The lifelong exercisers exercised 5 days/week with a weekly hourly total of 7 hours. for the past 52 =/- 1 years.
Maximal oxygen uptake was measured on a maximal cycle test and muscles biopsy done to determine a "muscle aerobic profile" (MAP for short). MAP refers to the degree of capillarization and metabolic enzymes eg. Citrate synthase,B-HAD and glycogen phosphorylase were determined by muscle biopsy in the lateral thigh.
While the MAP was the same as in the young exercising controls the 02 max of course was not .The set of long time exercising women was small, but rounding up women who have exercisers for fifty years is no small feat.
Comparing the 02 max in young women,exercisers and elderly control women we find: 44,26 and 18 .
The authors conclude : " the data suggest that skeletal muscle metabolic fitness may be easier to maintain with lifelong aerobic exercise than the more central aspects of the cardiovascular system."
The authors mention the fragility index and quote that the value for men is 17.5 ml/kilo/ min and make their educated guess about what it is for women giving 14 ml/kilo/min as the value. I am not sure why women would have a lower number since the index is corrected for weight. Folks fortunate to have values well above those numbers are said to have more physiologic reserve to withstand and survive various homeostasis challenges whose frequency is a function of age.
This index should not be confused with another fragility index which gives an indicator of how robust are the results of a clinical trial.See here for more on that. (A clinical trial would have an FI of 1 if the hypothetical movement of one patient from the success column to the failure column would make the study no longer statistically significant ( at the p of 0.05 level)
1) Gries,J et al Cardiovascular and skeletal muscle health with lifelong exercise
JAP 125: 16736 2018 (full text available on line)