Help me understand target heart rate

July 17, 2021 11:40 AM

I cycle a lot for commuting/errands as well as fun/exercise in a relatively flat city, with most of my rides being under 30min. I’ve never focused on endurance and haven’t monitored my heart rate until recently. This summer, on an extended visit in a place with actual topography, I'm trying some endurance training. In this hilly landscape I’m seeing my heart rate varies considerably over the course of a ride, but averages about 93% of max, which is well above target heart rate. Is this too high? Details:

These rides feel great. They're vigorous to the extent that holding a conversation would be difficult on climbs, but I don’t feel like I’m overdoing it. I'd hate to have to intentionally slow my pace. And how would I even keep my heart rate in the target zone if there's lots of climbing?

My goals are cardiovascular health and building endurance. Am I getting much benefit if my pulse averages well above target heart rate, regardless of how it feels? Is it dangerous? I'm also seeing varying definitions of target heart rate, so I'm not even completely sure what I should be aiming for.

I’m in good overall health and not on any meds. I'm using an old Apple Watch as the heart rate monitor, which may not be super accurate but is pretty consistent. FWIW, my actual maximum heart rate seems to be a bit higher than what the formulas say it should be.

posted by theory to Health & Fitness (11 answers total)

Best answer: (Not a doctor, just someone who has done heart rate training). Humans vary an awful lot. Most formulas for heart rate max are just broad heuristics. Unless you have done something like a step test, you probably don’t know yours actually is. I could always blast through the 220-age max estimate on interval training.

So I would just be happy that you are enjoying the rides. As long as you aren’t going anaerobic, you’ll be making cardiovascular improvements. I would only be worried about overtraining if you are starting to flag on the rides. That would be the sign that you are overdoing it. You don’t mention how often you are doing these rides or how long the rides are. As long as you listen to your body and don’t compromise the next session by going too hard on the current session and getting plenty of rest between rides. It’s fine to have a range of heart rate zones, unless you are training for competition and need to scientifically balance your training sessions, all exercise is good exercise.

Without more details, it’s hard to really say if it’s dangerous. Briefly being at close to max heart rate for a healthy person isn’t usually dangerous. Sometimes consumer grade heart rate monitors can (or could) report an arrhythmia as a heart rate spike so if you are worried an ECG test from a Doctor will rule that out.
posted by DoveBrown at 12:47 PM on July 17, 2021 [3 favorites]

The rigorous way to determine your maximum heart rate is to do a stress test, where they hook you up to heart monitors to make sure you don't die and then run you on a treadmill until you feel awful.

The formulas are just an estimate, and the recommended target zone is also just a guideline.

If you feel good at the heart rate where you're exercising, keep doing that.

If you're concerned, talk to your GP about a stress test.
posted by BrashTech at 12:49 PM on July 17, 2021 [1 favorite]

Max heart rates are sport-specific. Your max heart rate on a bike will be lower than your max heart rate running. Heart rate training zones are sport-specific, too, and without the stress test mentioned above, you are probably better off going by perceived effort.

The heart rate can be a feedback metric over time. If you do a longer ride consistently and compare your heart rate between rides, you will hopefully see an increase in speed at the same heart rate. That tells you your fitness is improving.
posted by TORunner at 1:09 PM on July 17, 2021 [1 favorite]

Response by poster: These rides are roughly 60 minutes, about 5 times per week so far. I've been planning to increase the time and reduce the frequency.

I guess my question isn't so much about danger, but rather if it’s feasible to get a decent aerobic workout or do endurance training in really hilly terrain since my heart rate will go into the anaerobic zone so often. For aerobic exercise (according to the charts) I should keep my heart rate about 20-25 bpm lower than it’s been averaging.
posted by theory at 1:14 PM on July 17, 2021

Recovery is when you get stronger, and typically needs 48hr between strenuous efforts -- so go easy on alternate rides. Rehydrate and make sure you have enough salt in your diet.

I like Sally Morgenthaler's heart rate zones, wherein we each find layers to the exertion, basically in tiers from basic activity, breathing heavily, active but can't talk, then your legs burn because your lungs aren't delivering enough oxygen, then your muscles deplete their energy stores and your blood sugar.
posted by k3ninho at 1:46 PM on July 17, 2021

Best answer: I wouldn't put much faith in the typical formulas for max heart rate. If there's a long, steep hill in your area, try riding up that at full gas to get a better idea of your max heart rate. Also, I am skeptical that on a one-hour ride, you are averaging 93% of your max heart rate. That's a very intense workout that should leave you wiped out the next day.

