AP BIOLOGY

Detailed explanation-1: -Marathon runners rely on aerobic respiration because it provides a sustained energy release from muscles required for running long distances. If anaerobic respiration occurs, it would quickly cause muscles to cramp up. This means that the runner would not be able to run for long.

Detailed explanation-2: -A marathon is considered an aerobic dominant exercise, but higher intensities associated with elite performance use a larger percentage of anaerobic energy. The lactate threshold is the cross over point between predominantly aerobic energy usage and anaerobic energy usage.

Detailed explanation-3: -This energy system is called the Oxidative System as it uses oxygen (aerobic) to fuel muscles. It kicks in about 5 minutes into exercise and can last for hours so is the primary energy system for marathon running.

Detailed explanation-4: -When we run aerobically, our breath feels very accessible. Your body receives this oxygen and uses it to produce energy and power your muscles to keep going. It is also able to release the waste products that are water and carbon dioxide with each exhale. Anaerobic running happens on those hard runs.

Detailed explanation-5: -Aerobic respiration, which relies on oxygen, is about 20 times more efficient than anaerobic respiration, which does not use oxygen. Aerobic activity, like distance running, cycling, cross-country skiing, has you breathing in a lot to keep going.