We’ve all known for years that altitude training restricts the amount of oxygen delivered to the muscles, and as such encourages the body to create more haemoglobin—a specialised protein that binds to oxygen in the lungs so that the oxygen can be transported to the rest of the body—in red blood cells to deliver more oxygen to the oxygen deprived muscles. This is one of the best-known advantages of altitude training and acclimatisation.
A less common fact, is that altitude actually restricts the volume of blood the heart can pump with each beat. One might assume that if there was less oxygen in the air, the heart would work harder and pump a greater volume of blood around the body in an attempt to make up for the oxygen deficit. However, the opposite is true. Whether this was due to air pressure, oxygen debt, or something else entirely was only hypothesised.
New research, published in The Journal of Physiology, unearthed why this is the case.
The research has shown that because there is less oxygen at altitudes above 3,000m, it leads to a decrease in the volume of blood the heart pumps around the body, this is due to an increase in blood pressure around the lungs. These factors play a role in the reduction in volume the heart can physically pump with each beat.
These findings will help us to further understand the body’s ability to adapt to different environments, in this case altitude. It will improve our understanding of exercise performance and could lead to breakthroughs in our understanding of altitude training for athletes.