If you have a structured training program or work with a coach, your runs may be divided into sections of particular intensity levels; these intensities relate to heart rate ranges. My coach will often use the categories of aerobic, tempo, and threshold with finer gradations within each indicated by things like "easy" or "lower" or "upper".
It can be tricky for those new to running to understand and distinguish among these zones. I thought I would share my interpretations in case you find them helpful for your own training!
Easy Aerobic = This means go as fast as you can while convincing yourself it feels easy (or that it should feel easy, and that if you were more fit it would be easy, so it must be easy. See how that works? Easy is a state of mind, not a pace, silly!). In this zone, you can run and simultaneously fiddle with your iPod and Garmin and alert your Facebook friends and Instagram followers that you are presently running.
Aerobic = This is a little faster so posting a running selfie may not happen, but you should still be able to pay pretty good attention to podcasts like Competitor Radio, This American Life, or Radio Lab on your iPod. At this pace you are content to keep going (at least to the end of the playlist) and the urge to stop is minimal.
Upper Aerobic / Lower Tempo = see: Tempo (it's practically the same, so round UP!)
Tempo = This is the pace of consistent yet sustainable suffering. This pace is comprised of equal parts wanting to keeping going and wanting to stop. Forget podcasts now, as blood is redirected from the listening parts of your brain to your legs, it's music only, and you may or may not even hear what is playing. You've clocked in for work.
Upper Tempo = see: Threshold (the round-UP thing again)
Threshold = This is pretty much full-on. At this pace all you can think about is when can you stop but you keep going anyway. You are imagining your competitors and asking yourself how bad you want it. You think of your A race. You remember that the more you sweat in training, the less you bleed in battle. Tricks to holding this pace: count steps, run to the next tree/mailbox/blade of grass/rock, and mantras. You may find yourself repeating some random out-of-nowhere nonsensical mantra like "run for puppies" or "legs like a weed whacker" or a line from a song (probably one you hate) and it will go on auto-repeat for a creepy long time. If you are running a threshold interval properly, you should begin to be annoyed by every song on your iPod - the very same ones you loved at Tempo pace. It's all part of cultivating that mental toughness!!
So I hope that helps to better understand the intensity levels that make for a varied and productive run session. Have fun out there!
