F45 Training F45 Training Brookhavenis a 45 minute workout that will challenge you like never before. The F stands for functional training, a mix of cardio, resistance, hybrid and recovery workouts geared towards everyday movement. 45 is the total amount of time for sweat-dripping and heart-pumping fun. Classes are developed for any fitness level, whether you are just starting your fitness journey, or it's class 1000. F45 Training is here to bring you the world's most innovative workout. Team Training, Life Changing!