Fast or Slow: How to Become a Better Runner in 30 Days

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#16 Fast or Slow


Are you a fast twitch runner or a slow twitch runner?


Fast twitch (FT) and slow twitch (ST) muscle fibers differ in “mitochondria density, capillary density, oxidative and Glycolytic enzyme activity, creatine phosphate stores, and contraction velocity.” (Magness, p.199) So basically FT fibers use more glycogen and ST fibers use fat for energy. If you want more power, FT fibers are your body’s pick. However, ST fibers can recover more quickly.

You start with a certain percentage of each, FT and ST fibers, but you can train to change the ratio. Yet, your tendency is one way or another. So knowing if you are more of a FT runner or ST runner, can impact the workouts that bring you success.

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Are YOU FT or ST?

There are many ways to find out the answer but the simplest way for you to get an indication right now is:

Are you known for your finish kick? Or do you push the pace, putting pressure on your competitor for the entire race?

Finish Kickers most likely have a higher percentage of FT fibers.

If you can run long at a faster steady pace than your race peers then your muscles may be composed more of ST fibers.

Why does ST vs FT dominance matter?

Because you can either enhance your performances or suffocate them.

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Fast Twitch Dominant Runners

You love feeling fast. With the wind flying through your hair and your legs strongly kicking back, you like pushing your lungs to capacity. You most likely have a higher percentage of fast twitch muscle fibers. Take advantage of that speed and preform a weekly speed training session (ex: cruise intervals, 2-3 minutes with longer standing recovery), however, hold yourself slightly back, leaving the race to dig your deepest and win. BUT, don’t drop the long run from your training. You do need to have aerobic training in order to run any race over 100 meters. Run a longer, slower run at your easy pace at minimum every 14 days, more often (every 7 days) during the first third of your training season.

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Slow Twitch Dominant Runners

You want to run forever. You’re the runner that wants to just keep going. In your last race you knew that if the race was longer you would have beat your competition. After the first third of your training season, save your long run for every 10-14 days. I know, that is crazy, miss your regular weekend long run! Well, you don’t need to totally miss it but you can instead lower the distance by a third and add in tempo training. Take your mile race time and add 1 to 2 minutes, that is your new tempo pace. After initial warm up miles, pick up your pace to tempo. Every 8 to 10 minutes go back to the easy pace for one minute. Continue until you have a mile left and enjoy an easy cool down.


If you are fascinated by individualizing your training based on slow versus fast twitch dominance then get yourself a copy of Steve Magness’s book, The Science of Running. It is a heavy book, literally, but well worth the devotion to understanding running training. Get your highlighter ready!


We all have a heart, lungs, and muscles and they work similarly, we still have our own fingerprint. Approach training as you would with building a house, using a standard blueprint but making adjustments to arrange your own unique home. Use an architect, coach or knowledgable training partners, to customize.

This 30-day series is a quest for me as a writer, coach, and runner. I promise to write about running for 30 days in a row. In doing so I intend to gain in knowledge and expression of running and daily life. My hope is that we all grow together.

UPDATE: Writing for you has helping me run more often and with more delight. I am digging deeper into my knowledge base and favorite books. You have responded that you love it! Write me or comment below and give me your feedback! What topic do you want me to cover? How has this blog impacted you? Do you have a story to share?

Shelly Binsfeld

Running Coach in Minnesota

Optimize your Hard Work in an Intelligent Way