The Muscle Fiber Ratio Test
I previously wrote about the importance of muscle fiber ratio for sports performance. Now I'll explain how you can simply assess which fibers you have. Although these methods do not give an exact percentage result but rather an estimated value, this is sufficient for planning your training. The precise determination of muscle fiber ratio can only be done by analyzing a piece of muscle tissue taken from the muscle (e.g., surgically excised) — which is why this type of examination is performed only very rarely and, of course, most athletes do not need it. At most, it can be important for top athletes aiming to maximize performance.
Non-invasive muscle fiber ratio tests
Non-invasive means: without penetrating the body. In other words, a harmless method, since you don't need to puncture, cut, or remove muscle tissue from the body.
I describe two such testing protocols in this article. Their methodologies are similar and the conclusions drawn from the tests are also similar. So pick the one you prefer based on which you like better. One is the test defined by Dr. F. Hatfield, the other by Charles Poliquin.
Why should you do such a test?
The information obtained from testing and measurement helps you create a training plan that best matches your muscle fiber ratio. Based on the data you can understand why certain training methods help your progress and why others do not produce the expected results.
With the muscle fiber ratio test you can determine the fiber composition (and thus the muscle capabilities) for each muscle group. This helps you design the most optimal training plan/rep range/weight for every muscle group/exercise!
Attention! The muscle fiber ratio differs between your individual muscles! That is, if you measure your thigh muscles, the obtained value characterizes your thighs and it is unlikely to apply to, for example, your arm or chest muscles. Perform the test for all important muscle groups required for your sport.
What do you need for the test?
- A weight training gym where you can safely perform maximal strength testing.
- An assistant (e.g., personal trainer, coach). On the one hand they will help you during heavy lifts (for example, help unrack a weight that gets stuck on you), and on the other hand they will help document the test (count reps, record results).
- The selection of the appropriate exercises. Determine the exercise that will be used to test the maximal strength of the given muscle group (for example, the squat helps assess the strength of the thigh muscles). This exercise should be performed both for the maximal strength test and for the muscle fiber ratio assessment.
Dr. F. Hatfield muscle fiber ratio test
- Select an exercise (e.g. squat)
- Determine the weight you can lift for a single repetition with maximal effort (1RM) (example result: the max weight you can squat up and stand with is 150 kg, but 155 fails)
- After the maximal strength test, rest for 15 minutes
- With 80% of the max weight (in the example: 120 kg) perform as many repetitions as you can
Result evaluation
- Fewer than 7 repetitions – fast-twitch (FT) fibers dominate the muscle group
- 7 or 8 repetitions – mixed fiber type
- More than 8 repetitions – slow-twitch (ST) fibers dominate
If FT fibers dominate, train with heavy weights and low repetitions. If ST fibers dominate, you need lighter weights but higher repetitions.
Charles Poliquin muscle fiber ratio test
- Select an exercise (e.g. squat)
- Determine the weight you can lift for a single repetition with maximal effort (1RM) (example result: the max weight you can squat up and stand with is 150 kg, but 155 fails)
- After the maximal strength test, rest for 15 minutes
- With 85% of the max weight (in the example: 127.5 kg) perform as many repetitions as you can
Result evaluation
- Fewer than 5 repetitions – fast-twitch (FT) fibers dominate the muscle group
- 5 repetitions – mixed fiber type
- More than 5 repetitions – slow-twitch (ST) fibers dominate
If FT fibers dominate, train with heavy weights and low repetitions. If ST fibers dominate, you need lighter weights but higher repetitions.
As you can see, these differ only minimally from each other and their conclusions are identical. They provide a good enough estimate for planning the training that is optimal for you.
