Former Division I track athlete and two-time Figure Olympia and 14-time IFBB champion Erin Stern shares three crucial training tips for HIIT workouts. Tip 1: Warm up with a dynamic circuit.Tip 2: Exert all-out effort per sprint.Tip 3: Allow yourself to get full recovery between each sprint.Check out Erin's Women Strong Profile to hear her incredible story of triumph over adversity — and get more of her epic life, training and nutrition advice!