Question

why do we tried on quick exercise

Answer 1

The dogma was that athletes get tired when their bodies hit physical limits their muscles run out of oxygen or fuel or become damaged by the accumulation of toxic by products such as lactic acid. This in turn triggers pain and fatigue forcing us to stop exercising until we recover.

Answer 2

The dogma was that athletes get tired when their bodies hit physical limits—their muscles run out of oxygen or fuel, or become damaged by the accumulation of toxic by-products such as lactic acid. This in turn triggers pain and fatigue, forcing us to stop exercising until we recover.