High-altitude training has a glamorous reputation: elite runners disappear to mountain camps and return fitter than ever. The science behind it is straightforward. At altitude, the air holds less oxygen, so your body produces more red blood cells to carry what oxygen there is. More red blood cells means more oxygen delivered to working muscles when you return to sea level, which can improve endurance performance. The effect is real, but it is also smaller, slower and more complicated than the marketing suggests, and for most amateur runners it is a marginal gain rather than a magic trick.

The most studied approach is live high, train low: sleep and spend most of your day at altitude, but do your hard workouts at lower elevation. The reason is that training quality collapses at altitude. You simply cannot run as fast or as hard with less oxygen, so a runner who does all their training up high often loses fitness from the reduced intensity even while their blood adapts. Living at roughly two thousand to two thousand five hundred metres and coming down for key sessions gets the best of both worlds. That is why altitude camps are built in places with a high town and a low track nearby, not on a single mountain peak.

Timing matters as much as elevation. Red blood cell adaptations take roughly three to four weeks of living at altitude to develop fully, and a weekend trip to the mountains does almost nothing for your blood, however good it feels. The benefits also fade within a few weeks of returning to sea level, so altitude training needs to be timed to peak for a specific race. Arriving at altitude and racing immediately is a bad idea: your body needs several days to acclimatise before it can train properly, and racing in the first forty-eight hours at altitude is when performance is at its worst.

Altitude carries real risks that get less attention than the benefits. Altitude sickness can affect anyone, regardless of fitness, and its symptoms, headache, nausea, poor sleep and dizziness, should never be trained through. Sleep quality often worsens at altitude, which hurts recovery. Appetite drops, which makes it harder to eat enough to support training. And iron is the hidden limiter: your body needs iron to build new red blood cells, so an iron-deficient runner will get little benefit from altitude and may get worse. Get your iron levels checked before any altitude trip, and supplement only under medical guidance.

For most amateur runners, the honest truth is that altitude training is a poor investment of time and money compared with the basics. Consistent training, adequate sleep, good nutrition and a well-structured plan will improve your running far more than a mountain trip. If you live near hills, regular hilly runs give you much of the muscular benefit of altitude work without the cost or the risks. And if you do live at altitude already, train smart: accept that your paces will be slower than at sea level, judge efforts by heart rate or perceived effort rather than pace, and be patient with adaptation.

Altitude training makes sense for competitive runners preparing for a specific goal race, with at least three weeks to spend at moderate altitude, a budget for travel and accommodation, and a coach or plan that accounts for the reduced training intensity. If you are a trail runner who already races at altitude, acclimatisation is also a practical necessity, not a performance hack: arriving a week early for a mountain race can be the difference between finishing strong and walking the second half. For everyone else, it is an interesting experiment for later, after the fundamentals are already in place. Fitness is built at home, on the trails you run every week, not in a single dramatic trip to the mountains.