Why 12 Round Fitness? Rethink your training with 12 Round Fitness Parkhurst! 12 Round Fitness Parkhurst provides High-Intensity Interval Training (HIIT) group based workouts designed by professional athletes and trainers to provide the ultimate ‘total body’ workout. Our workouts are designed around the format of a 12 round boxing contest and combine functional strength and cardio exercises with boxing skills and drills designed to trigger the “after burn effect” and leave you burning calories and fat for up to 16-38 hours post workout! With no set class times and no need to book in you can start within 3 minutes and be finished in 45!