i. the deadlift
The deadlift is a movement that has a special place in pretty much every serious strength athlete's heart. Generally, this is the movement in which any given individual can lift the most weight: human beings were made to pick heavy shit up. It's probably the simplest compound movement, or at least the most natural to most people, which probably lends to its charm.
You can lift something really heavy and it's relatively easy to do? I'm sold.
The actual movement starts with the weight on the floor, and the athlete's start position is generally hips pushed back, legs slightly bent, and chest up and out. He pulls the bar up, keeping the arms straight, and ideally he pulls up the shins and thighs until he's standing completely upright. Now deadlifting is generally a pulling movement, but this is speaking from the experience of someone who's 5'5". The taller you are, or more accurately, the longer legs you have in relation to the rest of your body and arms, the more you're going to have to bend the knees in order to get an optimum back angle. If you're stooped over too much with your back getting parallel to the floor, you're killing your leverage, which is good if that's what you're trying to train, but not if you're just trying to deadlift. Taller or longer-legged guys are going to have a bit of "push" action off the floor with the quads, a little bit of a squat, before the hamstrings and glutes take over to begin pulling. And obviously the taller you are, the farther the bar has to move, sucks for you folks of average height, classical weightlifters such as myself have it easy.
The movement is close to a total-body recruitment of force. It's the hamstrings and glutes that actually move the weight, and the lower back that supports the weight during the pulling phase of the movement, and collectively these muscle groups are referred to as the "posterior chain," they almost always act in concert in athletic movements. You don't really notice until the weight becomes more and more significant, but pretty much the entire back plays a role in the deadlift. The latissimus dorsi are used to pull the bar in, up the legs and closer to the center of mass, and the trapezius muscles produce tension in order to keep the shoulders pulled back. Also, any movement that requires a tightening of the torso, i.e. preventing back flexion to occur against resistance, develops the entire trunk, so all those muscles that make up the abdominals and the obliques and whatever the fuck else is in there all get their share of fun, too. Sorry folks, anatomy is fun to an extent but there is a point at which I stop caring what muscles do what and you should, too. Bottom line: deadlifts will make you aware of your body and how it is composed in a very painful and pleasant way.
When people talk about putting on mass, or when people talk about getting stronger, the thing that they're probably going to tell you to do, if they're old school or caveman (like me), or at least one of top five things they tell you to do, will be to deadlift, "pick up heavy shit." The posterior chain and back have a lot of potential; they're some of the largest muscle groups in the body. Also, the movement requires tightness of various parts of the trunk and extensions of it against resistance, meaning your entire body is working while moving the weight. You never really shrug your shoulders up when you deadlift, but the day after the workout your traps are going to hurt a lot because they were keeping the shoulders from slumping forward during each pull, they were resisting a significantly greater downward force than they have been accustomed to. As far as putting on mass goes, remember that this is generally the movement in which people can move the most weight, as opposed to pressing or squatting something; the stress-effect of training the deadlift is greater than just about anything else you could do with a barbell.
ii. deadlifting and recovery
All these great benefits of the deadlift don't come easy, though. This is a phenomenon more pronounced in pulling than anything else, but it takes a lot out of you if you start getting heavy. In weightlifting, the deadlift is either avoided or scheduled well before or after a meet because the recovery a heavy session requires takes a while, and because in the meantime, the important pulling, like accelerating a clean, is going to suffer. This is referred to as neuromuscular inhibition; in an effort to avoid a potentially harmful stressor (extreme muscle tension), the nervous system inhibits the amount of force the muscles can produce after having been exposed to intense resistance. This happens with anything, benching, squatting, the clean-and-jerk, but you notice it most with the deadlift because it employs so many crucial muscle groups; the muscles in your back that stabilize overhead (and other) movements, the lower back which is the posterior parallel to the abdominals and plays a role just as important in doing EVERYTHING, and the posterior chain, which is what we as humans and as athletes rely on a lot of the time to do basic movements such as sprinting, certain phases of a squat, and of course pulling.
