This is the perfect press angle for complete chest gains

Chapters:

00:00 Intro

00:31 Horizontal shoulder flexion

01:52 Incline bench press

02:40 Decline bench press

03:40 EMG research

07:26 Ultrasound research

09:14 My online PT Certification course

10:09 Ultrasound research

11:26 The single long term study

16:35 Conclusion

18:58 Outro

Transcript:

The incline bench press does not do what you think it does. In bodybuilding lore the idea is that an incline bench press is better for the upper pecs, the clavicular head, which is attached to the clavicle and decline bench pressing, pressing down is better for the lower pecs. It kind of intuitively makes sense.

The decline press you press down, it’s the lower pecs that are activated more, if you press up, it’s the upper pecs are activated more. However, if you really think about it biomechanically it doesn’t necessarily make sense. When you’re doing a horizontal shoulder flexion, or adduction, so basically bringing the elbows together from the front like a fly type movement or press, when you’re doing that movement all of the fibers of the pecs should be maximally recruited. You’re doing a horizontal shoulder flexion movement so all horizontal shoulder flexors, when that is the primary limiting factor for the movement should be maximally engaged. If you do elbow flexion it’s the elbow flexors that activate. Only if something significantly prevents a muscle from activating will it not fully contribute.

That might be the case with bi-articulate muscles where one function of the muscle is at odds with the movement and the other is beneficial. For example, the hamstrings during a squat. If they would activate they would assist in hip extension, which is good, but they would also sabotage the quads because they do the opposite of the quads and they would flex the knee. The force production that they contribute is not net beneficial for the exercise and therefore the muscle doesn’t contribute. That is not the case with either the upper or the lower pecs during a flat or horizontal bench press.

When you are at 90° of shoulder flexion, so your arm is straight out to the front and you are doing a bench press or a fly type movement all of the fibers should be maximally recruited because the pecs are like a fan shaped muscle. All of these fibers assist in pulling the origin and the attachment closer together, which means the arm goes towards the middle of your body. That’s horizontal shoulder flexion. If you do a horizontal shoulder flexion you’re going to recruit the horizontal shoulder flexors. if you now incline the bench, you don’t necessarily activate the upper pecs more they should already have been maximally active to begin with. Yes, they will still contribute even if you shift the demands from horizontal shoulder flexion to vertical shoulder flexion, so just raising the elbow, but there’s no improving over the flat position, you would expect at least biomechanically. You do reduce the activity of the lower head because as the demand of the exercise, the force production demands shifts from horizontal shoulder flexion being the limiting factor, to shoulder flexion like an overhead press being the limiting factor, you will progressively recruit the lower pecs less because the lower pecs can only assist in the horizontal shoulder flexion. So when that is no longer the limiting factor of the movement they will no longer fully contribute. Plus, they will also pull the elbow down a little bit.

The same goes for a decline bench press. It logically biomechanically follows that the upper pecs at some point of decline at least, will stop contributing as much, and if you would fully decline, you cannot do this with a press, but at some point you would just be doing pure adduction and you would just be bringing your elbows to the side in that case. So similarly, with a decline press you would expect that the lower pecs remain fully active, but the upper pecs stop contributing as much. So you do change the ratio, but you don’t necessarily train the lower pecs better. In the rest of the video I’m going to be focusing on the incline bench press, because the decline bench press is not very popular for good reason. You limit the range of motion which we know now is very detrimental for muscle growth, you don’t get as full of a stretch as you do with a flat bench press, and most people want to, if anything, emphasize their upper pecs because it’s more of a common problem that people have overdeveloped lower pecs relative to the upper pecs. or at least that’s people’s perception. So decline bench press for many reasons is not very popular. It’s not a great exercise and it’s also not very in demand. So I’m going to be really focusing on incline bench press.

The first line of evidence comes from EMG research. Electromyography measures the level of muscle activity. Basically, it’s a measure of the signals sent to the muscle to activate it to the level of electrical activity going on. And that should correspond with muscle activation, recruitment, and subsequently muscle tension, and in some way at least muscle growth in the long term.

