I've worked for a company that makes pressure plates, that allow you to analyze running patterns (with or without shoes). I've done research at a specialized running shoe shop and my father is an orthopedic shoe manufacturer. So in short, my opinions are fairly biased, but by no means scientifically proven.
While md5sum names some great rules of thumb, they apply to every shoe and don't help you determine what type of shoe you're looking for.
First a short note: Adidas did a study way back in 1987 and found that most injuries come from:
Injuries caused by training:
- Wrong intensity of training: 12%
- Too rapid increase in intensity: 9%
- Several others: 9%
Injuries caused by shoes:
- Bad quality of shoes: 17%
- Wearing your shoes for too long: 11%
- Wrong kind of shoes: 44%
As you can see, picking the right kind of shoes is pretty darn important! So how do we pick one?
When you dissect a shoe, it's made up out of two main components:
- the upper, which is the mesh, leather or synthetic material + the shoe laces;
- the sole of the shoe, which can consist out of several layers
The first component is composed the same for nearly every pair of running shoe. While the last around which it is made, may or may not fit your foot (see md5sum's answer for some excellent advise there), you won't find much variety within a certain brand. However, you should note that this is mostly true for the running shoes. Don't even consider running on those cheaper aerobic or tennis models, because you'll fall in the trap Adidas found earlier.
The other component, which is the sole of the shoe. Now when I say sole, I'm actually referring to everything that is below your foot when you're inside the shoe. Trying to discuss all the bits and pieces that compose it depends strongly on the brand and their design-department.
When limiting choices towards endurance running and excluding fancier shoes that are meant for trail running or sprinting on a track. You're left with a shoe sole that serves several functions:
- offer stability and control of motion,
- shock absorption and/or reduction,
- protection against the underground and overuse/strain,
- enhancing your performance
Shock absorption is mainly determined by your body weight, rather than the type of shoe. When you're lighter, you can get away with having a 'softer' (as in lower shore values) soles than when you're heavier. When I say shock absorption, don't immediately think: Nike Air! because most absorption comes from flexing your joints, rather than compressing your sole.
There are several 'special' features for motion control, though you can safely assume that unless you have some severe disorder, you probably don't need any of the extreme models. With extreme, I mean shoes with extreme angles at the heel or other gimmicks:
If you're 'normal' you fall in one of three groups: those who pronate too much, those who run neutral, those who don't pronate enough (or supinate). Don't mistake this for the other three types people like to call out: flat, normal arched and high arched feet. Hate to break it to them, but since the shoes all have the same shape on the inside, they surely aren't adapted to your arch! No I'm talking about biomechanics here:
These pictures depict the maximal motion in this subjects ankle, that your running shoe is trying to limit. Funny enough, I almost never encounter shoes that help against eversion (supination), so choice boils down to: how much pronation do you have, ranging from excessive to normal?
This boils down to three main types of shoes:
- Heavy support shoes, you can recognize them by having a very straight last and the arch area is either entirely filled or there's antipronation support running from the back till the ball of the shoe. You can recognize this by its gray color or at least using a distinctive color difference between the inner (medial) and outer (lateral) side of the shoe.
- Moderate anti-pronation shoes, these often only have the antipronation support in the heel area. Again, you can recognize this by the grey color.
- Neutral shoes, these have no special features for reducing pronation (that the other two models don't have already).
So how do I know which one I need?
Well one easy way of determining this is looking back at your history:
- You never had anti-pronation shoes and didn't sustain any injuries? --> Get neutral shoes
- Do you run a lot and for long distances? Neutral shoes
- You're not overweight? --> Neutral shoes unless move point 3 applies. If not, more stable shoes
- Did you ever have any injuries that are linked to pronation? Get more stable shoes.
If you're overweight and you have a history of pronation-related injuries then yes, probably you need the heaviest kind of support you can get. In most other cases, the neutral shoe is of such decent quality that you don't need anything else.
So isn't there any choice at all?
Well, yes all the brands will tell you they have superior technologies built into their shoes and they're all right. But sadly for them, that technology also has to fit your foot. When you take 5 different brands and you start to test them on a treadmill, you probably end up having to chose between two brands, because the rest 'didn't feel right' and you end up picking the one with the fancy colors.
What do I do if I want to start with running and don't know what's good for me?
Typically, it depends on many things, but any good running shop should be able to advise you based on your conditions. What's your posture, age, physique, level of activity, general health, your goals with running, training intensity etc...? But all in all, in most cases a good stable running shoe is more than sufficient. When you have a good shoe, the other factors from the Adidas study become more important: running too hard, on a too hard underground, for too long, far too often in a short amount of time will causes injuries no matter what shoes you wear.
Any final words?
Seasoned runners will generally disagree with my advice, but it isn't catered to them. Because if you're capable of running a lot and very often, chances are that natural selection decided you're a pretty good runner or else Mother Nature would have stopped you in your tracks long ago. This means that you get to wear lighter shoes or silly shoes like the Vibram ones, because you let your body do all the work. That's mainly where the performance enhancing comes from: leaving as much of the shoe out to not get in your way.