The routine is a 12-minute kettlebell workout that uses a strict regimen-repetitions of 20 seconds of kettlebell exercises followed by 10 seconds of rest. The kettlebell exercises were the sumo squat, swing, one-arm clean and press, and sumo deadlift. The responses to the kettlebell circuit were similar to a time-matched interval-training workout on a stationary bike. Caloric expenditure and heart rate were similar between workouts. The study expanded our view of high-intensity exercise. A high-intensity kettlebell circuit can substitute for high-intensity interval training workouts on a stationary bike or elliptical trainer.