Performing a close-grip bench press on the Smith machine is the most reliable, test-backed strategy for building titanic triceps quickly. Why?
Because you can devote 100% of your attention to blasting your triceps.
In other words, you don't have to waste valuable energy stabilising the barbell. And you most certainly don't have to hold yourself back over a fear of not being able to re-rack the weight.
However, before you can realise the countless close grip bench press benefits for yourself, there are 3 fatal mistakes that you must avoid. Otherwise, you'll be putting your joints in jeopardy.
Gripping the bar too narrowly is the most common close-grip bench press mistake—and it's by far the most devastating. Many lifters falsely believe that placing their hands inside shoulder width—or even just a few centimetres apart—is the best way to fire up their triceps.
Unfortunately for them and their wrists, this couldn't be further from the truth. Not only does research show zero benefits to using a closer-than-shoulder-width grip, but it also proves that such a grip places tremendous strain on your wrists.
Moreover, gripping the bar inside shoulder width kills your strength because your triceps and shoulders can't fire properly. And guess what that means?
A puny pair of arms because your triceps aren't getting the tension they need to grow—that's what. So, if you want to keep your wrists healthy while maximising your tricep development, use a shoulder-width grip and nothing narrower.
The triceps are hinge joint—they only work in straight lines. So keep your elbows pinned to your sides.
If your elbows move in a diagonal line (as they would during a regular bench press), then you're not tucking your elbows enough. Plus, you're shifting the tension onto your chest, which defeats the purpose of performing the exercise—and it stresses your shoulder ligaments.
And listen, I know that some of you lads like to think that your lats are just too big for you to be able to tuck your elbows. But if pro bodybuilders can keep their elbows tucked, then so can you.
If using an excessively narrow grip is the quickest way to wreck your wrists, then neglecting to retract your scapula is the quickest way to sabotage your shoulders.
Now, I don't want to bore you with endless anatomy talk—I'll let your ageing physio do that.
However, you need to understand that when you don't squeeze your shoulder blades together and puff your chest out, you're reducing the subacromial space in your shoulder capsule. Subacromial space? Say what? It sounds complicated, but all it means is that your rotator cuffs become restricted, which often results in shoulder impingement syndrome and bursitis (painful).
But, by retracting your scapula (which is to say keeping your shoulder blades pinned back), you naturally give all the small components of your shoulders more breathing room by increasing the subacromial space. Have I still got your attention?
Since the triceps function to extend the elbow (as in lock out a bench press), they're naturally the prime movers in the Smith machine narrow grip press. You can, however, increase their activation even further by employing what bodybuilders call the mind-muscle connection.
This is where you actively think about stretching and contracting the muscle as you lift the weight. And, with practice, these internal cues (as scientists call them) can provide you with a much more intense arm pump since you naturally get better at "switching on" the muscle, so to speak.
The front delts are highly active during the close grip Smith machine press because they're the body's main shoulder flexor. In practice, this means that they raise your arm in front of your body—as in a front raise.
Some bodybuilders believe that the close grip bench press is an especially effective inner chest exercise. But is this just broscience?
Well, yes and no. You see, the pecs assist with what's called transverse shoulder abduction. Or, in plain English, bringing your arms across your body (like in a chest fly). So, since your arms are naturally closer to the midline of your body during a close grip press, the inner chest is indeed highly contracted.
However, it doesn't receive the same kind of stretch that it gets during the traditional bench press because your elbows move straight up and down (or at least they should) rather than out to the sides.
So overall, I'd say that close grip bench is worse than regular bench presses for your inner chest because the stretch portion of a rep is generally considered to be more important for muscle growth than the contraction.
The bench press is the world's most deadly shoulder slaughterer—it wrecks its victims' rotator cuffs with devastating efficiency. But, despite their agony, they keep coming back to their irresistible terroriser because they'll do anything to get a bigger chest. And that most certainly includes sacrificing their shoulder health.
Of course, with a few smart modifications, you can turn the bench press into a much less hazardous exercise. However, it's never going to rival the close grip Smith machine bench press in the safety department (though wearing a Sling Shot can improve your form).
Anyway, the close grip bench press is extremely shoulder-friendly. Since research shows that bench press grips beyond 1.5x shoulder width increase injury risk, it follows that more moderate grips are much healthier for the shoulders.   
The triceps are an explosive, fast-twitch muscle—they grow from lifting heavy weights like a baby grows from drinking milk. It's why benching pressing powerlifters have much bigger arms than the old ladies who do tricep kickbacks with pink dumbbells—they understand progressive overload.
The bottom line is that no exercise overloads the triceps and forces them to grow more than the Smith machine narrow press.
Forget stabilising the bar. Forget the awkward lift off. Forget holding yourself back so that you've got enough energy to re-rack the weight. Forget free weight barbells. The close grip Smith machine bench press is the new cure for small triceps—protein required.
Ok, let me ask you a question: what's the fastest way to increase your bench press strength?
If you answered "roids", then you'd be correct. But do you know what the second-fastest method for increasing your bench press strength is?
I'll tell ya—becoming more explosive.
Muscles are designed to move explosively. How else do you think humans escaped predators in the past?
By not priming your triceps for explosiveness, you're leaving a ludicrous amount of bench press strength on the table. And you're probably missing out on a lot of muscle growth too.
Thankfully, the Smith machine close grip bench press (CGBP) is the perfect exercise to expedite your explosiveness because you're putting your triceps in their strongest pressing position. As a result, you can naturally produce more power and move the bar faster, which are the two cornerstones of explosiveness.
And to think people still do bodyweight bench dips.
The Smith machine tricep bench press works wonders for beefing up a puny pair of arms. However, if it's more chest size that you're after, then few exercises are better for adding masses of pectoral muscle than heavy decline Smith presses.
Performing Smith machine tricep extensions at the end of an arm workout is a fun yet effective way to fill your sleeves. Using nothing but your bodyweight (or an optional weighted vest), these triceps extensions help your arms to grow faster by recruiting all of the remaining muscle fibres that your workout couldn't reach.
Bodyweight tricep extensions are a surprisingly challenging exercise, so don't underestimate the results that you can achieve by performing them.
If there was ever a true "tricep push up"—this is it. Besides strengthening your core, the medicine ball push up taxes your triceps by making them work harder to stabilise your body. It's a brilliant exercise to do with just your bodyweight. But by adding a weighted vest into the mix, it could easily become your go-to mass builder for triceps.
In terms of the Smith machine close grip bench press vs the barbell close grip bench press, there are a few key differences to consider.
First—and most importantly—the Smith machine version is much safer than the traditional lift because you can re-rack the bar at any point in the set with a simple wrist turn. This inherent safety enables you to train without a spotter.
Also, the Smith machine narrow grip press enables you to focus purely on your triceps because you don't need to stabiliser the bar. This enhanced focus naturally leads to a stronger mind-muscle connection and likely more muscle growth, too .
Lift with between 6-12 reps per set if your goal is to build muscle. If you're a powerlifter, then you can also dip below 6 reps, which will help you develop more strength.
Perform between 3-5 sets in any given workout. The more advanced you are, the more sets you should perform. However, beginners can grow from performing just 1-3 sets because the triceps already get a lot of work from other pressing movements.