Should You Train Your Slow Twitch Fibers?

Slow twitch fibers got a bad reputation in the power world. Slower, weaker… what self-respecting lifter or wrestler would want to train them? Yet cutting-edge Russian research tells us that every type of athlete, from marathoner to powerlifter, has a lot to gain from training slow twitch fibers.

First, I will talk about the needs of powerlifters and others who pursue strength events in which the speed of contraction does not matter: Iron Maiden/Beast Tamer Challenge, the front lever, the iron cross, etc. Then we will deal with power athletes like Olympic lifters and sprinters, and finally with a wide spectrum of athletes needing endurance, from fighters to ultra-endurance runners.

Slow Twitch Fibers for Sprinting
Franz Snideman, Senior SFG, a 10.7sec 100m sprinter

I. Slow Fiber Hypertrophy for Absolute Strength

While it is true that slow twitch (ST) fibers do not get as thick as their fast twitch (FT) brothers, we have known since the sixties that per square inch of cross section, they are just as strong. In other words, two finger-thick bunches of fibers, fast and slow, are equally strong. Sure it takes a higher number of thinner fibers to make up that bunch, but why would that matter?

Consider the study by Selouyanov in which experienced athletes did very light and slow squats* and increased their 1RM by 25.6% in six weeks. Are you interested now? Not surprisingly, there are elite Russian powerlifters such as Dmitry Kasatov and Alexander Grachev who use state of the art ST fiber hypertrophy protocols as an integral part of their training.

Should you do it too? Perhaps. There are two downsides:

  • First, something has got to give. Your time is limited and so are the resources of your endocrine system. You will have to introduce ST hypertrophy training at the expense of something else — and your programming will greatly increase in complexity.*
  • Second, many 1RM guys and gals simply despise slow, “go for the burn” reps (understandably).

There are upsides too. A high-mileage lifter is able to dramatically reduce his heavy training mostly to the practice of the competition lifts while taking care of hypertrophy with light ST exercises. Reportedly, this is what great Vasily Alexeev did for his back. His back problems prevented him from doing heavy deadlifts (snatch and clean pulls). So he developed a secret variation of the back hyper* and kicked everyone out of the gym and locked the door when he did it.

Another upside is maximizing one’s muscular development — if this is your goal. You are a heavyweight lifter, a football lineman, a power bodybuilder.

If you need to watch your weight, you still could use this tactic locally. E.g., if your goal is to improve a press — kettlebell or barbell military press, bench press, handstand or one-arm push-up — adding a triceps ST hypertrophy protocol to your regimen is neither going to tip the scale, nor make your training too complex or draining.* The same applies to a grip master pumping up his forearms.

If you fancy yourself a “hard gainer” trying to bulk up, I anticipate your idea to do this type of training exclusively. When it comes to your upper body, don’t even think about it! An average person’s upper body muscles are 70% fast twitch. Even if you are far the other way, you are still loaded with FT fibers and they have a much greater potential for growth. Combine FT and ST hypertrophy training perhaps, but do not go exclusively ST.

For the legs it may not be a bad idea. They have a fifty-fity average ST/FT ratio and you might be skewed far into the ST. Your answer could be training like an injured lifter — moderately heavy singles, doubles, and triples to address the neural and psychological components of strength plus light ST hypertrophy work.

II. Slow Fiber Hypertrophy for Power Athletes

Since fast fibers contract faster than the slow ones, it does not seem to be a good idea on the surface. Yet, according to maverick Russian professor Victor Selouyanov, you would be making a grave mistake:

“[Although] maximal speed of ST and FT muscle fibers differs by 20-40%, the contraction speed in real athletic actions does not exceed 50% of the maximal contraction speed.  Thus an increase in strength of the ST fibers increases power and speed practically in all types of athletic activity.  Even in a sprint.”

Selouyanov and Turaev established that 50% of the sprinting power comes from slow fibers! Then they subjected a group of experienced sprinters to a leg ST hypertrophy regimen. Their 100m times improved from 10.9 seconds to 10.7 seconds.  In other experiments, Seluyanov increased the athletes’ standing jumps through ST hypertrophy.

The pros and cons of introducing slow fiber hypertrophy training into your regimen are the same as for powerlifters and Iron Maidens.

III. Slow Fiber Hypertrophy for Endurance Athletes

A short answer is, absolutely! One’s endurance, be it in an MMA fight or in a marathon run, is dependent on the mitochondria that enable the muscle to use oxygen.* And slow fibers, unlike fast ones, come pre-equipped with mitochondria. It will be a game changer for your “conditioning.” For instance, in another study by Selouyanov, eight weeks of ST squats upped the anaerobic threshold by 20%.

