It is always the case that women would have to work doubly (or more than that) harder than their male counterpart, be it in career or otherwise. This was recently reiterated by a research finding which was published in "American Journal of Physiology-Endocrinology and Metabolism".
According to this study, the reason for this is attrributed to the use of growth hormone by women whereas men use testosterone for the same purpose. The amount of growth hormone secreted is proportional to the intensity of the exercise regimen or their work out.
When William J Kraemer who is the chief author of this study was contacted for his comment, he said that women need to have a heavy exercise schedule with more repeats to achieve optimal results in building muscle and bone. When a woman undergoes a vigorous and intense weight training programme, it results in heavier secretion of growth hormone. Apart from helping them build muscle and bone, the growth hormone helps women in a good metabolism, aids them combat stress related issues and assists in repairing the damaged tissue.
This study was funded by U.S. Department of Defense Women's Health.