If we look at the EMG research, muscle activity of the upper pecs is not very much enhanced by using an incline, exactly as you would expect based on the biomechanics. You do see a very pronounced reduction in the lower pec activity when you incline the bench press. For example, if we look at the graph here, which is representative, multiple studies have confirmed this, the trend is the same in most of the studies. So you can see here at the top that as you progressively incline the bench, you get closer to an overhead press, then at the top you can see that the front delts start contributing a little bit more. Actually not that much difference, which makes sense because again, during a flat bench press, front delts assist the pecs with horizontal shoulder flexion.

Now if you go one down, you can see that the upper pecs there is somewhat of a trend that they increase as you inclined the bench from 0 to 30 degrees. And I’ll go into this in a bit more detail later, but I think it’s in part because a flat bench press for many people is not actually a truly horizontal bench press. When you do a flat bench press and you bench press with an arch, which most people do, that is effectively creating a bit of a decline. So if you think of like, 90 degree shoulder flexion, the arms fully straight ahead and then arch the upper back, you can already see it’s essentially the effect of a decline. Like if I would stay the same and I would just lean back, or if I stay in this position, but I arch my back a lot, in terms of the angle between the chest and the arm it is the same effect. You reduce the level of shoulder flexion and with an incline you increase it. So effectively when you’re benching with a little bit of an incline, like in these studies, 15 to 30 degrees incline, that offsets the effect of arching on reducing shoulder flexion.

So arching reduces the degree of shoulder flexion. It reduces the angle between the arm in its pressing trajectory and your pecs, whereas inclining the bench increases it. So they offset each other. And you get basically back to the 90 degree shoulder flexion, which is kind of the ideal press with a very slight incline. And these data kind of support that, but if you look one measure down you look at the middle pecs, then you see that there is a pronounced decrease. The more you incline the bench, the lower the activity in the middle pecs. And the lower pecs are basically the same, which makes sense because there isn’t really a middle backs. There is just a sternal head, which is the pecs, the fibers that are attached to the sternum, your middle of your ribcage, the bone in the middle here, and you have the clavicular head, which is the upper pecs, which are the fibers that are attached to the clavicle.

So middle pecs doesn’t really exist. There’s also no inner pecs, by the way. You do feel certain parts of the muscle more and generally in full contraction you get the squeeze, you tend to feel up more in the middle part and the stretch you feel more in the outer part, but that’s just a sensation issue. It’s not actually a difference of function within the pec fibers. There’s no inner or outer pec differentiation in terms of functionality. And if you look at the bottom part here you have the triceps and it stays about the same.

Findings of the triceps are a little bit mixed. In general it doesn’t seem to change much and we’re also not going to go into it into much detail in this video. Incline bench press, decline bench press, whatever, it doesn’t actually have that much effect on the triceps, probably. So what is the general take home message of the EMG studies? Well they actually align perfectly with biomechanics in that when you incline the bench you maintain high tension and high muscle activity levels and recruitment in the upper pec fibers, but in the lower pecs you significantly reduce the contribution, you significantly reduce force output. You do get emphasis on the upper pecs as you do an incline bench press, but incline bench pressing in absolute terms is not better for your upper chest than flat bench pressing. You’re just reducing, you’re isolating it more, you’re reducing the contribution of the lower pecs without increasing the stimulus for the upper pecs.

In addition to the biomechanics and the EMG research, we also have ultrasound research and it perfectly aligns with EMG research and again the biomechanics. So we have one particularly nice study that looks at ultrasound changes and EMG activity in the pecs with flat versus incline bench pressing and as you can see here, swelling in the upper pecs with incline bench pressing was no greater than with a flat bench press, but the swelling in the lower pecs was significantly less. And this pattern was the same in the ultrasound muscle swelling and the EMG muscle activity showing that EMG research does actually correspond with other metrics like ultrasound, there’s also a lot of research that EMG muscle activity corresponds with the pattern of muscle activity, as measured by MRI. EMG research does not linearly translate to muscle growth very well at all. That’s for due to numerous factors, but in terms of measuring muscle activity within a very constrained set of movements, when the research is very well conducted, it’s actually not that bad.