*Stand by for a series of articles that will expand on the topics I have marked with an asterisk, as well as detailed training protocols. A heads up: slow twitch fiber hypertrophy training is done very differently from what you might expect. So do not rush for the “burn” until you read the directions.

Read more:
How to Build Your Slow Fibers, Part I
How to Build Your Slow Fibers, Part II
How to Build Your Slow Fibers Part III

Pavel Tsatsouline
Pavel Tsatsouline is the CEO of StrongFirst, Inc.

46 thoughts on “Should You Train Your Slow Twitch Fibers?

  • Coach Tsatouline,

    I have just recently stumbled on this article and was hoping to see if you have scientific/research articles in English on this subject manner. I’m looking to do my thesis on this subject and was hoping to find more relative articles of which I was told have primarily been done in Russia and not the US.



  • Pavel,

    Can you direct me to how to apply Selouyanov’s methods to olympic lifting, jumping and throwing events. I have yet to see specifics as to programming training.

    Thanks for your continuing contributions to strength and sports performance!

  • Can you please give examples of how to apply the slow training to olympic lifting and jumping and throwing events.
    Thanks for the great and thought provoking info!

    • Jan, make sure to arrange to your schedule to train your quick and explosive events when you are fresh. And for a couple of days after a ST hard leg day avoid them altogether.

  • Hi Pavel.

    This is a really awesome article thanks. Is there anyway possible to get the original research or work on the topic as done by Selouyanov & Turaev? There are alot of S&C coaches (they also eat chicken & play cricket though) here that keep away from slow movements as they say they want to focus on power & speed and that speed is the biggest determinant in power development (which is true according to Verkhoshansky and my own experience ) but I have always been a firm believer that the slower work can feed into the power work to improve it.

    Thanks again

    Strength & Honour from South-Africa.

  • Hi Pavel,

    This is a great article to read because there is a lot of confusion about aerobic fitness and slow twitch type one fibres. Having built the foundation of my interest in exercise physiology from the Endurance sports and subsequently developed an interest in strength sports I’m so glad to see this train of thought in the strength community. There is much confusion on the real nature of ‘fat burning’ and what metabolic training entails. particualarly the idea that slow twitch means slow and weak. I really struggle with the much quoted concept of HIT training as a method of burning fat and developing endurance / conditioning. Because it goes against the principles of how muscles derive their energy. To undertake metabolic conditioning to burn fat means that you have look at how the body metabolises food and then how you train you body to utilise fat and extract the energy effeciently. How powerful and developed your aerobic fibres are is defined by your body’s effeciency at utilising this energy. Put simply there is no contradiction in saying you could be running very slowly and still be running anaerobically. conversely, you could, like mark allen, be running a 5.12 min per mile pace for 13 miles at a purely aerobic pace. That pace is anything but slow!

    I’ve heard Dan john frequently mention Phil Maffetone’s Heart Rate Training system, here’s a link to his concept of aerobic vs anaerobic.

    Phil by the way, coached Mark Allen to his 6 straight ironman wins. He also advocates what he calls ‘slow weights’ for endurance runners. Not far off easy strength or greasing the groove.

    It’s good to see two paradigms meeting.

    • Paul, HIT, among other things, aims to build up the buffering capacity. More than one way to build endurance.

      Peter Park introduced me to Maffetone’s work; very good!

  • How I would combine it with S&S? I’m thinking about reducing the swings and adding some very slow KB FSQ 4×5 before each S&S session.Or should I do my oxidative session in different day, maybe one day S&S and one day FSQ ?

    • Maybe I should do swings before the squats to save my fast fibers from exhausting.

      • Victor, if you were to add such SQs to SS, I would do it in a separate session later in the day.

  • Pavel,

    Interesting stuff. I have a question though: if slow fibers are necessary for endurance because of mitochondria, how does that square with Al Ciampa’s endurance protocol that uses only swings? Aren’t swings inherently fast fiber movements?



    • Andrei, Al’s protocol, like some of Selouyanov’s protocols, aims at developing mitochondria in fast fibers thus making them more enduring.

      • Pavel, do you think that better endurance could be achieved by adding slow fiber development to Al’s swing protocol? Or would the two just get in each other’s way?

        • Andrei, in theory—yes. In practice, the more variables you have, the harder they are to control. I would stick to Al’s protocol for the duration he has specified without adding anything—and experiment later.

