A different clock

Half the people you train beside, raise, work with and love run on a different clock, and almost no fitness advice accounts for it.

In 2016 Stacy Sims, an exercise physiologist who had raced bicycles, got tired of being handed training and nutrition plans built from studies on college-age men. She wrote ROAR arguing that the menstrual cycle, pregnancy, perimenopause and menopause change how a woman's body uses fuel, recovers, builds muscle and handles heat, and that the default plan is built for someone else.

Her argument runs on the hormones. In the first half of the cycle, when estrogen is low and then rising, a woman's body handles carbohydrate and intensity well and recovers fast. In the second half, when progesterone is high, core temperature is up half a degree, sodium leaves faster, and the body is slower to build muscle and quicker to break it down, so protein matters more and hard intervals land worse. After forty, as estrogen declines, she says the old advice of long slow cardio and less food is the opposite of what works; the body now needs the signal of heavy load and the raw material of protein to hold muscle and bone.

This key goes to everyone, men included. If you coach, parent or partner a woman, the default plan is wrong for her, and you should know that it exists. If you are a woman, this is the first key that asks you to write down where you are instead of where the plan assumes you are.

Nobody told me this for most of my adult life. I had been handing people the default plan with a straight face.