5 reasons you should be focusing on big bang-for-your-buck exercises
Let's say you buy a crappy old apartment and want to do it up. It hasn't been looked after, and top to bottom, it just looks like a dump. Well, you decide to give it an overhaul and begin by painting the skirting boards, and I mean really painting the skirting boards. You get good quality paint and new brushes and go to town spending hours and hours making sure the skirting boards look perfect, while the rest of the apartment still looks like a dump. That doesn't matter though, because those skirting boards are looking pretty damn good.
If any of this sounds stupid to you, then why are you doing the equivalent in the gym? Your whole body needs a lot of work, and yet you insist on focusing on your biceps with isolation exercises like dumbbell curls. I have some bad news for you: if you're a fat guy, and you do a lot of curls and improve your arms, you'll still be a fat guy, albeit with slightly bigger arms. The good news, however, is I have the answer for you: compound exercises.
In short, isolation exercises are exercises which move only one joint. For example, a bicep curl targets the bicep, and only moves the elbow joint (in theory - I realise a lot of people curl starting with the legs and swinging with their back). A chin up, on the other hand, is a compound exercise as you move at the elbows and the shoulders. It targets the biceps as well as the back - like a two for one deal.
Now you know what a compound exercise is, here are 5 reasons you should do them instead of isolation exercises:
1. Use more weight, use more muscle
Not only do compound exercises use more muscle as they have to both stabilise the body and move multiple joints, but compound exercises also allow you to use more weight. Think about how much weight you can lift in the bench press, compared to how much weight you can do in the chest/pec fly. Unless you're sporting DD cup sized pecs and skinny arms, you should be able to lift far more in the bench press. More weight recruits more muscle fibres and this is what you want for maximum benefit.
2. More weight, more total work
Excuse the nerdiness for a second, but energy expenditure is related to "work". "work", in basic terms, can be defined as force x distance. Force can be defined as mass x acceleration. Distance can be defined as how far. Acceleration can be defined as how fast. I hope I'm not confusing you.
Basically this means that moving a greater weight over a greater distance requires more "work", which uses more energy. Think about lifting 50 lbs a little bit off the ground, compared to lifting 100 lbs up above your head. As compound exercises allow you to use more weight, and generally have much greater range of motion (i.e. distance the weight travels) when compared to isolation exercises, they are going to burn more energy. If you have any interest in not being overweight, this is a good thing, and another reason to choose compound over isolation when selecting your exercises.
3. More muscle recruited, more hormones released
Hormones are not just good for making chickens big and muscular - they work the same in humans too, that's why bodybuilders and athletes alike inject themselves with hormones in the pursuit of larger, stronger muscles and smaller testicles. What you might not know is that your natural levels of hormones in your body are influenced by resistance training (and because your body makes them itself, your balls won't shrink either). What you probably don't know is that the type of resistance training affects the amounts of hormones released.
Specifically, if you recruit more muscle mass, you will release more growth hormones into the blood, and you will get massive, provided that's what you want. If you want to lose fat, it'll do that too. And if you want to earn more money, dress better and fix your stupid haircut, it probably does that as well.
You can skip this point if you want to spend the rest of your life moving purely in sequences of bicep curls, shoulder raises, tricep extensions and leg extensions. Fair enough, and in some situations I imagine it would look pretty good (a robot-dance competition maybe).
On the other hand, if being coordinated and able to use your body effectively and efficiently means anything to you, compound exercises will help you do that. Rather than training muscles and joints individually and independently, as in isolation movements, compound exercises develop inter-muscular coordination and the neural pathways that allow your body to work as a unit.
5. Muscular balance
If you skipped point 4. to go to a robot-dance competition, you might as well start auditioning for roles as Quasimodo while you're at it. An issue with training the body with isolation exercises is just that - you have to train everything in isolation. That makes it pretty easy to forget certain muscles, especially if you can't see them in the mirror. While you're checking out your well developed pecs and biceps in the mirror, your back is lagging, and your shoulders are being pulled forward into a hunch to rival the Notre Dame bell ringer himself.
The simple solution is to stick with compound exercises for the vast majority of your training. If, for every pushing exercise you do, you make sure to include a pulling exercise, you'll most likely take care of that back and remain upright like your fellow homo sapiens.