Considered one of the quickest ways to take your fitness to the next level, the high-intensity interval training of a LES MILLS GRIT workout builds cardiovascular fitness and lean muscle while sending calorie burn through the roof. WHAT IS HIGH-INTENSITY INTERVAL TRAINING? High-intensity interval training (HIIT) is any workout that involves short, intense bursts of … Lire la suite de ALL YOU NEED TO KNOW ABOUT LES MILLS GRIT