Céline asked questions about heart rate training recently, and I started to answer them there. But my comment turned out to be longer than her post, so I decided to put it here instead.
Here’s the low-down on heart rate training as I’ve understood and practiced it for the last 3-4 years. (And, yes, I was similarly confused when I started down this road, too. Hopefully this will get you over the hump.)
Target heart rates are highly individual, but (in general) your maximum heart rate is limited by your age and roughly follows this formula: maxHR = 220 – age. This is basically as fast as your heart can beat.
You won’t be able to train (much less race) near your maximum heart rate for very long, but your highest intensity intervals will be in the neighborhood. These are your “VO2 max” intervals. Anaerobic energy sources don’t last very long, which is why you can’t sustain this effort for more than a minute or two. It’s where you might be when you’re sprinting at the end of a 5K or when you go “all out” at the pool. You can train your VO2 max heart rate upward a bit, but this plateaus.
I described threshold heart rate (a.k.a., lactate threshold heart rate, LTHR) on your previous post. It’s lower than VO2 max, and can be moved upward quite a lot as your muscles become more efficient at producing energy and clearing lactate. It’s a good goal effort for medium-ish races–like a 10K–because it’s pretty much the level of effort you could sustain for about an hour. The longer the race or event, the lower you need to be below LTHR to survive. The good news is, you don’t have to be much below it to go for hours and hours at a fast pace . . . typically 80-85%. As far as I can tell, “tempo heart rate” is the training zone just upward of your LTHR.
Recovery heart rate is pretty much any effort less than about 75-80% of LTHR. It’s a good place to be for a lot of your easier workouts (and/or the easier parts of your hard workouts). Training at this level helps improve your “economy” without taxing you too much. If I understand correctly, it helps train your body to use fat effectively as a fuel source so you’re not relying solely on carbohydrates. (This is good for everyone and extra good for those of us with diabetes. Of course, adaptation leads to its own BG challenges.)
A lot of these different heart rate targets get wrapped up into different “zones.” I hesitate to get too deep into this now, because there are many different zone systems out there. I prefer using this one:
- Zone 1 is super-easy
- Zone 2 is recovery
- Zone 3 is just below threshold/LTHR
- Zone 4 is LTHR-VO2 max
- Zone 5 is maximal.
This much I know. About whether your training zones depend on activity . . . Here I’m starting to get a little bit out of my depth, but I’ll proceed with that caveat.
Your zones should be the same across your aerobic disciplines: swimming, biking, running. They may feel different, though. Personally, I’ve seen that my maximal and VO2 rates are the same when I bike or run, but I do “feel” like I’m working harder to get to them when I’m on the bike. It’s also much harder for me to reach those rates on the bike when I’m not outdoors. I’m not sure why that is, but lots of people have this same experience. I have, however, been doing a bit of indoor bike training recently which proves that I can push myself to spend a lot more time at or near LTHR, but it requires more mindfulness and feedback. I’ve also noticed over the years of training with a heart rate monitor that an hour running at LTHR and an hour biking outdoors at the same heart rate is equally taxing.
And here’s the key thing: Your heart rates—like blood glucose—are just numbers that you use to make other decisions. They’re targets you use to get faster. Raising them isn’t necessarily a goal in itself. Rather, you’re using the zones to go faster within each zone over the long haul. Your targets will definitely change, but don’t think they necessarily have to keep going up and up.