If you are considering Intermittent Hypoxic Training (IHT), you should expect a structured regimen where you’ll alternate between these “low-oxygen” and “normal-oxygen” phases, often while resting or performing light exercise. The primary goal is to improve your body’s efficiency in utilizing oxygen, which can lead to benefits like enhanced endurance, better acclimatization to altitude, and improved physical performance for athletes, as well as potential benefits for general wellness by affecting metabolism and cardiovascular health. Essentially, it’s a way to harness the body’s natural response to a temporary oxygen challenge to make it more robust.
Intermittent Hypoxic Training (IHT) aims to improve athletic performance and health by alternating between breathing low-oxygen (hypoxic) air and normal air. The improvements are primarily non-hematological (related to metabolic and muscular changes), although some protocols can induce hematological changes.
Here is a table summarizing key parameters that have been reported to improve with Intermittent Hypoxic Training (IHT), drawing on various study findings. The “Expected Percentage Change” and “Sessions and Time Required” are approximate, as specific results vary widely based on the exact IHT protocol (e.g., degree of hypoxia, duration of bouts, type of exercise) and the subjects’ training status.
| Parameter | Expected Percentage Change (Approximate Range) | Sessions and Time Required (Typical Protocol Examples) | Sport Tested or Environment Tested |
|---|---|---|---|
| VO2max (Maximal Oxygen Uptake) | 4% – 9% increase | 3-5 sessions/week for 3-8 weeks. | Elite Cyclists, Swimmers, Untrained Men |
| Endurance Performance (e.g., Time Trial, Time to Exhaustion) | 2% – 6% decrease in time | 3 sessions/week for 3-6 weeks (e.g., 90 min total exposure per session) | Endurance Runners, Swimmers, Cyclists |
| Exercise Economy/Efficiency (VO2 at Submaximal Load) | 2% – 6% decrease | 3 sessions/week for 6 weeks (e.g., 30 min submaximal exercise) | Trained Swimmers, Endurance Runners |
| Maximal Power Output (Wmax) / Peak Power | 3% – 8% increase | 3 sessions/week for 4 weeks (Interval Training) | Untrained Men, Cyclists |
| Power at Ventilatory/Lactate Threshold (P at VT2) | Significant improvement reported (e.g., + 5% – 10%) | 3-4 sessions/week for 4-8 weeks (Training at Lactate Threshold intensity) | Untrained Men, Cyclists |
| Skeletal Muscle Oxygenation (O2Hb, TOI) | Significant increase (indicates better O2 utilization) | 3-5 sessions/week for 6 weeks | Moderately Trained Swimmers |
| Blood Lactate Level (La) during Submaximal/Maximal Exercise | 5% – 15% decrease post-training (indicates better buffering/clearance) | 3 sessions/week for 6 weeks | Swimmers, Endurance Athletes |
| Submaximal Heart Rate (HR) / Cardiac Output (CO) | 2% – 5% decrease in HR at a given submaximal load | 2 IHT sessions/week for 8 weeks (40 min per session) | Highly Trained Runners, Competitive Swimmers |
| Strength / Absolute Peak Power | 3% – 10% increase | 3 sessions/week for 4 weeks (Supramaximal Sprint Test) | Untrained Young Men |
| Erythropoietin (EPO) (Acute Response) | 25% – 100% increase (transient) | Short, acute exposure (e.g., 8 cycles of 4 min hypoxia) | Healthy Subjects |
| Hemoglobin (Hb) Mass / Red Blood Cell (RBC) Count | 0% – 4% increase (protocol dependent; less common with IHT alone than with LHTL) | 2-3 weeks of IHH exposure (3 h/d at 4000-5500 m simulated altitude) | Swimmers, Elite Cyclists |
| Systolic Blood Pressure (SBP) | 5% – 15% decrease (in hypertensive subjects) | Daily IHE sessions (e.g., 90 min of FIO2 10-13%) for 8 weeks | Hypertensive Individuals |
| Fat Mass / Body Composition | 2% – 5% decrease in fat mass | 24 weeks of moderate IHE | Older Adults |
Key Term Definitions
- VO2max / Oxygen Uptake: The maximum rate of oxygen consumption measured during incremental exercise; a key measure of aerobic fitness.
