Question: how much exercise can a human do a day?

Hannah Moir answered on 8 Mar 2016:

Children and young adults should be achieving 60 mins per day of physical activity, and some research has shown up to 120 mins a day can be beneficial. But too much too often without recovery and breaks can cause overtraining and burnout which can cause chronic fatigue a illness which is bad, So moderation is key. Professional athletes will train 2-2 times a day but this is over time and there body has got used to it. Some athletes who do ultra events can run for up to 30hrs covering long distances well over 100miles, but they would need a long recovery time after and would not be doing this on a weekly basis and there bodies have adapted over time throhgh appropriate training for this sort of event