At this point, it is essential to understand what the subject's objective is in analysis.
If we speak of a sedentary, the differentiation of proteins in the various meals takes on an almost marginal role. Proteins are ubiquitous macronutrients and their contribution is associated with the vast majority of foods; obviously there are substantial differences in the content of essential amino acids, but by virtue of the fact that a sedentary is characterized by an almost constant metabolism, there are no conditions that require the selection, differentiation or dissociation of meals.
If we talk about an amateur sportsman, it is not necessary to increase food proteins "in percentage" because, favoring energy expenditure with exercise, a proportional increase in the energy consumed is also necessary, increasing the quantitative intake of food, therefore also of proteins. Rather, in addition to the general indications of the sedentary, it would be appropriate to have an eye on the biological value of the introduced proteins, trying to guarantee their "animal" origin (meat, fish, molluscs, crustaceans, eggs, milk and derivatives) for at least 2 / 3 of the total; in the case of vegeterianism or veganism, care should be taken to compensate each other for proteins of medium biological value (cereals + legumes).
If we talk about an elite sportsman, the quantity and quality of proteins become a determining factor.
In endurance athletes or middle distance runners, the most abundant protein sources should NOT be routinely placed in meals "close" to training. It is NOT RECOMMENDED to consume good protein sources before the performance, as the digestibility of this macronutrient is decidedly lower than that of sugars which, however, represent the main energy source during prolonged muscular effort. For the same reason, if the athlete performs 2 daily training sessions, it is essential to optimize the storage of energy reserves at the moment most favorable to anabolism, or the immediate training POST. Especially in the 15 minutes following the end of the service, or in any case within the first hour, it is therefore essential to consume more carbohydrates with a high glycemic index by limiting the proteins that would slow down digestion and absorption. On the other hand, in all other daily meals it is RECOMMENDED to insert protein foods in adequate portions.
NB. In the event that there is a real difficulty in reaching the daily protein level (for managing meals, poor digestibility or poor appetite) it would be appropriate to integrate with amino acids in the POST-training meal.
On the contrary, in the sportsman who trains strength, given the lower frequency of training it is possible (and advisable) to insert protein foods even in the POST-training meal. These athletes find advantage in increasing strength, so ALSO of muscle hypertrophy and in certain subjects guaranteeing a constant protein intake during the day (up to 30g per meal) facilitates myofibril anabolism by increasing recovery and in the long term also the performance.
In bodybuilding, where it is essential to minimize fat mass, foods are often replaced by food supplements. In this case, it is possible to make a distinction in the use of protein powders and amino acids: if integration is to be carried out before sleep, it is necessary to seek a digestion and absorption LENS (although in my opinion, in hypersensitive subjects, this is a unhealthy practice for the stomach); for this purpose it is recommended to use a product derived from milk serum or egg. Furthermore, as regards the integration of the POST-training meal, I would make a further distinction: in the mass phase, when it is fundamental to "feed the muscle", I would prefer a significant supply of carbohydrates with a high glycemic index (such as bread or of polished rice) associated with a modest supply of amino acids or FAST absorption proteins, distributing the remainder of the requirement uniformly over the day with food; on the contrary, during cutting or definition when (alas!) it is often necessary to periodically reduce carbohydrates, after training I would recommend a more important integration of FAST absorption proteins possibly associated with a few low glycemic index sugars. Among the fast-absorbing proteins, the market offers a wide range of products: whey, soy, isolated, semi-hydrolysed, hydrolysed etc. proteins.
Ultimately, the breakdown of protein intake has ONLY meaning in particular conditions such as extreme sporting activity and in competitive bodybuilding; in normal conditions, it is sufficient to follow the national guidelines for a healthy and correct diet.
