Zone 2 at 3,259 Metres: Why I Ran Two Minutes Faster on Day Three, and Why That Is Not Progress
Ladakh field log · Day 3
Yesterday I ran 10'44" per kilometre in Leh. Today I ran 8'48". That is one minute fifty six seconds faster, in twenty four hours. It looks like a spectacular adaptation, and it is almost entirely something else.
I am publishing my training data every day from Ladakh. Yesterday's file showed a pace collapse that surprised people. Today's file shows what looks like a recovery from it. If I stopped there, I would be telling you a story the numbers do not support.
So here are both runs side by side, the four things that actually explain the difference, and the one measurement that did genuinely change.
The honest headline: I ran faster because the route was flat and I worked harder, not because I adapted overnight. Adaptation does not move a pace by two minutes in a day, and anyone telling you otherwise is selling something.
Both Runs, Side by Side
Same watch, same shoes, same chest strap, one day apart.
| Metric | 26 July, day 2 | 27 July, day 3 |
|---|---|---|
| Distance in one hour | 5.59 km | 6.81 km |
| Average pace | 10'44" per km | 8'48" per km |
| Average heart rate | 129 bpm | 138 bpm |
| Maximum heart rate | 146 bpm | 147 bpm |
| Heart rate zone | 96% below 137 bpm | 76% between 137 and 154 bpm |
| Elevation gain | 121 m | 20 m |
| Average gradient | About 2.2% | About 0.3% |
| Average elevation | 3,302 m | 3,259 m |
| Time of day | 6:00 AM | 6:08 PM |
| Temperature | 8°C | 19°C |
| Cadence | 154 spm | 169 spm |
| Stride length | 61 cm | 67 cm |
| Ground contact time | 331 ms | 296 ms |
| Running efficiency | 84% | 95% |
| Aerobic training effect | 2.3 | 2.7 |
| Training load | 58 | 81 |
The Four Things That Explain the Gap
If you only read the pace row, you would conclude that three days at altitude transformed me. Read the rest of the table and the story falls apart.
The route was seven times flatter
Yesterday I climbed 121 metres across 5.59 kilometres, an average gradient of roughly 2.2%. Today I climbed 20 metres across 6.81 kilometres, roughly 0.3%. That is not a small difference. Running uphill at altitude is brutally expensive, because the moment you need more oxygen is exactly the moment there is less of it available. A flat valley road and a hill loop are not the same test.
I worked harder, by nine beats per minute
Yesterday's run spent 96% of its time below 137 bpm, which is my recovery zone. Today spent 76% of its time between 137 and 154 bpm, which is aerobic endurance, or Zone 2. That was deliberate. Day two was a below Zone 1 shakeout and day three was a proper aerobic session. Comparing them on pace alone compares two different jobs.
Evening, not dawn, and eleven degrees warmer
Yesterday was 6:00 AM at 8°C. Today was 6:08 PM at 19°C. Most people run measurably better in the evening than immediately on waking, and cold slows early pace while the body warms up. A dawn run and an evening run are not interchangeable data points.
Today's route was 43 metres lower
Yesterday averaged 3,302 metres. Today averaged 3,259. That is a marginal difference and I mention it only because leaving it out would be selective. It is real, and it is small.
What Actually Did Improve
Two things in today's file are worth your attention, and neither of them is the pace.
Heart rate recovery of 44 beats
In the two minutes after I stopped, my heart rate fell by 44 beats per minute. Heart rate recovery is a straightforward window onto how quickly your autonomic nervous system switches out of work mode, and a large, fast drop is generally a good sign. On day three at 3,259 metres, that is the most encouraging number I have recorded so far. It says my system is handling the environment, not fighting it.
It is one reading and I will be watching whether it holds, falls, or improves over the coming weeks. A declining heart rate recovery alongside rising resting heart rate is one of the earliest signals that someone is accumulating more stress than they are clearing, and it is one of the things we track daily on our residential programme.
My running mechanics normalised
Cadence rose from 154 to 169 steps per minute. Stride length went from 61 to 67 centimetres. Ground contact time dropped from 331 to 296 milliseconds. Running efficiency read 84% yesterday and 95% today.
Some of that is simply the flat road. But yesterday's numbers describe a shuffle, and today's describe running. That shift, in twenty four hours, is a reasonable sign that my body was less overwhelmed on day three than on day two.
How to Run Zone 2 at Altitude
Zone 2 is the aerobic base work that most endurance training is built on. At sea level, plenty of people run it by pace. At altitude, that will wreck you.
- Set the ceiling by heart rate, before you start. Mine was 154 bpm today, the top of my aerobic endurance band. The pace is whatever that produces.
- Expect the pace to look wrong. If your Zone 2 pace at altitude does not embarrass you slightly, you are probably not in Zone 2.
- Walk the hills if you have to. Holding a heart rate ceiling on a climb at 3,300 metres often means walking. That is not failure, it is the session working.
- Do not step up intensity daily. I went below Zone 1 on day two and Zone 2 on day three. The next step is not Zone 3 on day four. It is more Zone 2.
- Compare like with like. Same route, same time of day, same effort ceiling. Otherwise you are measuring the weather.