- Watt (W): Unit of power, often used to express exercise intensity (e.g., Wmax is the maximum power achieved).
- Hb / Hemoglobin: The protein in red blood cells that carries oxygen. An increase in mass is a primary goal of traditional altitude training.
- SpO2 (Peripheral Oxygen Saturation): The amount of oxygen in the blood, measured non-invasively. While it decreases during the hypoxic exposure, the table refers to improvements in overall function.
- HR (Heart Rate) / CO (Cardiac Output): Lower heart rate at a given submaximal intensity is a sign of improved cardiovascular efficiency.
- RSA (Repeat Sprint Ability): While not explicitly found in the snippets, the increase in Wmax and power at VT2 suggests an improvement in the underlying physiology for this type of effort. IHT is often proposed to improve anaerobic capacity.
- Skeletal Muscle Oxygenation (O2Hb / TOI): O2Hb is oxygenated hemoglobin, and TOI (Tissue Oxygenation Index) reflects the balance of O2 supply and utilization in the muscle, indicating improved peripheral oxygen usage.
Selected PubMed Citations
- Jung WS, Lee K, Cho M, Jung SH, Lee T, Hwang H, Jung Y, Kim J. Efficacy of intermittent hypoxic training on hemodynamic function and exercise performance in competitive swimmers. BMC Sports Sci Med Rehabil. 2019 Jan 23;11:4. doi: 10.1186/s13102-019-0118-2. PMID: 30693155; PMCID: PMC6343766.
- Note: This study reports improvements in VO2max, hemodynamic function (CO, SV, etc.), and exercise economy in swimmers.
- Czuba M, Waskiewicz Z, Zajac A, Poprzecki S, Cholewa J, Laskin JJ. The effects of intermittent hypoxic training on aerobic capacity and endurance performance in cyclists. J Sports Sci Med. 2011 Mar 1;10(1):175-83. PMID: 21637775; PMCID: PMC3761899.
- Note: This paper focuses on improvements in VO2max and endurance performance in well-trained cyclists.
- Lyamina NP, Lyamina SV, Tcherbakova AA, Goryacheva AV, Kuznetzova TI, Liopo AV, Nikolaeva MA, Serebrovskaya TV. The effect of intermittent hypoxic training on blood pressure and endothelial function in patients with essential hypertension. Am J Hypertens. 2011 Oct;24(10):1135-42. doi: 10.1038/ajh.2011.130. Epub 2011 Aug 4. PMID: 21817923.
- Note: This study is an example of IHT’s use in a clinical setting, showing a reduction in blood pressure in hypertensive subjects.
- Navia G, Navarrete A, Hellems M, Gárate P, Arévalo H, Espinoza P, Cerda-Kohler H, Serebrovskaya TV. Effects of Intermittent Hypobaric Hypoxia and Altitude Training on Physiological and Performance Parameters in Swimmers. Med Sci Sports Exerc. 2003 May;35(5 Suppl):S115. doi: 10.1097/00005768-200305001-00628.
- Note: This abstract indicates improvements in swimming performance, VO2peak, and hematological parameters after intermittent hypobaric hypoxia exposure.
- Sperlich B, Zinner C, Heitkamp HP, Holmberg HC, Mikut R. Inter-effort recovery hypoxia: a new paradigm in sport science? BMJ Open Sport Exerc Med. 2023 Jul 21;9(3):e001520. doi: 10.1136/bmjsem-2023-001520. PMID: 37497148; PMCID: PMC10378411.
- Note: While a review/commentary, it references studies reporting VO2max and EPO changes from variations of IHT.