I've seen a lot of drinks which seem to be protein shakes with extra carbs and probably some other bits in them specifcially designed for quick recovery after cardio.
Do these actually work or is it just as good to have a bowl of soup for example? What are the pro's and cons?
The best replacement drink after cardio exercise is chocolate milk. It's got the 3:1 carb to protein ratio that's been determined to be the optimum, it's cheap, and easily obtainable. (There are studies that reference this as well.)
Cardio exercise, especially if you are training long distances (Such as marathoners, triathletes, etc) where you are exercising for upwards of 1 hour, it's as much about recovery as anything. Replenish fluids (Again, chocolate milk :D), and get a good solid meal of real food soon after, and you should be good to go.
Yes. From Recovery Nutrition for Athletes (from the NSCA's Performance Training Journal):
Athletes who are serious about their performance should consume a high carbohydrate-moderate protein meal (with fluid) or recovery drink after every workout, practice, and competition. It is also best advised to consume carbohydrate and protein with fluid during exercise and/or immediately post exercise.
The body is pretty good at getting what it needs from whatever you happen to eat, so as you suggest, a bowl of soup would work quite well. The Swiss Army in the 70s (most likely before that too) would drink boullion from a thermos to recover from endurance training, and it was apparently also popular for long distance competitions around that time as well. Obviously that's a matter of making use of what you have available to you.
As far as supplements specifically designed for recovery go, I would avoid them unless I know exactly what's in them, if they're doing the carb and protein balance using refined sugars and a single protein source, that's not going to be particularly healthy. It's also going to cost a lot as they'll claim they're charging for the formula. You'll get better nutrients from something complete and balanced.
Also, you'd have to ask why you're needing to recover so quickly after doing cardio. Any improvements you make to your body will be done while resting, and that's a rather slow process. Quick recovery would suggest you're having to do something else right after, which would likely impede any progress you're making.