The Test I Should Have Been Running
Here is the honest lesson from my own two days of data: I gave myself two files that cannot be compared.
So from tomorrow I am fixing one route, one time of day, and one heart rate ceiling of 137 bpm, and I will repeat it through the next several weeks. Same road, same cap, same conditions as far as Ladakh allows.
If acclimatisation is doing what it should, the pace at 137 bpm will come down while the heart rate stays fixed. That trend, across weeks and on a controlled course, is the only honest way I can show you that altitude adaptation is happening. A faster day on a flatter road is not evidence of anything.
I will publish every one of those tests, including the ones that go backwards.
Frequently Asked Questions
What is Zone 2 training at high altitude?
Zone 2 is aerobic endurance work, sitting below your threshold and above recovery pace. At altitude it must be set by heart rate rather than pace, because the same heart rate produces a far slower pace than it does at sea level. My Zone 2 band is 137 to 154 bpm, and at 3,259 metres that produced 8'48" per kilometre, well outside my sea-level easy range.
How quickly do you adapt to altitude?
Not in a day. Early changes in the first days are largely ventilatory and fluid-related and are modest. Meaningful increases in oxygen carrying capacity take weeks. If your pace jumps dramatically overnight, look for a flatter route, a harder effort, better conditions, or a different time of day before you credit adaptation.
Why was my pace faster on day three but still slow?
Because effort and output stay dissociated at altitude for some time. On day three I ran at a genuine Zone 2 heart rate on a flat road and was still one minute thirty four seconds per kilometre slower than the slow end of my own easy pace band. The gap narrows over weeks, not days.
What is a good heart rate recovery number?
A larger, faster drop after stopping is generally a favourable sign, and mine was 44 beats over two minutes on day three. Absolute values vary a great deal between individuals, so the useful signal is your own trend over time rather than any single figure. A falling heart rate recovery alongside a rising resting heart rate is worth taking seriously as a sign of accumulated fatigue.
Should I increase training intensity every day at altitude?
No. I went below Zone 1 on day two and Zone 2 on day three, and the next step is more Zone 2, not a harder zone. Building aerobic volume at a controlled heart rate is the work. Adding intensity early at altitude is how people end up losing days.
How do you measure whether altitude training is working?
Fix the variables. Same route, same time of day, same heart rate ceiling, repeated over weeks. If the pace at a fixed heart rate improves while the heart rate stays constant, that is a meaningful signal. Comparing two different routes on two different days measures the route, not your fitness.
- All training figures in this log are taken from the author's own device files recorded on 26 and 27 July 2026: COROS PACE 3 with POD 2 and a chest heart rate monitor. Raw activity screenshots are published alongside these articles.
- Barometric pressure at altitude. At roughly 3,600 m, barometric pressure is approximately 480 mmHg compared with approximately 760 mmHg at sea level, giving roughly 40% fewer oxygen molecules per breath. The fractional concentration of oxygen in air remains approximately 20.9% at all altitudes.
- Levine BD, Stray-Gundersen J. "Living high-training low": effect of moderate-altitude acclimatization with low-altitude training on performance. Journal of Applied Physiology. 1997;83(1):102-112. Randomised controlled trial establishing that haematological adaptation to altitude develops over weeks, and that training quality is degraded while at altitude. PubMed
- Health advisory, District Administration Leh, Union Territory of Ladakh. All arriving tourists must complete at least 48 hours of acclimatisation before travelling to higher altitude areas. leh.nic.in
Niraj Kumar Borah
Founder and head coach of Fitness Bootcamp, a residential health transformation programme running in Rishikesh, Ladakh, Manali, and the north east. Since 2020 he has guided more than 4,600 guests through structured, fully supported transformations.
He has spent four to six months of each year in Ladakh for several years, and has raced the Ladakh Marathon in 2023 and 2024. He is here from July to September 2026, running the routes and testing the acclimatisation protocol our residential group will follow from 16 August, and racing the 11.2 km on 13 September. He publishes his own training data daily, including the sessions that go badly.
- VDOT Certified Distance Running Coach · VDOT O2
- Certified Heart Rate Performance Specialist · NESTA
- Precision Nutrition Level 1 · Precision Nutrition
- Affiliated HYROX Performance Coach · verify on the HYROX register
- Mountaineering, Adventure Course · Jawahar Institute of Mountaineering, J&K
- Ladakh Marathon · 5 km 2023, 11.2 km 2024, racing the 11.2 km on 13 September 2026
- Full background and competition record · read here
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See the programmeThis log is general educational information about the physiology of altitude and training, and is not medical advice. Ascent to high altitude carries real medical risk, including acute mountain sickness and, rarely, high altitude pulmonary or cerebral oedema, which are emergencies. If you have any cardiovascular, respiratory, or haematological condition, are pregnant, or have a history of altitude illness, please speak with your doctor before travelling to altitude. Individual responses vary considerably, and the readings published here are one person's and should not be used as a benchmark for your own. Figures were recorded on 26 and 27 July 2026. If you believe any figure here is inaccurate, please contact us with the source and we will correct it.
