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REVISED HOT WEATHER GUIDELINES

(Updated November 2005)

For sporting clubs and associations and the physically active

Why use guidelines?

Every year in hot weather Sports Medicine Australia SA Branch (SMASA) receives requests from sporting clubs and associations, individuals, and members of the media asking:

·      Should our sporting event be modified or cancelled?

·      Should our training be modified or cancelled?

·      When is it safe to play sport or be physically active in the heat?

To help organisations, coaches, teachers and other individuals when conducting sport in hot weather, SMASA has produced this revised set of guidelines. These new guidelines are based on the latest research as well as the expertise of SMASA’s medical and scientific members.

Most people understand the importance of physical activity for good health, but it is just as important to understand that when activity levels rise the risk of harm must be minimised. This fact is even more important for those who have not recently or regularly taken part in sport or physical activity.

These guidelines are not binding, but SMASA reminds all parties that they must act responsibly. We encourage a commonsense approach and consideration of the comfort and well-being of all individuals, including participants and officials.

Modification or cancellation of events, training or withdrawal from participation may be appropriate even in circumstances falling outside these recommendations.

There are many factors to consider when clubs and associations are contemplating modifying, postponing or cancelling sporting events or training.

Sporting organisations need to be aware of the difficulty of setting ‘one size fits all’ guidelines in this area. For normally healthy active people, the dangers from heat illness are likely to arise from high-intensity exercise such as endurance running. Most community sport does not reach this level for periods long enough to cause serious harm. Many types of sport, such as cricket and tennis, are usually safe at higher temperatures because of the lower intensity of the play.

One area of higher risk for organisers of community-level sport is in the management of marathons, fun runs and bike rides. These events are more likely to see participants push themselves beyond their normal boundaries of activity and organisers need to take extra precautions.

However, at any time, high intensity exercise in a hot environment, with the associated elevation of body temperature, can lead to heat illness. Heat illness in sport presents as heat exhaustion or the more severe heat stroke.

Heat exhaustion

Heat exhaustion is characterised by:

• High heart rate

• Dizziness

• Headache

• Loss of endurance/skill

• Confusion

• Nausea

The skin may still be cool/sweating, but there will be signs of developing vasoconstriction (e.g. pale colour). The rectal temperature may be up to 40°C and the athlete may collapse when activity has ceased. Rectal temperature should only be measured by a doctor or nurse.

To avoid heat exhaustion, individuals should immediately cease activity and rest if they feel unwell during exercise. They will benefit further if they rest in a shaded area with some passing breeze (from a fan if necessary) and if they obtain extra hydration. Misting or spraying with water can also help.

Heat stroke

As with heat exhaustion, heat stroke is also characterised by:

• High heart rate

• Dizziness

• Headache

• Loss of endurance/skill

• Nausea

• Confusion

However, it is important to note that athletes with heat stroke will also exhibit dry skin and are likely to collapse.

Heat stroke may arise in an athlete who has not been identified as suffering from heat exhaustion and has persisted in further activity.

The only way to reliably diagnose heat stroke in a collapsed athlete is to measure the core temperature via the rectum. Rectal temperature should only be measured by a doctor or nurse.

Heat stroke is a potentially fatal condition and must be treated immediately. It should be assumed that any collapsed athlete is in danger of heat stroke. The best first-aid measures are to ‘Strip/Soak/Fan':

• Strip the athlete of any excess clothing

• Soak the athlete with water

• Fan the athlete

• Place ice in the athlete’s groin and armpit regions.

The aim is to reduce body temperature as quickly as possible. The athlete should immediately be referred for treatment by a medical professional.

Important: Heat exhaustion or heat stroke can still occur even in the presence of good hydration.

Dehydration

Dehydration is fluid loss that occurs during exercise. It is mainly due to perspiration and respiration. Dehydration will make an athlete more susceptible to fatigue and muscle cramps. Inadequate fluid replacement before, during and after exercise will lead to excessive dehydration, which may then lead to heat exhaustion and/or heat stroke.

