Fadi, firstly thankyou for taking the time to write a detailed and considered response.
My pleasure Simo, you're welcome sir.
When I mentioned overall mass in my question I was certainly not suggesting that squats were going to directly increase the size of your biceps. I thought it was inferred that since your OP was specifically discussing building 'huge muscular legs' that overall mass was in reference to this. So if I indeed do meet someone who tells me to squat to grow my biceps then I will set them right or send them your way!!
All good mate, my bad. Sorry about that.
I have another question though regarding exercise and protein synthesis, I may be going of topic a bit here so apologies in advance.
Not a problem, let's deal with the subject head on, perchance we'll both enrich our understanding of the topic further.
I have seen the material you posted in another thread around the effects of leucine on protein synthesis and read other interviews and articles with Dr Lane Norton. It is my understanding that whilst the correct diet (feeding) causes protein synthesis it is also effected by resistance exercise, so to make it really simple. Resistance exercise and Feeding is more effective than just feeding alone.
You're 100% correct Simo. In fact, a great emphasis has been placed on the catalyst by these scientists (and lifters in their own right), and that catalyst is non other than resistance exercises as you've rightly mentioned above. Actually, Dr Norton would tell you that the so much talked about 80% / 20% nutrition/training has no basis in science, and if anything, he leans more towards the training as the trigger for the whole anabolic cycle to follow post workout. So again, you're right on the money mate.
I have also seen studies that suggest that resistance exercise in the 70-90% of 1 RM has a greater effect on protein synthesis than exercise in the 20-40% 1RM range, so again to make it simple, more intense resistance exercise has a greater effect than less intense resistance exercise. Hopefully we agree on this.
I would love to agree Simo, however the latest scientific study conducted by Dr Stewart Phillips suggests that a set of 30% of your 1RM, when taken to failure, not only matches the 90% high intensity set, but exceeds it slightly. So I really do not see us disagreeing with each other here as much as having additional information not known before, now being added to the bigger picture of one's approach to muscular hypertrophy focused training. Happy to link that study, otherwise simply type the doctor's name and mention high repetition training. I've already put both the written study as well as a video lecture by the "Stu" Phillips on the forum.
So now my question, have you seen or read any studies that show whether particular exercises have a greater effect on protein synthesis than others ?
No I have not. And from what I've read, the prevailing understanding out there in the scientific community seems to speak of volume, effort, and frequency of training as being the main drivers of protein synthesis.
Do some specific exercises give more bang for buck ? For example does a squat do more than a leg press or vice versa?
Sure, but one needs to analyse such a deep question with likewise a deep answer, if justice to it is to be had here. On the surface, my (or the common) reply would be yes sure Simo, squats one compound movement, does in fact give you more bang for your buck than the leg press, yet another compound movement. This begs the question now, what "bang" are we really talking about here? I read your profound question this morning and it got me thinking (I like to think), so thank you.
You see, I need to bring an element of time here in order to give you a comprehensive answer. A compound exercise is great especially when you're a beginner. In fact , it's a must. Why is that? Because a compound exercise will dictate to you as well as indicate to you where your strengths and weaknesses lie. Not to do the basics as a beginner would be to end up looking like Popeye the sailor man. And no this was not a joke. If you look at Popeye, it seems that he favoured some serious isolation exercises, namely the wrist curls. The point I'm trying to make here Simo is that, left to our own devises, we would look seriously abnormal as far as muscle proportions are concerned.
Now as you move on from the beginner level and start to see some serious muscular development with your physique, the isolation exercises become paramount, as these are what really separate the bodybuilder from other iron lifters. I do not like to call isolation exercises "refinement" exercises but rather builders, and very serious muscle builders at that. In fact and to take this further, I do not like the term isolation at all. Why is that? Because it conjures up a wrong mental picture of some "easy" single joint only mover. Let's see now, I've written a whole article here on the number one upper body squat exercise (which hardly) anyone does these days, and that is the d/bell pullovers. Now that's an isolation exercise if we are to make our qualification as being a single joint movement. A d/bell concentration curl; a d/bell triceps kickback, and seated leg extension are all single joint "isolation" exercises, but can we even begin to compare these with the likes of a standing b/bell curl or a d/bell pullover? The answer is no we can not compare. Muscles do not work in isolation of each other, as there're always other secondary muscles at play, and/or plenty of stabiliser muscles working over time (such as in the standing b/bell curls) to insure we don't collapse onto ourselves.
Perhaps the above doesn't answer your real question:
For example does a squat do more than a leg press or vice versa?
The correct answer here would be , it depends. Also, at what cost? In other words, does the stress placed onto your spine outweighs the benefits you're getting through squatting? Perhaps you like to go light and rep it out so to speak. In which case, we need to ask, can your cardio-respiratory system sustain such load, or would that system give out before your muscular (quads/posterior chain/glutes etc.) is appropriately fatigued or stressed through a sustained muscular tension? When we're done here, we ask, is there not a better and more versatile way of placing your feet (when squatting) so as to shift the focus from (in my case) placing too much emphasis on the adductor longus (that's your inner thighs), where my pants used to always suffer with holes due to the rubbing/friction caused there. Sure my legs were big all over (28" at 5,3" tall), but had I continued squatting only, proportions within the leg muscles would've been a big issue. The leg press in my case, would give a lot more for my muscle buck here, as it freed my legs' stance from one restricted position (wide/ish), to an unlimited option of feet placements onto the pressing plate. Changing feet stance in one's squat is not an option, as one's line of power generation is governed by one's body's mechanics..., this law becomes pliable once one moves onto the leg press.
I'll stop here. Thank you.