The average person has a roughly equal ratio of slow-twitch to fast-twitch muscle fibers, but some people genetically have a greater ratio of one type of muscle fiber over the other. This gives them an advantage in certain types of sports. Have you ever wondered what the fiber composition of your muscles is? Here’s a simple test that will give you a rough idea of what your own muscle fiber composition is.
What Kind of Muscle Fiber Composition Do You Have?
This is a quick test using weights that will tell you whether you have more of one muscle fiber type than another. It’s called the D.F. Hatfield muscle fiber test. Enjoy the results, but keep in mind it’s only an approximation. The only way to know the true fiber composition of your muscles is to do a muscle biopsy.
Start by determining what your one repetition maximum is. You can do this in our free online Workout Manager. This is the amount of weight you can lift with good form only once. Once you know your one-rep max, choose a weight that’s 80% of that value. Rest 15 minutes before starting, then do as many repetitions as you can do with good form using your chosen weight.
If you can lift the weight more than 8 times, you probably have a predominance of slow-twitch muscle fibers. On the other hand, if you can’t do 7 repetitions, you’re fast-twitch dominant. If you can lift the weight 7 or 8 times, you likely have a pretty equal ratio of fast-twitch to slow-twitch muscle fibers.
What Do the Results Mean?
If you’re slow-twitch dominant, you may have some natural advantage when it comes to endurance-type activities such as long distance running. On the other hand, if you have a higher ratio of fast-twitch to slow-twitch muscle fibers, you may be a natural for sports that require sprinting, jumping or power moves.
Of course, the muscle-fiber type is only one factor when it comes to success in any sport. Just because you have more of a certain fiber type doesn’t necessarily mean you’ll maximize that potential. Training, motivation and other factors like nutrition play a role too.
Knowing your predominant muscle fiber type can help you get better results from your training. If you have a predominance of fast-twitch fibers, your muscles may respond better to heavier weights and lower reps. If you’re a slow-fiber type, an endurance-type workout using a lighter weight and more repetitions may be more beneficial for your muscle type. At the very least, it’s interesting to know what ratio of muscle fibers you have.
References:
Exercise Physiology. Fifth edition. 2001. McArdle, Katch, and Katch.
Bodybuilding.com. “The Magic Workout: Is There Such a Thing?”
Related Articles By Cathe:
Muscle Fiber Composition & How It Changes with Age
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All About Fast-Twitch and Slow-Twitch Muscle Fibers
Can You Change the Ratio of Muscle Fibers You Have Through Training?
Resistance Training: Why You Should Train Using a Variety of Rep Ranges
4 Reasons You Lose Muscle Size & Strength with Age
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Wow! this is good information to know I will give this test a try tonight!
sounds very interesting-will give it a go.
I think I’d rather have the muscle biopsy. ; ) Just kidding! lol Thought that was a pretty good slow-twitch joke!
Maybe not. Ha!