To avoid dehydration, SMASA recommends that:

• Athletes drink approximately 500 millilitres (two glasses) in the two hours prior to exercise

• Athletes exercising for more than 60 minutes drink 500-700 millilitres (two to three glasses) of cool water or sports drink. This should be sufficient for most types of exercise.

• After exercise, fluid deficits should be replenished to ensure athletes are re-hydrated but not over-hydrated

• Refer to SMASA’s free ‘Drink Up’ brochure, available as a web download at http://www.smasa.asn.au/resources/resources.htm or from your local National Pharmacies store.

Points to consider:

• During an event, will players and officials be able to consume enough water? Even a small degree of dehydration will cause a decrease in performance.

• Athletes should not over-hydrate. Drinking too much fluid can lead to a dangerous condition known as hyponatraemia (low blood sodium). They should aim to drink enough to replace lost fluids, but not more than that.

Cancelling or Modifying a Sporting Event or Training

Before cancelling or modifying a sporting event or training, consider the following factors:

• Environmental

• Host (personal)

Remember to consider all participants, including the umpires, officials and volunteers involved.

Environmental Factors

1. Temperature

Ambient temperature is the most easily understood guide available and is most useful on hot, dry days.

Further information might be gained from what is known as the Wet Bulb Globe Temperature (WBGT), which is suitable for hot, humid days.

The Bureau of Meteorology (BOM) publishes a list of ambient temperatures, which is easily understood and is most useful on hot dry, days, and WBGTs, which is suitable for hot, humid days, for many locations in Australia, including regional areas. You can check these readings and obtain a guide for the relative risk for your location at www.bom.gov.au/products/IDS65004.shtml or by clicking the local ‘heat alert’ button at  http://www.smasa.asn.au/resources/resources.htm

NB: It is important to look for unusual ‘heat wave’ conditions or variations from the average temperature for a particular time of year. This is one situation when there may be a greater danger of heat illness.

2. Duration and intensity of an event

• The combination of extreme environmental conditions and sustained vigorous exercise is particularly hazardous for athletes. The greater the intensity of the exercise, the greater the risk of heat-related symptoms, e.g. distance running is more of a problem than stop-start team events.

• Player and official rotation may also be considered.

• Reducing playing time and extending rest periods with opportunities to re-hydrate during the event would help safeguard the health of participants.

• Provision of extra water for wetting face, clothes and hair is also important.

• A fan to enhance air movement would be beneficial.

3. Conduct of competition and training (hydration and interchange opportunities)

• Associations may consider dividing games into shorter playing periods rather than halves to allow for extra breaks.

• Coaches may consider alternative training times and venues during hot weather.

• As little as five minutes of rest can cause a significant reduction in core temperatures.

• It is important to consider the welfare of officials, as well as players.

4. Time of day

• Avoid the hottest part of the day, which is usually 11 a.m.-3 p.m. Consider scheduling summer competitions, training or other sporting events outside this time, regardless of the temperature.

5. Local environment

• Radiant heat from surfaces such as black asphalt or concrete can exacerbate hot conditions.

• The type of exercise surface and the amount of sunlight vary significantly with different sporting activities and therefore must be analysed for each individual sport.

• An air-conditioned indoor venue will provide suitable conditions for training or events. A hot indoor venue or an outside venue without shade cannot be considered an acceptable environment.

• Adequate airflow should be considered. Placing fans in change rooms and other locations would be appropriate.

·        Air movement decreases heat stress. However, a ‘following’ wind can increase problems for runners or cyclists by actually reducing air movement.

Host (personal) factors

1. Clothing

• The type of clothing used in sport is vital in minimising health risks associated with exercise in heat.

• Fabrics that minimise heat storage and enhance sweat evaporation should be selected.

• Lightweight, light-coloured, loose-fitting clothes made of natural fibres or composite fabrics with high wicking (absorption) properties that provide for adequate ventilation are recommended as the most appropriate clothing in the heat. This clothing should complement the existing practices in Australia that protect the skin against permanent damage from the sun.

