For decades, elite endurance athletes have sought an edge by training in the thin air of mountainous regions. The allure of altitude training lies in its promise to stimulate physiological adaptations that enhance oxygen delivery and utilization, thereby improving performance upon returning to sea level. For triathletes, whose sport demands sustained aerobic power across three disciplines, optimizing oxygen dynamics is paramount. While the concept is simple – exposing the body to a reduced oxygen environment (hypoxia) – the specific strategies for implementing altitude training are varied, each with its own theoretical basis, practical considerations, and scientific support. Understanding the different models of altitude training and the research evaluating their effectiveness is crucial for triathletes considering this powerful, albeit complex, training modality. This article will explore the physiological responses to altitude, detail the primary altitude training strategies – Live High, Train High; Live High, Train Low; and Intermittent Hypoxic Training – discuss the scientific evidence for each, and examine the practical implications for triathletes.
When an athlete ascends to altitude, the reduced barometric pressure means there are fewer oxygen molecules per breath, creating a state of hypoxia. The body initiates a cascade of physiological responses to cope with this oxygen deprivation¹. Acutely, ventilation (breathing rate) increases, and heart rate rises to deliver more oxygenated blood to the tissues². Over days and weeks, chronic adaptations occur, a process known as acclimatization. A key adaptation is the increased production of the hormone erythropoietin (EPO) by the kidneys, which stimulates the bone marrow to produce more red blood cells³. This increase in red blood cell mass and hemoglobin concentration enhances the blood’s capacity to transport oxygen from the lungs to the working muscles⁴. Other chronic adaptations include increased capillarization (growth of new small blood vessels) in the muscles, improving oxygen diffusion; changes in muscle enzyme activity to enhance more efficient oxygen utilization; improved buffering capacity to tolerate metabolic byproducts; and adjustments in ventilation and cardiac output regulation⁵. These adaptations collectively improve the body’s ability to function with less oxygen, theoretically translating to enhanced performance when oxygen is readily available at sea level.
One of the earliest and most straightforward altitude training strategies is Live High, Train High (LHTH). In this model, athletes reside and conduct the majority of their training at moderate to high altitudes, typically between 2000 and 3000 meters (approximately 6,500 to 10,000 feet)⁶. The theoretical benefit of LHTH is maximizing the exposure to hypoxia, thereby stimulating significant EPO production and driving the chronic physiological adaptations mentioned earlier⁷. The continuous hypoxic stimulus is intended to lead to a robust increase in red blood cell mass, providing a substantial boost to oxygen-carrying capacity upon return to sea level.
However, the primary practical challenge and potential limitation of LHTH is the inability to perform high-intensity training at the same absolute speeds or power outputs as at sea level due to the reduced oxygen availability⁸. While the athlete’s relative effort might be very high, the absolute workload achieved is lower. This can potentially limit the stimulus for adaptations crucial for high-end performance, such as improvements in neuromuscular function, anaerobic capacity, and the ability to tolerate and clear lactate at high speeds⁹. Research on LHTH has shown that it can lead to improvements in VO2max and sea-level endurance performance¹⁰, but some studies have highlighted that the reduced training intensity at altitude might compromise specific race pace preparation, particularly for events requiring sustained high power output or speed¹¹. Logistical difficulties and the increased recovery demands associated with living and training in hypoxia are also practical considerations.
The strategy that has garnered the most significant scientific support and is often considered the gold standard for endurance athletes is Live High, Train Low (LHTL). This approach, popularized by the research of Dr. Benjamin Levine and colleagues, involves athletes living at moderate altitude (typically 2000-2500 meters) to stimulate the beneficial hematological adaptations (increased red blood cells), but descending to lower altitudes (below 1000-1200 meters) for their key high-intensity training sessions¹². The theoretical advantage is gaining the systemic benefits of chronic hypoxic exposure (living high) while maintaining the ability to train at high absolute intensities in a normoxic or near-normoxic environment (training low)¹³. This allows athletes to maximize both central adaptations (oxygen transport capacity) from living at altitude and peripheral adaptations (muscle efficiency, power output, speed) from training at intensities relevant to sea-level competition¹⁴.
The body of research on LHTL is extensive and generally demonstrates its effectiveness in improving endurance performance in well-trained athletes¹⁵. Studies have shown significant increases in red blood cell mass, VO2max, running economy, and time trial performance upon returning to sea level after an LHTL intervention¹⁶⁻¹⁷. The ability to combine the physiological drive for increased red blood cells from living in hypoxia with the high-quality training stimulus at lower altitudes appears to be a highly effective combination for many athletes. However, individual responses to LHTL can vary, with some athletes showing a strong “responder” profile while others may be “non-responders” with minimal hematological or performance benefits¹⁸. The reasons for this variability are not fully understood but likely involve genetic factors and individual physiological characteristics.
