Category: Health and safety

Dehydration

Sweating is the way in which the body maintains its core temperature at 37 degrees centigrade. This results in the loss of body fluid and electrolytes (minerals such as chloride, calcium, magnesium, sodium and potassium) and if unchecked will lead to dehydration and eventually circulatory collapse and heat stroke. The effect of fluid loss on the body is as follows:

Electrolytes

Electrolytes serve three general functions in the body:

• many are essential minerals
• they control osmosis of water between body compartments
• they help maintain the acid-base balance required for normal cellular activities

The sweat that evaporates from the skin contains a variety of electrolytes. The electrolyte composition of sweat is variable but comprises of the following components:

Sodium
Potassium
Calcium
Magnesium
Chloride
Bicarbonate
Phosphate
Sulphate

A litre of sweat typically contains 0.02g Calcium, 0.05g Magnesium, 1.15g Sodium, 0.23g Potassium and 1.48g Chloride. This composition will vary from person to person.

Carbohydrate

Carbohydrate is stored as glucose in the liver and muscles and is the most efficient source of energy as it requires less oxygen to be burnt than either protein or fat. The normal body stores of carbohydrate in a typical athlete are:

70kg male athlete – Liver glycogen 90g and muscle glycogen 400g
60kg female athlete – Liver glycogen 70g and muscle glycogen 300g.

During hard exercise, carbohydrate can be depleted at a rate of 3-4 grams per minute. If this is sustained for 2 hours or more, a very large fraction of the total body carbohydrate stores will be exhausted and if not checked will result in reduced performance. Recovery of the muscle and liver glycogen stores after exercise will normally require 24-48 hours for complete recovery.

During exercise there is in an increased uptake of blood glucose by the muscles and to prevent blood glucose levels falling the liver produces glucose from the liver stores and lactate.

Consuming carbohydrate before, during and after exercise will help prevent blood glucose levels falling too low and also help maintain the body’s glycogen stores. Many athletes cannot consume food before or during exercise and therefore a formulated drink that will provide carbohydrate is required.

Rehydration

Fluid absorption

There are two main factors that affect the speed at which fluid from a drink gets into the body:

the speed at which it is emptied from the stomach
the rate at which it is absorbed through the walls of the small intestine

The higher the carbohydrate levels in a drink the slower the rate of stomach emptying.

Isotonic drinks with a carbohydrate level of between 6 and 8% are emptied from the stomach at a rate similar to water. Electrolytes, especially sodium and potassium, in a drink will reduce urine output, enable the fluid to empty quickly from the stomach, promote absorption from the intestine and encourage fluid retention.

What’s wrong with water?

Drinking plain water causes bloating, suppresses thirst and thus further drinking. It stimulates urine output and therefore is inefficiently retained. A poor choice where high fluid intake is required. Water contains no carbohydrate or electrolytes.
Calculating personal fluid needs

During an endurance event you should drink just enough to be sure you lose no more than 2% of pre-race weight. This can be achieved in the following way:

Record your naked body weight immediately before and after a number of training sessions, along with details of distance/duration, clothing and weather conditions

Add the amount of fluid taken during the session to the amount of weight lost – 1 kilogram (kg) is roughly equivalent to 1 litre of fluid.

After a few weeks you should begin to see some patterns emerging and can calculate your sweat rate per hour

Once you know what your sweat losses are likely to be in any given set of environmental conditions, you can plan your drinking strategy for any particular event

Sports Drinks

There are three types of Sports drink all of which contain various levels of fluid, electrolytes and carbohydrate.

The osmolality of a fluid is a measure of the number of particles in a solution. In a drink these particles will comprise of carbohydrate, electrolytes, sweeteners and preservatives. In blood plasma the particles will comprise of sodium, proteins and glucose. Blood has an osmolality of 280 to 330mOsm/kg. Drinks with an osmolality of 270 to 330mOsm/kg are said to be in balance with the body’s fluid and are called Isotonic. Hypotonic fluids have fewer particles than blood and Hypertonic have more particles than blood.

Consuming fluids with a low osmolality, e.g. water, results in a fall in the blood plasma osmolality and reduces the drive to drink well before sufficient fluid has been consumed to replace losses.

