Tracking Resting Heart Rate Can Help Improve Your CrossFit Performance

Don’t Just Do Something–Sit There! : Making The Most of Passive Tracking

By Coach Mike Flanagan (11.20.20)

Whether it’s counting reps or watching the clock, punching weights into Wodify or charting new PRs, CrossFit loves data.  We want athletes to actively track as much as they can inside the gym, and to use their data to personalize workouts and set appropriate goals.    But if you own a smart watch, fitness tracker, or other “wearable” technology,  you also have access to reams of passive data from all time you’re not in the gym.  This is the first of a series of posts about this passively tracked data, and how you can use it to manage your workouts and recovery alike.

First, some terminology: when discussing active v. passive tracking, we’re referring not to physical activity, but to whether or not you’re consciously working to monitor and record the data in question.  To use an analogy, if you notice it’s cold and turn up the heat in your house, that’s active monitoring—you’re in the loop.  But if you allow your thermostat to respond when the temperature dips, that’s passive—you were able to “set it and forget it.”

There are several “streams” of data that most fitness trackers and smartwatches will passively capture for us.  In future posts, we’ll talk about sleep monitoring and NEAT (non-exercise activity thermogenesis; or our “step count”).  But if you’re new to mining your own data, you can start by looking at your device’s charts of your resting heart rate (RHR), and asking yourself three key questions:

  • Over the long term, how is your aerobic fitness?  There’s no universal scale for RHR and fitness levels: everyone’s RHR is different, based on age, genetics, body composition, and exercise habits.  But as a general rule, if your heart and lungs are strong and working efficiently, your heart won’t need to beat as often to get your body the oxygen it needs: i.e. the lower your RHR, the better your overall aerobic fitness.   The key here is that real adaptation to exercise takes time; we’re talking about trends over weeks or months, not days.  By stepping back and taking the long view, you can see which direction you might be trending, and why. (Fig. 1)

  • From day to day, are you getting enough rest, or might you be over training?  The process of adapting to exercise is a gradual one, but our body’s response to exercise can be almost immediate.   If you establish the habit of monitoring your RHR , then you’ll start to see these short-term responses.  Even hours after class, you might find that your RHR remains a few beats higher than average, especially if you pushed yourself close to your limits: perhaps it was max deadlift/squat day, or maybe an attempt at a PR for Fran.  Usually, a good night’s sleep is all it takes to set your RHR back to normal levels, but if you string together a few days of very intense effort, you might see a “staircase” pattern emerge where these small “micro-spikes” start to stack up and not come back down.  If so, that’s a great sign that it’s time for a rest day, to allow your body to fully recover. (Fig. 2)

  • What else might be “stressing you out”?  Stress isn’t just a state of mind;  you can very easily “stress” your body by eating or drinking things that aren’t healthy, or that simply don’t play well with your physiology.  (For example, our fridge at home is stocked with non-fat yogurt and milk-based protein drinks, but dairy literally makes my wife sick—that’s just genetics.)   In turn, lack of sleep, insufficient hydration, or not enough mental “down time” can also add up in ways that you might not consciously realize, and all can trigger an elevated RHR response.   If you start to see your RHR going up from day to day, and it’s NOT because of intense exercise, it might be time to pay attention to other factors and perhaps make small changes to help you “dial in” your fitness. (Fig. 3)

In almost every way, tracking your RHR as part of a healthy lifestyle is the opposite of a lot of what you may read in newsletters and magazines—it’s not a shortcut, a “life hack,” or “one weird trick for a flat belly by New Year’s . . . “   It’s just a simple practice—and a little bit of a nerdy one at that: you’re looking at data, asking yourself what it means, and making adjustments accordingly.  It can only complement—not replace—the essential work of getting your heart REALLY pumping in class.  Regardless, whether you look at your data every day, or once every few months, it’s still going to be there, thanks to the passive tracking happening on your wrist: you don’t need to lift a finger.


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