They learn to balance on one foot; walk on their tiptoes; and climb, hop and skip. Three-year-olds can pedal, use a handlebar and operate three-wheeled vehicles, such as tricycles, but they do not have the balance required to operate a bicycle with only two wheels.
Yoga and Pilates are also very common exercise classes, and there are dozens of different variations of these as well. Chances are, if one is looking for a specific type of exercise class, there is a gym somewhere that offers it.
Some sports are thus inherently aerobic, while other aerobic exercises, such as fartlek training or aerobic dance classes, are designed specifically to improve aerobic capacity and fitness. It is most common for aerobic exercises to involve the leg muscles, primarily or exclusively. There are some exceptions.