After four years of field hockey at Duke, my wife/co-coach, Megan, joined the track team for a fifth year. On some random Tuesday in October, I was out on an easy run, full of youthful vigor. For a complete visual, I was also rocking a pair of yellow construction headphones with an antenna and everything, since I was too oblivious and/or too indebted to wear something that wasn’t free off the back of my dad’s Ford Ranger.
As I jammed up a hill, listening to radio beaming through that four-inch-long antenna, I got startled by movement to my right. Was it a deer? A fashion blogger wanting to know the secrets of my cranial style? No, it was a streaking blue wave of Megan’s teammates. They flew by me, leaving me in their dust. From Megan’s training log, I knew they had an easy day on the schedule between workouts and races. Their easy runs were just very, very fast. That story of consistently fast easy running plays out at many colleges across the country every year.
And I would argue that it’s often the opening credits of a horror story.
Their easy runs were just very, very fast. That story of consistently fast easy running plays out at many colleges across the country every year. And I would argue that it’s often the opening credits of a horror story.
The Inverted-U of Easy Paces
I didn’t fully understand what I was seeing at the time. But observing the athletic trajectories of tons of athletes over the years showed a pattern. Megan and I even gave it a name for coaching purposes: “The Inverted-U” of easy paces (we talk about it more on our podcast here). We named it that because the trademark office said that “2 Fast 2 Furious” was already taken.
The Inverted-U describes how athletes’ easy paces often get faster as they start out. That pace progression can be a great thing—being able to run faster all the time is a good proxy for fitness at first. And here is the hardest conundrum that many athletes face: as they travel up the Inverted-U and their easy paces get faster and faster, often they’ll have massive breakthroughs. At the top, they may even set a huge PR or win a national championship.
The Inverted-U describes how athletes’ easy paces often get faster as they start out. That pace progression can be a great thing—being able to run faster all the time is a good proxy for fitness at first. … The problem is that what is rewarded as a runner builds up can be the same thing that is viciously punished later.
The problem is that what is rewarded as a runner builds up can be the same thing that is viciously punished later. As an athlete starts, particularly at younger ages, they are often aerobically limited. Faster easy runs are major aerobic stresses, with tons of time around and above aerobic threshold. That aerobic tide can rise so rapidly that it brings all the running economy ships with it.
But there’s an iceberg ahead. Eventually, the initial aerobic gains are mostly grabbed, and only marginal aerobic gains are left. Now, the risk:reward calculus of those faster easy runs shifts. They can cause a significant stress build-up, leading to background chronic stress that accumulates over months and years. It pulls away from effective workouts and starts slowing down adaptation rates. Sometimes, the iceberg rips into the hull. Terrible injury cycles or endocrine/nervous system overtraining can sink promising careers.
If you have followed college running enough, you know what may happen next. Right after hitting the peak on the Inverted-U, far too many athletes sputter for a bit before quitting the sport entirely. Reinforced by a culture that can elevate the outliers over everyone else, they may keep trying to pursue the same training approaches that led to their great successes in the first place. And as a result, they’re left running into the iceberg over and over, questioning everything.
This story has hope! On the other side of the Inverted-U, runners can learn that it’s OK to slow down their easy paces. They find out that what may have served them at first is no longer applicable because they are different athletes with different physiologies. The easy paces slow back down again (though not on every easy run). But the races get faster and faster for a decade or two or three. Seeing athletes achieving personal bests into their 30s and 40s and beyond, you realize that the Inverted-U may be misnamed—it’s a lot more like a rainbow. And with patience, giving your body time and space to traverse that rainbow of easy paces can end at a pot of gold. Or gold medals.
Why Easy Paces Vary
First, let’s take a step back. Why are we calling all of these different paces “easy runs” when they are clearly different stresses altogether? That’s because of how most approaches view training. For example, a 2019 study in the Journal Of Strength And Conditioning Research lumped all training into five boxes: races, short intervals, long intervals, tempo running and easy running (I wrote about that study here). The easy-running catch-all box included everything that was slower than a pace an athlete could hold for a few hours. So it would likely include everything from steady running just slower than marathon pace to 100-mile pace to run/walk approaches, which are all very different stresses on the body.
