The short answer: easy runs make up the majority of marathon training volume, and most runners run them too fast to get the aerobic benefit they’re supposed to deliver. The fix isn’t just slower. It’s a pace calculated from your current fitness, not a generic formula or a guessed effort.
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Almost every runner I start working with runs their easy days too fast. Not by a little. Often by a full minute per mile or more.
It’s rarely intentional. It usually comes from training with a group at a pace that isn’t theirs, chasing a number that felt right on a good day, or simply not having a real, calculated number to run by in the first place. Fixing this one thing is often the single biggest lever in a training plan, more than adding a workout type or increasing mileage.
Easy running builds the aerobic infrastructure, capillary density, mitochondrial density, fat oxidation efficiency, that determines how fast you can sustain effort over 26.2 miles. Speed work sharpens the top end. Without a real aerobic base underneath it, there isn’t much top end to sharpen.
Start from a recent time trial or race, adjusted for how well it was executed. Pacing errors, heat, or poor fueling can make a result look worse than your actual fitness. Once you have an honest number, it should set your easy pace, not a feeling and not a fixed formula applied the same way to every runner.
This is the same principle behind every pace in a real training plan, covered in full in How to Train for Your Fastest Marathon.
The popular easy-pace formulas, a fixed percentage of max heart rate, don’t fit every runner the same way. A peer-reviewed comparison of the popular heart rate formulas in marathon runners found the gap between estimated and measured max heart rate large enough that a formula built for one runner can be meaningfully wrong for another.
There isn’t really a “too slow” for easy running, but there’s a real “too fast.” The goal is landing in the specific range where aerobic fitness improves without adding meaningful fatigue.
A rough guide: you should be able to hold a full conversation. If you’re speaking in short phrases, you’ve drifted into moderate effort, not easy. That’s the same mistake that turns a planned recovery day into unplanned extra training stress.
Easy runs are the Smart foundation underneath the Hard workouts. A typical week includes 3 to 4 easy runs, one tempo run, one interval or fartlek session, and one long run.
Get the easy days wrong, and the hard days suffer too, since you show up under-recovered instead of ready. Get them right, and the rest of the week’s harder training actually produces the adaptation it’s meant to. That’s the whole logic behind why most marathon training plans fail, and it applies just as much to injury prevention, covered in How to Train for a Marathon Without Injury.
Flat terrain makes it easier to hold a genuinely easy pace, since there are no hills forcing effort up mid-run. Easy miles along the St. Pete waterfront let runners settle into a real, calculated pace without fighting terrain to get there.
That’s part of the structure behind the St. Pete Run Club: a community where runners are encouraged to stick to their own paces, even on a group run, rather than match the pack.
How do I know if I’m running my easy runs too fast?
If you can’t hold a full conversation, you’re likely running too fast for a true easy effort. A pace calculated from a recent, adjusted time trial is a more reliable guide than feel alone.
Should I use a heart rate formula for my easy pace?
Generic formulas are a reasonable starting point, but research shows meaningful variation between runners using the same formula. A pace derived from your own recent performance is more precise.
How many easy runs should I do per week during marathon training?
Most training weeks include 3 to 4 easy runs, making up the majority of weekly mileage, alongside one tempo run, one interval session, and one long run.