Some people think that EMG research is completely useless because it doesn’t translate linearly to muscle growth. You have to be very careful in knowing how to interpret it and the study has to be well conducted, needs to have the appropriate normalization, for example, the electrodes have to be placed on the right spots. But when all of that is done, EMG research does have pretty good validity. It corresponds with ultrasound, it corresponds with MRI to measure muscle activity, and it also corresponds with subjective muscle activity. So when people say that they are training harder or when they feel the exercise is harder EMG activity is also higher. And we also see that objectively as you increase the weight for an exercise EMG muscle activity also increases. So EMG research has tons of limitations, but it definitely has its use cases and in the absence of other like long term data for muscle growth, which we’re going to go into in a moment, it is imprudent to completely disregard it simply because it has some limitations, especially when it aligns with the biomechanics.

And how does ultrasound work? Well, ultrasound basically measures the actual size of the muscle and therefore the change in the muscle size, the muscle thickness or the cross-sectional area, both were measured in this study and both increased in a similar pattern. It’s a measure of both muscle damage and muscle activity, because when a muscle is more active, there are fluid changes and generally the muscle swells. You also get the pump, and you can see that in ultrasound or MRI as an increase in muscle thickness or cross-sectional area. So it’s kind of a blended measure of muscle activity and muscle damage. At least it’s a measure of something going on in the muscle and we do have some research indicating that the acute swelling in a muscle does correspond with long term muscle growth. But it’s not the same as saying that the pump translates into muscle growth. Because the degree of ultrasound muscle swelling is not necessarily the same as the amount of pump that you feel like.

It’s very difficult to get a sense of internally what is the actual cross-sectional area increase in my muscle, right? It’s more of a sensation of the burn and yeah, the muscle is pumped, you see veins and stuff… That doesn’t necessarily correspond with the actual ultrasound muscle thickness level. Broadly speaking, ultrasound completely agrees with biomechanics and EMG research: Incline pressing – same effect for the upper pecs, but lower activity in the lower pecs. So far all lines of evidence show what researchers call consilience, that all lines of evidence agree with each other. However, here’s where things get interesting.

We only have one long term study measuring muscle growth with incline versus flat bench pressing. And normally I would say the best we have is a long term study actually measuring the level of muscle growth. Unfortunately, the research here does not correspond with the theory at all, and the research findings of this study are a little bit peculiar. So this was a study from 2020 by Chaves et al. in Brazil and they had untrained individuals for eight weeks bench press with either flat or 44 degrees incline. Basically 45 degrees. And they also had a group that did a combination of both with half the volume in flat bench press and half the volume in incline bench press. So here are the findings.

After eight weeks, there weren’t a lot of statistically significant differences between the groups, but overall the trend was very clearly that incline bench pressing was simply straight up superior to everything else. If you look at the pattern of muscle growth here, pattern was actually the same for the upper, middle and lower pecs. On the top left here, the second intercostal is the second rib down, basically upper pecs. Statistically significantly even the incline bench press had greater muscle growth than the horizontal and a combination groups.

Okay, this part I could have believed for sure. Maybe the theory is just wrong and the, you know, the intuition is actually right that, you know, when you look at the third intercostal, so this is like one rib down, which is more middle pecs, it’s actually the same pattern. No longer statistically significant, but if you just look at the dots it’s very much the same pattern. And then if you go to the fifth intercostal space, which is the lower pecs, it’s pretty much all the way down on the chest… Again, the same pattern. And this I find very incredulous.

I would have believed it if the pattern was: with an incline bench press you get more growth in the upper pecs, and less growth in the lower pecs. But the finding that incline bench pressing in absolute terms here is simply best for all of the fibers of the pecs, this was like a 33% higher level of muscle growth in absolute terms, with incline bench pressing for the lower pecs than with the flat bench press. Not statistically significant. So if we just go by statistical significance then the finding would be: incline bench pressing is better for the upper pecs, upper chest and equally effective for the rest of your pecs. But the trend here clearly is just that incline bench pressing is better for all of the pecs, which I find quite incredulous.

If you look at the strength changes, it’s similarly incredulous. Here you see the percentage change in “load lifted”, which is basically strength gains and you see that the change in load lifted for the horizontal bench press with horizontal was worse than with horizontal and incline. This was not statistically significant, but the trend is again that adding incline bench pressing to flat bench pressing is just superior. Now, this might be and some other research supported this because when you add exercise variety it improves motor learning. Especially in untrained individuals when you do a couple of different exercises that are kind of similar it improves the motor learning and it might facilitate strength development. If we look at the change in load lifted for the incline bench press, so strength gains on the incline bench press, we see that incline bench pressing is significantly better than doing a combination of horizontal and incline bench pressing. Again, this is incredulous.

