MUSCLES ENGAGED Quadriceps The quadriceps (quads) are a group of four muscles on the front of the thigh. They allow your knee to straighten and provide stability when standing. Your quads are the most important muscle group for maintaining the ability to stand and to walk independently. Back (middle) Middle back muscles are very important as they help to support and strengthen the core muscles at the front of your body. 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 while holding the TRX handles in each hand. Step 2 Sit back on your heels and lower yourself into a squat keeping your arms extended in front of you. Step 3 Stand back up through your heels and pull your body forward until your thumbs touch your ribcage.