Traditionally, most elite runners are extremely mum about their training and weekly mileage leading up to big races. But Allie Kieffer—who finished seventh in the 2018 New York City Marathon with a personal best of 2:28:12 and likes to challenge the status quo—was very transparent about her training on social media. In fact, three days postrace, she tweeted out a photo of her exact training plan, which included all the times she cut a workout short if she wasn’t feeling 100 percent. She captioned it “The Anatomy of a PR.”

Many of us runners are a little Type A (okay, maybe a lot Type A), and our first instinct is to see things through to completion. If a training plan calls for a seven-mile tempo run at half-marathon pace, we’ll do everything we can to get it done—even if we feel like crap during it. But sometimes this hardcore dedication could actually be hurting us—mentally and physically—if we’re not flexible.

Watch: Allie Kieffer talks about being transparent with her training hits and misses prior to her seventh-place finish at the 2018 NYC Marathon:

preview for 2018 New York City Marathon Preview: Allie Kieffer

“No training plan has to be set in stone,” says running coach John Honerkamp, a certified running coach who served as the coordinator of the NYC Marathon’s official online training program for six years. “It’s good to have a schedule, but you can allow flexibility. You’re not going to not finish your race because you swap days [for a long run].”

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It’s tempting to just follow a training plan as if you’re checking off items on a to-do list, but the real secret to success comes from learning how to tune in and listen to your body during training. This takes a lot of experience and some experimentation, but it can pay off big time (as was the case for Kieffer). Here are four other times when it’s totally okay to switch up your training schedule.

When to Switch Up Your Training Plan

1. Your resting heart rate is higher than usual.

Checking your resting heart rate each morning is a good way to keep tabs on your cardiovascular health, especially while training.

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“A higher heart rate means your body is more stressed, which means you might not have much energy,” says Polly de Mille, R.N., an exercise physiologist at the Women’s Sports Medicine Center at the Hospital for Special Surgery in New York.

If your normal resting heart rate is elevated by 10 to 15 percent or more, you should tweak that day’s scheduled workout, says Pete Rea, elite athlete coach and coordinator at the ZAP Fitness Team U.S.A. Training Center. As for what kind of tweak, usually pulling back on intensity and/or distance will do the trick. For instance, if you’re training for a marathon, try running for three hours instead of the scheduled 20 miles, so you still get time on your feet, but you’re not pushing your body as hard.

The longer the distance you’re training for, the more wiggle room you have in the plan. “Nailing every workout and hitting everything that’s on paper is less important when training for longer distances than shorter ones, like a 5K,” Rea says.

While you have a little less flexibility for shorter, more precise distances, your resting heart rate could be elevated if you’re stressed, dehydrated, or not getting enough sleep, and if you feel like you need to call your workout, you should.

2. Your usual paces are off.

If you’re in the middle of a tempo run or interval workout and your paces are way slower than what they typically are, Honerkamp suggests cutting your losses and ending it early.

“Maybe you haven’t recovered from a previous workout or race well enough,” he says. “You might just feel horrible because you’re doing too much—rest is just as important as work.”

And de Mille agrees, saying that many of the gains you make are actually during recovery.

“When you finish a very hard workout, your electrolytes, fluids, and glycogen stores are depleted, there are small micro tears in your muscles, and you’re probably mentally drained,” she says. “Your body needs time to repair and replenish.”

3. You feel an injury coming on or getting worse.

You really need to tune in to your body when you feel pain that’s injury-related, Honerkamp says. If you feel an existing injury flaring up or a new ache or pain that doesn’t feel quite right, you should either stop and take a day off or cross train, then reassess.

“That [scheduled] long run isn’t as important as your race,” he says. “The key is listening to your body and using common sense.”

While some injuries are, unfortunately, unavoidable—say, tripping on a curb and twisting your ankle—others like a stress reaction are easy to dodge if you’re smart about training. To allow your body to safely adjust to your goal little by little, build your mileage up slowly. (The 10 percent rule—increasing your weekly mileage by no more than 10 percent—can be helpful to follow.)

4. You’re coming down with a cold or you’re already sick.

If you feel yourself starting to get sick, Rea says it’s beneficial in the long term to take a day off so your body can focus on fighting the illness rather than powering through a workout and recovering. Being smart about it might mean the difference between one day off or several days on the bench.

This is especially true if you feel the cold in your throat or lungs, says Honerkamp. Coughing or chest pain is a sign to rest up. If it’s just a head cold that’s sinus-related, going for a run can sometimes make you feel better, since exercise can help with congestion.

When You Should Power Through

Running is largely a mental game. That being said, sometimes you just might not be in the mood to do 6x800-meter repeats at 10K pace. We get it, but once you actually get out the door and onto the track, you might feel differently.

“See how you feel five to 10 minutes in, then make the decision,” de Mille advises. “Sometimes it really is more mental rather than physical, in which case, just keep going.”

Even if your legs feel dead—speed workouts and long runs can do that to you—it’s important to know what running on tired legs feels like so that when you’re at mile 23 of a marathon, you know what to expect. However, de Mille suggests staying alert for any aches or pains that signal a more serious injury (in which case stop, cross train or rest, and see your doctor if it doesn’t seem to be getting better).

Another time you should keep your scheduled workout? Less than ideal weather. It’s easy to check the weather, see that Sunday is sunnier and warmer than Saturday, and decide to move your long run. But it’s good to gain experience running in weather that isn’t perfect, since you can’t predict what it’ll be like on race day. For instance, just because your race is in April doesn’t mean it won’t be 30 degrees, windy, and sleeting. (We all remember the 2018 Boston Marathon.) So training when it’s cold and snowy—or 95 degrees and humid—might actually give a leg up on race day.

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