“VO2 max” has become a buzzword in fitness and biohacking, but what does it measure in our bodies? How useful is it as a metric, and how can we optimize its principles? To learn more, I am joined by researcher and science writer Brady Holmer. Brady specializes in health, nutrition, and exercise, giving him a unique perspective on fitness and wellbeing. He explains that VO2 max provides a general measure of one’s cardiovascular system; it factors in the heart’s stroke volume, or the amount of blood pumped out in a single beat, as well as the lungs’ ability to take in oxygen and the skeletal muscles’ ability to absorb that oxygen. “VO2 max is measured in milliliters of oxygen per kilogram body weight per minute… Improving it by three milliliters per kilogram per minute was associated with an 11% reduction in all-cause mortality.” Additionally, VO2 max has been found to be a stronger predictor of mortality than current cardiometabolic risk factors, such as smoking. Considering the growing importance of this metric, Brady encourages listeners to focus on improving their cardiorespiratory fitness using their VO2 max as a guide. He recommends using online resources to determine where your VO2 max should lie, enabling wearable devices to track your metrics, and engaging in high-intensity workouts to best utilize the new technology. “If you want to elevate your ceiling, your performance ceiling, you have to train near that ceiling.” Listen to the full episode to learn more about this new “vital sign.”