Bench presses and flies both work the muscles of your chest -- but that is where the similarities end. The bench press exercise is a compound exercise that targets more than one muscle group. Flies are an isolation exercise that targets only the chest. Each type of exercise has its place in a workout program.
Bench Press Exercise
The bench press, a compound exercise that targets your chest, shoulder and arm muscles, has several variations, but the most common version is on a flat bench with a barbell. To perform the exercise, lie on your back on the bench just below the racked barbell. Grab the bar with your hands slightly wider than shoulder-width apart. Start by lifting the bar off the rack and holding it over your chest with a slight bend in your elbows. Lower the bar to your chest, extend your arms to the starting position and repeat. Perform two sets of 10 to 12 reps.
Chest flies, an isolation exercise that targets your chest muscles, are typically performed with dumbbells. The only movement occurs at the shoulder joints -- there is no movement at the elbows during a fly. To perform the exercise, hold a dumbbell in each hand and lie on you back on a weight bench. Start with your arms extended above your chest with your palms facing each other. Slowly lower your arms out to the sides in an arc motion until the weights are level with your shoulders. Pause for a count of one and then lift the weights and return to the starting position. Perform two sets of 10 to 12 reps.
Benefits of Bench Press
You can work more muscles in less time with compound exercise, such as the bench press, making it more time-efficient than a chest fly. The American College of Sports Medicine, ACSM, recommends basing your weight training on compound exercises, such as the bench press. The bench press is also a more functional exercise than the fly, meaning it more closely mimics regular movements you do in real life activities. Think of pushing a box or piece of furniture. This is very similar to a chest press.
Benefits of Flies
Although flies are an isolation exercise and mainly target only your chest muscles, they still have a place in your workout routine. ACSM does recommend selecting mostly compound exercises, but the guidelines also suggest filling-in your workout with some single-joint exercises. Flies allow you to focus on your chest, which is especially important if your chest is a weak spot or requires rehabilitation from an injury. Perform flies after bench presses to fully fatigue the chest at the end of your workout.