For older adults and previously inactive individuals, exercise intensity should fall closer to what percentage of the maximal heart rate?

The answer is 50%.

The-related number of thumps every moment of the heart when working at its greatest that is generally evaluated as 220 short one's age achieved 90 percent of his most extreme heart rate when tried on a treadmill. 
It is prescribed that you practice inside 55 to 85 percent of your most extreme heart rate for no less than 20 to 30 minutes to get the best outcomes from oxygen consuming activity. The MHR (generally ascertained as 220 less your age) is the maximum furthest reaches of what your cardiovascular framework can deal with amid physical movement.