Heart rate and pace are two of the most common metrics runners use to determine how hard they’re working, but often, they’ll use one or the other. By using the two together, you can get a good idea of how your fitness is progressing and use that information to guide your training. Intimidated by numbers? Don’t worry — comparing the two is easier than you think.
Decoupling simply means two things separating from each other. In the case of aerobic decoupling, these two things are your heart rate and pace. When you’re running at a pace that is manageable for you, your heart rate should remain relatively steady. If you’re very fit (perhaps you’re in the latter stages of a training block), your heart rate should remain steady as your pace increases — at least, to a point.
When one of those two variables begins to deviate from the other, they are decoupling. This means either your heart rate is increasing significantly as your pace increases, or your heart rate is staying the same as your pace declines. Let’s unpack what those changes mean:
Increased heart rate with increased speed
When your heart rate increases dramatically relative to your increase in pace, it means there is a higher cost for you to maintain that pace. In other words, it is much harder for you to run at that pace for that length of time, and you need more training in order to maintain that pace.
The good news is, that’s what training is for. When you look at your data after your run, you can see where your heart rate and pace decoupled (your heart rate increased or your pace declined), which is the point at which you became inefficient. The goal of your training should be to run longer at that pace before you reach that point.
For example, if you’re training for a 10K with a goal time of 50 minutes, you need to be able to run 5:00/km for 50 minutes. If you can only maintain that pace for 30 minutes before you reach the point of inefficiency, that’s your starting point for your workouts.
Heart rate stays high as pace declines
If your heart rate remains high even after you’ve decreased the pace, that’s an indicator that you’re not yet efficient at that pace. That being said, there are a few other factors that could affect how quickly your heart rate comes down after a hard effort:
- Heat and/or humidity can make it difficult to cool your body down, which will make your heart work harder even at a slower pace.
- Dehydration causes you to have a lower volume of blood circulating through your body, which means your heart has to beat faster to compensate.
- Running up a hill will increase your heart rate, even though your pace is slower than running on flat ground.
Heart rate and pace stay consistent
If you don’t see any significant changes (less than five per cent deviance) in your heart rate or pace, that is an indicator that you are running efficiently at that pace. This is ideal when you’re doing an easy run, but won’t help you see any big performance gains in workouts. If you see this happen in a workout, take it as permission to increase the pace.
For example, let’s say you do a 30-minute tempo run at the beginning of your training cycle, and you notice your heart rate beginning to jump after about 20 minutes. You continue training, and a few weeks later, you do the same 30-minute tempo again at the same pace but this time, your heart rate stays consistent. When you do that workout again in another couple of weeks, you can increase your pace and challenge yourself a bit more. Eventually, your heart rate and pace will decouple again, so that’s your new goal.
Heart rate, pace and performance
Knowing your pace is crucial for determining what your goal time should be in a race, and your heart rate is an excellent way to gauge effort. By putting the two together, you can get a good picture of how fit you are, and what you need to work on so you can improve performance and smash your running goals.