During his World Cup preparations earlier this month, Barcelona's Spanish international Andres Iniesta was quoted in the Daily Mail as saying that even the fittest players could be left tired and lethargic from the tropical conditions they’re likely to experience in Brazil.
But how much does heat and humidity really affect a player’s performance? And is there anything European players can do to prepare for it, or are they destined to play at a physiological disadvantage because of the climate in which they were born?
Firstly, sports scientists actually managed to quantify the degree to which heat and dehydration affects sports performance. Published in the sports journal entitled, Sport nutrition: an introduction to energy production, researchers claim becoming dehydrated by as much as five percent can lead to a reduced physical capacity of up to 30 percent.
To put that into perspective using a sporting example, the winner of the men’s London 2012 Olympic marathon was a Ugandan athlete, Stephen Kiprotich. According to Olympic.org, he won the race in a time of two hours, eight minutes and one second. Based on the above premise, if he was dehydrated by five percent, in theory, he would have finished in a time of around 2:46:00 and placed 84th out of the 85 who finished the race.
Granted, becoming five percent dehydrated is quite extreme, but based on the teachings from the Thermal and Mountain Medicine Division at the U.S. Army Research Institute of Environmental Medicine as well as the work published by the Undergraduate Research Community at California University of Pennsylvania, becoming dehydrated by just one percent impacts performance.
In fact, players can expect to experience any of the following symptoms based on the corresponding level of dehydration:
- 1% dehydrated: reduced lung capacity and signs of thirst present.
- 2% dehydrated: symptoms of thirst continue accompanied by loss of appetite and endurance.
- 3% dehydrated: dry mouth and performance impaired.
- 4% dehydrated: perception to exertion increase accompanied by persistent discomfort.
- 5% dehydrated: difficulty concentrating, increased heart rate and trouble breathing.
- 6% dehydrated: symptoms increase, headache and decreased proprioception and balance.
- 8-9% dehydrated: dizziness, real difficulty breathing, confusion and increased weakness.
- 10% dehydrated: involuntary muscle spasms, loss of balance and tongue swelling.
- 11% dehydrated: heat exhaustion, delirium, stroke, difficulty swallowing and death may occur.
Sports journals and military teachings aside, the women's marathon during the 1984 Los Angeles Olympic Games remains one of the best case studies to illustrate how dehydration influences sports performance, when Gabriela Andersen-Schiess of Switzerland refused medical assistance as she staggered onto the track for the final 400m. Her twisted torso, limp left arm and seized right leg still serve as a haunting reminder of the importance of hydration.
Therefore, it’s safe to say that heat and dehydration may play a major role in this year’s World Cup. But how can coaches combat the "average highs of 30ºC (87ºF) and more than 80 percent humidity," as reported by The Telegraph?
Firstly, by addressing the basics. According to The Associated Press via USA Today, FIFA's manual on football medicine says that "players' bodies need three days minimum, and ideally 14-21 days, to acclimatize to heat. Once that happens, they can cool more quickly and lose fewer minerals through sweat."
Seeming to adopt this school of thought, Roy Hodgson and the entire England camp have taken their training around the globe in an effort to replicate the hotter conditions of Manaus, as reported by the Daily Star. Italy have resorted to training in saunas, and their team physician, Enrico Castellacci, was quoted on the Fox News website as saying, "we've tried to reproduce the environmental conditions that we will likely find, above all in Manaus, but also in Recife and Nata."
This is especially important, since the lost "minerals" mentioned in FIFA’s manual on football medicine are called electrolytes, which are essentially electrically charged particles that create the electrical impulses needed for nerve activation and muscle contractions.
If your body contains too many electrolytes, the kidneys will flush them out since the body is self-regulated by your diuretic-like hormones. But when your electrolyte balance is low—caused by excessive sweating—they need to be replaced, otherwise the electrical impulses signaling your muscles to contract become less efficient, which at best affects performance and at worst can be fatal.
Again, to help quantify the significance of electrolytes on sports performance, scientists at the Human Performance Laboratory at the Sports Authority of India conducted a study on elite-level athletes.
The scientists had subjects perform 60 minutes of semi-intense training, giving one group a carbohydrate-electrolyte drink and the other group a placebo. Performance time and heart rate were noted and blood samples were collected for the analysis of glucose and lactate levels.
Results found that the group that consumed the carbohydrate-electrolyte drink saw an improvement in total endurance time, heart rate responses and blood lactate during exercise, as well as a significant improvement in cardiovascular responses, blood glucose and lactate removal post exercise too.
Ultimately, scientists concluded the carbohydrate-electrolyte drink helped to improve performance, enhance lactate removal and delay the onset of fatigue.
A possible reason why Roy Hodgson backed Group D rival Italy’s request for more frequent drink breaks, as reported by The Guardian, is because they would significantly aid performance.
Another method of combating the heat that’s being utilized in teams' World Cup preparations is a form of hydrotherapy that helps regulate the body’s temperature. According to the aforementioned Fox News article, players have been soaking their clothing in water; although it sounds so simple, science proves this action could dramatically help.
A study published in the Journal of Science and Medicine in Sport took nine endurance athletes and had them perform two bouts of exercise, on three separate occasions. The bouts were separated by a 15-minute rest period where athletes were immersed in water with a temperature of eight degrees Celsius at hip level. Through monitoring heart rate, blood lactate and body temperature they concluded cold water "immersion applied between repeated exhaustive exercise bouts significantly reduces temperature and enhances post-immersion running performance."
Based on the evidence, it appears that European teams are doing everything they can to prepare for the World Cup conditions. Plus, backed by credible research and military teachings, they may even succeed in leveling the playing field against their tropically born, physiologically advantaged opposition.