85% of max heart rate, explained.
85% of your maximum heart rate is the line that separates a real VO₂max interval from a warm-up. It's the threshold the Norwegian 4×4is built around — here's what it means, roughly where it falls by age, and how to actually get there.
What 85% of max heart rate means
Your maximum heart rate is the highest your heart can beat in all-out effort. 85% of that number is a fixed fraction of it: max HR × 0.85. It marks roughly the lower edge of the intensity that pushes your VO₂max upward, which is why it's the gate for the 4×4 protocol.
85% of max heart rate by age (estimated)
Using the age estimate 208 − 0.7 × age for maximum heart rate, then taking 85%:
| Age | Est. max HR | 85% (4×4 threshold) |
|---|---|---|
| 20 | 194 bpm | 165 bpm |
| 30 | 187 bpm | 159 bpm |
| 40 | 180 bpm | 153 bpm |
| 50 | 173 bpm | 147 bpm |
| 60 | 166 bpm | 141 bpm |
| 70 | 159 bpm | 135 bpm |
Estimates only. Individual max heart rate varies by 10–20 bpm from any formula, so these are a starting point — see how to find your max heart rate for better methods.
How to reach and hold 85%
- Warm up first. Cold legs take much longer to get the heart rate up; 10 minutes of building effort gets you primed.
- Use a slight hill or higher resistance. The easiest way to spike heart rate without all-out sprinting.
- Don't sprint the first 30 seconds. Build into it so you can hold above 85% for the full four minutes.
- Watch live heart rate, not pace. Heart rate is the target; pace is just one way to move it.
The practical problem is that the one to two minutes it takes to cross 85% gets miscounted as “interval” time by a normal timer. A threshold-gated timeronly counts the minutes you're actually above 85% — so every session delivers the same dose.
Frequently asked questions
- What is 85% of my max heart rate?
Multiply your maximum heart rate by 0.85. If your max is 190 bpm, 85% is about 162 bpm. Using the age estimate 208 − 0.7 × age, a 40-year-old's max is around 180 and 85% is about 153 bpm — but your true max can differ by 10–20 bpm, so a measured max is far better than an estimate.
- Why is 85% the threshold for the Norwegian 4×4?
85% of max heart rate is roughly the lower edge of the intensity that drives VO₂max gains. The 4×4 targets the 85–95% band; staying above 85% for the full four minutes is what makes each interval a real VO₂max dose.
- How long should it take to reach 85%?
About one to two minutes of hard effort from a warmed-up state. That ramp-up is exactly why a threshold-gated timer matters — it doesn't start counting the four minutes until you actually cross 85%.
- Is 85% of max heart rate hard?
Yes — it's a genuinely hard effort, around 8 out of 10. You should be able to say a few words but not hold a conversation. If you can chat comfortably, you're below the threshold.
Train at VO₂max.
Stellar Intervals reads your live heart rate and only counts the four minutes while you're above 85% of max — so every session is the same dose.