What Is Altitude Therapy? Simulated Altitude & IHHT Explained

Altitude therapy uses short, controlled exposure to lower-oxygen air — the kind you would breathe in the mountains — to prompt the body to adapt. Once limited to athletes who could travel to high-altitude camps, it is now available at sea level through simulated altitude and IHHT (intermittent hypoxic-hyperoxic training). Here is where it came from, how it works, who uses it and how to do it safely.

By Randall Chesnutt, O₂ Pro Academy · Last updated

A short history of altitude training

Interest in altitude took off around the 1968 Mexico City Olympics, held at about 2,240 meters (7,350 feet). Endurance results there were slower than expected, while athletes who lived at altitude performed strongly. Coaches and scientists began asking whether living or training in thin air could give an edge.

Over the following decades, research showed that time at altitude can raise red blood cell mass and change how muscles and the breathing system handle oxygen — but also that training hard at altitude is difficult, because athletes cannot reach the same intensity in thin air.

Live high, train low

A landmark study by Levine and Stray-Gundersen (1997) tested a practical answer: live at moderate altitude to gain the adaptations, but travel down to train at normal intensity. Runners who “lived high, trained low” improved their 5,000-meter times more than those who lived and trained at sea level or lived and trained high.

That model is still widely used by elite endurance athletes. Its limitation is obvious: most people cannot move to the mountains for weeks at a time. That is what led to simulated altitude.

Simulated altitude

Simulated altitude lowers the percentage of oxygen in the air instead of lowering the air pressure. This is called normobaric hypoxia. It can be delivered through altitude tents and rooms for sleeping, through masks connected to a hypoxicator, or through chambers used in sports-science labs.

Researchers continue to debate how closely normobaric hypoxia matches real altitude, but it gives a controllable, repeatable dose — which is exactly what practitioners need.

Intermittent hypoxia: small doses, repeated

Intermittent hypoxia means alternating short periods of lower-oxygen air with periods of normal or higher-oxygen air, rather than one long exposure. A widely cited review by Navarrete-Opazo and Mitchell (2014) described its effects as “a matter of dose”: modest, short, repeated exposures were associated with beneficial adaptations in many studies, while severe or prolonged exposures — like those seen in untreated sleep apnea — are associated with harm.

That is why professional altitude therapy is built on careful dosing and monitoring, not on how low the oxygen can go.

What is IHHT?

IHHT, or intermittent hypoxic-hyperoxic training, is a refinement of intermittent hypoxia. Instead of recovering on room air between low-oxygen intervals, the client recovers on higher-oxygen air. The goal is a comfortable session and faster recovery between cycles.

During IHHT the client sits or reclines with a mask on while a system alternates the air every few minutes. A finger pulse oximeter tracks blood-oxygen saturation (SpO₂) and heart rate, and many systems adapt the cycle length to the client's response. Early studies, such as a randomized trial in older adults by Bayer and colleagues (2017), have reported improvements in exercise tolerance and some cognitive measures. The research is promising but still limited, with mostly small study groups.

Start with the Certified Oxygen Performance Specialist™ (COPS™) — $197, self-paced, lifetime certification. Start with COPS™ →

Altitude therapy vs other oxygen services

Altitude therapy is often confused with other oxygen-based services. Hyperbaric oxygen therapy (HBOT) does the opposite: it raises air pressure so the body absorbs more oxygen. Exercise with oxygen therapy (EWOT) adds extra oxygen during a workout. Altitude therapy briefly reduces oxygen to create a controlled challenge, then allows recovery.

Each has its place, and some practices offer more than one. The key is matching the service to the client's goal and health status, and explaining clearly what each can and cannot do. Our IHHT vs HBOT guide compares the two most common options side by side, and our EWOT guide covers exercise with oxygen.

Who uses altitude therapy?

Altitude therapy is now used in a wide range of settings:

What a session looks like

A typical IHHT session takes 30–45 minutes. The practitioner reviews the client's screening form, places a pulse oximeter on a finger and fits the mask. Some systems start with a short test to see how the client responds to lower oxygen. The session then alternates low- and high-oxygen phases, usually a few minutes each. Clients often read, listen to music or rest.

Most programs run as a series — for example two to three sessions a week for several weeks — and track simple measures such as resting heart rate, how quickly SpO₂ recovers and the client's BOLT Score.

Safety

Altitude therapy is generally well tolerated when clients are screened and sessions are monitored, but it is not for everyone.

How practitioners get certified

There is no government license specifically for altitude therapy, which makes training and standards even more important. O₂ Pro Academy's Certified Altitude Therapist™ (CAT™) program covers hypoxia physiology, screening and contraindications, session protocols, monitoring, client programming and running the service in a practice. It is a private professional training credential, not a license.

Most practitioners start with the Certified Oxygen Performance Specialist™ (COPS™), which builds the foundation in oxygen science, breathing, the BOLT Score and client assessment, then specialize with CAT™. To see how altitude therapy compares with hyperbaric oxygen, read our IHHT vs HBOT guide.

This is educational, not medical advice. Oxygen and altitude-based services are not a substitute for diagnosis or treatment by a licensed clinician. Anyone with a heart, lung, blood, neurological or other serious medical condition, or who is pregnant, should get clinician guidance first.

Frequently Asked Questions

Is altitude therapy the same as IHHT?

IHHT is one form of altitude therapy. “Altitude therapy” is a broad term for using lower-oxygen air to prompt adaptation; IHHT alternates low-oxygen and higher-oxygen phases through a mask at normal pressure.

Does simulated altitude work like real altitude?

Partly. Simulated (normobaric) altitude lowers the oxygen percentage rather than the air pressure. Many responses are similar, but researchers still debate how closely it matches real altitude.

How long is an altitude therapy session?

A typical IHHT session lasts about 30–45 minutes, usually as part of a series of sessions over several weeks.

Who should not do altitude therapy?

People who are pregnant or who have significant heart or lung disease, uncontrolled high blood pressure, recent stroke, epilepsy, severe anemia or an acute illness should not do it without clinician clearance.

How do I become an altitude therapist?

There is no government license for altitude therapy. O₂ Pro Academy offers the Certified Altitude Therapist™ (CAT™), a private professional training credential. Most people start with the Certified Oxygen Performance Specialist™ (COPS™) foundation course.

O₂ Pro Academy credentials (COPS™, CAT™, CHT™, CBS™, CVS™) are private professional training credentials issued by O₂ Pro Academy (Spoken About Media, LLC). They are not government licenses and do not expand anyone's legal scope of practice.

Start with COPS™ — $197 · Certified Altitude Therapist™ (CAT™)