You could do a complete cardio workout of jumping jacks. However, performing jumping jacks for long periods can be monotonous and difficult to maintain. In addition, landing from the jumps can place stress on your musculoskeletal system. However, jumping jacks work great when incorporated in a circuit workout that consists of multiple types of exercises. For example, you could do a circuit that features 60 seconds each of jumping jacks, squats, pushups, sprints and crunches, and then go through the circuit five times for a 25 minute workout.