While every coach differs, “easy” generally describes a wide range of paces, with each athlete dictating exactly how fast to run based on how they feel. Coach Jack Daniels gives a pace range based on race times. Coach Phil Maffetone may constrain easy much more based on aerobic threshold. Coach Renato Canova often guides easy running based on marathon pace. But across all the different approaches, athletes are often left unsure of how exactly they should pace these runs, which make up around 70% to 90% of all training in most systems. So what does easy pace really mean?
Across all the different approaches, athletes are often left unsure of how exactly they should pace these runs, which make up around 70% to 90% of all training in most systems. So what does easy pace really mean?
Coach Maffetone’s approach is a good placeholder to structure the rest of the conversation. You may have heard of the rough formula for calculating easy effort heart rate: 180 beats per minute minus age. In that formulation, a 40-year old athlete would run easy paces at 140 beats per minute or fewer. That formula is a simplified way to get at aerobic threshold, or the intensity range when the body switches primarily from lipid metabolism to glycogen, breathing picks up, and efforts become less sustainable for many hours. Under that? Easy. Over that? Go screw yourself.
For a feel of your aerobic threshold, you can get lab tested if you want to dial it in or use the MAF calculation if you want a very rough approximation. You can also use some field testing that provides a rough-but-individualized approximation (I prefer an adaptation of the Friel Method, doing a 30-minute hard time trial, taking the average heart rate from the last 20 minutes and multiplying that by around 0.80 to 0.85 for a general feel for AeT, adjusting based on how it feels). But ideally those things just act as spot checks to calibrate that what you perceive as easy is actually easy on days you need to recover.
Why Easy Running Is More Complicated Than AeT
Those athletes traveling up the Inverted-U are almost certainly running above aerobic threshold on many easy runs. That’s OK in moderation—after all, I’d bet that many NCAA national championship performances at endurance events feature a lot of AeT+ easy running given how fast many college teams run. The problem is that it also increases cortisol production, induces fatigue and can impact the hormonal/nervous systems. Young athletes can often adapt through that fatigue, particularly when they have lots of aerobic gains to make and just a few years in school to make them. Ah, to be young and full of raging hormones. So too can beginner athletes at any age with lots of aerobic gains to make.
Sometimes, experienced athletes can thrive with the same approach. For example, faster easy runs became all the rage when it was revealed that some of the Nike Oregon Project male athletes training under Coach Alberto Salazaar would sometimes end easy runs at just over 5 minutes per mile. Salazar is now banned from coaching due to doping practices, so perhaps the example gains some clarity. But even if there was no chemical assistance involved, there will always be outliers that can continue to adapt as stress is thrown at them for many years.
It gets back to the old egg analogy about training theory. Toss 100 eggs at a wall, and a few may not break. If a philosophy forms around the approach of those unbreakable eggs, we might think the secret is going full speed into a wall. When thinking about growth, check to see if there is a graveyard of shattered shells lying around.
On the flipside, athletes training on a strict MAF approach may almost never exceed aerobic threshold. That may also have major flaws, since athletes are not just lungs with legs—developing the low-level aerobic system at the expense of all else risks creating athletes that are not neuromuscularly or biomechanically adapted to actually go faster.
If I had a dime for every time someone emailed asking why MAF training made them slower, I’d be able to upgrade from those janky yellow headphones.
If I had a dime for every time someone emailed asking why MAF training made them slower, I’d be able to upgrade from those janky yellow headphones. However, there are success stories with strict MAF, like Ironman Champion Mark Allen. Usually, those athletes are outliers in their own right—very efficient, so that their focus on easy effort and big volume make a fast athlete because their physiologies are born to go fast in the first place.
On top of that, it’s not like each run is just a constant percentage above or below aerobic threshold. Paces vary, hills can increase heart rate, it may be hot, you may see a coyote or a goblin or Ted Cruz in a Hawaiian shirt. For trail runners in particular, most athletes will go well above aerobic threshold just to get up steep hills (I know I do). It can all seem like an overwhelming amount of information! From that fire hose of info, let’s put it all into three simplified funnel statements:
The best easy run pacing involves a range of stimuli based on how an athlete feels.