I would have believed it if there was indeed an effect of adding exercise variety that improves strength gains, but then you would expect that adding the horizontal bench press to the incline bench press also improves strength gains for the incline bench press. The fact that incline bench pressing is best for incline bench press strength, but flat bench pressing is not best for a flat bench press strength especially with the pattern of muscle growth being superior for all areas of the pecs for the incline group, it strongly suggests that something just made the incline group have better gains. Maybe they trained harder, maybe there were more genetically gifted individuals in that group. This would be a case of type I error. Maybe I’m just completely biased and I want to stick with the theory but there was actually a very good reason that we should be very cautious with the study results.

There was a 35% dropout rate. That’s very, very high for a study in which you get physically active individuals that are already doing sports or something that were not strength trained, but they were doing some type of sport multiple times per week, I think three times a week, and all you require from them is that one time per week they go to the gym because this was a low volume program, which again makes the findings even more incredulous because they have very big changes, the differences between group without a high volume training intervention Just training the bench press once per week, what I think it was 4 to 6 sets. So the demands on the subjects were very low. These were people that were already very interested in fitness and just for just eight weeks, one time per week they had to go to the gym. That’s it.

So in a study like this you would expect a very high adherence. In most of these studies in English speaking countries at least, also in the Netherlands and the like you see that compliance for these studies is normally very high. 35% dropout is high even for a nutrition intervention in which you very carefully have to track your macros. That is a very, very big red flag and it increases the chance that you get some difference between the groups that was unintended, where you randomized people at the start to get indeed a random distribution of individuals, and people train approximately equally hard in all groups. But when you get a very high dropout rate like this, it significantly increases the chance of type I error that do get some weird findings that just don’t make any sense. They’re just a fluke. Especially when you combine it with eight week intervention in untrained individuals on a low volume training program, I would say that these findings are sus to say the least.

So where does this leave us?

Well, it leaves us in a bit of an uncomfortable spot. Biomechanical analysis, EMG research, and ultrasound research all suggest that if you incline the bench, you reduce the activity of the lower pecs, thereby emphasizing the upper pecs more, but your upper chest growth will probably not be enhanced because the absolute stimulus is not greater. When you do a flat or horizontal bench press you should get maximal recruitment of all the fibers of the pecs because that is their mechanical function. However, the only study we have basically suggest that incline presses are straight up superior. But like most studies in exercise science it is a small and short study and in this case, it’s also a Brazilian study with a very high dropout rate. Personally, I am the most confident about the biomechanical analysis, especially seeing as it’s also supported by EMG and ultrasound readings, which means I don’t see a whole lot of use for decline and incline bench pressing. If you want to emphasize the upper pecs – incline bench pressing is very good, but I think you’re best off doing most of your bench pressing with a roughly 90 degree angle between your pecs and your arms.

However, this does not mean that you’re actually doing a horizontal or flat bench press because as I said, when you bench press with an arch, which most people should probably do for shoulder health reasons and to pre-stretch the pecs and for stability, that’s a topic for another video though, when you bench press like that, you are essentially turning it into a slight decline and if you use a moderate incline like 15 to maybe 30 degree incline, if you have a really big arch, that offsets declining effect of your arch and puts the angle of shoulder flexion back to approximately 90 degrees, which theoretically should engage all of the fibers of the pecs. So I recommend by default that should be the position in which you do most of your pressing if the goal is total pec development. I recommend that you do most of your pressing with a slight incline. If you want to emphasize the upper pecs specifically, it does make sense to use a larger incline, but note that it’s unlikely, at least in my view, to significantly enhance growth in the upper pecs. It’s mainly going to decrease growth in the lower pecs. Decline bench pressing has very little utility, because it’s probably also not going to enhance gains in the lower pecs for the same reasons, plus, the reduced range of motion and reduced stability when you’re bench pressing without your feet on the ground and a good ability to retract the scapula into the bench. So decline bench pressing – I’m particularly not fond of. Incline bench pressing does have its use, but I think it doesn’t do what most people think it does, which is enhanced growth in the upper pecs.

Alright! I hope that helps you with your chest gains. If you like this type of evidence based content I’d be honored if you like and subscribe.