How to Execute Long, Slow Distance Training for Serious Endurance Gains

The purpose, benefits, and tips for nailing this crucial workout. (Hint: You should probably slow down!)


When you toe the start line of a 10K, your race day is going to be totally different than if you were running a marathon. But despite the contrast in those two race experiences, there are some workouts that are crucial to have on your training plan leading up to an event, no matter what distance you’re gearing up to crush.

Enter: long, slow distance training. Simply put, the idea is that you’ll work up to spend as much time on your feet as you will on race day, but you’ll be doing it at a slower pace. Yes, it’s how marathoners spend virtually every Saturday morning — but it’s also the backbone of any training plan.

…you’ll work up to spend as much time on your feet as you will on race day…

It may seem counterintuitive to jog longer runs so slowly, but doing just that is key to reaping this run’s benefits. Keep reading for all the details about how to use the long slow distance run in your training schedule to work for you — and help you nail a PB at your next race.

The Purpose of a Long, Slow Distance Run
“The long slow day is the single most important run in any training plan, regardless of race distance,” says Mark Wooten, an ultramarathoner and run coach with Life Time. “The goal is two-fold: to increase muscular endurance and condition ourselves to be more aerobically efficient.” Running long and slow boosts your cardiovascular system, so delivering blood and oxygen to your muscles becomes less taxing on your heart and lungs.

Keeping the pace easy also boosts your ability to run farther and farther because it trains your body to tap into the right energy source.

“When you’re in your aerobic zone, you maximise your body’s ability to burn fat as fuel,” explains Meg Takacs, a run coach and founder of the Movement & Miles app. “You want to master burning fat instead of glycogen, which you have a limited supply of. This way, you can run more comfortably, for longer periods of time — and the better your body gets at doing this, the more time you can spend on your feet.”

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How Long, Slow Distance Training Makes You Faster
“The long slow day doesn’t necessarily increase our race pace — it’s what helps us sustain our race pace,” says Wooten. “Ultimately, this keeps a runner from falling-off of pace as the race endures, which, consequently, leads to faster finish times.”

To truly get faster, adding a speed workout or two later in the week is also important. Maintaining an easy pace during the longer distances helps you go as fast as possible during those speed workouts. It’s that balance of runs and efforts that’s a magic formula when it comes to race success. “When the gun goes off on race day, our race pace should feel slow compared to our speed work — and because of our long slow days, we’ve built the muscular and aerobic endurance to hold that pace for a very long time,” says Wooten.

To make sure you’re finding the right balance, think of the 80/20 rule, advises Takacs, meaning you should do 80 percent of your runs at a low intensity and only 20 percent at a higher, anaerobic effort.

You aren’t being lazy following this ratio; elite runners go at an easy or recovery effort for the vast majority of their workouts as well. Plus, research backs up the idea that combining low-intensity training with high-intensity interval training is the best way to improve your endurance performance.

Why You Should Keep the Long Run Slow
A lot of runners are guilty of kicking up the pace too much during a long run. You might do it because you’re anxious about your goal race pace and want to convince yourself that it’s doable. Or you might just want to get that run done as soon as possible. “Plans that call for a mileage goal tend to subconsciously encourage us to run faster,” says Wooten. “You might think, I have 16 kilometres on the plan today. Let me get that done as quickly as possible so that I can handle the long list of other things I need to do on my Saturday.”

But remember: The main purpose of the long run is to build aerobic efficiency, and that won’t work as well if you veer into anaerobic territory. “A harder effort on the long slow day will likely take a greater physical toll and could have a negative effect on the quality of the following week’s workouts,” warns Wooten. You’ll also be more likely to hit the wall during your long run or suffer an over-training injury.

Keep in mind that a slower pace doesn’t mean you’re barely hoofing along out there on your run. In fact, your cadence, or steps per minute, should be about the same at the slower speed as it will be during your race pace, says Wooten. “To put it differently, running for two hours on a long slow day and running a two-hour race would actually take the same number of steps — and that’s some good reassurance to keep in your back pocket as you approach the starting line,” he says.

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Exactly How Long and How Slow You Should Go
The distance you’re covering during a long training run is challenging in itself — for a marathon, for example, you’re likely working up to about 32km at the peak of your training schedule. So it’s good that the pace should be easy — and we mean easy. “This aerobic run should be done at a low intensity, a pace that feels almost effortless,” says Takacs. “The pace should be one you could maintain for what should feel like forever.”

You might think of it as a minute to 90 seconds slower than your goal race pace. But you really don’t need to be that specific or to look at your watch repeatedly. The simplest way to determine it is to keep it a conversational pace. A good rule of thumb, says Wooten, is that you should be able to breathe through your nose if you’re holding an appropriately chill speed.

If you prefer to gauge effort by RPE, aim for less than 5 on a scale of 1 to 10.

If you’re training by heart rate, think mid to upper zone 2 — no more than 60 to 70 percent of your max heart rate — as the sweet spot you should try to settle into for your long runs.

In terms of distance, a good goal is to gradually increase the duration of your long run until you’re on your feet for the same amount of time you expect to be come race day. So if you’re planning for a two-hour half marathon, work up to a two-hour long, slow run. If you’re aiming for a 3:30 marathon — yep, your longest long run should top out around three and a half hours.

The duration of your long run can translate to a certain number of kilometres, though some coaches advocate for not even keeping tabs on your mileage but, instead, simply maintaining an easy pace for a set amount of time, based on your race distance. “If you know that you’re dedicating a certain amount of time to your run, it’s a little easier to just be content with sustaining the moderate effort — because running harder won’t get us done any more quickly,” says Wooten. “Also, our hearts and our cells don’t actually care about mileage; it’s all about the minutes of work that they’re doing that are promoting the changes.”

All that said, the bottom line is: Don’t stress. “Try not to get too caught up on pace per mile and don’t force it if [your long slow distance run] happens to be slower than the week before,” advises Wooten. “Sleep, heat, humidity, weekly workload, and stress all factor into pace on a particular day. Just forget about the numbers, zero in on the right effort, and find your flow.”

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