Anaerobic Exercise:

Anaerobic, "an" + "aer" = "without air," exercise is one in which your cells do NOT rely on oxygen from the blood for energy. Instead, your body takes sugar from your muscle's glycogen stores (short-term glucose storage) and converts it into lactic acid. This lactic acid buildup may lead to muscle cramps, a familiar feeling for those who regularly sprint or go all out in a particular exercise. This is why anaerobic activity is usually of a shorter duration, roughly 20-30 minutes each time with rests in between.

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