For endurance athletes, small improvements can produce big differences.

A 1–4% change in performance may only represent seconds over a short event, but across a marathon, long-distance cycling event or Ironman, that improvement can potentially translate into minutes.

Altitude training has been used by elite endurance athletes for decades. But one of the most common questions we hear is:

What could altitude actually mean for my performance?

That is why we created the Box Altitude Performance Calculator.

Instead of simply explaining the physiology behind altitude, the calculator allows you to enter your own sport, current performance and planned altitude exposure and receive a personalised performance scenario.

Why athletes use altitude

When oxygen availability is reduced at altitude, the body begins adapting to the environment.

One of the most studied adaptations is increased erythropoietic activity — the process involved in producing red blood cells.

Haemoglobin inside red blood cells transports oxygen around the body. Increasing total haemoglobin mass can therefore increase the body's capacity to transport oxygen during endurance exercise.

This is one of the physiological principles behind the Live High, Train Low approach.

Rather than performing every training session at altitude, athletes can accumulate altitude exposure during the hours they are sleeping and recovering, while continuing to complete key training sessions closer to sea level where power, pace and training quality can be maintained.

How much altitude exposure matters?

Altitude is not simply an on/off stimulus.

The total dose of altitude exposure matters.

Research examining altitude training has estimated an average increase in haemoglobin mass of approximately 1.1% for every 100 hours of altitude exposure across traditional altitude and Live High, Train Low protocols.

Other research involving trained cyclists found that approximately three weeks of simulated altitude exposure at 3,000 metres for around 14 hours per day increased haemoglobin mass by approximately 3.3%.

Studies using nightly simulated altitude have also demonstrated increases in haemoglobin mass after athletes accumulated substantial exposure while sleeping.

This is why thinking in terms of total altitude hours, rather than simply the number of nights, can be useful.

For example:

100 hours of exposure may represent an introductory altitude block.

200–300 hours represents a considerably larger physiological stimulus.

400 hours represents a substantial accumulated altitude dose.

Individual responses, however, vary significantly.

What determines your response to altitude?

Two athletes completing exactly the same altitude protocol will not necessarily achieve exactly the same response.

Factors can include previous altitude exposure, iron availability, training status, genetics, altitude dose, recovery and the altitude used.

Iron status is particularly important because iron is required for red blood cell and haemoglobin production.

This is one reason the Box Altitude Performance Calculator asks about both your altitude history and iron status rather than simply applying one number to every athlete.

Turning physiology into performance

An increase in haemoglobin mass does not automatically translate into an identical percentage improvement in race performance.

Performance is influenced by many variables, including:

training quality, aerobic capacity, economy or efficiency, nutrition, heat, pacing, recovery, course profile and an athlete's individual physiological response.

For this reason, the Box Altitude Performance Calculator provides a scenario range rather than promising a specific result.

It models three possibilities:

Conservative response

A lower-end scenario representing a relatively modest response to the altitude exposure.

Expected response

A central estimate based on the exposure and information entered into the calculator.

High responder

A higher-end scenario demonstrating what the result could potentially look like in an athlete who responds particularly well.

These figures are designed to make altitude exposure easier to understand — not to guarantee a race result.

What could altitude mean for your race time?

This is where percentages become much more interesting.

Imagine two athletes both improve by the same percentage.

For a 20-minute cycling time trial, that improvement might represent seconds.

For a three-hour marathon, it could represent several minutes.

Across a nine, ten or twelve-hour Ironman, relatively small percentage changes can potentially translate into considerably larger differences in finishing time.

Our calculator translates the scenario into something much easier to understand:

your potential time saved and projected performance time.

For triathletes, it can also break the calculation down across:

Swim

Bike

Run

and then combine the disciplines into an estimated overall finishing time.

Why sleeping at altitude is different

Traditional altitude camps can be extremely effective, but they require athletes to travel to altitude for extended periods.

Simulated altitude makes it possible to create a hypoxic sleeping environment at home.

An athlete can therefore accumulate eight, ten or more hours of altitude exposure overnight without adding another training session to the day.

Over several weeks, those hours accumulate quickly.

Eight hours per night for 25 nights is already 200 hours of exposure.

Ten hours per night for 30 nights produces 300 hours.

This ability to accumulate a substantial altitude dose while continuing normal training is one of the major reasons simulated altitude is used by endurance athletes and high-performance programmes.

Calculate your own altitude performance scenario

Rather than looking at someone else's altitude programme, you can now model your own.

The Box Altitude Performance Calculator allows you to select:

• Running, cycling, swimming or triathlon

• Your event or race distance

• Your current performance time

• Your planned altitude exposure

• Your previous altitude experience

• Your iron status

For triathlon, enter your individual swim, bike and run times and the calculator can model each discipline as well as your overall race.

You will then receive your personalised performance scenario directly by email.

 

A tool for planning — not a performance guarantee

Altitude adaptation is highly individual.

The calculator is therefore designed as a planning and education tool rather than a prediction of exactly what will happen to an individual athlete.

Its purpose is to help answer a more useful question:

If I accumulate a meaningful altitude dose and respond to it, what could that improvement potentially mean for my actual performance?

That gives athletes a much more tangible way to think about altitude than simply looking at changes in haemoglobin mass or VO₂max.

If you would like help determining an appropriate altitude sleeping system or altitude exposure strategy, the Box Altitude team can also help you determine the most appropriate setup for your training environment.

 

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References

Gore CJ, Sharpe K, Garvican-Lewis LA, et al. Altitude training and haemoglobin mass from the optimised carbon monoxide rebreathing method determined by a meta-analysis. British Journal of Sports Medicine.

Clark SA, Quod MJ, Clark MA, Martin DT, Saunders PU, Gore CJ. Time course of haemoglobin mass during 21 days live high:train low simulated altitude. European Journal of Applied Physiology.

Levine BD, Stray-Gundersen J. Dose-response of altitude training: how much altitude is enough?