The idea of interval training is that you run a specific distance at a fast pace (typically 5K or faster), then recover by resting, walking, or jogging for another specific distance or time, and then repeat:
By doing this, you stress out your cardiovascular system and build up lactic acid in the muscles—which boosts body fuel, strength, and stamina—while then letting yourself recover and prepare for the next tough interval.
As you might imagine, the shorter the recovery interval between repetitions, the greater the aerobic benefit.
I took a quick survey of a few fellow RunOregon bloggers to see how many incorporate interval training. Not counting me, three out of seven respondents do in fact run intervals on a more or less weekly basis. Of the ones who do run intervals, here were the brief reasons they gave for doing so, along with an example of the kind of interval training:
#1 Reason: “EPOC- HIIT [Elevated Post-exercise Oxygen Consumption — High Intensity Interval Training] is the most efficient use of time- I’m a girl and like the concept of the afterburn.”
Sample Routine: “Totally random- I’ll pick a landmark or something and sprint to – in the summer, sometimes I’ll sprint during the sunny spots and ‘recover’ along the shady areas.”
#2 Reason: “To increase speed.”
Sample Routine: “TEMPO: 1 Mile WU [warm up]; 2 x 2 mile T (Tempo) with .25 Recovery in between and 1 Mile CD (Cool down).”
#3 Reason: “To assist with finishing kick capability and 5K times.”
Sample Routine: “4×800 with 400m rest.”
So there’s a variety of ways of adding high intensity/interval training to your running workouts, from the more informal fartleking described in the first example, to the more structured repetitions/intervals in the third example. When I’m motivated, I do these once a week, choosing in advance from 12 x 1/4 mile with 1/4 mile jog recovery, 6-8 x 1/2 mile with 1/4 mile walk/jog recovery, or (once in blue moon) 4 x 1 mile with 1/2 mile jog recovery. Once I’m in a regular groove, I look forward to these . . . well, sort of look forward to them. It’s a chance to cut loose and run fast, in contrast to, say, long slow distance runs.