This exercise provided courtesy of Billy Polson, founder and co-owner of DIAKADI Body training gym, voted best personal training gym in San Francisco by CitySearch in 2006.
The classic dumbbell fly works your chest and your inner chest muscles in particular. The one-armed alternating variation has you do one side at a time, increasing the difficulty of the exercise and isolating each side of your chest individually.
Lie on a flat bench with your feet on the floor and dumbbells held in each hand at the bottom of the dumbbell fly position, with the dumbbells out to the sides so that your palms are facing up, your elbows slightly bent and level with your back, and your palms facing inward with a firm, yet relaxed grip. Keep your shoulders retracted and your chest high. Engage your abdominals to prevent your back from arching (see Photo 1).
- From the starting position, keep one arm in place and use the chest muscles to lift the other arm and dumbbell up above your shoulder, keeping the moving arm held in the same slightly bent position as you lift. Bring the dumbbell up until it is straight up above your shoulder. Keep your shoulders back and your chest flexed throughout the movement; note that in order to keep this flexion, you may not be able to lift the dumbbell as high up as you might expect (see Photos 2 and 3).
- From the top of the one-armed fly, reverse direction and return the dumbbell to the starting position (see Photo 4).
- As soon as both arms are back down in the starting position, lift the other arm in a dumbbell fly, using your chest to bring the dumbbell up above you (see Photo 5).
- Alternate arms throughout the set.
To increase the level of difficulty of this exercise, perform the alternating dumbbell flys while lying back on a stability ball. Lie back on the top of the stability ball with your chest at the peak of the ball and your head resting on the ball. Squeeze your hips, abs, and legs in order to make a sturdy flat bridge with your lower body. Keeping your palms in and your elbows soft, perform alternating dumbbell chest flys, keeping your chest high and shoulder blades retracted throughout motion.
About Billy Polson: Billy Polson is the founder and co-owner of DIAKADI Body training gym, which was voted the best personal training gym in San Francisco by CitySearch in 2006. A competitive swimmer and triathlete in his own right, Polson has over 15 years of experience working as a coach and trainer, and was recently named by Men's Journal Magazine (December 2005) as one of the Top 100 Trainers in America.