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 a standing position with your feet shoulder width apart or wider Hold the TRX in on hand and have your other hand at your side. Step 2 Pull yourself forward trying to keep your shoulder squared and your back flat. Step 3 To make the exercise more challenging, make your body more horizontal to the floor.