Well, I suppose I will start off with a bit of back story. To help you understand exactly why I began weight training. I am 21, and have been milling around, watching life go by as it tends to do. I have very little experience with the world of weight training and recently decided I need to change that. I am also in the process of becoming a Fire Fighter and have 5 months to get into shape for a Physical Apptitude Test administered by the County.

Anyway, since exactly, October 1st, 2007, I have begun weight training in preperation for this event. Now, my routine involves working out just about every muscle I can, biceps, triceps, abs, chest, lower back, upper back, deltoids, calves, buttocks, quads, etc etc... My friend, who is by no means a weight training guru, told me that I should focus on specific muscle groups per session. Instead of doing everything at once. Although, I can't help but notice that over the past three weeks I have made, what appears to be, a significant change in my muscle mass. Is this an illusion? Is my friends advice accurate?

Also, last bit of information, I am 6'4" and weigh about 185-190lbs. I'm not sure if that information is needed, but I thought it may help people determine whether I am crazy or sane.

Thanks alot everyone!

I say 1 hour of full body workout, three times a week is far better than spending many hours working out just 1 muscle group.

If your diet is correct, and your weight training is short and intense, you'll see the benefits.

For what you are going for, I would say that this is probably exactly what you don't want to do. I have no idea what this test is like, but as a firefighter you want to be able to functionally use your body, even much more so than the average guy. This means training your muscles in the gym to work as they will when you will need them.

It's really difficult to know what he means, but I'd find a way to do a full body workout which uses mostly large compound movements and very few isolation exercises. Squats, deadlifts, rows, chins, dips, presses - and variations on all of them - these sorts of things.

What are you doing now (what exercises in what order)? I'm sure a lot of folks here would be happy to take a look at it and provide some advice.

Like people have said, full body workout is the way to go. But the reason you've seen a significant chagne in muscle mass is that newbies to wieght lifting will see significant results early on no matter what program they use. Your friends advice is not accurate unless you are a steroid taking body builder.

Your main friends in lifting are the Deadlift, Squat, Bench, and Bent Over Row.

You also need some military press and pullups in there, and you've covered almost every base.
As a fire fighter, or anyone trying to bulk, you need to do deadlifts. studies show that firefighters are able to pick things up with the least strain on their backs because you learn how to on the job. Deadlift is the best back strengthening exercise there is, and it'll be your best friend.

You will see great results following a simple program, you could even switch between just two workouts, 3x per week.

lets say,
Squats,
Bench
Bentover Row
Lunges

Deadlift
Military press
Pullups
Bulgarian squats