It's something many long suspected, but now we finally have scientific proof.
A study has found women are naturally more fit than men.
The research was conducted by employees at the University of Waterloo in Ontario.
It compared the uptake of oxygen and the extraction of the chemical element from muscles between 18 young women and men during treadmill exercise.
The uptake of the element by the body places less strain on the cells produced during exercise, and is considered to be an important indicator of aerobic fitness.
The sample of people were all around the same age and weight, ensuring that the results had statistical validity. The researchers found women outperforming men consistently - their bodies were around 30% faster in handling oxygen.
Researcher Richard Hughson said this was indicative of a "superior aerobic system", while lead author Thomas Beltrame said the research contradicted the idea of men's bodies being naturally more athletic.