MUSCLES ENGAGED 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). Obliques Many people put a lot of focus on working their abs but forget their surrounding neighbors; the oblique muscles. Obliques serve as stabilizers, and are used in almost every physical activity. Exercising your obliques should be a very important part of your workout program. Equipment Used Stability Ball A stability or exercise ball is a ball constructed of soft elastic and filled with air until firm.Most stability balls range from a diameter of approximately 35 to 85 centimeters (14 to 34 inches). Dumbbells The dumbbell, a type of free weight, is a piece of equipment used in weight training. It can be used individually or in pairs (one for each hand). Dumbbells vary in weight from 3lbs. up to 150lbs. Exercise Instructions Step 1 Lie on your back with the shoulders squared in the center of the stability ball. Extend your feet to a 90 degree angle. Extend your arms fully with the dumbbells in line with your shoulders. Step 2 Lower the dumbbells keeping your arms parallel until the dumbbells are down at the side of your head. Step 3 Fully extend your arms back up to the starting position contracting the tricep muscles at the top, pause, and then repeat the action.