very best form of exercise a human being can do is springing nothing is harder in a short period of time you do a max effort sprint you will see how tired and exhausting it you go lift weights for thirty seconds you're not going to be that tie but when you sprint all your muscles are used to create a huge auction debt you create all of this crummy dioxide build up dropping your p a the maximal physiological challenge you can do in a human being ensures your time is sprinting