A long run or big strength-training session might leave you too exhausted to fix yourself a recovery meal. That’s of course not ideal and the best way around it is to pre-prep your recovery snack. However, if that is not you, make sure you do take in some form of protein fast, if you are planning on training again the following day.
According to a study published in the Journal of Sports Science and Medicine: "Protein supplements facilitate muscle repair and mitigate muscle damage markers during recovery." To massively a paraphrase the science: Protein helps give your body what it needs to repair and replenish itself from the ‘damage’ done during training. This repair process in turn builds improvement. Super simplified, you understand.
Protein should not only be taken right after your workout, but, if it was a heavy session continued every three-to-four hours after.
Typically, the recommendation is 0.4-0.5g per kilo of bodyweight as your first protein recovery hit right after your session. The key here is that it doesn’t actually matter too much what it is (which is why protein recovery shakes are so popular) and, indeed, there is a big body of research out there that shows how milk is one of the best naturally occurring protein drinks you can have. (More info from another study, here).
There are countless recipes and protein powders out there, the key as with any other training and race nutrition is to find out what works for you (through experimentation) and then stick with it.