• If clothing is worn for protective reasons, it should only be worn while training and competing in hot weather. Some examples include leathers in motorcycling and mountain biking, protective equipment for hockey goalkeepers and softball and baseball umpires. Non-breathable clothing should be removed as soon as possible if the participants or officials are feeling unwell in hot conditions. The body should be cooled immediately via ventilation and/or a cool spray such as a soaker hose or a hand-held spray and a fan.

These guidelines apply to the clothing worn by players, umpires, other officials and volunteers.

Rectal temperature should only be measured by a doctor or nurse.

2. Acclimatisation of the participant

• Preparation for exercise under hot conditions should include a period of acclimatisation to those conditions, especially if the athlete is travelling from a cool/temperate climate to compete in hot/humid conditions.

• Children will acclimatise slower than adults.

• Regular exercise in hot conditions will facilitate adaptation and will help prevent performance deterioration or heat illness during later competitions. Sixty minutes acclimatisation activity each day for seven to ten days provides substantial preparation for safe exercise in the heat.

Acclimatisation of the participant includes umpires, other officials and volunteers as well as players.

3. Fitness levels/athletic ability of participant

• A number of physical/physiological characteristics of the athlete will influence the capacity to tolerate exercise in the heat, including body size and endurance fitness.

• In endurance events, accomplished but non-elite runners striving to exceed their performance may suffer from heat stress. The potential for heat-related illnesses would be exacerbated if they have not acclimatised to the conditions and have failed to hydrate correctly.

• Overweight and unconditioned athletes, umpires, officials and volunteers will also be susceptible to heat stress.

·         Refer to SMASA’s free ‘Drink Up’ brochure available from www.smasa.asn.au/resources or your local National Pharmacies store.

4. Age and gender of participant

• Female participants may suffer more during exercise in the heat because of their greater percentage of body fat.

• Young children are especially at risk in the heat. Prior to puberty, the sweating mechanism, essential for effective cooling, is poorly developed. The ratio between weight and surface area in the child is also such that the body absorbs heat rapidly in hot conditions.

• In practical terms, children must be protected from over-exertion in hot climates, especially with intense or endurance exercise.

• Although children can acclimatise to exercise in the heat, they take longer to do so than adults. Coaches should be aware of this and limit training for non-acclimatised children during exposure to hot environments.

NB: Children tend to have a more commonsense approach to heat illness than adults. They listen to their bodies more and will usually slow down or stop playing if they feel distressed in the heat. Children should never be forced to continue sport or exercise if they appear distressed or complain about feeling unwell.

• Veteran participants may also have difficulty coping with exercise in the heat. Reduced cardiac function is thought to be responsible for this effect.

5. Predisposed medical conditions

• It is important to know if athletes, umpires, officials or volunteers have a medical condition or are taking medication that may predispose them to heat illness. 

• Examples of illnesses that will put the participant or official at a high risk of heat illness include asthma, diabetes, pregnancy, heart conditions and epilepsy. Some medications and conditions may need special allowances.

• Participants and officials who present with an illness such as a virus, flu or gastro or who are feeling unwell are at an extreme risk of heat illness if exercising in moderate to hot weather.

• Participants or officials who may be affected by drugs or alcohol may be at an extreme risk of heat illness if exercising in moderate to hot weather.

• SMASA has produced pre-exercise health check guidelines. These should be used if pre-existing medical conditions are suspected or if the participant has no recent record of activity. The guidelines can be downloaded from the SMA national website at www.sma.org.au

6. Other factors to consider

• Preventative measures can be undertaken to minimise heat injuries. Examples include the provision of shade, hats, appropriate sunscreen, spray bottles and drinking water.

• It is important to have trained personnel available to manage heat injuries and designated recovery areas for patients.

• In situations where heat problems may be expected, an experienced medical practitioner should be present.

Heat stroke is potentially life threatening. Any indication of this condition should be immediately referred for medical assessment.