Get a group of experienced runners together, and sooner or later the topic of conversation will turn to heart rate. Maybe someone will talk about how they bailed on their speedwork last week because their resting heart rate was higher than normal. Maybe someone will casually mention how the nurse thought her equipment was wrong the last time they went in for a physical because their resting heart rate was so low. I have heard several conversations on this topic that turned into a bizarre form of reverse one-upmanship, where the winner was the one with the lowest value. In the interest of trivia, the winner of the game usually brags about a resting heart rate around 40.
Even if you’re not interested in impressing people at the group run, your resting heart rate is a valuable tool that can help you stay healthy in your quest to big PRs.
Even if you don’t track your heart rate when you run, you should at least be checking in on it first thing in the morning. Not only can it help you track your overall aerobic fitness (as you gain fitness, your resting heart rate will decrease), but it’s also one of the first (and most objective) signs of overtraining. If your body isn’t recovering well, your resting heart rate will be higher than normal. This is somewhat expected on the day after a long run or vigorous speed session, and if it returns to normal after a day or two, you’re fine. When you start getting into the danger zone is when it’s too high for several days in a row. That’s your body waving a white flag and crying out for a break. If you’re not tracking your resting heart rate, you could easily miss this sign and run yourself right into the ground.
While you can take your resting heart rate any time that you’re sitting around being physically still, the best way to do it is to measure it first thing in the morning. Not only does this give you an easily reproducible set of circumstances (which makes comparing values day-to-day easier), but it’s also the point at which your heart rate is likely to be the lowest. After all, you’re just about as well rested as you’re going to be, having spent the past several hours asleep, right? The exception is if you wake up with an alarm clock. In that case, the shock and awe approach you’ve used to wake yourself up (combined with the leap out of bed to hit the snooze button) will certainly bring your pulse up quite a bit. However, if you can lay still and take a few deep breaths (without falling back asleep), your heart rate will return to its resting value within a minute or two. You’ll want to take it for a few days during a low-intensity part of your training (i.e., not in the middle of your peak week of marathon training) to get an idea of what your baseline is.
Of course the next question is, how high is too high? A good rule of thumb is to back off if your resting heart rate is 10% (about 5-7 bpm) above normal. That doesn’t necessarily mean that you need to take the day off, but it does mean that you need to take it easy. If you’ve got speedwork scheduled for the day, postpone it and stick to some easy miles. If you’ve got a longer run scheduled, shorten it up. Repeat as needed until it comes back down to normal. If a few days of taking it easy aren’t enough to bring it down, then you’ll need to seriously consider taking some rest days. Overtraining doesn’t just affect your race times, it affects every system of your body. If you push it too hard and get into a seriously overtrained place, it can take several weeks of rest for your body to fully recover. Better safe than sorry, right?
Next week, I’ll go over some tools you can use to help measure and track this new piece of data.
Do you take your resting HR in the mornings? Why or why not?