Translation: Both total physical activity, and time between periods of physical activity, affect mortality.Patterns of Sedentary Behavior and Mortality in U.S. Middle-Aged and Older Adults: A National Cohort Study
Both the total volume of sedentary time and its accrual in prolonged, uninterrupted bouts are associated with all-cause mortality, suggestive that physical activity guidelines should target reducing and interrupting sedentary time to reduce risk for death.
So the lesson for us is to spread our activity out over the day, as much as practically possible, with no more than 30 minutes between periods of activity. (I am taking inactivity or sedentary to mean lying or sitting down.)
Even if it doesn't help increase our activity level ceiling, it will help reduce the adverse impact of low activity levels.