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The case for eliminating junk miles

Why Reid Coolsaet's training doesn't include junk miles

Easy miles and junk miles are two terms that often get conflated in the running world. Both terms usually refer to slow, easy running, designed to promote recovery and build aerobic capacity, but there’s distinction between the two. Easy miles can turn into junk miles when they actually end up leaving you more tired than refreshed. Here’s how to decide if your easy day is actually doing you more harm than good.


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Reid Coolsaet is a 2:10 marathoner who owns the fourth-fastest time by a Canadian in the event. Coolsaet says he doesn’t really incorporate any junk miles into his training, but explains the fine line between easy and junk. “My definition for junk miles is when I’m running so slowly that it doesn’t really feel like running. For me that’s slower than 5:30 per kilometre. But if I go out and do a run a 4:40 per K, then I don’t see those as junk miles.”

Photo: Maxine Gravina

The runner says that easy running is actually 80 per cent of his training which is common for marathoners. “I run easy on days when I’m not working out and then also on warmups and cooldowns. Only about 20 per cent of my running I’d consider quality, which is at marathon pace or faster.”

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Easy days hard, hard days harder

When training is going well, it’s very easy to get excited and make all of your days hard. But Coolsaet cautions against this as well: “Some athletes can get away with running hard all the time, but most can’t. You do get fitter faster, but I don’t think this is good for sustainability or makes you faster long-term. What I’m saying is that I don’t think this increases your ceiling, while simultaneously making you more injury-prone.”

Reid Coolsaet
Photo: Lululemon Toronto/Canada Running Series.

When easy turns to junk

The line for Coolsaet between easy and junk miles is when his body is struggling at a normally comfortable pace. “If I can’t go out and run five minutes per kilometre, then my body needs a day off more than it needs a run.”

Runners should keep this rule in mind. If your easy day feels like a slog, consider making it a cross-train, or better yet, taking the day off. Another option is to schedule a weekly off day to avoid junk miles in your training. The weekly off day is great for preventing injury, and also frees up a little time so that runners can do some rehab work or simply get a little more sleep.