MUSCLES ENGAGED Back (middle) Middle back muscles are very important as they help to support and strengthen the core muscles at the front of your body. Biceps Biceps are the pair of muscles on the front of the upper arm connecting the shoulder to the elbow. Your biceps are used in everything from turning a doorknob to lifting heavy items. Strengthening your biceps can greatly reduce the "flabby arms" look. Equipment Used TRX Trainer Suspension training is a type of fitness training that uses a system of ropes and webbing called a "suspension trainer" and uses your own body weight as resistance. Exercise Instructions Step 1 Start in an extended position with your back straight, your hips tucked in and your feet shoulder width apart. Step 2 Keeping your wrists straight, pull your body up towards the handles of the TRX until your hands are at the side of your chest. Step 3 Slowly lower your body back down to the starting position keeping full control throughout the entire range of motion.