There are a number of zone systems out there; the one I go by is Andy Coggan's. In that system, you'd want to be in Zone 1 or 2 for a recovery ride.

I've got an Apple Watch and have compared it to the results from a chest-strap heart-rate monitor, and the two have agreed very closely. So I think that's fine. But it is hard to track your heart rate as you go. I set up zone alerts in a cycling app I use, and found it incredibly annoying. Turned it off after one ride. If you had a cycling computer out in front of you, you could keep an eye on it, but that's more money that you might not want to spend.

But unless you've got very specific training goals, all this is overkill. The question is not whether you'll get fitter doing what you're doing—you will—but whether you'll get as fit as possible as efficiently as possible, and whether your workouts are optimized for very specific training goals. It is feasible to do low-intensity rides in hilly areas. Just shift down and take it easier up the hills. I live in a hilly area and for my distance rides, I try to keep my average heart rate below 75% max.
posted by adamrice at 3:20 PM on July 17, 2021

I think k3ninho meant Sally Edward's heart rate zones. Here's a quick summary of how that works.
posted by Brent Parker at 3:20 PM on July 17, 2021

I had a running coach tell me that I should subtract my age from 180 to build endurance. Keep that number within five points. It worked for me.
posted by loveandhappiness at 3:39 PM on July 17, 2021

Best answer: Bikers trying to extend endurance don’t base it on heart rate, they base it on time spent at particular intensity levels. In particular they want to spend time at the lower third of their power band (as measured in wattage). However you have two ways on a bike to maintain an intensity or power level, cadence (RPM how fast your turning the pedals) or torque, how hard you’re pushing on the pedals (higher gear). In other words I can maintain 20mph on a flat road by pedaling quickly at a lower gear or slower at a higher gear, which way this is done wavers for different cyclists.

Higher cadence is going to (in an oversimplified explanation) tax your cardiovascular system harder and raise your heart rate higher but tax your muscles less. Lower cadence can bring your heart rate down but you’re more likely to burn out your legs quickly (knowing this, during rides I’ll switch between the two modes, to “rest”).

Anyway as you hit the hills you may be downshifting to a lower gear and switching into a high cadence and your heart rate is going up. However your muscular load is going down - so unless you feel like you’re doing a sprint, its highly unlikely that you’re going anaerobic despite your heart rate going up. It’s entirely possible that your still providing plenty of oxygen to your muscles. It’s just all turning over faster.

So really I think focusing on your heart rate is distracting from what you’re trying to achieve. Building endurance will inherently build your cardiovascular system. Google building endurance on a bike and follow those instructions. Most importantly on days you do feel you might have gone too hard, take a day off - either don’t ride at all or ride a pace where you can maintain a conversation. Rest days are huge to building endurance, its counter productive to overwork.
posted by bitdamaged at 7:47 PM on July 17, 2021

In case anyone shows up in this thread and wants to have a lower heart rate while biking:

I had one of those smart watches that tells you your heart rate for a little while, and it informed me that my heart rate did not get particularly high while I was riding a recumbent bike. I'm not sure if it was me (I ride slow) or if it was the fact that I was in a seated position, but I definitely think it might be the recumbent position. Even just standing and wandering around got my heart rate up more.
posted by aniola at 8:16 PM on July 17, 2021

So I recently read 80/20 Running which is clearly a book about running and not cycling, but the principles of endurance training are largely the same. The author quotes a lot of studies that show that doing more training in a lower heart rate zone (described as "zone 2" but which your HRM will probably categorize as "Zone 3" or "aerobic") is key to improving endurance.

That said, just getting out and riding regularly at any heart rate is good and unlikely to be harmful.

if it’s feasible to get a decent aerobic workout or do endurance training in really hilly terrain since my heart rate will go into the anaerobic zone so often.

Yeah, this is hard to avoid on a bike and my personal opinion is just to ride your rides. That said, if there's a flatter route available near you then maybe do one or more of your weekly rides at a lower intensity there to mix things up a bit. One fairly generic bit of training advice is that not every ride has to be you going out 100%.
posted by GuyZero at 9:52 AM on July 19, 2021