How to Understand Heart Rate

Wednesday, January 6, 2016

I recently got a GPS watch with a built in hear-rate monitor. I quickly realized that having a heart rate monitor is nice but it only helps you if know what the numbers mean. I did quite a bit of research and found that training using your heart rate is very helpful because your heart rate provides an objective measure of exertion, one that's usually more accurate than your mental gauge on how hard you are working.


In order for you to use heart rate in your training there are some terms you need to know. The first is max heart rate. Your max heart rate is the maximum rate your heart can beat. There are lots of ways to calculate what your max heart rate is but for simplicity I would go with MHR = 208 – 0.7(age).  Because I bet you don't like math just plug your age in the calculator I made below and it will spit out your MHR. For me (age 32) that put my MHR at 186. So if my heart rate goes up to 187 I will explode and die. Ok, not really. It's not a 'hard number' it's more of a good guess.


Even more important for runners is your lactate threshold heart rate (LT HR). Your LT HR is the point where lactate, a product of carbohydrate metabolism in the muscles, begins to accumulate because it’s being produced faster than the muscles can use it. Put even simpler it's when you are working out so hard that your body can't use all the lactate it produces. Ever been sore after a hard workout? Blame lactate. Lactate is a key part of how you get energy from your muscles when you run. So how do I find my lactate threshold heart rate? Unfortunately it's not as simple as plugging in a number.

There are a few ways to figure out your LT HR. The first is to go pay an exercise lab to do a threshold test on you. But who has time for that? The second way is to guess by feel. I know, it sounds mystical and it's not very exciting, but it will work just fine for you and me. Your lactate threshold heart rate is found at the fastest pace that you can sustain for 30 minutes (if you are not super fit), or 60 minutes (if you are very fit). The heart rate you have during that effort is your lactate threshold heart rate (LT HR). For most people you can find this during a 5k or 10k race effort. For me, this is about 158. This is also 85% of my MHR which corresponds to another popular, but less accurate method; estimating your lactate threshold based on a percentage of maximum heart rate (80-90% of maximum heart rate in trained endurance athletes). 

Got your LT HR figured out? Ok, great now here are the heart rate zones and what they mean:

Zones

Description

Use It For...

Example HR

Your Face in this Zone

Active Recovery

Barely even exercise. You are basically always in this zone unless you are dead or exercising. Living, sleeping, watching Netflix and basically just chilling. This zone means you are able to recover and repair your muscles from previous workouts. <127
Aerobic Threshold Very comfortable and quite useful for building aerobic fitness, fat-burning capacity, and endurance. 
Most of your runs should be here. Building your aerobic threshold is important because it will enable you to run faster for longer before you tip into anaerobic metabolism which cannot be sustained for as long.
128-141
Tempo Just faster than jogging pace, 'comfortably hard'. This is the automatic pace you will run when training. This will teach your body how to run at a fast pace for a longer distance. To do a tempo run jog for about 10 minutes, then do 3-5 miles at your 10k race pace. Then do a slow jog for about 10 minutes. 142-150

Sub-lactate Threshold  Running hard enough that it requires some conscious effort. This is where  tempo training merges into the threshold power zone for training. This is an excellent place to increase your power at lactate threshold without the huge training stress generated when you train at and above LT. In other words you pretty much get the benefit of LT training without as much stress on your body. 151-157

Lactate Threshold Even more stressful on the body than the previous zone. This zone is starts to become difficult to maintain for the long haul. Your goal is to build up to 3 x 15 minutes with 5 minutes of recovery between hard efforts. This is your basic HIIT. Working out here will increase your LT which means you can run faster! 158-160

Aerobic Capacity
Very intense and stressful, but when incorporated into your training in small amounts it will elevate your running performance significantly. To run here you must do it in short intervals.
As your aerobic capacity increases, you can run farther and faster. Run slightly faster (10 to 30 seconds per mile) than your 5-K race pace. Run this pace for 3-5 minutes then recover. Don't do this workout more than once a week. 161-166
Anaerobic Capacity   This is anywhere from the fastest pace you could do a mile to a full on max effort sprint. Do a set (4-12) of sprints as fast as you can for about 8-10 seconds. Do this only once a week and you can even do it up hills. You will be sore and you will run faster because of it. 167+

One great advantage to training based on heart rate vs pace is that heart rate percentages will remain the same. I might be in the tempo zone at a 7:00 min/pace but you could be in the aerobic threshold zone. Pace really isn't as helpful to your training as heart rate is. Everyone has different heart rate abilities based on genetics and training.

I've recently started to incorporate all this into my training and it has already paid off. I've let my recovery runs be slow (and I dont' feel bad about running slow) and I know that I really do need to push it hard some runs to get into that next 'zone'.  Until I did this I basically ran every training run as a tempo run. That's not effective because it doesn't let my body recover and I never truly push myself by going into the higher zones. How about you? Have you ever used heart rate training before? Has it helped?


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