up in the air

It also includes these fascinating paragraphs about the role of estrogen in different types of physical activity, directly debunking the widespread notion that estrogen is the weak human's hormone and only does weak human things:

Given the fitness world's persistent touting of the hormone testosterone for athletic success, you'd be forgiven for not knowing that estrogen, which females typically produce more of than males, plays an incredibly important role in athletic performance… The estrogen receptor—the protein that estrogen binds to in order to do its work—is deeply ancient. Joseph Thornton of the University of Chicago and his colleagues have estimated that it is around 1.2 billion to 600 million years old—roughly twice as old as the testosterone receptor. In addition to helping regulate the reproductive system, estrogen influences fine-motor control and memory, enhances the growth and development of neurons, and helps to prevent hardening of the arteries. Important for the purposes of this discussion, estrogen also improves fat metabolism. During exercise, estrogen seems to encourage the body to use stored fat for energy before stored carbohydrates. Fat contains more calories per gram than carbohydrates do, so it burns more slowly, which can delay fatigue during endurance activity. Not only does estrogen encourage fat burning, but it also promotes greater fat storage within muscles… which makes that fat's energy more readily available. Adiponectin, another hormone that is typically present in higher amounts in females than in males, further enhances fat metabolism while sparing carbohydrates for future use, and it protects muscle from breakdown. Anne Friedlander of Stanford University and her colleagues found that females use as much as 70 percent more fat for energy during exercise than males. Estrogen's ability to increase fat metabolism and regulate the body's response to the hormone insulin can help prevent muscle breakdown during intense exercise. Furthermore, estrogen appears to have a stabilizing effect on cell membranes that might otherwise rupture from acute stress brought on by heat and exercise. Ruptured cells release enzymes called creatine kinases, which can damage tissues… Linda Lamont of the University of Rhode Island and her colleagues, as well as Michael Riddell of York University in Canada and his colleagues, found that females experienced less muscle breakdown than males after the same bouts of exercise. Tellingly, in a separate study, Mazen J. Hamadeh of York University and his colleagues found that males supplemented with estrogen suffered less muscle breakdown during cycling than those who didn't receive estrogen supplements.