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. Back (lower) The lower back is often not trained because it is not visible in the mirror. If you have weak lower back muscles, there is nothing to help pull back against the spine, putting you at risk of developing poor posture (hunched over). Weak lower back muscles can also lead to lower back pain. Equipment Used Barbell A barbell is a piece of exercise equipment used in weight training, weightlifting and powerlifting. Barbells range in length from 4 feet (1.2 m) to 8 feet (2.4 m) and vary in diameter. Exercise Instructions Step 1 Start in a bent over position with your feet wider than shoulder width, your knees bent and your back flat. Step 2 keep your core engaged and your back flat as you pull the barbell up to your body. Step 3 Lower the bar back to the starting position without rounding off your shoulders and repeat.