A third altitude strategy is Intermittent Hypoxic Training (IHT). This involves repeated, short exposures to hypoxia, typically for periods ranging from minutes to a few hours, interspersed with periods spent in normoxia (normal oxygen levels)¹⁹. IHT can be performed by breathing hypoxic air through a mask while at rest (“intermittent hypoxia exposure” or IHE) or by exercising in a hypoxic environment (“intermittent hypoxic training” or IHT)²⁰. The hypoxic environment can be created using altitude tents, hypoxic rooms, or hypobaric chambers that simulate the atmospheric pressure of altitude.
The theoretical benefits of IHT are less consistently linked to significant increases in red blood cell mass, particularly with shorter daily exposures²¹. Instead, IHT is thought to potentially induce peripheral adaptations, such as improved muscle oxygen utilization efficiency, increased capillarization (though research findings are mixed), enhanced buffering capacity, and potentially improvements in ventilatory responses to exercise²². Research evaluating the effectiveness of IHT has yielded more variable results compared to LHTL²³. While some studies in specific populations or using certain protocols have shown improvements in performance markers²⁴, others have found limited or no significant benefits, particularly in highly trained endurance athletes²⁵. The optimal duration, frequency, and intensity of hypoxic exposure for IHT remain areas of ongoing research, and its effectiveness may be more protocol-dependent and individually variable than LHTL.
For triathletes considering altitude training, several practical considerations are important. Firstly, altitude camps or the use of hypoxic simulation equipment represent a significant logistical and financial investment²⁶. Athletes must be able to take time away from work and family and bear the costs associated with travel, accommodation, or equipment rental. Secondly, recognizing the potential for individual variability in response is crucial²⁷. Not every athlete will benefit equally, and careful monitoring of physiological markers (e.g., hematocrit, hemoglobin) and performance upon return to sea level is necessary to assess effectiveness.
Health considerations are also paramount. Athletes should undergo a medical screening before undertaking altitude training to identify any underlying health issues that could be exacerbated by hypoxia²⁸. Proper acclimatization upon arrival at altitude is essential to minimize the risk of acute mountain sickness, which can severely disrupt training and well-being²⁹. Altitude can also disrupt sleep patterns and potentially suppress immune function, increasing susceptibility to illness³⁰.
The timing of an altitude training intervention in relation to a key race is critical³¹. The typical recommendation is to complete the altitude exposure approximately 2-4 weeks before the target competition. This timeframe allows for the full benefits of acclimatization (including red blood cell production) to be realized upon returning to sea level while providing sufficient time for the body to re-acclimatize to normoxia and for any accumulated fatigue from the altitude block to dissipate, ensuring the athlete is fresh and ready to perform³².
Finally, integrating altitude training with the concurrent demands of triathlon presents unique challenges. Maintaining training quality across swimming, cycling, and running can be difficult, particularly at altitude where absolute power and speed are reduced. Coaches must carefully plan the training load and intensity distribution across all three disciplines during an altitude block to ensure that the athlete receives the necessary stimulus without becoming overly fatigued or compromising technical skills.
In conclusion, altitude training, through its induction of physiological adaptations to hypoxia, offers a scientifically supported method for enhancing endurance performance. The Live High, Train Low strategy currently possesses the strongest research evidence for improving parameters like red blood cell mass and VO2max, making it a favored approach among elite endurance athletes. While Live High, Train High and Intermittent Hypoxic Training have also been explored, their effectiveness appears more variable depending on the specific protocol and individual response. For triathletes, undertaking altitude training is a significant commitment requiring careful consideration of logistics, cost, individual variability, and health. When properly planned, timed, and integrated into a comprehensive training program for suitable athletes, altitude training can be a powerful tool to leverage the body’s adaptive capacity and contribute to achieving peak performance in the demanding sport of triathlon.
¹ West, J. B. (2000). Physiological effects of chronic hypoxia. New England Journal of Medicine, 343(26), 1976-1980.
² Wehrlin, J. P., Zuest, P., Hallén, J., & Marti, B. (2006). Live high—train low altitude training improves sea-level performance in male and female elite runners. European Journal of Applied Physiology, 96(5), 483-492.
³ Gale, W. F., Maxwell, P. H., Allen, T. D., & Ratcliffe, P. J. (1995). Renal oxygen sensing and the regulation of erythropoietin production. Clinical Science, 89(6), 557-567.
⁴ Levine, B. D., & Stray-Gundersen, J. (1997). ” Living high-training low”: effect of moderate altitude acclimatization with low-altitude training on performance.1 Journal of Applied Physiology, 83(1), 102-112.2
⁵ West, J. B. (2000). Physiological effects of chronic hypoxia. New England Journal of Medicine, 343(26), 1976-1980.
⁶ Levine, B. D., & Stray-Gundersen, J. (1997). ” Living high-training low”: effect of moderate altitude acclimatization with low-altitude training on performance.3 Journal of Applied Physiology, 83(1), 102-112.4
⁷ Wilber, R. L. (2001). Altitude training and athletic performance. Human Kinetics.
⁸ Bassett Jr, D. R., & Howley, E. T. (2000). Limiting factors for maximum oxygen uptake and determinants of endurance performance. Medicine & Science in Sports & Exercise,5 32(1), 70-84.
