Importància dels factors neurals en el rendiment de força
La capacitat per exercir força en un curt període de temps (coneguda com a ràtio de desenvolupament de la força) és un dels principals indicadors de rendiment en accions explosives.
Futbol Club Barcelona (FCB) is a centre of sporting excellence where it is recognized that appropriate nutrition is essential to health and performance of players. The Gatorade Sports Science Institute’s (GSSI’s) mission is to help athletes improve their health and performance through innovation, research, and education in hydration and nutrition science.
At FCB the different playing levels have varied competition programmes, with seasons of varying durations and matches played at various times of the year. For example, even at the professional level, programmes are often modified by the requirement to participate in additional competition, such as the Olympics, knockout cups, continental tournaments, and national team fixtures. The coordination of nutritional strategies would, therefore, seem difficult. However, it is important to note that the sports nutrition required to support performance is not specific to the team but specific to the individual player. Thus, similar nutrition principles can be applied to individual players across the varying football teams at FCB. Greater understanding of the physical demands of football has allowed a more scientific approach to training preparation and the manipulation of macronutrient ingestion to support training and match day performance and recovery. However, it is critical to have a working document that forms the basis for all recommendations. This is because we believe the most effective way to promote a culture of good nutrition practice is to adopt a multidisciplinary approach. In order to achieve this, everyone in the multidisciplinary team needs to work on the same basis. When trying to change a behaviour it is important that the player understands why he or she needs to change that behaviour and thus the team has to be able to explain the recommendations. However, a common challenge for practitioners embedded within football teams is to find time to collate the body of research to justify the recommendation.
In football, league competition does not require players to “peak” for an individual match. Instead, players are required to sustain a high level of performance over periods of weeks, if not months.
Thus, an objective of the professional football player is to maintain a body mass throughout the competitive season that is “realistic” from both a health and performance perspective. The energy intake and macronutrient content of the diet should be adjusted depending on the demands of training or match day performance as well as the specific goals of the player. Therefore, there is no “one size fits all” approach; rather the dietary requirements are specific to the individual player and should be modified depending on the work required (Jeukendrup 2014; Impey et al., 2016).
Besides consuming the macronutrients (i.e., carbohydrate, fat, and protein), players must consume relatively small amounts of certain micronutrients (i.e., organic vitamins and inorganic minerals) in the diet to maintain health (Rodriguez et al., 2009; Thomas et al., 2016).
Micronutrients have been reported to play a role in energy production, hemoglobin synthesis, bone health, immune function, and protection of the body against oxidative damage. They also assist with synthesis and repair of muscle tissue during recovery from exercise and injury (Rodriguez et al., 2009) (Chapter 8).
Unlike fat and carbohydrate, protein is not stored in the human body; all protein is integral and functional.
For example, contractile fibres within muscles and enzymes needed for many biochemical reactions in our body are all examples of proteins. An average 70 kg male player contains approximately 12 kg of protein and 220 g of free amino acids (Avril et al., 2003). Proteins are constantly broken down into amino acids and these amino acids then become available for the synthesis of other proteins. New amino acids are delivered through nutrition, whilst excess amino acids are either oxidized or metabolized to fatty acids or glucose. Muscle is an important tissue being responsible for 25-30% of whole-body protein metabolism and many of the adaptations we are interested in football occur within the muscle.
Fuel provided by ingesting carbohydrate plays a major role in the performance of many types of exercise and sport.
Carbohydrate and fat are the main fuels from a quantitative point of view, and these fuels provide the player with the energy required for training and matches. Carbohydrate is the most important fuel from a qualitative point of view as this is the fuel that is linked to high-intensity exercise performance as well as cognitive function.
The total water content of the human body ranges between 30-50 litres, which equates to approximately 55-60% of total body mass (BM).
Every day, water is lost from the players’ bodies in the form of sweat, urine and respiratory losses, whilst water is gained by the ingestion of foods and fluid in the players’ diets. The kidneys regulate water balance by adjusting urine output. Although the total body water content is remarkably constant, water turnover can be very high in some conditions such as when players train or compete in hot environments. In order to maintain fluid balance, water intake should be adjusted to fluid losses on a daily basis (Armstrong et al., 1998; Kavouras et al., 2012; Cheuvront & Kenefick 2014).
Supplements are commonly used by players in pursuit of improved performance, accelerated recovery and enhanced general health.
In fact, reports have suggested that 43-93% of soccer players take some form of supplement (Knapik et al., 2016). Values of 40-50% were reported during the 2002 and 2006 FIFA World Cups (Tscholl et al., 2008). It is important to note that there is rarely a need to supplement if the diet of the player is healthy, varied and balanced. There are exceptions where supplements can help performance or recovery but in any case, they should be consumed to “supplement” a healthy balanced diet, not as a replacement.
Regardless of the level of participation, injuries are an unfortunate aspect of football activity.
One important consideration in the return to play process is nutrition because it is one method to counter the negative impact of an exercise-induced injury (Tipton 2015). Thus, this chapter will first focus on common injuries in football before discussing the nutritional considerations for injury prevention as well as those interventions to complement the physical rehabilitation program.