You’re a busy person who wants to optimize every minute of training to achieve your goals.

I can help you. I’ve coached Olympians, national- and world-record holders, and national and NCAA champions. Each reached the pinnacle of the sport by making the most of the miles they ran while avoiding injury and burnout. To do that, you need to understand the demands racing requires of your body and train effectively to adapt your body to meet those demands.

The races that most runners train for are almost entirely aerobic events. Yes, even the mile or the 5K. To succeed at those distances, you need to be able to sustain a hard pace for several minutes, and often for more than an hour.

You need to be an aerobic monster.

I like to explain this idea by talking about a common race goal. Many of the women I coached collegiately wanted to break 5:00 in the mile. I would ask: “Can you run 75 seconds for one lap of the track? Of course you can, pretty easily. How about 2:30 for two laps? Yes, but it’s starting to get hard. How about 3:45 for three laps? Now that’s getting really hard. Could you then run a fourth lap in less than 75 seconds? Almost certainly not right now.”

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My point was that a short segment at your desired race pace isn’t a big deal. (If it is, you probably need a less ambitious goal.) If a reasonable goal for you is to break 20:00 for the 5K, then running 400 meters in 1:36 or 800 meters in 3:12 won’t be a major strain. You have the basic speed to run that pace comfortably. It’s sustaining the pace that’s the challenge. Being able to do that requires training that builds your high-end aerobic capacity. That’s what I mean by being an aerobic monster.

So, what does this mean in practical terms? Mileage isn’t everything, but most runners will become stronger aerobically by carefully and gradually increasing the volume of running they can handle. Increasing your mileage from year to year while still being able to hit your times in workouts and races will improve your VO2 max (ability to pump a lot of blood to working muscles), lactate threshold (ability to clear lactate and therefore not have to slow), and running economy (amount of oxygen needed to hold a certain pace).

By “handle” mileage increases, I mean being able to run at something more than a crawl without getting hurt or worn down. A little extra soreness or tightness is common at a newly higher mileage. A sharp new pain, soreness, tightness that doesn’t go away once you’re warmed up, is a warning sign. Similarly, if your goal is to run 6:00-per-mile pace for a 10K, but you’re so tired from upping your mileage that you struggle to run a 6:00 mile in training, you’re overdoing it. And if you’re no longer a coherent person during the rest of your day, with no energy for your real-world responsibilities, you’re definitely running too much (says the guy who in college studied standing up because he would fall asleep immediately if he read sitting down).

But there’s more to being an aerobic monster than simply how much you run. Take two runners who average 40 miles per week. One might run almost the same distance every day at about the same medium-effort pace. He’ll be a decent aerobic athlete. Another’s week might include a long run, a tempo run, and some shorter recovery days. She’ll be an aerobic monster.

Long runs and tempo runs are key to building your ability to hold a strong pace. I’d much rather have you run 12 miles on Sunday and four miles on Monday than eight miles each day. Tempo runs are especially effective at raising your lactate threshold, the point at which your effort goes from aerobic to anaerobic, causing you to slow in the next few minutes if you tried to keep holding a given pace. A steady diet of tempo runs will make you able to run aerobically at a faster pace and will lengthen the time you can hold that faster pace. A bonus: As you become more of an aerobic monster, your everyday runs will get faster at the same effort level, leading to that much more of a training effect.

To get an idea of what this all means in practice, consider the training of Heather MacLean, an Olympian I coach who was ranked ninth in the world in 2022 at 1500 meters.

Heather’s longest race lasts just four minutes. Yet much of her training before her peak racing season could be confused for that of a 5K or 10K specialist. For most of the year, she does a weekly long run and regular tempo workouts. Why? Because the same principle that was true for the collegiate runners who wanted to break 5:00 for the mile is true for Heather to break 4:00 for 1500 meters. (Her best is 3:58.)

The average pace to do so—64 seconds per 400 meters—isn’t a challenge for her to hold for one lap. What she needs is the ability to run the first three laps of the three-and-three-quarter-lap race aerobically, so that she can sprint against the best in the world in the final 300 meters. How did she get there? In large part, not by running all-out 400-meter repeats twice a week, but by the steady accumulation of long runs and tempo runs for months on end.

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In a typical year, one of Heather’s main targets is the outdoor U.S. championship in late June or early July. On that schedule, it’s only in April and May that her workouts start to look more like what you might expect for a world-class miler. But even then, she still does a good long run most weeks, and many of her track workouts include long repeats at 5K race pace. If she doesn’t have a tune-up race in a given week, she’ll usually do a tempo run. All of these elements preserve the aerobic monster status she built in the previous several months

You’ll know you’re becoming an aerobic monster when your training starts feeling more doable. You’ll find you’re finishing your long runs at a good pace, rather than hanging on and hoping they’ll end soon. On hard sessions, you’ll definitely be working hard, but you’ll feel stronger while doing so, and you’ll recover more quickly between repeats. You’ll simply feel more capable than before; any given run won’t seem to take as much out of you.

— Adapted with permission from the book Personal Best Running, by Mark Coogan and Scott Douglas