Water is essential to maintain blood volume, regulate body temperature and allow muscle contractions to take place. During exercise, the main way the body maintains optimal body temperature is by sweating.

Heat is removed from the body when beads of sweat on the skin evaporate, resulting in a loss of body fluid. Sweat production, and therefore fluid loss, increases with a rise in ambient temperature and humidity, as well as with an increase in exercise intensity.

Drinking fluid during exercise/work in heat stressed environments is necessary to replace lost sweat. This action will reduce the risk of heat stress, maintain normal muscle function, and prevent performance decreases due to dehydration.

(Source: Sports Dietitians Australia)

Muscle fatigue, lower concentration levels, thirst, loss of appetite, dark coloured urine.

It’s proven that water alone cannot sufficiently replace lost electrolytes. Pure water is absorbed slowly and cannot be retained by the body. During the first minute of consumption, the body absorbs HydraSafe™ significantly faster that it would water.

HydraSafe™ provides sodium to assist with replacing sodium lost in sweat and to assist in the prevention of cramping. HydraSafe™ may also contain carbohydrates which can assist in replacing carbohydrates used during extended periods of exercise/physical activity. The replenishment of these carbohydrates can assist with maintaining or improving energy and concentration levels.

During extending periods of time working outside:

• A good guide is 750ml fluid per hour (this could be a combination of HydraSafe™ and water)
• To establish how much fluid you need, try weighing yourself at the beginning and end of a shift. Each kg you lose is a litre of fluid you didn’t drink.
• For example – over a 12 hour shift you drink 500mls an hour (6 litres in total) but lose 3kg. That means that there was 3 litres of fluid you didn’t drink. 3kg over 12 hours is 250mls per hour. Therefore, you should add 250mls per hour to the fluid that you did drink and your fluid goal is 750mls per hour.

Working in heat stress environments will create an increase in body heat which in turn increases the blood flow to the skin. The body is attempting to carry the heat to the skin where it can evaporate, subsequently causing the cooling effect to take place. The body releases heat through the skin via sweat which is the bodies cooling mechanism. By increasing its work rate, the heart will pump faster in order to carry the blood faster to the surface – thereby releasing the heat from the body as quickly as possible. The following factors will limit the cooling process from taking place:

• Air temperature is too high
• Humidity is too high
• A high radiant heat load is present
• Too much insulating clothing constricting the worker

If the above factors are present then the body begins to experience physiological heat stress with differing symptoms depending on the degree of stress.

An electrolyte disturbance (disturbance of the salts in the blood) in which the sodium concentration in the plasma is lower than normal (below 135 mmol/L).

Whilst working in high temperatutes, sodium is lost through perspiration (sweat). A worker who only replaces the lost fluid with water could contribute to a decreased blood sodium concentration.

Early warning signs are often subtle and may be similar to dehydration:

• Nausea
• Muscle cramps
• Disorientation
• Slurred speech
• Confusion

At the first sign of nausea, muscle cramps or disorientation, it is recommended that the individual consume a sodium replacement product / drink. The individual should then seek medical attention to ensure that they have appropriately replaced the electrolytes in their body.

Prevention is always better than a cure. The best way for an individual to avoid hyponatremia is to plan ahead. Tips and recommendations for planning include:

• Use an electrolyte (sodium based) drink during exposure to heat stress environments. A hydration strategy in addition to water is highly recommended.
• Each individual should understand their personal fluid needs.
• Weigh yourself before and after a shift/activity and drink enough sodium based fluid to offset any fluid loss.
• Seek advice from a medical professional regarding your personal requirements.

The amount of fluid, and the timing of drinks depend on the individual and the sport / work being undertaken.

• You should always start work/exercise well hydrated. This will lower the risk of becoming dehydrated.
• Develop a plan for drinking during work/exercise based on your own sweat rates.
• Immediately after work/exercise, monitor your weight change to estimate your final fluid deficit. During recovery, you will continue to lose fluids through sweating and urine losses, so plan to replace 150% of this fluid deficit over the next 2-6 hours. (For example, if you lost 1kg, you will need to replace 1500mls to fully re-hydrate. (source: Sports Dieticians Australia)