Heart rate decreased suddenly and then MAP immediately fell because peripheral blood vessels were extensively vasodilated. The biker had an acidosis from hyperventilating and the respiratory integrating center was overwhelmed. End-diastolic volume was too high to maintain cardiac output and blood flow to the brain decreased.

Heart rate decreased suddenly and then MAP immediately fell because peripheral blood vessels were extensively vasodilated.

Explanation:

A VO2 max test is a clinical test done in a lab and is the ‘golden standard’ for measuring the potential and cardio-respiratory endurance of athletes and bikers.

It measures the oxygen carrying capability through a graded step test which determines the average power output. The maximal oxygen uptake along with cardiorespiratory responses is measured.

As per exercise physiology, the heart rate and cardiac output increases with exercise. When the potential is less, the resistance decreases, heart rate and mean arterial pressure also decrease .

all matter is made up of atoms

in any element all atoms are the same

elements in a compound are always in a constant ratio: apex