The reason women find it harder to breathe
than men during exercise is due to greater electrical activation of their
breathing muscles, shows a new study published in the
journal Experimental Physiology.
It is well established that women
experience greater shortness of breath during physical activity, from stair
climbing to long-distance running, than men of a similar age. This is true in
healthy young and older adults, as well as in patients with chronic heart and
lung disease. This study is the first to explain why this happens.
Dr Dennis Jensen, who led the study at
McGill University, Canada, says: "Our study uniquely showed that sex
differences in activity-related breathlessness could be explained by the
awareness of greater electrical activation of the respiratory muscles
specifically the diaphragm needed to achieve any given ventilation during
exercise in healthy young women compared to men.
Improve exercise capacity
"Our findings indicated that greater
electrical activation of the respiratory muscles during exercise in women is
needed to compensate for their biologically smaller lungs, airways and
This information could be used by
researchers and healthcare providers to help identify new treatments to relieve
the symptoms of breathlessness and improve exercise capacity for groups such as
the elderly and patients with chronic heart and lung disease.
Dr Jensen explains how the research was
carried out: "50 healthy, non-smoking men and women aged 20-40 years
completed a maximum exercise test on a stationary bicycle. During exercise, we
monitored the participant’s cardiovascular, metabolic and ventilatory responses
to exercise using computerised equipment.
"At regular intervals during exercise,
participants rated the intensity of their breathlessness using a 10-point
scale. Using a multipair electrode catheter placed in the participants'
oesophagus, we also recorded the electromyogram of the diaphragm (an index of
the drive to breathe that presumably originates in the central nervous system) throughout
exercise. These measurements were then analysed and compared between men and
Future research is needed to extend the
findings to other groups of men and women, such as those that are overweight or