First, let’s put things straight: if you want to build really big arms, then you’ll need direct arm work like – yes – biceps curls. There’s no way around this.
As an example, consider StrongLifts Platinum Member Tom (21, USA). When he joined my private coaching program, he was Squatting 145lbs, weighed 130lbs at 5’10″ and had 10.6″ arms. Today he is well on his way to reach 300lbs on the Squat at 156lbs BW (a 26lbs weight gain so far… in just a few weeks).
What about his arms? From 10.6″ to 11.6″. A 1 inch gain… without a single curl. Just heavy Squatting, Deadlifting, Pressing and Pulling.
I challenge you to find a non-Squatting curl monkey who achieves the same kind of arm gains in just a few months. Few non-Squatters will ever get anywhere by just doing biceps curl inside the Squat Rack. Even fewer skinny guys understand they can NOT build 18″ arms unless they also start eating more.
Before I reveal what the secret is here, I’ll tell you what it’s NOT: compound exercises like Squats and Deadlifts do not unleash more muscle building hormones than other exercises like Biceps Curls. Research clearly shows that the hormonal response is just too little to make a significant difference.
The real secret here is that heavy Squatters are by definition training at a higher intensity than non-Squatters. Everybody knows that the guy who trains hardest will achieve the biggest gains. Well you can train hard more easily with exercises like the Squat because they allow for heavier weights.
More important: Squat and Deadlifts are challenging. It’s the guy who does them, consistently, even though he may not always enjoy it, that develops the strongest mindset. And this is the most valuable asset you can ever gain.