Are you an athlete looking to build speed and cardiovascular endurance? Save this high-intensity 9-minute Treadmill Interval Workout by #GainfulFitPro JB (@athlete_m.e). The goal is to cycle these 3-minute sets a total of 3 times without a rest. After you reach 9 minutes, replenish and recover with Gainful Hydration 💦 Let us know what you think in the comments! Follow @athlete_m.e for more fitness demos and inspo.