I’ve seen plenty of situations where people can gain 2-3cm to their arm with only a small amount olf overall body weight gain. Go to any commercial gym and you will actually PLENTY of guys with pretty good arms and who are 70-75kg. They train arms, chest and delts, a little back and almost no legs… and they end up with pretty big arms, ok chest, ok delts, some back and no legs but overall they don’t weight much.
I have also worked with plenty of athletes who have added a lot of body weight without gaining much on their arms. A good friend of mine is Canada’s 2nd strongest man (competed internationally) and he started at 100kg with 42cm arms and is now at 130kg with 45cm arms.
And you mention local swelling etc, to lessen my point. But what about fat gain and arm size. HONESTLY gaining 10kg of MUSCLE in one year is an amazing year after the beginner stage. Fred Hatfield (since you like to name drops, I’ll do it myself) published date where he showed that past the beginner stage, at the most, you can add anaverage of 0.22kg of muscle tissue per week…and that is if you do everything perfect. That is around 10kg per year. And many experts wrote than an average, non-drug using male, can add 20-25kg over his “normal adult body weight” in muscle throughout his trianing career. So that would mean that the normal person could only add 4-5cm to his arms during his whole training career.
Here’s the thing. Don’t forget that McRoberta was of the “Bulking and cutting” school of thought… he recommended mega eating to bulk up. Guys of that era would routinely gain A LOT of weight, but a large portion of it (a lot more than the experts of the time believed) was fat. AT LEAST half of it. It’s hard to evaluate how much weight you need to gain when you don’t differenciate between fat, muscle and water.
Listen, the “you need to gain 5kg to add 1cm to your arm” is a white lie. A white lie is something inaccurate that you tell someone to get them to do the right thing… if you believe that you need to gain 5kg to add 1cm to your arm you will focus on eating and training the bigger muscles of your body instead of just doing arms.
BTW this forum is for me to help other people with their training issues. It is not a place to debate with me.
If you get bigger overall it means that you are focusing on the big lifts which, of course, will help you get bigger arms. And YES you need to gain some weight to add weight to your arms (heck just the tissue added to gain 1-2cm weighs something). But I do not agree with the 5kg for each cm “rule”. I think that for some it will be a lot less than that (depending on their genetics and type of training).
I’d like to know how McRoberts came up with his ratio (I’m pretty sure that Charles took that from him). My theory is that he looked at bodybuilders of his time and asked them what their body weight and arm size was when they started out and what they were right now. And he calculated the average weight gained, and the average arm size progression and came up with his rule.
But by then whole body session with only big basic lifts where the norm. VERY few people specalized on arms and certainly not the competitive bodybuilders, so this ratio doesn’t take into account what could be possible to accomplish by doing more work for arms.