Aerobic Threshold and RPE

You’ll notice in your plan that we refer to aerobic threshold (AeT) and rate of perceived exertion (RPE) frequently. As we delve into training, it’s important to figure out what effort to do the majority of training. What differentiates training from exercise is that training has purpose for each workout. That sounds dramatic, but maybe a better way to say it is that with training we have general principles we follow to continually improve, and to do that, it’s important to know what you’re trying to accomplish with each session. However, if you’re like me, you might not want to have a set structure, and running or whatever sport you do is what you do for joy and a release from the structure of every other thing in your life. Have no fear, all of what you signed up for is still useful. I like simplicity and the simplest concept is that the vast majority of your time training needs to be easy. Our body likes stability and incremental change, so the way we teach our body that we can do things is by doing them frequently and gradually doing a little bit more. So for your aerobic workouts, we want to be at an effort that our body things is manageable. That means that you can carry on a conversation and you’re not sore afterward, or at least not sore by the next day, so you can head out again. Think of these as putting money in the bank. Each deposit isn’t huge, but it’s small enough that you can do it day after day and by the end of the quarter, or year, you’ve accumulated a decent amount! It’s also good to think of training as a long term endeavor, so if we continue with the bank analogy, you won’t see your money really grow until you’ve been saving for a while. Sure, you could make one big deposit, but that could mean that you won’t be able to make another for a long time if it took all your available money.

So, for any of the easy distance workouts, make sure they’re actually easy. One way to do so is to wear a heart rate monitor and do a test where you go out for an hour and keep your heart rate under 180-your age. That formula works decently well as a starting point, but if you’ve trained a lot over the years, it tends to be a little conservative. You can also go out for an hour and only breathe through your nose. There’s a metabolic shift that happens when you go from your aerobic system (burning primarily fat) to needing to pull in your anaerobic system (called glycolytic metabolism that uses more carbohydrates). On the cellular level you produce more CO2 with glycolytic metabolism, so you need to open your mouth to release the excess CO2. We’ve had many athletes (including us) do metabolic testing in the lab and nose breathing correlates with the aerobic threshold. Finally, you can also use rate of perceived exertion, which is a scale to ten where ten is as absolutely hard as you can go. The trick with RPE is to be honest with it. It’s easy to creep up the effort but tell yourself that it’s still a 5/10. I like to couple RPE with energy the next day and soreness. Another measure is imagining you dropped your keys midway; could you go back to get them and feel ok? The chart below shows the RPE numbers. Note that it has mouth breathing starting at 4 but in my experience it’s a 5.

If you’re just getting back into a routine after an injury, illness, or any other reason, an hour will be too much, but the intensity is still really important. Even if you’re going for 15 min, go at an easy effort so you can build the volume first. Speed will come, but only after your body can do more easy work. Think of making a cake (that’s more fun than a building) and you have to make the cake before you can frost it.

Ok lots of analogies there. Let me know in Slack if you have any questions!