Standard arm circles are key to helping you warm up for your workout, but they're not going to do much toward getting your arms sleek and toned. They're mainly designed to work your shoulders. Some ways exist to work your arms slightly harder while doing arm circles, but they're not the ideal toning exercise.
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Purpose of Arm Circles
Arm circles primarily serve as a way to warm up your shoulders and upper body as part of a dynamic stretching routine prior to your workout. After jogging in place or brisk walking for about five minutes, hold your arms straight out from your sides and make circles with them. Your hands should move at least a foot for the best warmup. Go forward for 20 repetitions, then reverse the circles for 20 more.
Just the act of keeping your arms outstretched works your biceps and triceps some, although not enough to truly tone and define the muscles. Increasing the intensity can help you get a better muscle burn going, however. Instead of sticking to small circles, make your circles gradually larger until you're doing windmill arm circles, where the circles are so big they're basically vertical. Do this fast to get your heart rate up to help prepare for your workout. Increase the repetitions so you're doing at least 20 windmill-type circles in each direction after building up from smaller circles.
Weight It Up
Adding weights also increases the intensity, but it focuses most of the extra strain on the shoulders rather than your arms. If you're doing high repetitions, your biceps and triceps might feel fatigued from holding the weight outstretched, but your shoulders bear the brunt of the work. Keep your back straight while performing arm circles, especially weighted circles, to help prevent injury.
Bicep Circles for Toning
One type of exercise often called a circle can help tone your biceps, although you don't actually make a full arm circle movement. To perform a bicep circle, start in a squat position with your elbows bent and your hands up and facing your body, holding a 5- to 8-pound weight. Bring one hand in toward your shoulder as you lower the other weight slightly, rotating them in a circular motion so you alternate which one is coming in and which is going outward. Keep your elbows slightly bent at all times. This also works your shoulder some, but the main focus is on toning your biceps.