You might think that if someone is a fast runner, they must have huge calf muscles and explosive bursts of speed. But there's more to it than that.
Usain Bolt, the former track and field athlete, still holds the world record in the 100-meter sprint at a blazing 23.35 miles per hour (37.57 kilometers per hour).
That's incredibly fast by normal human standards, and even elite athletes can't quite match it.
So why, scientifically speaking, can some people sprint while others tend to be slower but longer-distance runners?
Body Composition Makes a Difference
One key factor that influences your running speed is your body composition, including how your muscles work.
The human body is made up of over 600 muscles that work together to allow you to move in different directions and at varying speeds.
These muscles are made up of groups of fibers, with two main types: fast-twitch and slow-twitch.
Every muscle has a different mix of these fiber types. For example, in your legs, a fast-twitch muscle is the gastrocnemius, which helps with sprinting and jumping. A slow-twitch muscle is the soleus, which is used for walking and jogging.
In general, fast-twitch muscle fibers are larger and allow you to move quickly and generate a lot of force.
People who can sprint tend to have more fast-twitch muscle fibers. However, these fibers also get tired quickly, which limits how long you can sprint.
Endurance muscles, on the other hand, allow you to run at a slower pace for longer periods of time. Endurance athletes typically have more slow-twitch muscle fibers.
Since most of us are born with a certain number of each type of muscle, our abilities are largely determined by genetics. However, exercise can help train these muscles to become more developed in the way you want them to be.
The Brain
It's not just your muscles that affect your speed or endurance when you run. Your brain plays a significant role too.
That's because your skeletal muscles are controlled by your brain. In other words, you can think about doing something, and then do the movements that go with it.
For example, you can control the length of your stride, how your arms move, how your feet hit the ground, and even the techniques you use to breathe.
According to Dawn P. Coe, an associate professor at the University of Tennessee, Knoxville, these all can make a difference in how well you run and how well your running training goes.
Your mental game matters too. If you enjoy exercising and getting physical activity, it will make you more likely to excel.
Summary
- Body composition: Fast-twitch muscle fibers allow for speed, while slow-twitch muscle fibers support endurance.
- Brain: The brain controls muscle movements and mental factors can affect performance.
- Genetics: The number of each type of muscle fiber is largely predetermined by genes.
- Training: Exercise can help develop specific muscle fibers to improve running speed or endurance.