The reverse grip bench press is the best upper chest exercise for mass—it activates more muscle fibres of the clavicular (upper) pectoral head than any other exercise in existence. It's just a shame that the barbell version is such a risky movement. Otherwise, I think that it could easily replace the incline press.
However, there is an alternative, and he goes by the name of Mr Smith. You might have heard of him before because some people make their hatred of this poor fella very clear.
Me? I think he's a sterling chap—one who keeps you out of harm's way. It's why I always do my chest exercises on the Smith machine.
Ah yes! The Smith machine reverse grip bench press—that's his full name. What a wonderful stimulus he gives your upper chest! It's practically like being Arnold for the day!
Want a surefire way to wreck your wrists in a week?
Perform heavy reverse-grip bench presses—I'm talking one-rep max grinders—with a bent wrist.
Ok, please don't actually do that. Instead, once you've unracked the bar, you want to keep your wrists as straight as humanly possible. Imagine that you're throwing a punch in a boxing match. You'd obviously want to keep your wrists straight to stop your joints from absorbing the impact—and, you know, to knock the other bloke out.
According to the priority principle of strength training, the exercise that you perform first in a workout enjoys the fastest strength gains. Naturally, this benefit extends to muscle growth, too.
And listen, I know that you want to protect your precious flat bench press strength. But trust me, you're going to be gutted when you look at your beach photos next year and realise that you've still got the same saggy pecs that you've had since your teens.
Prioritise the reverse-grip bench press and watch your upper chest grow.
Using a narrow bench press grip might well help you to fill out your sleeves, but it's not going to do squat for your pecs.
Your chest muscles are like a rubber band—they need to be stretched to expand. And the best way to stretch your pecs and make them grow is by benching with a wide grip—especially when it comes to the reverse-grip bench press.
Even when performed on a flat bench (you can also do it on an incline) the reverse grip bench press activates significantly more upper chest muscle fibres than the traditional incline press .
Don't believe me?
Try this: raise one arm out in front you—palm down—and place your opposite hand on your upper chest, right below your clavicle. Now, rotate your palm so that it's facing upwards—think about turning your little finger as far as it'll go.
Did you feel the intense contraction in your upper chest?
Yeah, I bet you did. Now just imagine the muscle growth that this contraction will produce with some weight on the bar.
I'm salivating just thinking about it.
Since your elbows are naturally close to your torso during a Smith machine reverse grip bench press, it's actually a pretty good tricep builder. Just don't rely on it as your only tricep exercise, though. Because it's still primarily an upper chest exercise.
The front delts are highly active during reverse grip bench presses because the underhand grips put them in a position of intense shoulder flexion .
You might be surprised to learn that incline bench presses aren't the best upper chest exercise. And you might be shocked to the core to discover that some studies suggest that incline presses are no better than the regular flat presses for activating your upper chest! 
However, the reverse grip bench press—even when performed on a flat bench—is much more promising. Research from the Journal of Strength and Conditioning shows that bench pressing with a reverse grip activates between 25-30% more upper chest muscle fibres than lifting with an overhand grip .
This disparity is because your upper pecs are a potent shoulder flexor. And by that I mean they assist in raising your arm (hence why bodybuilders often perform low-to-high cable flys). Just look at the position of your delts when you switch from the overhand grip to the reverse grip. Your shoulders travel inwards, don't they?
This subtle movement—and the resulting pec contraction—is why the reverse-grip bench press is such a brilliant upper chest builder.
When you perform the reverse grip bench press Smith machine style, you're naturally placing your shoulders into external rotation. Now, besides making your upper pecs work harder, this positioning keeps your rotator cuffs safe because it gives them more room to move inside your shoulder capsule.
Ultimately, this dramatically reduces your risk of developing a shoulder impingement. Or, as I like to call it "bench presser's shoulder".
Have you ever heard of the novelty effect?
If you have, then great—you're probably enjoying the gains as we speak. But if you haven't, then allow me to open your eyes to this potent muscle growth accelerator.
Here's how it works: when you perform a brand new exercise (or come back to an old one after some time away), you force your muscles to adapt—and quickly. This is an evolved physiological mechanism that helps human to cope with the demands of the environment—hence why human existence was often referred to as the survival of the fittest.
But since we've stopped throwing rocks at each other, we no longer need to grow bigger and stronger (physically) in order to survive. However, we can still use the novelty effect to our advantage. Namely, to rapidly increase our muscle mass.
The best way to do this is by varying your exercise selection. Once you start to stagnate in strength progress (which is a good proxy for muscle growth) then it's time to switch things up for a few months.
And since most people have been doing incline bench presses since they were old enough to drink protein shakes, they're probably ready to receive some long-overdue upper chest growth. Maybe you're one of these people?
If so, then the Smith machine reverse grip bench press is where you should focus your attention. Once you make the switch from incline press, your chest simply won't know what's hit it. And as a result, it'll be left with no choice but to grow as fast as it possibly can.
Performing the reverse grip bench press Smith machine style is likely the safest and most effective way to stimulate your upper chest. However, if you're seeking overall upper body mass, then the incline Smith machine press is probably a better option because you can lift heavier weights and thus, overload your muscles with more tension.
If you know anything about my chest training philosophy, then you'll know that I'm very much a safety-first kinda guy. As such, I think that performing the Smith machine neck press for your upper chest is a hazardous endeavour—not just for your shoulder health, but also for your life.
Yeah, it's that dangerous.
As good as the Smith machine reverse grip bench press is, nothing beats the Smith machine barbell press when it comes to adding overall mass to your chest. It offers all the same muscle-building benefits as the free weight version—but in a far safer environment. I highly recommend it if you train without a spotter like I do.