Thinking about an altitude training camp to prepare your next goal, whether it's a trail, a 10K, a half-marathon or a marathon? Good call. But before locking in your dates, two crucial questions arise: how long should you stay for it to actually work? And when should you schedule your camp relative to your target race?
These are the questions every experienced runner asks, and the answers make the difference between a camp that transforms your season and a pleasant week in the mountains with no measurable effect.
Why the duration of an altitude camp changes everything
Altitude triggers a series of progressive physiological adaptations in your body. But these adaptations don't happen overnight. Understanding their timeline means understanding why the duration of your camp is the number one factor in its effectiveness.
The first 72 hours: hypoxic stress
As soon as you arrive at altitude (between 1600m and 2100m for an area like Font-Romeu / Mont-Louis), your body detects the drop in oxygen partial pressure. Your resting heart rate increases, your breathing accelerates, and you may feel unusual fatigue even during moderate efforts.
This is normal. It's even a good sign: your body is reacting to the stimulus. But at this stage, no lasting adaptation has occurred yet. A 3-day camp stops right here, at the stress stage, before the benefits.
Days 4 to 7: the priming phase
From around day 4, your kidneys begin to significantly increase production of erythropoietin (natural EPO). This hormone stimulates red blood cell production, improving oxygen transport to your muscles. The quality of your sessions begins to stabilize despite the altitude.
It's from this phase that the camp starts to make sense for an experienced runner.
Days 10 to 14: the performance plateau
The increase in hemoglobin mass becomes significant and measurable around day 10. Your quality sessions become productive again. This is where most experienced athletes notice a positive shift in sensations: altitude no longer 'holds you back', it 'builds you up'.
Weeks 3 to 4: full potential
Adaptations reach their maximum around 3 weeks for most experienced athletes. Beyond that, marginal gains diminish and the risk of accumulated fatigue increases.
What duration to choose based on your profile and goals?
7 to 10 days: the 'effective minimum' camp
This is the minimum duration to trigger real adaptations. Ideal if:
- You're preparing a 10K, half-marathon, or a 30 to 50 km trail
- You want a VO2max boost before an important competition
- It's your first altitude training camp
What you'll feel: tough sensations for the first 3 days, stabilization mid-camp, and a clear improvement from day 7 onwards.
14 days: the optimal format for experienced runners
This is the recommended duration to maximize the investment/benefit ratio. 2 weeks allow you to go through all adaptation phases, chain productive quality sessions, and return with solid adaptations.
This is the format that most club athletes and high-level amateur runners choose when preparing for an A goal.
21 days: the 'complete preparation' camp
Recommended if you're targeting a marathon, an ultra-trail or any demanding long-distance event. 3 weeks allow you to reach full adaptation potential and integrate a real training load block.
When to go relative to your target race?
The first window (D0 to D3): performing right after descent
As soon as you return to sea level, your hemoglobin levels are at their peak and your ventilation is still calibrated for altitude. Some athletes feel great and can perform well in the first 2-3 days after coming back down.
Heads up: this window is usable but varies between individuals. Travel fatigue and residual camp fatigue can take a toll, and legs may lack sharpness after weeks of training in thin air. If you're targeting this window, plan a low-fatigue return trip and ease off the last days of camp.
The trough (D4 to D12): the zone to avoid
Between these two windows, your body is in full transition. Plasma volume re-expands (temporarily diluting hemoglobin), ventilation normalizes, and the neuromuscular system readapts to sea-level speeds. This is the least favorable period to race.
The second window (D12 to D21): peak fitness
This is the most reliable and well-documented window. Your hemoglobin mass is still elevated, plasma volume has stabilized, neuromuscular coordination is back, and camp fatigue has been absorbed. Everything is aligned.
Concrete example: if your target race is June 15, your ideal last day of camp falls between May 25 and June 3.
Summary: the three phases after descent
| Period | Performance |
|---|---|
| D0 to D3 (1st window) | Good, but variable depending on residual fatigue |
| D4 to D12 (trough) | Suboptimal, body is in transition |
| D12 to D21 (2nd window) | Optimal, all adaptations are aligned |
Why Mont-Louis is an ideal base for planning your camp
The geographic position of Mont-Louis, at the crossroads of Cerdagne, Capcir, and Conflent, makes it the ideal base camp for combining different altitudes during a single camp:
- Acclimatization (D1 to D4): runs around Matemale Lake at 1550m
- Progression (D5 to D9): sessions around Font-Romeu and the CREPS track at 1800m
- Quality sessions (D10+): fartleks and VO2max intervals at La Calme plateau at 2100m
Mistakes to avoid when planning your camp
- Loading too hard in the first days. The temptation to 'make the most of it' from day 1 sabotages the camp.
- Neglecting recovery and sleep. That's where the adaptations are built.
FAQ: your questions about altitude camp duration
Is a camp of less than 7 days useless?
Not useless, but limited. A short 4-5 day stay can have mental and tactical benefits but lasting physiological adaptations don't really kick in.
Do you need to be an elite athlete to benefit from altitude?
No. Experienced amateur athletes benefit from the same adaptation mechanisms as elites, with similar relative gains.
Can you do an altitude camp twice in a season?
Yes, and it's even recommended. You should leave at least 6 to 8 weeks between two camps.
Should you adjust your diet during an altitude camp?
Yes. Energy expenditure increases, and iron and hydration needs are higher. Make sure to increase your carbohydrate and protein intake, and stay well hydrated throughout the day.
Can you race right after an altitude camp?
Yes, it's possible in the first 2-3 days after descent (first window). But reliability varies: travel and camp fatigue can interfere. The safest window remains 12 to 21 days after return.
Ready to plan your camp?
At LA NTV Training Center, we welcome experienced runners year-round in Mont-Louis (1600m), 15 minutes from the Font-Romeu CREPS track.
Book your altitude camp