In the research titled Cardiorespiratory Fitness and Adiposity as Mortality Predictors in Older Adults, tracking 2603 adults between 60 and 70 years of age, it was found that:
"Fitness is a significant mortality predictor in older adults independent of overall or abdominal adiposity. Practitioners should consider the importance of preserving functional capacity, by recommending regular physical activity for older individuals, normal weight and overweight alike."
But Fitness was evaluated in a treadmill with emphasis on the cardiopulmonary function.
For more information on it look for the paragraph the start with We determined fitness using a maximal treadmill exercise test and a modified-Balke protocol.
What I say that more FUNCTIONAL than walking fast long distances is the possibility to do the #22RiseUp (Going spherically up and down from the floor).
Doing the #22RiseUp every hour or so is a great way to change the static mode we live in and have a great shake of vitality in our system. Like a nutritional dose, small and frequent.
If you do the #22RiseUp here and there throughout your day, even if you don't get to 22 repetitions accumulative per day, you are still working on important aspect of being fit to stay physically independent for longer, maybe even to the last week of your life.
Another thing interesting to note that the most slim (At least lowest BMI) did not survice the 10 year period as good as the BMI category of 25.0-29.9.
"There were 450 deaths during an average follow-up of 12 years and 31 236 person-years of exposure. Death rates per 1000 person-years, adjusted for age, gender, and examination year were: 13.9, 13.3, 18.3, and 31.8 across BMI groups of 18.5-24.9, 25.0-29.9, 30.0-34.9, and ≥35 kg/m2, respectively (trend P=.01);"