Currently, there is very little scientific evidence that extremes of exercise are harmful or that they provide a health bonus .
Several studies have found that elite athletes, especially those who play endurance sports, live longer and require less medical attention than non-athletes.
More than half a million athletes analyzed
In a study that monitored almost 22,000 non-professional runners for 15 years, it was found that the death rate (including deaths from heart disease) of people who exercised more was neither higher nor lower than that of people who exercised more more moderate.
An even more thorough analysis of more than 600,000 people found that people who practiced extreme sports (that is, an exercise pattern that was more than ten times the recommended standard dose of 150 minutes per week) did not have a rate mortality significantly higher than standard dose.
By synthesizing these data , Meagan Wasfy and Aaron Baggish concluded that:
These findings reinforce the idea that light or moderate doses of exercise have a significant positive impact on health, but that increasing the dose does not appear to improve or worsen the effects.