⁹ Levine, B. D., & Stray-Gundersen, J. (2001). Living high—training low: effect of altitude training on performance. Journal of Applied Physiology, 91(1), 24-34.
¹⁰ Wehrlin, J. P., Zuest, P., Hallén, J., & Marti, B. (2006). Live high—train low altitude training improves sea-level performance in male and female elite runners. European Journal of Applied Physiology, 96(5), 483-492.
¹¹ Levine, B. D. (2008). Point: positive effects of intermittent hypoxia training on exercise performance. Journal of Applied Physiology, 105(3), 733-735.
¹² Levine, B. D., & Stray-Gundersen, J. (1997). ” Living high-training low”: effect of moderate altitude acclimatization with low-altitude training on performance.6 Journal of Applied Physiology, 83(1), 102-112.7
¹³ Millet, G. P., Faiss, R., & Brocherie, F. (2016). Effects of “living high, training low” in athletes: a narrative review. British Journal of Sports Medicine, 50(20), 1289-1295.
¹⁴ Levine, B. D., & Stray-Gundersen, J. (2001). Living high—training low: effect of altitude training on performance. Journal of Applied Physiology, 91(1), 24-34.
¹⁵ Saunders, P. U., Pyne, D. B., Telford, R. D., & Hawley, J. A. (2004). Factors affecting running economy in trained distance runners. Sports Medicine, 34(7), 465-485.8
¹⁶ Wehrlin, J. P., Zuest, P., Hallén, J., & Marti, B. (2006). Live high—train low altitude training improves sea-level performance in male and female elite runners. European Journal of Applied Physiology, 96(5), 483-492.
¹⁷ Levine, B. D., & Stray-Gundersen, J. (1997). ” Living high-training low”: effect of moderate altitude acclimatization with low-altitude training on performance.9 Journal of Applied Physiology, 83(1), 102-112.10
¹⁸ Chapman, R. F., Wilkerson, D. P., Billaut, F., Kirby, R. F., Layden, J. D., Rice, J., & Levine, B. D. (2013). Intermittent-hypoxia training improves 10-km running performance more than intermittent-hypoxia exposure. Medicine & Science in Sports & Exercise, 45(7), 1313-1321.
¹⁹ Millet, G. P., Roels, B., Schmitt, L., Woorons, X., & Richalet, J. P. (2010). Altitude training—scientific evidence and practical initiatives. Scandinavian Journal of Medicine & Science in Sports, 20(Suppl 2), 1-13.
²⁰ Faiss, R., Girard, O., & Millet, G. P. (2013). Effects of different modalities of hypoxic training on endurance performance. Scandinavian Journal of Medicine & Science in Sports, 23(5), e255-e262.
²¹ Gore, C. J., Clark, S. A., & Withers, R. T. (2007). Altitude training and sporting performance. Sports Medicine, 37(8), 659-662.
²² Millet, G. P., Roels, B., Schmitt, L., Woorons, X., & Richalet, J. P. (2010). Altitude training—scientific evidence and practical initiatives. Scandinavian Journal of Medicine & Science in Sports, 20(Suppl 2), 1-13.
²³ Eastwood, A., Driller, M., Woorons, X., & Girard, O. (2019). The effects of intermittent hypoxic training on cycling performance: A systematic review and meta-analysis. Frontiers in Physiology, 10, 802.
²⁴ Billaut, F., Gore, C. J., Logan, A., Slater, G., Corney, C., Scanlan, A. T., … & Aughey, R. J. (2013). V̇o2peak and time-trial performance are not improved after living and training at 2087 m. Medicine & Science in Sports & Exercise, 45(9), 1724-1734.
²⁵ Gore, C. J., Clark, S. A., & Withers, R. T. (2007). Altitude training and sporting performance. Sports Medicine, 37(8), 659-662.
²⁶ Wilber, R. L. (2001). Altitude training and athletic performance. Human Kinetics.
²⁷ Chapman, R. F., Wilkerson, D. P., Billaut, F., Kirby, R. F., Layden, J. D., Rice, J., & Levine, B. D. (2013). Intermittent-hypoxia training improves 10-km running performance more than intermittent-hypoxia exposure. Medicine & Science in Sports & Exercise, 45(7), 1313-1321.
²⁸ Bartsch, P., & Saltin, B. (2008). Sports science and medicine at high altitude. Scandinavian Journal of Medicine & Science in Sports, 18(Suppl 1), 1-3.
²⁹ Hackett, P. H., & Roach, R. C. (2001). High-altitude illness. New England Journal of Medicine, 345(2), 107-114.
³⁰ Millet, G. P., Roels, B., Schmitt, L., Woorons, X., & Richalet, J. P. (2010). Altitude training—scientific evidence and practical initiatives. Scandinavian Journal of Medicine & Science in Sports, 20(Suppl 2), 1-13.
³¹ Wilber, R. L. (2001). Altitude training and athletic performance. Human Kinetics.
³² Mujika, I., & Padilla, S. (2003). Scientific bases for precompetition tapering strategies. Medicine & Science in Sports & Exercise, 35(7), 1182-1187.11