Everyone knows that we need to breathe in oxygen from the air to fuel the muscles. But many people are less aware that the act of breathing itself requires oxygen to fuel the diaphragm and ribcage muscles — the ‘respiratory muscles’. The harder you breathe, the larger the oxygen demand from your respiratory muscles — potentially ‘stealing’ a significant amount of oxygen from the rest of the body, affecting performance.
Now a new study shows that this oxygen cost of breathing may be proportionately higher for women than for men. Nine men and nine women completed trials, during which the oxygen cost of breathing at a different range of simulated exercise intensities was measured. All the subjects initially performed an incremental test on a stationary bike to assess the relationship between breathing (ventilation) and different exercise intensities. They next performed a number of tests sitting on the bike without cycling, mimicking cycling ventilation patterns at different intensities.
At sub-maximal and maximal intensities, the respiratory muscles in the female subjects consumed a greater proportion of total oxygen compared to the males. This suggests that with more oxygen being diverted to the respiratory muscles, women are at a disadvantage performance-wise compared to equally fit men. But it also suggests that women could especially benefit from
the use of respiratory muscle-training devices (e.g. Powerbreathe).
J Physiol. 2015 b 4. [Epub ahead of print]
This article first appeared in the April 9 issue of Cycling Weekly