Limits of Running

Just a quick mention of recent research I came across, that was interesting at least, if not truly practicable for the most of us.  It seems that researchers at Duke, in analyzing extreme duration endurance events, those lasting 12 hours to greater than 250 days, there is a limit on the amount of energy that the average human can exert day after day.

The number comes up to 2.5 times the body’s resting metabolic rate or 4000 calories per day for an average person.  Energy expenditure day in day out at levels greater is not considered sustainable over the long run.  For the rest of us who do not do ultras, over a marathon we can expend a much greater amount relative to our resting metabolic rate, since it is a much shorter event duration.

An average person running over flat terrain burns between 100-140 calories, with variables being age and weight. With this in mind, if you choose to run a multiday event, up to 30-40 miles per day, day after day would be sustainable.