All runners are different. So many factors can play a role in determining your capabilities as a runner, and age is hugely important in this. As we grow older and our bodies change, the way we run tends to change as well. It's no secret that a 19-year-old college freshman and a 68-year-old retiree might need to pay attention to different things in their training.
Thanks to this handy guide from Runner's World though, you can learn your strengths and weaknesses as a runner at any age. For instance, runners in their twenties have dense bones and maximum muscle fibers-- but tend to neglect their sleep, nutrition, and hydration. In your thirties? You're in good company. The average age of U.S. marathoners is 38, and natural strength hits a high point in this decade, but you have to continue to strength train to prevent injury and improve your ability to utilize oxygen to increase speed.
Check out the full guide here, with advice and examples for runners ranging from the teenage years all the way to the 70s and beyond.