Temp regulat ion

Cl imat ic condi t ions

Guidel ines for fl uid intake

acc l imit isat ion

FQ3

WHAT ROLE DO PREVENTATIVE

ACTIONS PLAY IN ENHANCING THE

WELLBEING OF THE ATHLETE

ENVIRONMENTAL CONSIDERATIONS

High or low environmental temperatures can have a significant impact on the body’s physiological structures, as the body tries to adapt and maintain its core body temperature (thermoregulation).

ENVIRONMENTAL CONSIDERATIONS

TEMPERATURE REGULATION

For the body to maintain a constant core temperature, heat loss must match heat production. This process is controlled by the part of the human brain known as the hypothalamus.

TEMPERATURE REGULATION

The body has five diff erent ways in which to lose heat:

Radiation. This is the transfer of heat from one surface to another through space with no physical contact between objects, e.g. radiation produced by the infrared rays of the sun.

HEAT LOSS

Convection. This is the transfer of heat through direct contact with air or water (gases) and the body, e.g. skiing at a fast speed as opposed to skiing slowly in the same wind conditions.

Conduction. This is the transfer of heat from the body through direct contact to a cooler object, e.g. swimming in a pool on a hot day where the body transfers its heat to the water and warms the water.

Evaporation. This occurs when heat from the body in the form of liquid (sweat) is converted to a gas to remove heat from the body, e.g. sweating during a soccer match on a warm day. Heat loss during exercise is usually a result of evaporation.

Respiration. This is the transfer of heat through the exhaling of warm air and gases, e.g. an increase in breathing rate when bushwalking.

Exercising causes the body to produce heat.The evaporation of sweat is the body’s main source of

heat loss when exercising. However, exercising in hot and/or humid environments places stress on the body, making it more diffi cult for body to lose heat to maintain its core body temperature.

TEMPERATURE REGULATION

CLIMATIC CONDITIONS

TEMPERATURE

Both hot and cold climates place greater stress on the body, making it more diffi cult for the body to function eff ectively.

High humidity results in slower evaporation, therefore athletes find that sweating does not lower the body’s temperature so effi ciently.

When the body overheats, blood vessels undergo vasodilation—that is, they expand to allow heat to be lost more eff ectively.

As a result, the body is more susceptible to heat stroke and heat exhaustion, known as hyperthermia.

HOT AND HUMID CONDITIONS

Establishing the wet-bulb globe temperature (WBGT) is useful when determining humidity levels.

This measure is used at events such as the Australian Open Tennis in Melbourne.

Sports such as skiing, water skiing, ocean swimming and bushwalking expose athletes to cold weather conditions.

Cold conditions lower the core body temperature. In order to maintain the body’s core temperature, blood vessels constrict to reduce the amount of heat lost. This is known as vasoconstriction. If the body temperature drops too low, hypothermia can develop.

COLD CONDITIONS

In cooler weather it is also important to dress in layers so the body does not overheat—if the body heats up, one layer can be removed at a time, ensuring the body cools gradually rather than suddenly.

COLD CONDITIONS

When competing in an area that is above sea level, an athlete will have less oxygen available to their body than they would at sea level.

The lack of oxygen at high altitudes means the transportation of oxygen is limited.

ALTITUDE

Millions of people live with no apparent diffi culty at altitudes greater than 3000 metres above sea level. They are able to work and exercise comfortably because they are accustomed, or acclimatised, to the conditions.

ALTITUDE

Athletes can, however, undertake altitude training to prepare their bodies to cope with the change in oxygen levels at high altitudes. This training will increase their body’s physical capabilities to achieve greater oxygen uptake at altitude.

ALTITUDE

Short-term anaerobic work is not aff ected by altitude, but longer-term aerobic performances are diminished in high altitude. This is due to hypoxia, which is a condition where an inadequate supply of oxygen is available to the body.

At higher altitudes, atmospheric pressure decreases.

ALTITUDE

The air is less dense; that is, each litre of air contains fewer molecules of oxygen. In technical terms, this is described as a lower partial pressure of oxygen.

In this situation, a person would require more air in order to obtain the same amount of oxygen as would be obtained at sea level.

ALTITUDE

The benefits of acclimatisation are lost within 2–3 weeks after returning to sea level. Acclimatisation will not solve all the problems associated with exercising at altitude. For example, max VO2 will increase for some people, and decrease for others, after training at altitude.

Air pollution can cause injuries and illnesses to athletes participating in physical activity. An increase in air pollution can trigger asthma and various other respiratory illnesses.

High pollution levels during training or competition makes it harder for their bodies to take in oxygen.

AIR POLLUTION

GUIDELINES FOR FLUID INTAKE

The general guidelines for fl uid replacement during exercise include:• Up to 2–3 standard glasses (400–600 ml) of fl uid should be taken at least 30 minutes before activity commences.• Up to 1–2 glasses (200–300 ml) of fl uid every 15 minutes during physical activity in hot humid conditions.• For events up to 90 minutes , plain cold water is the best fl uid to take. Heavily concentrated salt or sugar solutions should be avoided as they reduce water absorption.• In events of intense exercise over 90 minutes in the heat, commercially available carbohydrate or electrolyte replacement fl uids may improve endurance performance by increasing glucose availabil ity.• After exercise replenish fl uid defi cit to ensure that the body is fully rehydrated but not overhydrated.• Complete rehydration should occur before participating in another event or training session.

GUIDELINES FOR FLUID INTAKE

ACCLIMITISATION

A training technique where an athlete experiences diff erent climatic stressors, causing physiological adaptations to occur.

EXAMPLE: Sydney football players playing in Cairns OR Cowboys playing in Canberra

Developing tolerance to expected performance conditions.

Enhanced through exposure and training in a simulated or real environments specifi c to expected conditions.

Acclimatisation to humidity takes 5-7 days.

Altitude takes two to three weeks depending on elevation diff erences,

ACCLIMITISATION