Some of the most dramatic breakthroughs I've witnessed have come at least partly from athletes learning to ignore pace during both training and racing. Some even happen with athletes that have been good about not pushing their effort too much just because the watch says it's slower than they expect. The fact is, pace is useless as a training metric, especially during your run. Further the simple mental energy of viewing pace and choosing whether or not it matters can affect the outcome of your run!
Pace is not an objective metric that determines the benefits you get from a run, or whether you should run faster/slower. Pace is an output – and it's what's happening inside your body that counts.
First of all, let's separate this into two issues – the difficulty of getting an accurate pace number from today's technology, and the fact that even an accurate number isn't a proxy for physiological work.
Don't worry – at the end, I'll give some suggestions about what to use instead!
Accurate Pace Measurements are Hard to Come By
Think your expensive hi-tech watch is giving you accurate numbers? Think again!
Remember - your GPS is triangulating radio signals from space, while you're moving, using atomic clocks accurate to quadrillionths of a second, and it even has to take special relativity into account.
An error of a mere millionth of a second would result in a quarter-mile error for that single data-point. Throw a building, tree or mountain in the way, and you've got even more issues.
Further, it only does this once per second (at best), and most consumer-level GPS devices are only accurate to 5-10 meters in ideal conditions. Compounding the problem, most recent running watches have prioritized battery life over accuracy. You can read an admittedly old article about GPS watch accuracy here.
So unless you are running on a track and taking accurate lap splits with a stopwatch, you're not working with a number that's accurate enough to be helpful. (And please don't do that unless you're a pro athlete/genetic anomaly. For most of us, the risks are not worth the small potential benefits. I talk more about this below.)
Pace is Not a Proxy for Physiological Work
The vast majority of training stimuli are based on internal physiological processes. Whether you are working at VO2max effort, easy aerobic effort, lactate threshold effort, or anywhere in between – it's what's happening inside your body that counts. That's largely determined by your effort.
Focus on the input, not the output.
The actual pace that manifests (the output) will vary due to hundreds of factors, only some of which we can even keep track of. Think about it – are you going to run the same pace on a day that's 90ºF with a dew point of 85º as you are on a day that's 50ºF and partly sunny? Of course not. Nor should you try. Even in a race.
Then we get into other factors like training load, muscle tension, life stress, sleep, HRV, hormones, altitude, running surface, age of your shoes, how long your shorts are, whether you drank coffee that day, and so many more. I'm not kidding. All of those and many more will affect your output.
These factors can amount to some pretty significant differences, and will affect not only your pace on training runs, but your race performances as well. This is one reason I encourage my athletes to not immediately start looking for a 'mistake' they (or we) made whenever they have a poor workout, long run or race. Sometimes, it's just not your day, and the reasons aren't always something you can analyze and control.
In fact, I've seen countless breakthrough races happen just a few weeks after an extremely frustrating performance. Did those athletes somehow build fitness in the three weeks between their marathons? Of course not – it's the other factors that changed, allowing the fitness they already had to shine!
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There Are Reasons to Think About Pace Sometimes... Sort Of...
Now there are reasons to prioritize situations where you can maximize the pace at a given effort. Note that I didn't say 'force your body to run a given pace, no matter how hard it is.'
Here's the thing: while you can get a similar training stimulus running hilly dirt roads in 90ºF temperatures, the neuromuscular stimuli are slightly different compared to doing an identical workout on shaded flat pavement when it's 55º. In simple terms, your legs are getting used to running a slower pace at that effort. So even though your VO2max might be improving, and your fitness improving overall, the running economy benefits might be marginally less.
Particularly for workouts or key long runs, you can think about factors that you know will decrease the pace that results from a given effort level. You still don't need to worry about the actual pace, you're just putting your body into a situation that you know will result in faster paces.
Sometimes, it's helpful to put your body in a situation where it can maximize the pace at a given effort.
Is this something you need to worry about a lot? For most people, no. As long as you are mixing up surfaces and temperatures over weeks and months, and of course doing strides and effective interval workouts regularly, you are likely getting plenty of neuromuscular benefits.
(Note that for non-elite athletes, mile repeats or even 800 repeats are not effective speedwork – be sure to subscribe for an upcoming article about this!)
