Altitude is a sneaky performance tax. At sea level, you can muscle through a bad pacing decision. At altitude, the bill comes due faster: higher breathing rates at lower workloads, higher perceived effort, disrupted sleep, and a real hit to repeatability within a day or across multiple days. Team sport data is a useful proxy for competitive fitness because both involve repeated high-intensity bouts and short recovery windows, and those repeated efforts are specifically vulnerable when oxygen saturation drops.

Below are three practical altitude scenarios that matter most for competitive fitness athletes:

1. preparing to compete at altitude

2. using altitude style training (hypercapnic plus hypoxic style exposure) to boost form heading into a major competition

3. using isocapnic protocols to support recovery while at altitude

Competing at altitude: what changes, and what to do about it

What altitude does to performance

At higher altitudes, there is less oxygen available, causing oxygen saturation to decrease in the blood vessels. That reduction in available oxygen increases strain at a given power output. The result is usually not a single catastrophic failure, but rather a series of small failures: less repeat-sprint capacity, slower recovery between efforts, and higher mental load to hold pace.

The best case plan: arrive early enough to adapt

If you can control logistics, the boring answer is still the best: arrive early and let your body acclimatize to the higher elevation.

• For endurance athletes, many best-practice recommendations suggest about 14 days for meaningful acclimatization before competition.

• For athletes training or competing at moderate altitude, guidance suggests reducing training volume up to ~50% and minimizing high-intensity work in the first 3 to 7 days, then gradually reintroducing intensity as acclimatization improves. It is possible to match your sea level performances at elevations of 2000 to 3000 meters, if you acclimatize for 10 to 14 days.

Competitive fitness translation: if you arrive early, the first week is not the time to prove toughness. It is the time to protect quality, manage intensity, and build confidence that your breathing, sleep, and pacing are settling.

If you cannot arrive early: you still have options

Many athletes land 12 to 36 hours before competition. In that case, you are choosing between imperfect strategies. A classic review notes two commonly used approaches: arrive as soon as logistically possible to get some acclimatization time, or arrive as close as possible to start time to reduce some acute negatives like sleep disruption. 

Competitive fitness translation: because competitions often span multiple days, arriving a touch earlier can still help you stabilize sleep and breathing before day one. If you truly must arrive late, you need a very deliberate pacing and recovery plan from the first event onward.

Using altitude style training to boost form before a major competition

Two distinct goals are often confused:

1. Pre-acclimatization: aims to reduce the shock of competing at altitude.

2. Performance boost at sea level: uses reduced-oxygen training to drive adaptations that carry over to competition. 

The evidence is more consistent for the first goal than the second, and there is still a lot of variance in how different individuals respond to either goal.

Pre-acclimatization at sea level

One of the papers by Chapman, cited at the end of the document, discusses a training strategy that can be done at low elevations. This is called intermittent hypoxic training, which means for some training sessions, the amount of available oxygen is reduced using special equipment. This can improve performance when they do compete at higher elevations, even when the athlete’s performance changes are less clear at lower elevations. 

Competitive fitness translation: if your event is at altitude and you cannot arrive early, pre-acclimatization blocks are one of the few levers you can pull ahead of time. This means finding a way to train with less available oxygen.

Hypercapnic-hypoxic training research signals

An 8-week study in Croatian elite swimmers reported a 5.35% increase in hemoglobin and a 10.79% improvement in VO2max. This was a combination of hypercapnic and hypoxic training. Hypoxic training means training with less available oxygen. Hypercapnic training is where you intentionally increase CO₂ levels in the blood by limiting breathing or using special devices.

Competitive fitness translation: improved oxygen transport and utilization can matter for repeated mixed modality efforts, especially across a multi-event weekend. The caveat is that protocols, athlete response, and transfer to sport-specific performance vary. Treat it as a targeted tool, not a guaranteed upgrade.

How to position this in a competitive season

A practical approach mirrors what high-level teams do with other environmental stressors:

• Use a training block far enough out to test response and refine dosing.

• Follow with a short refresher closer to competition if you are competing at altitude, similar to how heat acclimation is often maintained. 

• Track the athlete, not the theory: sleep quality, morning heart rate, perceived breathlessness, and session repeatability are often the earliest useful signals.