The advocacy of altitude training producing beneficial effects on sea level competitive performances persists. Researches in this area are not well designed and contradictory, with most supportive studies being authored by investigators who are not divorced from bias. In those living conditions, the environment is normobaric and hypoxic. Researches in this area too are not well designed, few in number, and produced by adherents. Little mention is made of the difference.
Atmospheric pressure has a direct physical effect upon fluids and organisms.
There is an instant physiological and tissue response to changes in atmospheric pressure. Humans and animals are sensitive to very slight pressure changes. For example, the behavior of many organisms reflects relatively small alterations in barometric pressure associated with weather. Whether or not an environment is normobaric or hypobaric could affect the responses of athletes. At this time, it is not known what those effects are.