When muscles work without enough oxygen, they produce a byproduct called lactic acid.
Get oxygen to your muscles
well if muscles run out of oxygen you might slow down and not breath proppely and you might also die.
because your blood carries oxygen to you muscles. without much oxygen blood won't be able to take lots to your muscles, and with little oxygen your muscles won't work as well and therefore you won't run as quickly :)
Anaerobic digestion
Lactic acid is associated with muscles experiencing lack of oxygen, which can occur during intense exercise or when the muscles are not receiving enough oxygen to produce energy aerobically. This buildup of lactic acid can contribute to muscle fatigue and soreness.
Without getting into it. The heart is just a muscle and muscles can't work without oxygen.
Yes, cardiac muscles cells have a very high oxygen demand, since they are constantly in motion. This is why any shortage of oxygen causes angina, or if the oxygen deprivation is long enough, it causes death of the muscle cells - what is commonly called a heart attack.
Arteries carry oxygen to the muscles of the body.
When oxygen runs out, the muscles and other cells need to obtain energy from oxygen and nutrients. Anaerobic respiration (respiration without oxygen) fills this need.
Anaerobic decomposition or anaerobic digestion.
The cardiovascular system sends oxygen to the muscles.