Heart rate zones for women, without the bro-science
What HR zones can — and can't — tell you, especially for women in midlife. Why perceived effort beats chasing numbers on a watch.
Heart rate zones are useful. They are also, in most of the popular content you’ll find on the internet, presented with significantly more precision than the underlying science actually supports — particularly for women.
So before you spend $400 on a chest strap and start feeling guilty when your zone-2 walk crept into zone 3 because you were excited about something on a podcast: a quick honest tour of what HR zones can and can’t tell you, and what to actually do with them.
The big problem with the standard formula
The number you’ve probably internalized as your max heart rate — 220 minus your age — has been around forever and is, by the standards of modern physiology research, not a great formula. It can over- or underestimate actual max heart rate by 10 to 20 beats per minute or more for many individuals.
Several better formulas have been proposed since:
220 − age (the old standard).
Popularized decades ago, never developed from modern, representative validation data. Can over- or underestimate true max HR by 10–20 bpm for many individuals.
Tanaka: 208 − (0.7 × age).
Generally more accurate than 220-age across populations. A reasonable default if you want a single number to anchor a watch zone.
Gulati: 206 − (0.88 × age).
Developed specifically from a study of women — and tends to give a lower (more accurate) number than the older formula for many of us.
A 47-year-old woman, by 220-age, gets a max HR of 173. By Gulati, she gets 165. That’s an 8-bpm gap, which moves the boundaries of every single training zone underneath it. If you’re chasing a “zone 2” target based on the older formula, you may actually be at the top of zone 2 or into zone 3 — which is a different workout than the one you think you’re doing.
All of these are estimates. Your actual max heart rate is whatever it is. The only way to truly know is a maximal exertion test — which most of us are not lining up to do.
What heart rate is actually telling you
In broad strokes, heart rate during exercise reflects how hard your cardiovascular system is working to meet the demand of the activity. Higher demand → higher rate. That much is reliable.
What heart rate is not a perfect measure of: how hard the workout actually is for your body, on this particular day, in this particular state.
Things that can shift your heart rate at a given pace, on a given walk:
- Sleep (poor sleep → higher HR at the same effort)
- Hydration (dehydration → higher HR)
- Caffeine (raises baseline)
- Stress (raises baseline)
- Hormonal cycle and perimenopause
- Heat (raises HR at the same effort)
- Recent illness (often raises HR for days afterward)
- Beta-blockers and other medications affecting HR response
A heart rate of 145 on a Tuesday after a great night’s sleep and a heart rate of 145 on a Friday after a terrible night’s sleep are not the same thing. The first is brisk-walk territory. The second is your body telling you it’s working harder than it should be at that effort, and you might want to back off.
A better anchor
Use perceived effort.
For most people doing structured walking, the most useful framework isn't hitting precise HR percentages. It's a 1–10 scale of how hard the effort actually feels — RPE — that accounts for whatever your body has going on that day.
RPE 3–4
Easy.
Conversational. You could sing if you wanted to. Your easy/restorative walk.
RPE 5–6
Moderate.
Talking is easy but you’d notice you’re working. Most LISS walking, including 6-6-6 territory.
RPE 7–8
Hard.
You can talk in short sentences but wouldn’t want to. Fast interval territory.
RPE 9–10
Very hard.
Talking is uncomfortable. Short bursts only. Walking rarely gets you here without high incline or load.
Use the talk test as a sanity check. Full sentences? Moderate or below. Short sentences only? You’re working. Can’t really talk? You’re hard.
Use HR as a data point, not a verdict. If you have a watch, look at it after the walk. Notice patterns over weeks: does the same pace produce a lower HR over time? (That’s fitness improving.) Does an “easy” walk show a much higher HR than usual? (That’s a signal — sleep, stress, illness, something.)
If you take beta-blockers or other medications that affect heart rate, your watch will tell you you’re loafing while your body is actually working hard. Trust your effort, not the number.
A note for women in perimenopause
Hormonal fluctuations, sleep disruption, hot flashes, stress, medications, hydration, and heat all affect resting HR, exercise HR, and recovery. During perimenopause, these variables may be more noticeable or less predictable than they used to be.
Your numbers will likely be more variable than they were in your 30s. A walk that produced a heart rate of 130 last week may produce 142 this week at the same pace. That doesn’t mean you’re losing fitness — it usually means your body is dealing with something. Don’t chase numbers on bad days. Use perceived effort. The HR data is most useful as a long-term trend, not a daily report card.
Practical notes
What to do with all of this.
Use your watch for
- Trends in resting heart rate — chronically elevated RHR can signal under-recovery.
- Fitness over time — same effort producing a lower HR as the weeks go by.
- Spotting an off day — when an “easy” walk reads way higher than usual.
Don't use it to
- Chase a specific number during a walk.
- Feel like you failed a workout because your HR didn’t hit a certain zone.
- Override what your body is telling you on a given day.
Treat the data as a signal, not a score
Heart rate zones are a useful tool, packaged in fitness culture with more precision than they actually deserve. The 220-age formula is rough. The better formulas are still estimates. Your response to exercise varies day-to-day. The data is most valuable when you’re willing to listen to your body when it disagrees with the watch.
Walk by feel. Check the watch occasionally. Adjust based on patterns over weeks, not minutes.
Coached walking, on iOS.
Spanno is the audio coach for women over 40. Real intensity, no impact, no guesswork. Free to start.
