When I'm running outside and have to stop at a traffic light, what is the best thing to do while you're waiting? Jog in place? Stretch? Walk in circles? — Timmy R., via email
What to do when you reach a red light depends on the goal of that particular workout. If you're going out for a steady state run, you should zig-zag. Simply turn and keep running. Chances are you will hit another red light, giving you the chance to turn back toward your original route. Running in place is another option, but it will not put the same demands on the body, and therefore is not as beneficial.
Here's why: A steady state run works to train the aerobic energy system, which uses oxygen and stored fat to produce energy. Steady state runs are beneficial for increasing overall endurance and burning fat, but the aerobic energy system only kicks in when an exercise (running) is performed for at least 3 minutes. During this type of workout you want to be constantly running. This will keep the body in the aerobic zone for the entire workout.
You can also use the opportunity to run intervals—I normally need to run several blocks of city streets to reach the park or river, so I'll run at 75 to 80 percent effort when traffic allows, and stop for rests at red lights. This will not only help increase VO2 max and speed, but the randomness of the rest and work intervals provides a beneficial "shock" to the cardiovascular and central nervous systems.
—John Cressman, Tier 3 Trainer, New York City