This exercise could be the most effective pec builder. There, I've said it. Am I committing a cardinal sin by saying the best exercise to build the pectorals isn't a big barbell lift? Well, hear me out.
This is coming from someone who loves the bench press, incline press, and heavy dips... someone who has benched 445 pounds. Yet, at the height of my pressing power, my chest was my least developed muscle group. (My delts and triceps did most of the work.)
The best way to develop your pecs is with an isolation exercise... kinda.
The flye press is the lovechild of a dumbbell flye and a dumbbell press. You do the eccentric (lowering) portion of the movement as a flye and the concentric (lifting) part as a press. There's a little more to it than that, but take a look:
Why is it the best pec-building exercise? To find out, we need to look at two of the main mechanisms behind muscle growth: muscle damage and mTOR activation.
When you want to maximize both, the key is to lengthen/stretch the muscle fibers while they're under tension. The more tension the fibers produce when they're lengthening, the greater the muscle damage, mTOR activation, and subsequent growth.
When the muscle fibers are producing more tension (more force), more actin-myosin bridges are created within each fiber. And the more bridges you have while you're forcefully stretching those fibers, the more damage you'll create.
The purpose of the concentric phase is to recruit more muscle fibers and make them produce more tension to increase the number of actin-myosin cross bridges. This sets up the eccentric to be done under the best possible conditions to trigger growth (lengthening the fibers under control while having maximum tension).
If you have very little tension at the end of the concentric range of motion, it'll be much harder to get the most out of the eccentric phase. That's the limitation of regular dumbbell flyes and even the bench press.
During a regular dumbbell flye, there's a lot of tension on the pecs from the bottom position up to around the middle of the range of motion. When you approach the end of the lifting phase, there's very little tension on the pecs.
The flye is a great exercise, in theory, because of the stretch you impose on the pectoral fibers. But because you lose a lot of tension at the end of the lifting phase, you make the subsequent lowering phase much less effective.
Not to mention that you can't use a lot of weight with normal dumbbell flyes, which also decreases fiber recruitment and tension.
That's where the dumbbell flye-press combo comes in. By doing the concentric portion of the lift as a press, you can use more weight (more tension) and because of the line of action (pretty directly against gravity) you can maintain a high level of tension right to the end much more easily than with a flye.
More weight and maintained tension mean that you'll start the eccentric phase, which you'll perform as a flye, much more effectively. You'll be using more weight and producing a lot more tension while you're stretching the fibers during the eccentric. This will cause more muscle damage, mTOR activation, and a greater growth stimulus.
How to Do It
- Start from the top (arms in a finished dumbbell press position). Lower the weights down slowly (4-5 seconds down). You want a slight elbow bend to shift most of the work onto the pecs instead of the biceps and front delts, but not too much.
- Go as low as you can, really feel a good stretch in your pecs.
- In the low position, bring the dumbbells in by flexing the elbows until the forearms are perpendicular to the floor, getting into a pronated position. Press up and slightly inward, focusing on squeezing the pecs.
- When you reach the top, start from step one.
- Once it's hard to keep lowering the weights under control and you likely won't be able to lift them back up, hold the low position of the flye as long as tolerable for your last rep. Try to eventually reach 30 seconds or more.
- There's no exercise that'll provide a better direct growth stimulus to the pecs, especially not with minimal equipment.
Do 6-10 reps per set. Lower the weight slowly (3-5 seconds) and lift at a moderate speed that'll let you concentrate on contracting the pecs. You should be able to use around 80-90% of the load you'd use on regular dumbbell presses.