Most exercises that are aerobic in nature, meaning they get your heart pumping and make you breathe harder, work your legs more than your arms. Climbing stairs, running, cycling, hiking and using a stair-stepper are some of the most common aerobic pursuits. Because the leg muscles are larger than the arms, the body works harder to pump blood to them during aerobic exercise. That doesn't mean you cannot do aerobic exercises that target your arms; you just need to use speed or use your arms and legs together.
A pedal exerciser is a small mini exercise bike with two pedals and a metal frame. To work your arms, but the base on a table and use your hands to pedal. Some pedal exercisers have detachable pedals so that you can screw on handlebars instead to make using the arms more comfortable. Pedal exercisers come in several price ranges, but even the basic ones have adjustable resistance so you can increase the resistance as you pedal until your breathing is noticeably faster.
An elliptical cross-trainer is a cardio machine that lets you work your arms and legs simultaneously. Regular elliptical trainers or gliders only work the legs, but the cross-trainers challenge the arms with a pushing and pulling motion of the metal arms that act similarly to walking poles. Set the resistance and concentrate on moving your arms. The feet pedals are used automatically because you are standing, but it is easy to relax the arms and let the lower body do the work unless you stay aware of what you're doing.
Calisthenics are body-weight exercises that burn calories and tone your muscles. Exercises such as pushups, pullups, burpees and even jumping jacks work the arms and challenge your cardiorespiratory system. You burn around 260 to 610 calories per hour doing these exercises, depending on your weight. Switch your exercises up so your arms do not get too tired. Throw in a few squats and situps to keep your heart rate up and give your arms a short rest.
Rowing on a rowing machine or in the water emphasizes your arms and upper body. A rowing machine for aerobic rowing is not the same as the weight machine called a seated row. Weight machines work the back primarily and do not involve as much body movement to make it an aerobic exercise. To use a rower, sit on the bench and hold the bar as if it were the handle of a paddle. Lean forward from the hips and extend the arms, then pull the bar toward you as you lean back. Moderate rowing in a canoe or in a rowing machine burns around 500 calories per hour, depending on your weight.