The swing engages several muscle groups, especially around the back down to the hamstrings. Additionally, your forearms and deltoids also get activated. Other dumbbell exercises, like twists and squats, also get several muscles from different parts of the body working at the same time. Now imagine combining all of those exercises into a high-intensity interval dumbbell weight training routine. High-intensity interval training is a popular way of exercising that alternates bursts of intense physical activity with lesser periods of rest or less strenuous activities. An excellent example of this is running as fast as you can for a minute, then walking for two minutes after, and continuing the pattern until your workout ends.
http://www.dumbbell2.com/intense-dumbbell-weight-training-need-tone-body/