Wednesday, November 30, 2005

Important findings on football nutrition and fitness

"Football players can stay healthy, avoid injury and achieve their performance goals by adopting good dietary habits," a three day FIFA conference on player nutrition agreed.

Invited participants were from the UK, Australia, Denmark, New Zealand, Scotland, Belgium, Sweden, Germany, Spain, Brazil, Mexico, US and included representatives from such major clubs as Real Madrid, Rangers FC, Manchester United, Blackburn Rovers FC, Sao Paulo FC and CD Chivas. A unique aspect of the meeting was the interaction of researchers with practical experts working in professional clubs. The goal of the meeting was to update the consensus statement issued 10 years ago with the latest findings so that the football community can benefit from the latest sports nutrition research.

Nutrition and hydration are important factors in athletic performance. Dehydration by as little as 2% of body weight affects performance. Food is the fuel source for the high energy demands of sport in general and specifically in football. In the presence of adequate and sound nutrition, the player is able to fuel the demands of their sport. Yet when food intake is inadequate or poorly chosen, fatigue occurs earlier, performance declines, and the risk for injury increases.

"The energetic and metabolic demands of football training and match play vary across the season, with the level of competition and with individual characteristics. Typical energy costs of training or match play in elite players are about 6 MJ (1500 kcal) per day for men and about 4 MJ (1000 kcal) for women," the seminar found.

"The football player should eat a wide variety of foods that provide sufficient carbohydrate to fuel the training and competition program, meet all nutrient requirements, and allow manipulation of energy or nutrient balance to achieve changes in lean body mass, body fat or growth. Low energy availability causes disturbances to hormonal, metabolic and immune function and to bone health.

"An adequate carbohydrate intake is the primary strategy to maintain optimum function. Players may need 5-7 grams of carbohydrate per kg body mass during periods of moderate training and up to about 10 g/kg during intense training or match play."

Over the course of the meeting, it became very apparent the key role that carbohydrates play in preparing for a match, performance during play, recovery from play, preparation for the next session and much more. One fact that became very clear: despite football being the most widely played game in the world, research on football performance lags far behind the extent of participation.

To understand the energy demands of football, Dr Jens Bangsbo (DEN) described the running volume and intensity required in football match performance. In addition, he showed how the interaction of aerobic and anaerobic energy supply during match play can affect the development of transient and overall fatigue during a match.

Football, like most all sports, requires the player to eat more than non-players. The needs of the footballer were address by Dr Louise Burke (AUS) who outlined the overall energy needs as well as the individual needs of protein, fat, and carbohydrate by focusing on the accidental or deliberate mismatch of intake vs. expenditure; a problem that is often seen in female players. This mismatch can affect not only performance, but also health issues related to hormonal, metabolic, and immune function.

Food intake on match day can have a profound affect on match performance. Dr Clyde Williams (UK) discussed how food choices, volume, and timing influence exercise performance later that day.

Football is played in all environments and regardless of the location, footballers dehydrate and lose sodium leading to reduced performance. Football-specific research in dehydration was presented by Dr Susan Shirreffs (UK) who outlined the degree of fluid losses and strategies to minimize the effects of dehydration on performance. The issue of extreme heat and scheduling fluid breaks was a lively discussion.

Physical training promotes physiological adaptations and with nutrition being a key factor in performance, it may well have some influence on the training-induced adaptations. This interaction was discussed by Dr John Hawley (AUS) who showed just how closely molecular and cellular events of skeletal muscle are related during both exercise and recovery and that nutrient intake and supplementation can be potent factors in training adaptations.

The worldwide popularity of football means that matches will be played in virtually every environmental condition. Dr Lawrence Armstrong (US) highlighted the impact of heat, cold, attitude and jet lag on football performance. Nutrition has been mentioned as a potential intervention when players change environments and Dr Armstrong provided evidence that favored or failed to support nutritional factors in counteracting environmental factors.

Dr Ron Maughan (UK) showed that beyond being an energy source, alcohol impacts multiple systems that can have a negative influence on performance and recovery from play. A further issue is that alcohol intake may influence nutritional choices that will further affect recovery after play.

No subject raises more debate than the use of dietary supplements. Dr. Peter Hespel (BEL) showed the extent of supplement use in sport and the problems associated in the unregulated supplement industry. In general, supplements have little if any effects on football match performance. A substantial fraction of supplements are contaminated with banned substances and the risk of a positive doping test outweighs any potential benefits.

Training and competition place extensive stress on the immune system. Dr David Nieman (USA) pointed out how the increase in training and poor food choices can impact the immune system by emphasizing the importance of carbohydrates not only in performance, but also in maintaining immune integrity.

Many feel that fatigue is isolated to muscle. Dr Romain Meeusen (BEL) outlined the complexity of the topic showing that the brain also suffers from exercise-induced fatigue. As in other studies, ingestion of carbohydrate during exercise can minimize the degree of fatigue in the brain.

The bulk of football-related research is directed at adult males, but with 20% of the worldwide player pool being female plus the massive numbers of youth players, the unique needs of these groups can not be ignored. Dr. Christine Rosenbloom (USA) presented information on females and youth players. Females and younger players are more likely to eat and drink less than needed and choose less carbohydrate than recommended.

Finally, the role of the referee was highlighted by Dr Tom Reilly (UK). During a match, each team tries to keep players hydrated during normal stoppages in play. In many situations, the referee has no one to provide fluids.

"Dr Reilly also showed that the referee runs as much as the players and must pay attention to their energy intake to be adequately fueled to delay fatigue as long as possible. A fatigued referee, either by dehydration or low muscle fuel, can have a significant impact on match outcome. Unfortunately, the impact of nutrition and hydration strategies on referee performance is largely ignored.

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