Several years ago My wife and i decided to put in a Stone Patio in our back yard. All together I think we had about 15 tons of River rock and pea gravel delivered. Between my wife, our two teenage boys and myself we moved all this rock from the driveway to the back yard and laid it in place. My wife did most of the placement and I did most of the "totin' and fetchin" She had the vision, we supplied the labor. My Wife outlasted both the boys (who are not couch potatos)and only quit when it was too dark to keep working. Yes she may not be a strong as I am, but what she may lack in physical strength, she more than made up for in endurance and also speed. As part of this project we also built raised gardens and while i could carry 4 40lb bags of topsoil at a time, she carried 2 at a time, and then emptied them into the garden and planted the plants.
In all honesty having a woman working with you is great. I think it actually inspires the men to give more effort whether they notice it or not.