It is important to understand that, for distance runners, interval training doesn't usually involve sprinting and hitting top speed one repeat after the next. It is all about pushing yourself out of your comfort zone, but generally at a controlled pace.
Nailing down what pace you should be running specific intervals is one of the elements of interval training that sends people running in the other direction. While there's no across-the-board pace prescription, there are some rough guidelines that can help get you started. For instance, if you're running 1-mile intervals, try to complete them at your goal 10K pace. For shorter intervals, like 800m, execute those at 5K pace, and 400m intervals should be slightly faster than that. This is where a coach can come in handy, but there are also online resources, such as Rickerman's calculator, that can help you figure out a pace range.
In terms of total distance, most interval training workouts fall somewhere between 2 to 5 miles, depending on the length of the intervals. You should also include at least a 15- to 20-minute warm-up and cooldown before and after. Keep in mind that completing a variety of intervals is important, whether you're running a 5K or a marathon. Just because you're training for a long-distance race doesn't mean you won't benefit from 400s faster than race pace.
Rest between intervals also varies based on your goals and current fitness. A good place to start is with equal rest, so if it takes you 90 seconds to run a 400m interval, jog slowly, walk or stop completely for 90 seconds in between. If endurance is your main objective, slightly less rest is usually sufficient. However, if speed is more important, getting adequate rest so you're able to continue running at that faster pace is necessary. In this case, you'll want to make sure your heart rate has dropped below 120 beats per minute before starting the next interval.
As you gain fitness, you can increase the speed and the number of intervals, as well as decrease your recovery time between intervals. For example, with added training, you 10K time will improve, so it makes sense to bump up your pace for 1-mile intervals. Similarly, an increase in endurance means you'll be able to handle a greater volume of distance within those interval sessions. "Like anything else, one progresses as they get stronger and faster," says Rickerman. "It takes time and patience. Consistency is key."race.