Extensive science and research validate that total body workouts, with intervals of high-intensity interval training (HIIT) that include both resistance and cardio, are highly effective. HIIT involves performing an all-out, exhaustive physical effort for a short time followed by a short, sometimes active, recovery.
The main emphasis for someone new to HIIT should be a routine that goes hard for 60 seconds and then breaks for 1-2 minutes, depending on the exercise involved. As you get accustomed to HIIT, you can lower the work to rest ratio from 3:1 to 2:1 and eventually even 1:1. During the high intensity interval, your goal should be to have your heart pumping at 85 percent of its maximum rate, or in simple terms on a scale of 1-10 of ease of breathing, you want to be at 8-9.