Final answer:
The muscles of power lifters and Olympic sprinters get energy without oxygen through anaerobic respiration that allows for quick ATP production, suitable for short and intense activities.
Step-by-step explanation:
The process by which the muscles of athletes like power lifters and Olympic sprinters obtain energy without oxygen is called anaerobic respiration. During their short, intense activities, these athletes rely on a rapid energy supply that can't be met quickly enough by aerobic respiration.
Anaerobic respiration utilizes processes such as glycolysis and fermentation to produce ATP for muscle contractions. This form of respiration is faster than aerobic, though less efficient, producing less ATP per molecule of glucose. However, it is ideal for short bursts of high-intensity exercise that last only a few seconds where oxygen availability is limited.