treshold pace? So, in cycling this would be like short high intensity intervals with short rest? For example 30/15s or 2min intervals with little rest? Am I getting this right?

Anecdotaly those type of intervals are handled much better by me than 5-8min type of intervals.

10k pace is probably your 30 mins power. So slightly faster than ftp
FTP = 300w
10 x 3 mins @ 310w with 1 min easy between.

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Sounds like a workout I am intriged to try. But it´s also some kind of workout that I never saw anyhwere at trainerroad library or any other platform. But worth a try! Actually, it is something like over-unders with VERY light unders.