Dumbbell flyes are considered an "isolation" exercise for building the chest.
Flyes were one of Arnold Schwarzenegger's favorite exercises and they are extremely popular in bodybuilding. But proper form is a must to avoid injury.
Muscles Worked
The chest muscles (pectoralis major, aka "pecs") are the primary movers. The sternal portion of the pecs (aka the "middle pecs" or overall chest) is emphasized the most. Front deltoids are also stressed. Triceps are involved to a much lesser degree than in dumbbell presses.
Advantages
Being an isolation exercise, flyes allow for greater recruitment of the chest muscles with less involvement from assisting muscle like the triceps. This lets you feel a strong contraction in the chest alone and allows for a strong mind-to-muscle connection.
Flyes are popular among bodybuilders as a way to add more volume to a workout (on top of presses), to build muscle and to achieve a great muscle pump.
Disadvantages
You can't use as much weight on flyes as you can on presses, so flyes are not as effective for maximizing strength.
Flyes also involve less muscle mass, so if efficiency is important to you, or if you can only choose one chest exercise, it would be better to choose a pressing exercise that lets you use more weight and recruits more muscle mass.
That's why flyes are often considered a finishing movement and are often added on top of presses, not instead of them.
Equipment needed
Dumbbells and a flat bench. (These can be performed on the floor if you don't have a bench).
Execution / Proper Form
Grab two dumbbells and begin with the weights over your chest with your elbows slightly bent.
Lie back while gently rocking the dumbbells into the start position over your chest.
With a slight bend in your elbows slowly lower the dumbbells out to the sides in a semicircular motion, keeping your palms facing up and maintaining the bend in your elbows.
Lower until your upper arms are approximately parallel to the bench or where you feel a slight stretch through your pectorals, depending on what your flexibility comfortably allows.
Return through the same path to the starting position and contract your chest muscles at the top.
Training Tips
Be sure to maintain a bend in your elbows throughout the entire exercise, even at the top. If you straighten your arms completely at the top, you lose some of the tension. Keeping the slight elbow bend makes it easier to squeeze at the top and feel the contraction.
Maintaining the bend in the elbows at the bottom is important to keep the stress on the pectoral muscles and off the elbows and shoulder joint and help avoid injuries to the pec tendon.
Lowering until you feel a slight stretch in your pecs - usually to where your upper arms are parallel to the bench - is proper form, but lower only as far as your flexibility and shoulder comfort allows.
Always avoid dropping down too low (below parallel). Over-stretching at the bottom can cause injuries to the shoulder joint, or the pec muscle and tendon.
Never drop the weights quickly, as this can increase the injury risk even more - lower slowly into a gentle stretch at the bottom.
Safety and Precautions
Many people have seen photos of videos of professional bodybuilders doing flyes with a deep stretch. That doesn't mean it's a good idea. Do not over-stretch on dumbbell flyes!
This is NOT a good exercise to go heavy on. The heavier you go, the greater the injury risk is amplified if you make any mistakes in form. As you do gradually progress the weights, putting slightly more bend in your elbows can reduce the risk.
Progressions (Make It Harder Or Add Intensity)
You can make flyes more intense by slowing your tempo slightly and using the peak contraction technique where you squeeze at the top of every rep. Drop sets are also a popular and effective intensity technique and a great way to cap off a workout.
