Tips on Speed Work

The most popular place to do speed work is at a standard 400-meter outdoor track. Such a track is precise and unvarying, so you get objective feedback about how fast you’re running. When you do speed work on the track, you’re doing intervals.
An interval workout has a defined structure. First, you run fast for a specified distance (usually one to four laps, which equals one-quarter to one mile). You have a rest interval of a set length, expressed either in distance or time, during which you jog very easily to recover from the fast run. At the end of that interval, you run fast again. You repeat this process for the number of times you had planned at the start of your workout.
Technically, the term intervals refer to the recovery portion of the workout, but everyone has his or her own usage for this term. Some people call the fast runs the intervals, as in, “I’m going to do mile intervals today.” (I will use the term this way in this book.) Other people don’t use the intervals term at all; they call the fast runs repeats, as in, “I’m going to do half-mile repeats today.” Don’t let them confuse you. If they talk about doing intervals, that refers to the workout as a whole; it means they’re doing speed work on the track. (Some runners just say they’re “doing a workout,” meaning that they’re going to do intervals as opposed to a normal training run.)
Most runners do intervals of one to four laps. Doing intervals that are one lap long is called doing quarters, because a 400-meter track is just short of a quarter-mile long. That’s a standard distance for intervals, but for the wrong reason. Seems so logical to do one lap fast at a time, so quarters have become a regular part of many people’s training.
But unless you’re going to be racing the mile, quarters don’t help most runners as much as longer intervals do.
Quarters are too short to require any real sustained effort, so you have to do tons of them to get the benefits that you get from fewer numbers of longer intervals. When you do longer intervals, such as two laps or four laps, you’re working at the intensity that’s going to be required of you in races for a longer period of time on each interval. Running fast for a longer time provides a better stress to your system.
How do you structure an interval workout? What’s best depends on what race you’re training for. If you’re concentrating on 5Ks, then you’re better off runnin shorter intervals at a slightly higher intensity. If you’re getting ready for a half-marathon, you should do longer intervals at a bit slower pace.