The Effects of Temperature on Performance
A look at how extremes in temperature can affect soccer players
By Lawrence Fine
Article contributed by soccerperformance.org


INTRODUCTION

A human being can only tolerate a variation of around 5° F in internal body temperature without physical and mental performance being impaired. Soccer players, like with many other outdoor sports, are at times subjected to extreme weather conditions. The temperature of the climate the game is played in is important, affecting body temperature and the ability to perform.

TEMPERATURE REGULATION

The control of body temperature depends on the balance between overcooling and overheating. The body’s normal temperature is 98° F. When playing soccer, heat production is increased and has to be removed or performance will be affected. Temperature must stay within a range of 98° F to 104° F. Body and the outside air temperature/humidity can be measured relatively accurately through the use of thermometers.

Most of the heat is conducted in the blood stream to the skin, where it is released into the environment in four different ways:

  • Conduction: excess heat is transferred through direct contact with an object (e.g. when swimming in cold water).
  • Convection: circulating air allows heat to be transferred to air passing over the skin (depending on the air temperature).
  • Radiation: Involves heat being lost from the body through radiation (e.g. loss of heat within a cold environment).
  • Evaporation: excess heat is transferred to sweat which is then evaporated. Sweating is the most important means of dissipating heat when exercising under hot conditions.
 However, even with the large heat loss through sweat evaporation, body temperature does rise during a match because not all of the heat produced can be released. Evidence also shows that due to the intermittent nature of soccer, the general increase in temperature is greater than that produced through continuous exercise. In addition, the higher the exercise intensity, the greater is the heat production.

COLD WEATHER

The harmful effects of exposure to cold are mediated by the balance between heat production and heat loss. There is a direct relationship between muscle performance and muscle temperature. As temperature decreases, so does performance. For example, muscle strength is impaired and a decrease in reaction time has been shown under cold conditions. Vasoconstriction, where the blood flow to muscles or the outer parts of the body is reduced, occurs.

Under normal conditions, body fluid loss can be around two liters, resulting in a negative effect on soccer performance (a loss of only two percent in body mass affects performance). Even in winter conditions, there is still a danger of dehydration if correct fluid replacement is not implemented. Studies under cold conditions have shown that if players do not drink sufficiently, significant dehydration still can occur.

The risk of injury also is increased when exercising in the cold. Whether this is due to a poor playing surface or incorrect warm-up procedures, athletes should take the necessary precautions to reduce the chance of injury. To reduce the effects of cold weather, players should be properly hydrated, undertake a good warm-up session and wear appropriate warm clothing. The coach must play a major role by making sure players are correctly prepared and checking if the climatic conditions are suitable.

HOT WEATHER

When playing soccer in hot weather, the heat lost through convection and radiation is minimal, requiring heat to be dissipated through sweat evaporation. In humid conditions the body's ability to reduce its temperature is further reduced as sweat evaporation is inhibited. The active muscles and the skin are in direct competition for the limited blood supply as the muscles need blood to provide the oxygen necessary to fuel them and the skin needs blood to facilitate heat loss. Thus, exercising in hot and humid conditions at the least lead to poor performance and at worst be dangerous to the participants.

The distance run by players has been shown to be reduced markedly when playing in hot conditions. Evidence also shows that the loss in body water can be more than three and a half liters (compared to two liters in normal conditions). As mentioned earlier, a loss of two percent in body mass affects match performance levels. A five percent loss will decrease the ability to exercise by as much as 30 percent.

Players can help reduce the effects of a hot climate through:
  • Fluid intake: adequate fluid intake before, during and after the game/training will help avoid dehydration. Players should be correctly rehydrated before competition and take additional drinks when possible. Before exercise, the player's weight should be at its norm. Drink absorption is at its best when mixed to a weak solution of 2.5 percent carbohydrate and rehydration drinks should contain sodium. Thirst is a poor indicator of hydration levels and probably indicates that the player is already dehydrated.
  • Judging their efforts: Many tournaments are played in hot and humid conditions, which are likely to affect playing performance. Players should try to judge carefully their efforts throughout the entire match without exhausting themselves from too much high-intensity exercise too soon in the game.
  • Planning: The coach can judge or measure whether the temperature is too hot for training. Training should not take place in temperatures above 104° F and can be moved to cooler periods (morning/early evening). Plenty of drinks must be made available and exercise intensity levels adjusted accordingly. Training should as well include regular rest periods. Particular attention to the conditions must be taken with children when training or playing matches.
  • Acclimatization: Players can become acclimated to hot conditions by spending a defined period of time in the designated place beforehand (10-14 days is recommended as a good adaptation period). However, training sessions should be shorter and easier at the beginning in hot weather. It seems as well that the higher the training level of individuals, the quicker their adaptation to hot conditions with one of the reasons being a greater ability to sweat.
  • Clothing/Skin Protection: Clothing should be light colored if possible and made of a lightweight, breathable material that allows sweat to evaporate. A soccer uniform soaked in sweat prevents heat loss, so should be changed frequently. Sun block can be used to prevent sunburn.

CONCLUSION

This article has described the effects of temperature on playing performance. Both the coach and player must take the necessary measures to prevent problems that arise when playing soccer in adverse weather conditions. Correct clothing, fluid intake, hydration levels, adaptation, planning and rest periods all play a part in maintaining playing performance. If temperature-related illness is suspected, consult a qualified doctor.


Editor's Note: Lawrence Fine produces FineSoccer.com, an online resource for a variety of tips, ideas and newsletters related to soccer coaching. A member of the NSCAA Website Development Committee, Fine also serves as volunteer assistant coach for an NCAA Division I men's team.