Muscles

Curious Kids is a series for children of all ages. If you have a question you’d like an expert to answer, send it to curiouskidsus@theconversation.com. Why are some people faster than others? – Jon, age 14, Macon, Georgia Usain Bolt, the world’s fastest person, ran a 100-meter sprint at a speed of 23.35 miles per hour (37.57 kilometers per hour). That’s mind-blowingly fast for a human. It’s about the same speed as cruising in a car through your neighborhood or in a school zone. It might not seem that fast when you’re in the car, but for a person? Few runners in the world can even come close. There are several reasons why some people can run very fast while others tend to run more slowly. Genetics – the traits you inherit from your parents – play a role, but so do your choices and experiences. As pediatric exercise scientists, we create and e...