Through these tests, lactic acid was measured because it is a material that causes the human body to feel fatigued and is generated when glycogen, which produces energy inside the body, decomposes as muscles are used.
It was found by numerous doctors and scientists that “mechanical performance gradually declined as the muscle accumulated large amounts of lactic acid” (Allen, 2004).
A reduction in lactic acid leads to a decrease in the fatigue the body feels, which is why lactic acid was the primary figure being measured in these tests.