“Nutritional Support for Altitude Training” was written by Dr. Kevin Sprouse. Dr. Sprouse is a team physician for the Cannondale Drapac Pro Cycling Team. He has a degree in exercise science and has board certifications in both Sports Medicine and Emergency Medicine. He practices at Podium Sports Medicine in Knoxville, TN.
There are two reasons why athletes choose to engage in training at altitude. For some, it is a matter of acclimatization. They have an upcoming race or event at altitude, and they want to allow themselves time to become accustomed to the environment. Otherwise, athletes tend to train at altitude in order to induce physiologic changes that will benefit them when returning to sea level competition. In either scenario, proper nutritional support is key to success.
There are numerous protocols for altitude training, but a few tend to predominate. “Train High, Sleep High” is the traditional model, where an athlete goes to altitude (usually defined as 2000-3000 meters) and stays for a period of time. They live and train where the partial pressure of oxygen is diminished. In recent years, there has been a trend toward “Train Low, Sleep High” which allows the athlete to continue training at higher intensity while still obtaining the benefits of altitude. The third protocol requires that the athlete live and train at an “intermediate” altitude, usually 1500-2000 meters.
Each of these protocols has different potential benefits and reasons for implementation, but the focus of this article is not specifically on altitude training, per se. The goal of any altitude training regimen is to trigger physiologic changes that will benefit the athlete’s performance. We will discuss a proper nutritional regimen to support such training and ensure that maximum benefit is achieved.
Ensuring proper hydration when training at altitude is crucial. Especially during the first few days after arriving, athletes tend to dehydrate readily. This phenomenon occurs because of increased breathing rates which exacerbate the respiratory water loss into the generally drier air. Furthermore, altitude effects a hormonal regulatory system at the kidneys which controls how much water you excrete in urine. These factors alone can lead to excess water loss of 1-2 liters per day! Because of this, athletes training at altitude should increase their fluid intake compared to what they would consume at sea level. Electrolyte-containing solutions can be helpful to encourage hydration and aid in absorption. Skratch Labs and Nuun both make great products which would be useful in such a situation.
Caloric Intake / Carbohydrates
When training or racing at altitude, energy expenditure has been shown to be many times higher than when at sea level. There are multiple reasons for this, but much of it can be attributed to lower partial pressures of oxygen and lower temperatures. Additionally, due to the lower availability of oxygen, more of these calories are provided by glycolysis…ie, carbohydrates. Because of these factors, athletes need to ensure adequate caloric intake with an increased contribution from carbohydrates initially. The intensity of training must still be considered when determining optimal macronutrient intake, but a greater dependence on carbohydrate, even for lower intensity training, must be considered.
Exercise at altitude causes muscles to generate increased levels of reactive oxygen species (“ROS”) leading to greater oxidative stress. To combat this, it is often recommended that athletes increase their intake of antioxidants. Studies in recent years have begun to question this wisdom though. Those same ROS molecules act as signals in the body, stimulating some desirable adaptive changes. Excess antioxidant supplementation has been shown to blunt this signaling, decreasing adaptation and fitness in some situations. While there is ongoing debate on this topic, some prudence and context regarding antioxidant supplementation should be used. When training at altitude, the goal is to stimulate such adaptation. In that case, excessive supplementation could be counterproductive. Focusing on antioxidant-rich whole foods is probably sufficient. It can be difficult to find good sources of fresh fruits and vegetables in some locales, so whole food supplements (like Vega’s Protein & Greens or BeetElite) can be helpful. When racing, however, the goals are different. An athlete is not trying to get fitter during a stage race, in most cases. Instead, the goal is to recover quickly from day to day. In these cases, supplementation is likely worthwhile. Vitamins A, C, and E are often used, as are glutathione, NAC, and quercetin. Interestingly, there are some suggestions in the literature that NAC may work as a potent antioxidant and avoid the blunting of training adaptation.
Iron / Folate / Vitamin B12
One of the main purposes of training at altitude is to trigger increased production of red blood cells and, subsequently, oxygen carrying capacity. Some types of training are more likely to trigger this than others, and some individuals seem to respond better than others. Regardless, proper nutritional support for an athlete’s hematopoietic (blood forming) system is necessary when training at altitude. Iron should be supplemented while at altitude, and an athlete should not go to altitude to train unless they have ensured that their levels of iron stores are adequate beforehand. This can be accomplished through basic blood tests by simply checking one’s ferritin level. Other important nutritional factors are folate and Vitamin B12. All are worth supplementing when training at altitude.
Vitamin D has certainly been a hot topic in sports science recently. Much of this stems from the identification of Vitamin D receptors on muscle tissue and subsequent suggestions that it is involved in both muscle function and recovery. Likewise, there is data showing that Vitamin D allows for relaxation of blood vessels, resulting in improved delivery of oxygen to muscles. For these reasons, athletes at altitude (or even at sea level, for that matter) should ensure appropriate Vitamin D stores. It is easy to do a blood test and determine one’s level and supplementation requirement. Most athletes should aim for a level of 60-80 ng/mL.
Ultimately, the goal of an athlete at altitude is either to perform at a high level on race day or to trigger beneficial adaptations during training. Both processes are highly dependent upon proper nutritional support to optimize the body’s physiology. The most important component of nutrition is a balanced and complete diet of whole foods, containing adequate calories and an appropriate macronutrient profile. Hydration is also paramount. In addition to these though, there is likely a role for targeted supplementation.