One of the more interesting findings of the past decade or so, as accelerometers allowed for a better calibration of exercise levels in epidemiological studies, is that even more mild levels of exercise are still quite well correlated with health and mortality in later life. The dose-response curve for exercise is steep when going from nothing to mild exercise, and then flattens out for moderate and greater exercise. In later life this is particularly pronounced, judging from the evidence at hand.
This investigation evaluated physical activity levels of 1,262 participants from the ongoing Framingham Offspring Study. Participants were an average age of 69 (54% women), and they were instructed to wear a device that objectively measured physical activity for at least 10 hours a day, for at least four days a week between 2011 and 2014. Participants were 67% less likely to die of any cause if they spent at least 150 minutes per week in moderate to vigorous physical activity - a goal recommended by the American Heart Association - compared to those who did not engage in more than 150 minutes per week of moderate to vigorous physical activity.
However, this investigation observed that, among the participants with an average age of 69, physical activity doesn't have to be strenuous to be effective. The researchers observed that each 30-minute interval of light-intensity physical activities - such as doing household chores or casual walking - was associated with a 20% lower risk of dying from any cause. Conversely, every additional 30-minutes of being sedentary was related to a 32% higher risk of dying from any cause.