Red, Pink and White: What you should know about your Muscles

Alright guys, we need to talk about muscle. In previous articles, I have addressed what all muscles have in common – they all contract and they all have mitochondria. And I talked about Aerobic verses Anaerobic exercise and how the muscles can work with oxygen or without oxygen to create the energy they use to contract. Now I need to let you all know that you actually have 3 different types of skeletal muscle

One body – Three types of muscle

Strip Soccer
Brings a whole new meaning to 'strip soccer' (source: jurvetson on Flickr)
If you striped all the skin from a person and just exposed the muscles you would see three different coloured fibers. It sounds super-gross but please try to imagine it: Red muscles, pink muscles, and white muscles. The red muscles are red because they contain lots of myoglobin: a protein that binds iron and oxygen. Your blood has a similar protein called hemoglobin which binds iron and oxygen. So when you see red, I want you to think about the globin molecule and an abundance of oxygen being present.

Red muscles also have lots of mitochondria. This too gives them a darker colour. And they also have lots of capillaries – these are small blood vessels which supply oxygen-filled blood to the muscle fibers. These red muscles are also known as “slow twitch fibers”. And guess what they do? They contract slowly for a long time without fatiguing. If you haven’t figured it out yet, these are the ‘Aerobic Muscles’ (ones you use during aerobic exercise). These are the muscles that use mostly oxygen to make their energy.

Now think about the white muscles. They don’t have as many mitochondria and the mitochondria they do have are smaller. They also don’t have as many capilaries. White muscles get most of their energy from sugar burning pathways (Google ‘Glycolytic Pathways’). These muscles are also known as ‘fast twitch fibers’. And guess what they do? They contract quickly, and with lots of force but can only do so for a short time before getting fatigued. And you guessed it, these are the ‘Anaerobic Fibers’ (the muscles used when doing anaerobic exercise). They don’t use much oxygen at all to create their energy.

So imagine what the pink ones are like. They are kind of in-between. They have mitochondria and  capillaries but not as many as the red muscles and not as few as the white muscles. These muscles are also highly trainable. This means they will act more like Red Fibers if you do lots of exercise that encourages red fiber use (aerobic exercise). Or they will become more like white fibers if you do exercise that encourages more white fiber use (anaerobic exercise).

Your muscle types are unique! So train them…

Now imagine you reach physical maturity, say 18 years old, and you’ve got all the muscle fibers you’re ever going to have. All that muscle is divided up between these three types of fibers. Some people are born with predominantly Slow Twitch (red) Fibers. Think of Kenyan marathon runners – long lanky athletes who might even look fragile. Some people are born with predominantly Fast Twitch (white) Fibers. Think of weight lifters and 100 meter sprinters – stocky athletes who have thick rounded muscles. Some people are a split between the two: not so big and not so lanky. Now, what about those pink fibers? Well, a fortunate few have a good proportion of these (trainable) pink fibers. These athletes will adapt to which ever sport they subject themselves to. If they spend a lot of time doing resistance training they will excel at more anaerobic sports. Conversely, if they spend lots of time distance running then the adaptation will swing toward an aerobic fiber distribution.

Pipe Cleaner Muscle ManWithout knowing any of this, individuals self-select for the type of activity that they will excel at. Usually athletes will gravitate to the sport which best fits their “Fiber Distribution”. A person with lots of white fiber can still run a Marathon, but they won’t rise to the top of the field. I love distance running and I’m not too bad at it. But I also like weight lifting which I’m not built for – but I like it all the same. Many girls may hate their large thighs and big rear end, but that is a gift to someone who wants to go into short track speed skating or volleyball. Some skinny guys may wish for pecs of iron but for an aspiring triathlete – long and lean is the way to go. Don’t spend any time beating yourself up about your body type. Find something you like working at and start training yourself.

Muscle building myth

So let’s be clear on this: all you can do is train the fibers you’ve got. You can’t make more muscle. You can increase the number of sarcomeres inside the fiber (I mentioned those last time) but you never make more actual fibers. And if they get badly damaged like from a gunshot wound or a stabbing, then they are gone. That said, the intact fibers around an injury will strengthen and adapt and providing there weren’t too many destroyed then you might not notice the missing ones.

There is more information to come that will further illuminate how our muscles respond to training. I hope this is all taking shape in your mind. And I hope you feel inspired to awaken the athlete within you.

Article by Matthew Linsdell

February 11, 2012

Matt is a certified personal trainer and has a degree in Environmental Science. He calls himself an evidence-based trainer, because training is a field which is littered with well-disguised pseudoscience – his emphasis is always on teaching the biology behind exercise. He lives at the edge of the beautiful and expansive Gatineau Park in Quebec and works across the water in Ottawa, Ontario. If he’s not out walking his two pit bulls, you’ll find him doing press ups with insanely large weights on his back. Follow Matt on Twitter at @smartfitmatt.

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9 thoughts on “Red, Pink and White: What you should know about your Muscles”

  1. daughter and I were both born with same body type: medium height, average weight and bone structure, short legs and arms. Propensity for packing on weight on thighs and butt. neither one of us is fast but seem to last long doing exercises such as walking or other aerobic activity when in shape. Can keep going all day long. Which muscle fiber do you think we predominantly have?

    1. Hi Chris, It would be impossible to say without testing you and also know how intensely you are working when you say you can “Can keep going all day long”. But as the article says it is the slow twitch red muscles which allow us to do long distance none stop work.

      Hope that helps.

    1. Hi Vichy,

      Short answer, no.
      Long answer, I remember years ago some research showing that if you surgically attach a nerve from a red fiber to a white fiber it will become a red fiber and vice-versa. So I would assume that the same would go for the nerves that attach to pink fibers. However this is highly impractical. And I really don’t know if this research went anywhere so don’t quote it to anyone.

      Thanks for the question.

      1. Im not sure if i understand so sry if this males no sense. In that case could you possible train your nerves to delop only pink fibres.

  2. Hi. I have an interesting question. Reading this and knowing my physical capabilities I’d say I have white muscles predominantly. However I am tall and not lanky but on the thinner side. But I’ve done more weight training and burst running. I’ve never gotten big but my strength is much higher than expected of a person my size. I am 6’1 and 130 pounds. Weight training though I got a dead lift of nearly 300, a triceps curl of almost 100, etcetera. So my question is basically what muscles do I have? Is it possible that I just trained most of my pink muscles for white and that’s why?

    1. Hi Gabriel,
      This is impossible to say from the information you provided.
      If you’re really interested I suggest going to a lab that does testing or try to get involved with a university which does testing for a research project.
      I hope that helps.

  3. Short answer, no. You’re born with a certain amount of pink fibers and you can train those pink fibers to be either white or red. But there is no type of training to give you more pink. Think of pink fibers as a type of fiber that doesn’t mind being white or red. But your white and red fibers are stuck being the way they are. But your pink fibers can always change back to either one depending on how you train them.

  4. Hi Chris, just sumbled across your article from the web. Here\\\’s a question, are we taking performance enhancing drugs and anabolic steroids into account? Someone with genetics for white muscle may be able to take cardarine and become an endurance beast, and someone with red muscle may be able to take trenbolone and become a world class powerlifter, if they put in the work

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