There’s an obvious benefit to running with someone who’s faster than you: The natural competition encourages you to pick up the pace, and over time, you’ll get faster. But what about when a slower friend asks you to join a run? It’s easy to want to shy away from that—you want to feel like you got in a hard workout after all—but occasionally, slowing down and doing a recovery run can actually make you run faster in the long term.

How slow is slow? Well, slow is a relative term. “I actually don’t like to use that word when I coach, because I think it gives people a negative connotation, and then that’s why they don’t want to do it,” says Jessie Zapotechne, a running coach . “Instead, we’ll call it a recovery run or sexy pace.”

What that really means is that you’re running at a pace that doesn’t tax your body. “It’s when you can hold a conversation while running,” she says—and not just with one-word responses.

“Instead, we’ll call it a recovery run or sexy pace.”

If you’re more of a numbers person, “you should be running at less than 65 percent of your heart rate reserve [HRR],” or the difference between your resting heart rate and your maximum heart rate, says Armen Ghazarians, a NASM-certified personal trainer and exercise physiologist.

To calculate that, you’ll need to do a little math. First, you’ll need your resting heart rate (that’s the number of pulse beats you feel in 10 seconds, times six). Then, determine your maximum heart rate (MHR). You can find an estimate of your max by using the Tanaka method [MHR= 208 – 0.7 x age], which is recommended by the American College of Sports Medicine. To find your heart rate reserve, subtract your resting heart rate from your maximum heart rate; for easy runs, calculate 65 percent of that number. Then add back in your resting heart rate to get your target heart rate for these runs.

For example, if your maximum heart rate is 180 and your resting heart rate is 50, subtract 50 from 180 to get 130. Then calculate 65 percent of 130 to get 84.5. Then add your resting heart rate of 50 to 84.5; the result, 134.5, is about the heart rate to aim for on an easy, recovery run. (Don’t worry about the 0.5 part.)

Here’s Why You Should Slow Down for a Recovery Run

“The most common mistake most runners make is that they think if they’re running easily, then they’re not getting much benefit,” says Brian Rosetti, a running coach. That couldn’t be more off-base because easy (or sexy pace) running comes with a laundry list of benefits.

First of all, as your body becomes more adapted to aerobic, slow runs, it’s going to use fat more efficiently, Ghazarians says. “This process is known as the fat adaptation effect,” he explains. “Faster anaerobic runs upwards of two hours mainly deplete stored muscle glycogen from carbohydrates. Slower aerobic runs, on the other hand, use approximately 50 percent fat for energy while the remaining 50 percent is a combination of glucose and protein for energy.”

The reason for this? Fat oxidation requires oxygen—and it’s very hard to run long distances at an all-out fast pace. “Long, slow distance runs are easier to sustain. So during these runs, your body has to constantly replenish the oxygen reserves it’s using to continue to produce energy,” he says. “And since fat metabolism requires oxygen, you condition your body to use fat as its main energy source rather than carbs. Eventually, this adaptation will allow you to run longer distances without having to refuel.”

Easy runs also train the cardio, respiratory, and muscular systems to work more efficiently. “They allow the body to better integrate its various systems,” says Ghazarians. “In turn, this will allow you to run with less effort on your faster running days.” Slower runs also train your slow twitch (type I) muscle fibres, “the ones that allow you to work aerobically to sustain your pace on long distances,” he says.

And while faster running is more likely to build up your muscle (think about how sprinters look compared to marathoners), slower running is going to help your tendons, ligaments, joints, and bones adapt to the stress of running. “It also strengthens them without causing immediate stress on them, which might lead to injury,” says Ghazarians.

The extra bonus there? That’s going to promote efficient running form because slower runs make it easier to focus on technique. During faster runs, he explains, the blood circulates away from your brain to meet the body’s oxygen demands, decreasing your ability to focus. So slowing down can help you zoom in on form.

Plus, slower running has some great mental perks. “I think about long runs as time on my feet versus speed,” says Zapotechne. And that can teach you to deal with physical discomfort—especially toward the end of a long race. Running with a slightly slower friend packs even more rewards. “There’s a real benefit to when you’re helping someone else learn how to be a better runner or even just serving as their motivation,” she adds. It can boost your own confidence too.

How Often Should You Slow Down?

This might come as a surprise, but most of your runs should be slow. “For someone who’s a working professional and recreational runner, we’d advise them to do one fast session, one long run at an easy pace, and two to three shorter, easy runs,” says Rosetti. That’s four out of five runs at a conversational pace.

“A lot of times, people have a hard time slowing themselves down and go out at a tempo pace for runs that should be conversational,” says Zapotechne. “Every run serves a purpose, and these easy paced runs are meant to help build your base mileage and/or fitness level.”

Running too fast too often can actually backfire. “You won’t develop the slow twitch (type I) muscle fibres necessary to withstand a long race,” says Ghazarians. “Fast twitch muscle fibres (type II) are extremely important for your last ‘kick’ in a race. Without an adequate supply of slow twitch muscle fibres, you simply won’t have the strength to run at your maximal pace at the end.” You also won’t rest and recover as well, says Rosetti. “So you’ll go into your next speed or technique workout and your risk of injury goes up—you might suffer some setbacks, and then you’re not as consistent, and you’re not improving as much long-term. So the subtle things can make a big difference.”

To stay healthy long-term, it’s about giving every run a purpose—and sometimes, that just means taking your sweet time.

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