  • Pavel I really respect your work and I thank you for all the knowledge that you put out there!

    I have an unrelated question but I’d be ever so grateful if you could answer it. When I bench press or do pushups or any kind of chest exercise, I end up feeling it more right under my shoulder blades and my lats than my chest. Am I doing something wrong? Do I just need to gain more strength in those muscles before my chest starts being worked out?

    Thank you sir!

    • Thanks, Marcos!

      Try forcing your chest out when benching. And be happy your lats are engaged.

  • Hey I remember you mentioning this in your recent podcast!! Thanks for the follow up article!!!

  • I was wondering about when applying strength training to exel in sports like soccer wich require alot of power and acceleration and changing of direction. So what would you do when training to increase acceleration for the 0-20 meters and just becoming more explosive?

    What exersices would you focus on, sets, reps, frequency etc ?
    Means the world

    • Dan, before specialized sport training you need a foundation of general strength. Please see “Easy Strength” I co-authored with Dan John.

      Hypertrophy of ST fibers is a legit strength training method.

      • Thank you

        How would you approach the Hypertrophy of ST fibers for the legs then for my soccer training/goals? what exercises, sets and reps would you do and how frequent?

        I bought your book “Easy Strength” but it does not mention the Hypertrophy of ST fibers in that book

        Thanx again

  • Pavel, I absolutely love your teachings. Your name was introduced to me by another Master (totally different field) I absolutely love and respect, two months back. I guess Masters recognize Masters! Ever I have been into whatever materials I can hold onto written by you. It was a pleasure listening to you speaking during the Tim Ferriss interview. All these information is new to me.

  • I have never had a biopsy, but am pretty sure I skew heavily to ST – former competitor in cross country (running and skiing), and rowing. I would certainly consider following a strength protocol for a number of weeks that is premised on this theory. I understood the protocol you described on the Tim Ferriss interview for squats, but was less clear on an upper-body ST protocol, if you think there is one. Is a specific program going to be part of a future blog?

    • Chris, one can be FT dominant in some muscles and ST in others; a biopsy typically taken in the vastus lateralis is not very informative.

      Stand by for articles with specific protocols.

  • So in S&S terms, this is almost like doing the get up with 10 second pauses per step or is that more isometric in nature? Can’t wait for your future articles. I hope you have a follow up book under the strong first banner. Thanks again!

  • Selyuanov and Val Nasedkin both champion theses methods. Also referred to as “oxidative squats”. Here is Val’s protocol:

    Slow Fibers

    • Increase of functionality of these can benefit the speed of movement (enhanced relaxation)
      Full of mitochondria, excellent for relaxation phase
      Can produce as much power as fast twitch of same size, just displayed differently.
      20% improvement in cross‐section = 20% improvement in anaerobic threshold.
      If we increase the size of the slow‐twitch, it can produce just as much power as fast‐twitch and less price to pay on the field because they’re purely oxidative

      • Protocol
        40‐70% intensity
        30‐60 second sets – until full exhaustion or pain in muscle
        4‐5 sets, 30‐60 sec rest between sets, 3‐4 series, 5‐10 min rest between series
        Walk, jog between series. Attempt to flush by‐product/waste
        Slower tempo: >4 seconds, no relaxation phase, always under tension/load
        1‐2 session / week, every 3‐5 days
        Creatine and hydrogen ions present in muscle during exercise and rest

        • Bryan, thanks for posting. I will be detailing some of Prof. Selouyanov’s protocols in upcoming blogs.

          A few comments on the one you posted:

          This intensity is appropriate for the legs only; much lower for the upper body.

          The superseries protocol (3 sets with 30 sec between them) is an advanced one.

          where did you find this in English?

  • I saw a video where somebody who was doing Bulgarian split squats was descending very slowly (like 10 seconds), then he exploded upwards on the ascent. Wouldn’t he be training ST fibers on the way down and FT fibers on the way up all in one exercise?

  • Sounds like and endorsement for previously scathed bodybuilding methods. They train like this. A few of the really strong ones (like Ronny Coleman) train both FT AND ST.

  • Looking forward to the series and programming tips. For me its a great article and it has made me rethink/change my mind on some topics.

    Also just like Carl above really enjoyed the interview with Tim Ferriss. The large brain representation of the hands helping to helping to cause spilll over to other areas is not something I had thought of.

  • Looking forward to the series and programming tips Pavel!

    Also, loved your recent interview on the Tim Ferriss show (and additional Q&A). Truly a masterclass and pleasure to listen to.

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