So yeah, recovery is kind of an issue with deadlifts, I mean early on you can do them multiple times a week and be fine, but as you start to get stronger and more efficient, and you're pulling a multiple of your bodyweight greater than 2, that's the stage when you do them like once a week for a month or two at a time before taking breaks, that's when you actually have to start scheduling a program, "OK, I'm going to train the deadlift for x amount of weeks, then transition to good mornings," or something like that.
There's a school of thought in training the deadlift, particularly among powerlifters, that you should deadlift heavy very rarely, and instead train movements that employ the same muscle groups that deadlifting does. If you're a powerlifter, you would low-bar, wide-stance box squat, because a powerlifting squat and the deadlift are both essentially pulling movements; the hamstrings and glutes are the primary movers in either case. You could also do good mornings, and vary the stance to emphasize hips, glutes, hamstrings, etc., and supplement these movements with other things like reverse-hyperextensions, and glute-ham raises. Weightlifters train pulling basically every training session through the snatch and clean, and they tend to train variants of the deadlift that involve a leverage disadvantage rather than the conventional movement.
iii. deadlifting, injury, and equipment
The movement's associated with back injury among the "popular" gym crowd, but it's not deadlifting that leads to injury, but bad biomechanics. Spinal flexion is what's correlated with lower back injury, which is why you keep your trunk tight. If you watch a safety video at a Wal-Mart or something where people move heavy objects, one of the things they're going to try to drill in your head is, "keep your back straight," don't let your back round, this is how you strain a lumbar. There's plenty of coaching cues that reinforce this, "chest up," "head up," you know, using an extension as a synecdoche for the desired motor pattern of the body as a whole.
The weight belt is a popular tool among many gym goers as a safety precaution for deadlifts or squats, but it's not a necessity (some feel that using it takes away from the development of the trunk), and some strength sport communities highly value things like a no-no-no squat or deadlift; no wraps, no belt, no spotters.
There's also some issues with some people when using a mixed grip - one palm facing the body, the other turned away, which is what people use to keep the bar from rolling out of their hands with a double overhand grip. The arm that's rotated outward has a tendency to let its bicep tendon tear with exceedingly heavy weights. This is one of those injuries that's as bad as it sounds, we're looking at reconstructive surgery. If your hands aren't strong enough and the weight's heavy enough the bar has a tendency to slip out of a double overhand grip, and if you train long enough without delving into the weirder stuff (grip-specific training) you're probably going to run into something that you can pull, you just can't hold it. Then you have to start doing bizarre shit like barbell holds for time and farmers walks and all this tedious bullshit that just sucks, or if you're like me and you don't give a fuck you can use wrist straps, though this is frowned upon by some communities and not legal in powerlifting competitions, but you know what, fuck them, they happen to do a lot of shit that weightlifters frown upon.
One more note about deadlifting and its relation to gear: in some powerlifting federations, they allow the use of squat suits, deadlift suits, and bench shirts, which are very, very tight-fitting suits made of a very tight, elastic material. They can come in single layers, or multiple layers, made of material as thick as denim. A deadlift suit is engineered to aid in pulling, and most users report that it helps the most off the floor, and can add a score or more pounds to your best pull, depending on the material and how many layers it's composed of. Equipment like this is part of the powerlifting game in some federations (there are
"raw," unequipped federations and meets), and it's also one of the causes of the criticisms of some forms of powerlifting.
Now you might see video of a powerlifting meet, and some people are deadlifting, and they're letting their backs round and their shoulders slump and everything is just wrong, wrong, wrong - realize that this is their competition, this is where they put it out on the line and take risks. Also remember that spinal flexion is correlated with lower back injury, not necessarily a guarantee of back injury. Some guys can pull with rounded backs all fuckin day and never even have to think about a chiropractor. Some clubs even have their lifters train specific rounded-back movements, so who fuckin knows man, but just to stay on the safe side, and because it's got more carryover to athletic skills, the general rule is keep the trunk tight, keep the back straight. You don't tackle with a slumped back, you don't shoot for a double-leg takedown and push your hips into the guy without a tight trunk, etc.
iv. deadlift variants
One of the cool things about pulling in general is that there's so many ways to do it. There's the vanilla deadlift, and then there's a few variations where you try to kill your leverage a certain way, which is either training for improving your deadlift or other pulling-type movements (i.e. snatch and clean).