Walk into any gym in america, and you'll see some strange stuff. You'll see guys who are 50 pounds overweight doing set after set of biceps curls, as if the ego-boosting effects of 17-inch biceps will somehow negate a 46-inch waist. Young guys lifting way too much weight with bad form, older guys lifting way too little weight on machines that require almost no attention to form, and everyone plodding along on treadmills and bikes with only the vaguest concept of why they're doing it. One of the oldest jokes in the gym is about the guy who'll circle the parking lot for 15 minutes to get the space closest to the front door, then go in and walk on the treadmill for a half hour.

The confusion is understandable. So many exercises, so many machines, so much conflicting advice. But we think strength training can be vastly simplified if you're willing to take a giant step back and ask yourself this question: Why do we have these muscles?

Nature doesn't care if you have ripped abs or big ol' honkin' biceps. Muscles have jobs, real jobs: They're attached to your bones to make those bones move. Bones move so you can catch something to eat, or elude something that's trying to eat you. The muscles you want to build are designed to help you run, jump, climb, throw, fight. And yet most of the exercises seen in a gym are designed to make your muscles look good flexing in a mirror. Exercises like crunches and curls are muscle-squeezers. They train isolated sets of muscles to contract without reproducing any useful movement. Since they're of limited use, your body will make limited accommodations. You could curl for hours every day, and your biceps will only get so big.

On the other hand, your body will make huge accommodations for squats, dead lifts, chin-ups, and the other important bone-moving exercises. These exercises use many groups of muscles in coordinated action to help you do something important for the survival of our species.

You could come up with any number of ways to classify exercises as they relate to human movements. We settled on these six: squat, dead lift, lunge, push, pull, twist. As you'll see, a workout based on this six-pack will work every muscle group in your body, major and minor. And it can't possibly get any simpler than that.

1 The Twist If you had to pick the most popular exercise at the gym, you'd probably choose the crunch. Now ask yourself why. It builds your six-pack, but, really, how important is that? Outside the gym, a forward bend at the waist is the easiest movement in the world -- gravity takes care of everything. A twist, on the other hand, can be as easy or hard as you want. If you're hitting a golf ball, you're trying to pound a light object into the next zip code. If you're wrestling an opponent or sow to the ground, you're twisting against something that may outweigh you. The muscles responsible for twisting, the obliques, are strong as hell. In fact, they could probably tear your midsection apart if not for the abs in the middle. One could even make the argument that the six-pack's only real function in life is to prevent your waist from twisting too much when you don't want it to.
THE CLASSIC: For the weighted Swiss-ball crunch, hold a weight plate across your chest as you lie on your back on a stability ball. Spread your feet wide, with your neck, torso, and thighs parallel to the floor, and crunch. Your goal is to gain strength to resist unwanted twists, so you should feel it throughout the abs. THE OPTIONS:The woodchop, at right, teaches you to twist the right way. You'll set up sideways to the stack, with your feet shoulder-width apart and the rope handle on the highest cable pulley. Rotate on the ball of your foot as you pull the rope down and across your body until the handle is just outside your far knee. Do all your reps, then switch sides and repeat.
2 The Squat If you think about how important jumping must've been to our ancient ancestors, it makes sense that all the muscles in your lower body -- from big ones like the quadriceps to relatively small and overlooked ones in your hips, ankles, and inner thighs -- get involved in a jump-mimicking exercise like the squat. THE CLASSIC: Stand with your feet shoulder-width apart, holding a barbell across the back of your shoulders. Push your hips back and lower your body until your upper thighs are parallel to the floor. Push down through the middles of your feet to return to the starting position. THE OPTIONS:Although nothing beats the original, you may want use the dumbbell squat for lighter-weight, high-rep sets.
3 The Lunge Squats and dead lifts teach you to lift heavy things with your feet parallel to each other. But in many situations, especially competitive ones, your feet are staggered and you move with lunge-like steps to the front, sides, or up (as when you're climbing). The muscles used are similar to those in a squat, with a key difference: Your hip flexors are more involved. Hip flexors are notorious for tightening up in those who camp out at desks. Lunges force them to contract quickly, increasing flexibility and strength.
THE CLASSIC: For a lunge, start with your feet parallel and about hip-width apart. Step forward with one leg, while simultaneously lowering your body until your forward thigh is parallel to the floor. Rise and step back to the start and repeat for all the reps, then switch feet. For the static lunge, start with one foot already forward and do all the reps from that position. THE OPTIONS:For the step-up, start in front of a sturdy step or bench knee- to hip-high holding dumbbells or a barbell. Put your left foot on the step, push down through your left heel, and lift your right foot onto the step. Step down with your right foot, and repeat. Do all the reps with your left leg, then repeat with your right foot on the step.
4 The Dead Lift Lifting a heavy object off the ground is about as useful a movement as we have. One of the key benefits of dead lifts is that you learn to do it without hurting your back. THE CLASSIC: Stand over a barbell with your feet shoulder-width apart. Grab the bar as at left. Roll the bar up to your shins, then squat down so your arms are straight, your back is flat, and your shoulders are behind the bar. Now stand up as you pull the bar up, keeping it close to your shins. Keep it close to your legs as you lower it all the way to floor. Reset your grip and repeat. THE OPTIONS:The split good morning, is a dead lift/lunge in which you start with one foot on a 4- to 6-inch step, push your hips back and bend forward as far as you can with your back flat. Do all your reps, then switch feet.
5 The Pull Pulls mirror the pushes below, but because pulling muscles were even more crucial to the survival of our tree-dwelling ancestors, you have more and bigger muscles devoted to it. (If you don't believe us, try rowing a boat by pushing the oars through the water.) As with pushes, your body emphasizes different muscles, or different parts of muscles, in your back, shoulders, and chest as you change the angle from which you're pulling. And ideally, your biceps and forearms should also be involved, which is why we favor exercises that have you pulling while grabbing on for dear life.
THE CLASSIC: For a chin-up, grab the chin-up bar with an underhand grip, your hands about shoulder-width apart. Hang at arm's length, then pull yourself up until your chin is over the bar. If that's too easy, add some resistance by putting weights in a backpack or hanging them from a "dip belt." You can also do pull-ups with an overhand grip wider than shoulder-width. THE OPTIONS:You'll see a lot of lifters doing three-point rows, in which their weight is supported with a hand and a knee on a bench, and one foot is on the floor. But that has limited real-life utility compared to the two-point row -- in which you stand, as if pulling an anchor or giant tarpon up onto a deck, with your feet shoulder-width apart. Hold a dumbbell in your left hand, palm turned toward your body, and put your right arm behind your back. Bend forward at the hips so your left arm hangs straight down from your shoulder. Pull the weight up to the left side of your torso. Do all your reps with your left arm, then repeat the set with your right.
6 The Push Few muscleheads would put all pushes or presses into one category. But why not? In the real world, whether you're using it to throw, fight, or move your car out of a snow bank, a push is mainly distinguished by the angle -- or range of angles -- at which it's done.
THE CLASSIC: For your incline bench press, set a bench at 30 to 45 degrees and use either dumbbells or barbells. Start with the weights straight over your chest, lower them, then push straight back. We also like the dumbbell shoulder press with alternating arms, at left. THE OPTIONS:The T push-up is a push/twist hybrid. Do a push-up, but as you push up, rotate up and to your right, with one arm pointed toward the ceiling so your body forms a "T." Do all your reps to one side, then repeat on the other. For more of a challenge, hold a hexagonal dumbbell in your raised hand. Or use two, twisting with one and balancing on the other.