“People in the best of health tend lose lung capacity of up to 50 percent over time even with good habits.”
I don’t believe it. If the health is otherwise good with no systemic issues and no bad habits, I think loss of lung capacity is derived from gradual lessening of lung use - becoming gradually more sedentary and less active over time. Older folks who do not have major health issues and remain physically very active still have lung capacity equal to their younger age.
All the studies I read did not consider variables in life activity, just age, in determining rates of lunch capacity decline; but most often what happens is the rate of physical activity declines with age, and I think then it is lung capacity that follows that.
I said “up to” 50 percent. Everyone is different and none of us will leave this Earth alive. I only say it because I know these things from my years as an RN. Genetics, exercise, strength, good habits do help as you said. Also while one might lose pulmonary function over time naturally, there is nothing that says that what you keep can’t be strengthened and protected.