Aerobic Exercise – Aerobic exercises are endurance type exercises that increase a person's heart rate and breathing rate over relatively long durations

(Note: Exercises where glucose in the muscles have enough oxygen to provide the most efficient way to release energy.)

Aerobic = With oxygen

Aerobic = The most efficient way to release energy to the muscles

The most efficient way for glucose to release energy is using:

Glucose + oxygen  →  carbon dioxide + water + energy

To learn the formula for this see Biology photosynthesis and respiration and remember the famous mnemonic:

COWS                     EAT           WET        GRASS        OUTSIDE

Carbon dioxide + Energy + Water → Glucose + Oxygen

or in reverse as in this case. 

Glucose + oxygen  →  carbon dioxide + water + energy