One very common piece of advice to lifters is to squat and deadlift heavy, no matter what their goals are. This is generally sound advice. Both exercises involve a very large percentage of the body's musculature. They help you develop a strong back, strong legs, strong gluteals (your butt), and even a solid midsection.
But do they give you big arms?
The received wisdom is, yes, they do. They involve so much musculature that they cause the release of extra growth hormone and you get big all over.
One thing that's always bothered me about this, though, is the "lightbulb syndrome." Those chicken-legged guys with underdeveloped backs but ape-like arms and a strong chest. They bench press like crazy, and that's another large compound exercise like squats and deadlifts...but they don't result in bigger legs, or even a good back. You need to train them directly to get the benefit of lifting. Why is that? Are squats and deadlifts magic?
In the second half of this rather dense article, Lyle McDonald examines the evidence about this.
Scroll down until you see:
West et. al. Elevations in ostensibly anabolic hormones with resistance exercise enhance neither training-induced muscle hypertrophy nor strength of the elbow flexors. J Appl Physiol. 2009 Nov 12.
Essentially, a study suggested that the elevated growth hormone release from heavy leg training didn't elicit additional arm size gains over just training the arms directly without leg training.
Of course, the study had folks training one arm one way and the other arm the other, so it's not clear if it would have been different if someone totally lacked leg training. It's only a single study. But it's interesting to see someone testing this common knowledge. I'd really like to see more studies on the subject.
I have to apologize, though, this isn't very basic. But it is related to the kind of basic advice you'll see for newbie lifters. Does this study, even if it's right on the money (training legs doesn't help arm size gains), mean you can skip squats and deadlifts?
You still need strong legs and a strong back to be usefully strong (carry stuff, pick things up), to have more athletic potential (run faster, jump higher), and not look like a lightbulb. But it does suggest that "throwing in some curls" is not a wholly crazy idea, at that, if you want bigger arms. And that if you want something to get better, you need to train it - no matter how are you are training the rest of your body.