My wife and I have recently bought new smartwatches (me: Garmin Venu 2, her: Fitbit Versa 3) and the things they tell us really makes a difference to how we exercise. What’s reported here looks like next level even to the detailed stats we’ve got already.

The team identified a set of 147 proteins that could indicate a person's VO2max, a marker of cardiorespiratory fitness, before the exercise program, and then a set of 102 proteins that could indicate the change in VO2max after it had been completed. Some of these proteins were also found to be linked to a higher risk of early death, highlighting a connection between cardiorespiratory fitness and long-term health.

“We identified proteins that emanate from bone, muscle, and blood vessels that are strongly related to cardiorespiratory fitness and had never been previously associated with exercise training responses,” says Gerszten.

Based in these revelations, the scientists developed what they call a protein score, which could be used to predict how much a person’s VO2max would change as a result of the exercise. Baseline levels of certain proteins were able to predict who would respond to the exercise with more reliability than established patient factors, according to the scientists, and also predicted which subjects would be unable to significantly improve their VO2max even after a sharp uptake in physical activity.

Source: Blood protein score might predict which exercise will benefit you most | New Atlas