It appears that everyone is born with different amounts of the two main muscle types, called slow-twitch and fast-twitch. You may have seen some people call this online pseudoscience, but the research supports this. Slow and fast muscle twitches work in very different ways and are responsible for various athletic functions. But don't worry – you can train to change the amount of slow versus fast twitch muscles you have, so all hope is not lost for your future marathoning career.
What is the difference between slow and fast muscle twitches?
The short answer is yes, and the medium answer is also yes – but researchers are unclear about the exact science behind the phenomenon. Our muscle fiber distribution seems to change every day and scientists have no formula for which intensity of which activities produces an exact result.
However, it has been generally observed that concentrating your workouts on endurance or explosive movements results in an increase in slow or fast vibrating muscles, respectively. So, if you've been beating hard on the treadmill lately, the percentage of your muscles that is slow is almost certain to grow.
For optimal overall muscle growth, you want to do both types of fitness training – after you finish a long, slow jog, don't forget to do some sprints or body weight exercises.  Training for slow-twitch
- Long, simple sessions on the treadmill. Spice it up with a few podcasts, YouTube channels or Netflix.
- Go for a walk with your dog in the neighborhood until you are both exhausted.
- Go for a swim in your local lake or swimming pool.
- Lift lighter weights for 12 or more repetitions, or do body weight exercises.
Training for fast-twitch
- Sprint, jump rope or HIIT cardio.
- Run or power up a hill as quickly as possible.  Explosive kettlebell movements.
- Lift heavier weights for three to five repetitions.
The information in this article is for educational and informational purposes only and is not intended as health or medical advice. Always consult a doctor or other qualified health care professional for any questions you may have about a medical condition or health goals.