Adaptation occurs in difficult-to-predict ways from training. If we truly understood the physiological line from stimulus to outcome, I think it’d look like a Jerimy Bearimy timeline from The Good Place. Given that squiggly, multi-dimensional uncertainty, providing the body with a range of stimuli is the good place to start.
When an athlete feels good, they can go a bit quicker on easy runs, sometimes toward marathon effort. When feeling like a Defcon 12 crapstorm, they can shuffle 5 minutes per mile slower than their marathon effort. From that origin point, pay attention to how the body responds. Are you ready for harder workouts? Are you excited to run? Do you feel uplifted or broken down? Keep traversing that iterative process, with room for it to change as your physiology changes over time.
There is no such thing as a pace that is too slow for easy running.
If you take nothing else away from this article, remember this point: you can go as slow as you freaking want. Musculoskeletally, slow paces can enhance slow-twitch muscle-fiber recruitment and reduce injury rate while improving recovery. Aerobically, they can improve lipid metabolism and result in more efficient angiogenesis as capillaries form around muscle fibers. Biomechanically and neuromuscularly, going slow can avoid the pitfalls of going too fast, where athletes take excess energy to go a pace that won’t lead to enough adaptations to justify the inefficiency.
If you take nothing else away from this article, remember this point: you can go as slow as you freaking want.
And finally, slow runs can be saviors for the endocrine and nervous systems, reducing cortisol while improving hormone balance, helping athletes adapt to long-term training.
When an athlete feels good, it can be productive to spend time at or above aerobic threshold on easy days.
If you venture into harder territory on easy runs, it’s OK when you feel good and efficient during the run, and you aren’t experiencing excessive recovery cost after. Look at almost any pro athlete, and you’ll see it sometimes, particularly on uphills and in long runs. Some accounts say Coach Canova’s athletes spend over a quarter of their weeks running a bit faster, but not quite workout efforts. Coach Jerry Shumacher’s training principles are shrouded in mystery, but most agree that quality, upper-end-aerobic long runs are a key element.
The same principles that may lead to breakthroughs on the upslope of the Inverted-U likely apply to all parts of a running journey, just in moderation. Faster easy runs supercharge aerobic stimuli, possibly improving the outputs at which the body uses fat instead of carbohydrates as fuel. They can increase muscular output, improve resiliency and probably have some weakly-understood neuromuscular benefits as well. Maybe it’s even more complicated, related to protein expression and epigenetics. Those benefits are most relevant as an athlete starts out, but they’re a part of the spectrum of adaptations that matter later on too.
Just never force easy runs to be faster against the will of your physiology and psychology.
While adaptation is complicated, we have a brilliant supercomputer that fully understands it: our brains. Every second, the brain incorporates an incomprehensible number of variables to understand how we feel. Listen to it.
Most of the time, easy means a minute or two per mile slower than marathon pace, with variation based on external factors like terrain and temperature. When you feel good and have evidence you’re recovering well from all life/running stress, easy may progress toward marathon pace throughout a run, possibly even faster at the end, or harder on ups. When you are tired, you can run at something a tick above walking pace.
The final big point that is especially important in the world of shared GPS files and Instagram posts: easy pace is not a proxy for your fitness or ability.
The final big point that is especially important in the world of shared GPS files and Instagram posts: easy pace is not a proxy for your fitness or ability. Across the studies and observations I have seen, variation in easy pace does not dictate outcomes in any significant way for similarly situated athletes. A fast easy day on Strava could be great training, or it could be thinly veiled self-destruction, and there is no way to know from the outside.
You can almost never go too slow, but you can go too fast. And finding that individual balance is part of the fun of being a lifelong, ever-changing runner.
David Roche partners with runners of all abilities through his coaching service, Some Work, All Play. With Megan Roche, M.D., he hosts the Some Work, All Play podcast on running (and other things), and they wrote a book called The Happy Runner.