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. Triceps Triceps are an often forgotten muscle group. Triceps are located on the opposite side of the biceps at the back of the upper arm. Well strengthened and defined triceps make the arm look bigger and sleeker (reducing the "flabby arm" look). Equipment Used Resistance Band n/a Exercise Instructions Step 1 Start in a standing position while holding an exercise band in each hand. Step 2 Keep your arms straight and and your back flat as you pull your arms down to your hips. Step 3 Raise your arms back up to the starting position with full control.