Coping with Reduced Oxygen (Hypoxia) and Higher Carbon Dioxide (Hypercapnia)

Simulation of High Altitude Training

If you took a moderately paced run alongside an elite athlete, you would expect that his or her breathing would be light, rhythmic, easy, and effortless. You certainly wouldn’t expect him to be huffing and puffing like a steam train.

A study by Japanese researchers Miharu Miyamura and colleagues from Nagoya University, of ten marathon runners and 14 untrained individuals found that athletes had a significantly greater tolerance to carbon dioxide at rest when compared with untrained individuals. The study found that for the same amount of exercise, athletes experienced 50 to 60 percent less breathlessness than that of untrained individuals.

It has been said that one of the main differences between endurance athletes and non-athletes is their response to low pressures of oxygen (hypoxia) and higher levels of carbon dioxide (hypercapnia). In a paper entitled, ‘Low exercise ventilation in endurance athletes’, that was published in Medicine and Science in Sports, the authors found that non-athletes breathe far heavier and faster to changes in oxygen and carbon dioxide when compared with endurance athletes at equal workloads. The authors observed that the lighter breathing of the athlete group may explain the link between “low ventilatory chemosensitivity and outstanding endurance athletic performance.”

In a study by Woorons, it was noted that trained athletes had a lower ventilation than untrained men. This was probably due to a weaker hypercapnic ventilatory responsiveness (improved tolerance to carbon dioxide) in trained athletes.

In other words, endurance athletes are able to tolerate a greater concentration of carbon dioxide and lower concentration of oxygen in the blood during exercise. Intense physical exercise results in increased consumption of oxygen and increased production of carbon dioxide, so it is vitally important that athletes are able to cope well with these blood gas changes.

Reduced breathing frequency has been shown to reduce the ventilatory response to carbon dioxide. Holmer and Gullstrand suggested that breath controlled induced hypercapnia during training may actually be the determining factor in improving performance, instead of the coveted hypoxic training technique.