Fitness
VO2 max and longevity: strong associations, careful conclusions
Fitness predicts outcomes in cohorts. That does not turn a watch estimate into a personalized survival forecast.
Everyday function
Consider fitness, strength and the physical abilities that matter in daily life.
Function
Grip strength is a useful signal. Function tells a fuller story.
A stronger squeeze predicts better outcomes in populations, but the practical goal is preserving what you can do.