There are an infinite number of ways to train the body; from body pump to spinning to power lifting to swimming; the choices are endless. With the experience of working with a large variety of individuals, I have found each individual responds differently to different modes of exercise. Body pump may work wonders for some, while heavy weight training is the answer for others. Yet some folks may respond best to a moderate amount of weight and reps. So what gives? Why do we all respond differently to exercise and how can we predict what will work best for ourselves?
While there are many factors that come into play, one of the most important factors is your muscle fiber type. In the simplest terms, we have two different types of muscles in our body; type I and type II fibers. Type I fibers are “slow twitch”, meaning they respond well to training that is biased towards endurance. Type II fibers are “fast twitch”, meaning they respond well to strength, power, speed, and agility training. Everyone has both type I and type II fibers in every muscle. The percentage of each, however, is different from person to person. An elite tour de France cyclist is likely dominant in type I slow twitch fibers, while an Olympic Weight lifter is likely dominate in type II fast twitch fibers. Most of us mere mortals are somewhere in between. So what does this mean for you and your training?
There are metrics we can use to predict our fiber type. Here are a few question to ask yourself to help determine yours:
- 1. Do you find it difficult to add lean body mass? You are probably type I slow twitch dominate. Your body will respond better to low weights, high reps, running, spinning, and endurance based swimming.
- 2. Do you add muscle easily? Chances are you are type II fast twitch dominate. Your body will respond well to high weight, low reps, plyometric training, and agility training.
- 3. Body type also can predict fiber type. Ectomorphs generally are slow twitch, mesomorphs fast twitch, and endomorphs somewhere in the middle.
- 4. Finally, there are some protocols for predicting your fiber type. The below protocol is for advanced lifters and should be done under the supervision of a fitness professional. This protocol is from Charles Poliquin:
Determine your one repetition maximum (1RM) on an exercise
Rest for 15 minutes
Perform as many repetitions as possible with 85% of your 1RM
Less than 5 repetitions – you are fast twitch (FT) dominant
5 repetitions – you have mixed fiber type
More than 5 repetitions – you are slow twitch (ST) dominant
If you are FT dominant, then you should use heavier loads and lower repetitions predominantly in your training. ST dominant individuals, on the other hand, will respond better to lighter loads and higher repetitions.
If you have hit a plateau in your training, refocus your training with a bias towards your fiber type. Take note of how your body responds and tinker with your program over time. The only way to truly find what works is to play around with different routines until you find the sweet spot. Regardless, always make sure to mix it up! Focus your training towards your fiber type, but consistently varying your workout in terms of exercise variety, load, reps, and sets is still important to your body responding to your exercise program.