Professional football is constantly evolving, and, at present, it demands players very high physical and technical requirements. In such a strict outlook, nutrition plays a key comprehensive role in optimising elite football players’ performance during the training and the games, and also maintaining their overall health throughout the season. 

As football itself, science behind sports nutrition is also quickly evolving, and professionals have to be aware of the new findings and innovations.  In this way, the Union of European Football Associations (UEFA) gathered a sports nutrition group of experts as well as professionals working with elite football clubs and national associations/federations to make an expert statement (James Collins et al., UEFA expert group statement on nutrition in elite football. Current evidence to inform practical recommendations and guide future research, 2020) about many relevant topics in nutrition in elite football. One of the key points of the document is the special nutrition section for training days nutrition.

The basis for training day nutrition

Even though there is a lot of research about games physical demands (read ref.1-3), the detailed analysis of the usual training loads of elite football players is relatively recent and it is still limited (read ref.4-7). Besides, absolute daily training loads depend on many factors, including the season phase (read ref.7), the player’s position (read ref.7), the coach’s philosophy (read ref.6, 7), the game frequency (read ref.8), the player’s condition (read ref.6), the specific training goals for the player or the rehab from an injury (read ref.9).

We have to add to these variables the fact that the training sessions in the gym and on the field are not always performed in a systematic and structured sequence (read ref.10), and the order of these session can influence the players’ normal macronutrients (read ref.11). In fact, both absolute daily intake and distribution of macronutrients intake have the capacity to affect training performance and recovery, and to modulate training adaptations.

Carbohydrates requirements for training

Glucose molecules (key to maintain effort longer) are mainly obtained from the intake of carbohydrates or through glycogen stores. Given the role of muscle and liver glycogen supporting energy production during a match (read ref.12), it is important to consider their contributions to training goals. 

Given the lower absolute daily loads on typical training days (this is, one session per day in one game a week microcycle, for instance), together with the fact that players do not typically perform structured training outside the club, intakes ranging from 3 to 6 g/kg of BM (Body Mass) could be enough to suffice fuelling and recovery. Among carbohydrates we can highlight rice, pasta, flour or bread.

Protein requirements for training 

Daily football training places tension and cellular damage on musculoskeletal and tendinous tissues, which creates the need of remodelling and repairing these protein-containing structures to maintain and enhance their integrity and function.  Players could benefit from provision of higher quantities of protein than are needed by the general population. 

The recommended daily allowance for proteins is 0,8 g/kg BM/day in Europe (read ref. 13), but higher intakes up to 1,6–2,2 g/kg BM/day seem to enhance training adaptation (read ref.14). Such levels of protein intake could easily be reached with a mixed diet provided the energy intake is enough to meet the training demands (read ref.15). 

Fat requirements for training 

Dietary fat (edible fats and oils that could be animal or vegetal such as the ones coming from salmon or olive oil) is an essential part of a player’s training nutrition as an energy source, vehicle for the intake and absorption of fat-soluble vitamins and source of essential fatty acids. 

Athletes are often advised to adjust fat intake to allow protein and carbohydrate requirements to be met within total energy targets and to follow the community guidelines regarding minimum intake of trans fatty acids and caution with the intake of saturated fats. This usually leads to the recommended fat intake from 20 % to 35 % of the total dietary energy. 

Essential micronutrients requirements for training

For elite football players, training as well as game demands could increase the requirements for some micronutrients to support the metabolic processes within the body. There are many micronutrients classifications, including vitamins, minerals and essential trace elements like vitamin D, iron or calcium for growth and optimal development of the body. 

Vitamin D 

Vitamin D is a controversial topic in sports nutrition since it has been reported that inadequate serum vitamin D concentrations (relationship between the quantity of substance per volume unit) affect muscle functioning and recovery (read ref. 16) and compromise immune health (read ref.17), so it is essential that football players who are deficient are identified and treated accordingly. 

It is a unique vitamin in the sense that it could be synthesised in the skin via sunlight exposure, with less than 20% of the daily needs typically coming from the diet (read ref. 18). It is a seasonal vitamin with differences depending on the time of year and geographical location.

Iron 

Iron is the functional component of haemoglobin (protein inside red globules which transports oxygen from the lungs to the body tissues and organs) and myoglobin (tiny protein able to catch oxygen inside muscle cells to produce enough energy for muscle contraction.) So, iron deficiency (identifiable via a blood test), even without anaemia, could have negative implications for aerobic performance (read ref.19–21). It is interesting to keep in mind that, when possible, iron should be consumed from highly bioavailable sources, including meat and seafood. 

Calcium 

Calcium is important for maintenance of bone tissues, skeletal muscle, cardiac contraction and nerve conduction. The largest store of calcium in the body is in the skeleton and this store is mobilised when dietary intake is inappropriate, which leads to a demineralisation of the bone tissue through the action of parathyroid hormone. 

Dairy products are the main dietary sources of calcium, but it can also be found in green leafy vegetables, nuts and soya beans. An athlete diet should include a higher intake of 1500 mg/day to optimise bone health in cases of relative energy deficiency in sport (RED-S, a pathology caused by an imbalance between energy expenditure and caloric intake in elite athletes) (read ref. 22). 

Sources:

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