High-intensity interval training (HIIT) workouts are short in time, but high in intensity. By going all-out and challenging yourself to perform the exercises in the shortest amount of time possible, you're guaranteed to get your heart rate pumping, says Grigas.
Perform each of the movements below using a three-round, 21-15-9 rep count. For example, you'll do 21 jumping lunges, followed by 21 push-ups, then perform 15 jumping lunges and push-ups, then a round at nine reps.
Jumping lunges: From a standing position, jump into a lunge, with your right knee bent at a 90-degree angle. Then, push up through your heel and switch sides in the air, so your left leg is bent at a 90-degree angle. That's one rep.
Push-ups: Keep the elbows snug to the body as you lower your chest to the ground and then raise back up.
