I’d read an article by Jason Karp that reminded me that I like to think of three types of run workouts: Slow, Tempo, and Anerobic. And often self-trained athletes (sometimes even coached athletes) will run these assignments either too slow or too fast. What difference, you say…? Well, you can, of course, get ‘better’ by just going out and running but tuning the engine at various levels is required for maximum horsepower over the range needed for racing rpms and speeds. I might add, this general information also applies to bike workouts; where endurance , tempo (Lactate Threshold), and VO2max also are prescribed by coaches.
SLOW or ENDURANCE RUN
People usually run too fast during their slow-run days (I, too, have a tendency to feel that “I’m not working hard enough. This isn’t making me faster.”) But the benefit is from the duration of the slow run, and running it faster actually negates the value of this workout by putting stress on the legs and slows your harder run day.
The purpose of easy and long runs is to stimulate and build the [biological system] so that you can hold on through the long haul. Run sites might talk about a pace relative to your 5k or 10k pace….I prefer to think of heart rate, which for slow runs should be about 70-75% or a little more of your maximum HR range. This is basically HR Zone 2, and Zone 2 can feel adequately stressful at the higher end.
The tempo run (called by a variety of names: AT, LT, ….) is where are able to sustain the pace and is juuusst under the line where you are starting to meet your maximum oxygen availability. It’s a little difficult to find that place and takes some practice; tends to be 85-90% of max HR or toward the higher end of Zone 3.
The length of time you can sustain that pace is based on your endurance (remember the ‘slow run’, mentioned above, that added more oxygen-utilizing components to your muscles) so the longer you can sustain that pace you’ll be capable of holding any pace up to that level. To put it another way, it’s the fastest you can go and keep on going without oxygen deprivation. ….sounds like a good thing to be able to do.
ANEROBIC CAPACITY or VO2max
You run VO2 intervals to increase the amount of oxygen you’re using by running at the speed where your maximum heart rate happens. There are several biological functions improved by these intervals so that you can sustain this level of activity longer. I’ve noticed it improves my being “used to” the feeling of operating at VO2max levels and, indeed, can perform better and longer at those levels. It also recruits the fast-twitch muscle fibers which we endurance athletes don’t have as many of.
A typical VO2max interval workout might involve 3-5minutes at fast pace with a couple minutes between each one. The rest interval would be short enough to keep the HR up. The pace for that level of heart rate is adequate, and increasing the pace beyond that is counter productive. A couple of other caveats is 1) make sure you warm up for at least 10 to 15 minutes before doing VO2 runs and 2) these workouts are fairly stressful so don’t put two into one week.
Without complicating the whole thing at this point, a mix of these workouts can be judiciously used in one workout.