Plenty of studies have compared the health effects of working out once a day—say, for an hour—versus splitting up the workout into two 30-minute sessions or even shorter bouts of exercise. The truth is it doesn't matter, it all depends on intensity. If you could run for an hour at 7 miles an hour it wouldn't matter if you split that up, but if you were to run for 2 half hour periods one at 12 miles an hour and the other at 10 miles an hour that would be better than one hour. I think that spliting it up could really benefit you if you can have a greater intensity spreading it out. How ever If you are building endurance you would want to go for a longer time and not split it up.
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