R. Van Thienen, Exercise Physiology Research Group, KU Leuven
Endurance athletes often participate in altitude training camps and live up to it with great expectations. Indeed, scientific findings reveal that participation in a training camp performed at terrestrial or simulated altitude can enhance exercise performance up to 10 %. This gain in performance is largely due to an increase in red blood cell production (erythropoiesis) resulting from a higher rate of erythropoietin – (EPO) secretion in a low-oxygen environment.
However, not every athlete returning from an altitude camp experiences an improvement in endurance performance. These athletes are often classified as ‘non-responders’ as opposed to those athletes who do benefit: the ‘responders’. This classification, however, is somewhat outdated. It appears that if the red blood cell mass and physical performance of an athlete have improved after a first altitude training camp (responder?), possibly no changes are seen after a second camp (non-responder?), but after a third camp 3 a performance-enhancing effect is seen again… Therefore, a more modern scientific view is that ‘non-responders’ are in fact often potential responders who are not well prepared for altitude exposure.
Athletes must meet some specific conditions in order to allow for an optimal response to altitude exposure. In the absence of adequate preconditioning, the response to altitude is likely to be impaired. The Australian Institute of Sport (AIS) has summarized the possible causes of inadequate response to altitude as the ‘Six I’s of Altitude Adaptation’:
- Iron deficiency: Ample iron availability is essential for the production of new red blood cells (~erythropoiesis). Therefore, make sure your body’s iron stores are saturated 2-3 weeks before the start of your altitude camp. Also provide a sufficient supply of iron during the entire length of your stay at altitude (nutrition + supplements if needed). Simultaneous intake of vitamin C (orange juice) can improve the absorption of iron in the body.
- Illness: Whenever you are ill and suffer from e.g. a gastro-intestinal infection or have a cold, your immune system is activated. The subsequent inflammation disrupts your body’s iron metabolism and diminishes bone marrow sensitivity to EPO, resulting in a lower erythropoiesis. Simply put: during an altitude camp, your body produces less red blood cells when you’re ill compared to when you’re just healthy.
- Inflammation: Inflammation does not only occur in your body when it has to fight an infection caused by bacteria or viruses. Damage to musculoskeletal tissue such as a bursa, tendon or muscle also activates your immune system (see point 2 above), which in turn impairs the production of red blood cells.
- Intensity: Training too hard and too early in an altitude training camp not only results in fatigue, but can also ignite symptoms of micro-inflammation in your muscles These mechanisms are likely to inhibit red blood cell production Therefore, it is essential that training and recovery, including sleep, are well-balanced especially during the early stage of altitude exposure. In case sleep quality is reduced, consider sleeping at a lower altitude for some nights. This is even more important than during similar high-load training blocks at sea level. By all means, avoid excessive fatigue and overtraining during your altitude camp. Both a good coach and ‘monitoring system’ are pivotal.
- Energy intake: Provide extra dietary protein and carbohydrates during residence at the altitude. Your need for this anabolic building material for your muscles, nervous system, red blood cells,… is elevated compared to sea level (see above, point 1). Sufficient intake of carbohydrates is also essential for your immune system to function properly!
- Investment/Interest: This is related to the mental aspect of an athlete’s life. An overreached, run-down athlete will produces less EPO than normal at altitude, and in addition his bone marrow will be less sensitive to EPO and thus produce fewer red blood cells. In a similar way, mental stress caused by performance drop, emotional distress, sleep deprivation,… can also affect adaptation to altitude training. Therefore, make sure you enroll into your altitude training camp with a high level of physical and emotional well-being.
Organizing a training camp at altitude is a demanding project both on a financial and logistical level. Hopefully these 6 advices will help you benefit from it to the full extent!