Pace doesn’t reflect the extra effort of running stopwatch uphill or the ease of running with a tailwind or into a headwind, Your GPS watch shows your pace has dropped to 11:00 min/mile. What is your pace telling you?
Pace seems like the answer to our measurement problem, right? Pace measures how long it takes us to cover a given distance. Isn’t that all a runner really needs to know? Thanks to GPS smart watches, we’re so accustomed to seeing minutes per mile on our wrists that we’ve become a little brainwashed about what pace truly measures.
Pace is a measure of how long it takes to go a given distance. With pace, we know how fast the athlete is running, but we still don’t know how hard this is for her.
We also don’t know the terrain or wind conditions. Pace doesn’t reflect the extra effort of running uphill or the ease of running with a tailwind or into a headwind. Varying terrain and elevation can markedly affect pace. Finally, pace has a margin of error of about 5%.
Running a hill is the classic way to show the flaw of relying on pace. Pretend you are running on flat terrain at 9:00 minutes per mile pace and you approach a hill. As you run up the hill, you slow down. Your GPS smart watch shows your pace has dropped to 11:00 min/mile. What is your pace telling you?
Your pace is telling you that you have slowed down. That’s all. Your pace doesn’t know you’re running up a hill because all it measures is time and distance. Your pace simply predicts how long it will take you to run 1 mile at your current speed.
There’s more. On flat terrain, 11:00 min/mile is easier than 9:00 min/mile. But now you’re running up a hill and your smart watch is showing you a pace of 11:00 min/mile. Is your pace on this hill reflecting an easier effort? Is running up this hill easier than running on the flat?
Of course not! Running up hills is harder than running on flat terrain!
Or is it?
Yeah, it probably is, unless running up hill slowly is physically easier for you than running faster on the flat. In this example, we really don’t know and the pace displayed on your wrist doesn’t help. Your pace just shows your speed in real time. Based on your experience, you have to make a subjective judgment about your performance. (A power meter can tell you exactly what’s harder by showing your actual work output.)
Now let’s say you crest the hill and run back down the other side. You speed up and your pace falls to 7:00 min/mile. What does your pace show? It simply shows that it will take you 7:00 minutes to run a mile at this rate of speed.
Is running down the hill easier or harder than running up the hill? We know it’s easier, yet your GPS smart watch’s pace display seems to be telling you that you are running faster and therefore working harder.
Let’s try one more example. Pretend you’re running on level ground at 9:00 min/mile pace and approach a hill. You decide not to tire yourself out too much because you’ve got a long race ahead. You decide to use RPE to maintain your current effort level from the flat terrain as you run up the hill and down the other side. As you run up the hill, you must slow down to keep what you feel is the same RPE, so your pace might rise to 12:00 min/mile. As you run down the other side, you’ll have to run a lot faster to keep the same perceived effort level, so your pace will fall to 6:00 min/mile. As you hit level ground, your effort level remains the same as before, so your speed will return to your previous 9:00 min/mile pace.
Did your GPS pace show you how hard you were working? Absolutely not. By design, you were working at the same level of effort the entire time (or so you estimated from your subjective RPE).
You maintained a consistent level of effort going up and coming down, but compared to running on flat terrain, your pace makes it seem as if you were barely jogging up the hill and then running for your life back down.