That said, if you have a habit of doing all your runs on hilly, technical routes or in hot weather, you should try to mix in some situations where your pace is maximized for your effort. If you are an advanced or elite athlete, especially at shorter distances, it may even be helpful to find some highly-controlled situations for speed workouts periodically, such as a flat, deserted, paved and shaded road or even a track if necessary.
There's a huge difference between choosing 'fast situations' and trying to force your body into doing things that are counterproductive.
Remember, I'm not telling you to push harder to run a certain pace – just control for factors that you know will limit your pace like terrain and weather!
For elite and sub-elite athletes dealing more with sharpening fitness rather than making physiological progress, there can be reasons to look at pace purely from the biomechanic and 'practice' perspective, but this is exceedingly rare, and needs to be done on a track with a coach in-person.
What to Think About Instead
So if you shouldn't be thinking about pace, what should you think about?
The answer to that... is complicated. In an ideal world, most of your runs or workouts should be based on effort, which is really a big jumble of multiple internal sensations. However not everyone has a finely-tuned sense of effort, and effort doesn't have a clean and simple 'number' that is easy to think about and reference.
What about heart rate? Well, that suffers from similar issues as pace – accuracy and relevance. If you're getting heart rate from your wrist - it's almost surely not accurate enough. Even if you tested it and think it's 'good enough.'
If you're using a chest strap, it might be accurate enough, if you wet it beforehand or use gel, and it's a good quality strap with a fresh battery.
Assuming it's accurate, is it a good number to use in replace of effort? Well, it's certainly more useful than pace, but it's still not perfect. Factors like cardiac lag, cardiac drift, effects of caffeine and even what you're thinking about while running can cause this to be less helpful than you'd think.
Cardiac lag is the time delay between when you increase your effort, and when your heart rate plateaus at that effort. For this reason, heart rate is useless as a guide for short intervals such as speed work.
Cardiac drift is the gradual increase in heart rate over the course of a run or race, despite no changes in effort, making heart rate less accurate for long runs and races.
Caffeine increases heart rate, but decreases perception of effort – the generally accepted net result is that you will race faster.
Here's a fun experiment you can do right where you're sitting or lying: Check your pulse. Now close your eyes, and imagine yourself running an upcoming race. Imagine yourself out-kicking a competitor to break the tape in front of TV cameras, or running a breakthrough PR, or whatever a huge dream goal is for you. Check your pulse again. Did it increase? Simply thinking can increase your heart rate.
The Bottom Line
I recommend my athletes use a combination of effort, heart rate, and the subjective sensation of pace, while understanding the variables at play with each, and prioritizing what is likely to be most accurate.
In most situations that's going to be Effort > Heart Rate > Subjective Pace
What do I mean by "subjective pace?" How fast your legs feel like they're running. We've all had days when the legs feel like they are slogging along but the effort is really high. Or vice-versa, days where you feel like you're flying at a low effort. That subjective pace can be helpful at times. However it should still be the first one you ignore of these three.
For most runs and workouts, I also encourage athletes to use the 'lowest common denominator,' or whichever number will result in the easier/slower run.
The difference is not usually large enough to negatively impact training by going too easy/slow, but the same difference in the 'too-hard' direction could be enough to flip the body from overreaching into overtraining, or lead to injury.
Occasionally for advanced athletes with no significant injury/overtraining history, it can be helpful to prioritize the opposite for interval workouts in certain circumstances, generally limited to once a month or so.
My favorite technique for helping athletes learn to calibrate their sense of effort: remove the pace display from your watch for a few weeks. I mean for all runs.
After your first couple weeks, you can consider turning it back on for key workouts and long runs, but I still recommend doing most runs without any pace display. I also find it helpful to put heart rate on a separate screen, accessible only periodically to help you line up the sensations in your body with that metric.
June 2023 Update: I've had a significant number of athletes keep the pace display off for nearly ALL their runs, as well as races. I recommend trying that! So many athletes effectively hold themselves back based on preconceived notions of their capabilities, and fear of failure. Make up your mind to GO FOR IT!
Are you going to try this? What other questions do you have about pace, effort and heart rate?
Comment below!
Share this info with a friend who stares at their watch too much!
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