Question: I am a competitive ultramarathon runner. Will training at high altitude improve my time?
Answer: High Altitude is typically defined as being above 5,000 feet in elevation. When athletes train at altitude, the first thing that happens is that their heart rates and respiratory rates increase. This even occurs at rest. This helps counter the lower partial pressure of oxygen in the air at altitude. Remember, even at sea level, oxygen comprises only 20.9% of the air we breathe. In response to being at altitude, your kidneys then start to produce more erythropoietin (EPO), which is a hormone that stimulates your bone marrow to produce more red blood cells, which are the cells that carry oxygen in your blood stream. Your kidneys also excrete more base to restore the acid-base balance in your blood stream, which ultimately makes you less tolerant of lactic acid in your blood stream. Thus, athletes reach their lactate thresholds sooner at altitude than if they were training at a lower altitude no matter what level of fitness they have attained. If someone has had his or her maximum aerobic power (VO2 max) measured at sea level, it will most certainly be lower if it were measured at altitude around the same time frame. In fact, VO2 max is reduced by 1% to 2% for every 390 feet above 4,900 feet in elevation.
Over time, it is felt that an athlete who lives and trains at altitude gets more efficient at utilizing oxygen. There is an increase in the number of mitochondria (energy producers in our cells) and oxidative enzymes (the proteins that scavenge free radicals). Indeed, research has shown that training at high altitude can improve performance at high altitude and translate to increased endurance at sea level. The benefits of training at high altitude have been touted since the 1940s. The U.S. Olympic Team built its first training facility in Colorado Springs in 1978 because of its higher elevation. Furthermore, the benefits from altitude training can last for more than two weeks after athletes leave their high altitude training location. It is no wonder that 95 percent of all long distance running medalists at the world championships and the Olympic Games since 1968 have either lived or trained at altitude. However, the advantages of training at altitude may not be as significant as suggested in the lay press. Some of the best long distance runners in the world are from Africa and many of these runners train at low or intermediate altitudes. Moreover, their hemoglobin is only slighlty elevated in comparison with most people. Thus, high altitude training may only impart an incremental benefit in elite athletes.
If, for example, an athlete from Los Angeles was coming to compete in the Leadville 100, it is recommended that he or she acclimate for a period of three to six weeks before competing, if possible. If adequate time for acclimatization is not possible, many experts advise athletes to schedule their competition immediately upon arrival to higher altitude. This is because cardiac output does not begin to fall until 72 hours after arrival. Although this hypothesis has not been scientifically tested, many medical experts appear to accept this notion as reasonable. However, that would be one painful Leadville 100!
Critics of high altitude training argue that red blood cell concentrations normalize within a few days of returning to a lower altitude, and athletes who train at lower altitudes benefit from the ability to train at higher intensity at a lower elevation. Furthermore, they argue that athletes can experience decreased immune function and sleep disturbances at high attitude. Even at moderate elevations, there is sleep disturbance and even periodic breathing in some susceptible athletes.
In an effort to allow athletes to benefit from the increased workload at sea-level conditions while taking advantage of the metabolic conditions at high-altitude, coaches and trainers have concocted a training regimen called the “live-high, train-low” approach. In this scenario, training is carried out at low altitude in order to increase one’s anaerobic threshold and VO2 max, but sleeping is done at high altitude so that red blood cell counts increase.
Several different low-oxygen living or sleeping spaces have been developed to allow athletes to train at sea level but live in a hypoxic room that simulates an altitude of 6,500 to 9,800 feet. Several studies suggest that using the live-high, train-low method can result in improvements in EPO, red blood cell mass and VO2 max.
However, medical experts agree that more testing is required to validate this method.
Dr. Rick Cunningham is a Knee and Shoulder Sports Medicine Specialist with Vail-Summit Orthopaedics. He is a Physician for the US Ski Team and Chief of Surgery at Vail Valley Medical Center. Do you have a sports medicine question you’d like him to answer in this column? Visit his website at www.vailknee.com to submit your query.