Slow Twitch vs Fast Twitch

What are these?

They are the difference between a high intensity spin class and a long run on the treadmill.  Do you ever wonder which one is better?  The quick answer is BOTH and here is why;

Type I (Slow) twitch fibers are suited for endurance and are slow to fatigue because they use oxidative metabolism to generate ATP (require oxygen to burn fuel and FAT, aerobic cardio).

Type II (fast) twitch fibers are efficient for short bursts of speed and power and are quicker to fatigue.  They rely on glycolytic enzymes to burn fuel (sugar storage, anaerobic cardio)

Your body is an engine. Go from a V6 to a V8 by activating all of your muscle fibers.

Here are the facts: (from my research and what I believe to be true!)

  • You are born with all of the muscle fibers you will have, most of us are 50/50 fast/slow but some people have more or less than others and therefore find it easier to run marathons or sprint short distances.
  • Fast twitch fibers burn sugar and Slow twitch fibers need oxygen therefore burn fatty acids for fuel.
  • You are recruiting fast twitch fibers when you sprint or get your heart rate above the target zone (anaerobic).  This is why you don’t last very long at that speed or intensity, the fibers are quick to fatique.
  • Interval (anaerobic) Cardio, If done for longer than 20 minutes, will deplete your bodies sugar storage.  You might see stars or get dizzy because your blood sugar will drop, so eat an hour before doing this!
  • You are recruiting your slow twitch fibers when you run a long run and maintain a constant heart rate.  You will be in the prime fat burning zone if you do this for than for 40+ minutes.
  • Muscles are made up of slow and fast twitch fibers so working both is important to make sure you engage your entire muscles when contracting during either workout or throughout the day.

Bottom line: Interval cardio (sprint, spin, circuit training) is needed to make sure your fast twitch fibers don’t fall asleep.  Endurance cardio (long runs, rides, walks, etc) that keep your heart rate in the “target zone” (aerobic) engages your slow twitch fibers and therefore burns fat.  If you include both styles of training in your workout routine, you will burn fat AND recruit more of your muscle fibers to burn fat during and after your workouts are over, allowing you to see results in less time.

Read  it yourself in this great article:

How to do Interval Cardio:  Get on a cardio machine and warm up for 10 minutes.  Then put the magazine down or put it on a page with a really motivating picture and leave it alone.  Crank up the music and go 30-45 seconds at an all out speed resting for an equal amount of time.  Repeat it 5 times.  Then increase your resistance or incline every minute maintaining a steady speed.  Reach a peak and come back to level ground or resistance slowly.  Sprint again at the end 2 times for 60 seconds each, resting a minute between.  Cool down at a level speed and incline.  Have fun with it, make it up and always have a plan (a set number of repeats, times, level increases, etc.).  Follow any 20 minute interval workout with a 20-30 minute endurance run and you burn sugar, work all fibers, and end in a fat burning zone!:)  Hello skinny jeans.

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