Building muscle fast can be easy as one, two, three, if you go big and go home. Here is an effective muscle building circuit that works multiple muscle groups in the least amount of time. One exercise targets your lower body and the Push-Pull exercises build your upper body. The Workout: Do 8-12 repetitions. Do 3-6 rounds Rest for 75 seconds after each exercise The Circuit Barbell Squat: How To: Set your feet shoulder width apart. Hold bar across your upper back with overhand grip. Initiate the movement by first pushing your hips back, then bend your knees and lower your body as deep as you can. Drive your heels into the floor keeping your torso as upright as possible. Pull up: Trainer’s Tip: The difference between a chin up and a pull up is for a chin up, you use an underhand grip and for a pull up you use an overhand grip. Incase you’re wondering, a chin up is a little easier because it uses more biceps to assist with the range of motion. Because of this you can switch between pull-ups and chin up to target your biceps and back. Barbell Shoulder Press: What & Why: Shoulder presses target front and middle deltoids and triceps while activating the upper traps, rotator cuff and serratus anterior. Making it a great mass building exercise and improves the stability and mobility of the shoulders.