Which is most suitable?

Isotonic – quickly replaces fluids lost by sweating and supplies a boost of carbohydrate. This drink is the choice for most athletes – middle and long distance running or team sports. Glucose is the body’s preferred source of energy therefore it may be appropriate to consume Isotonic drinks where the carbohydrate source is glucose in a concentration of 6% to 8% – e.g. High Five, SiS Go, Boots Isotonic, Lucozade Sport.

Hypotonic – quickly replaces fluids lost by sweating . Suitable for athletes who need fluid without the boost of carbohydrate – jockeys and gymnasts.

Hypertonic – used to supplement daily carbohydrate intake normally after exercise to top up muscle glycogen stores. In ultra distance events high levels of energy are required and Hypertonic drinks can be taken during exercise to meet the energy requirements. If used during exercise Hypertonic drinks need to be used in conjunction with Isotonic drinks to replace fluids.

Want to make your own?

Isotonic – 200ml of orange squash (concentrated orange), 1 litre of water and a pinch of salt (1g). Mix all the ingredients together and keep chilled

Hypotonic – 100ml of orange squash (concentrated orange), 1 litre of water and a pinch of salt (1g). Mix all the ingredients together and keep chilled.

Hypertonic – 400ml of orange squash (concentrated orange), 1 litre of water and a pinch of salt (1g). Mix all the ingredients together and keep chilled.
Dental Health

Sports drinks commonly contain citric acid. All acids have an erosive potential but the method of drinking will influence whether or not those acids effect the teeth. Sports drinks should be consumed as quickly as possible, preferably with a straw and not be held or swished around the mouth. Retaining drinks in the mouth will only increase the risk of erosion. Refrigerated drinks will have a reduced erosive potential as the acid dissolution constant is temperature dependant and cold drinks are absorbed more quickly.

Food for thought

In a trail conducted by scientists in the city of Aberdeen it was determined that a 2% carbohydrate-electrolyte drink provided a more effective combat to exercise fatigue in a hot climate when compared to a 15% carbohydrate-electrolyte mixture.
[Galloway SDR & Maughan RJ, The effects of substrate and fluid provision on ermoregulatory and metabolic responses to prolonged exercise in a hot environment. Journal of Sports Sciences, Vol 18, No5, pp339-351]

Seven Rules of Hydration

The rate of passage of water from your stomach into your small intestine depends on how much fluid is actually in your stomach. If there is lots of water there, fluid flow from stomach to intestine is like a springtime flood; if there is little water, the movement resembles a lightly dripping tap. Therefore, to increase stomach-intestinal flow (and overall absorption of water) you need to deposit a fair amount of liquid in your stomach just before you begin your exercise. In fact, 10-12 ounces of fluid is a good start. This will feel uncomfortable at first, so practise funelling this amount of beverage into your “tank” several times before an actual competition.

To sustain a rapid movement of fluid into your small intestine during your exertions, take three to four sips of beverage every 10 minutes if possible, or five to six swallows every 15 minutes.

If you are going to be exercising for less than 60 minutes, do not worry about including carbohydrate in your drink; plain water is fine. For more prolonged efforts, however, you will want the carbohydrate.

Years of research have suggested that the correct concentration of carbohydrate in your drink is about 5 to 7%. Most commercial sports drinks fall within this range, and you can make your own 6% drink by mixing five tablespoons of table sugar with each litre of water that you use. A bit of sodium boosts absorption; one-third teaspoon of salt per litre of water is about right. Although 5 to 7% carbohydrate solutions seem to work best for most individuals, there is evidence that some endurance athletes can fare better with higher concentrations.

In research carried out at Liverpool John Moores University, for example, cyclists who ingested a 15% maltodextrin solution improved their endurance by 30 per cent compared to individuals who used a 5% glucose drink. The 15% drink also drained from the stomach as quickly as the 5% one, though many other studies have linked such concentrated drinks with a slowdown in water movement.

A 6% “simple sugar” drink will empty from your stomach at about the same rate as a fancy 6% “glucose polymer” beverage, so don’t fall for the idea that the latter can boost water absorption or enhance your performance more than the former, and don’t pay more for the glucose-polymer concoction.

Contrary to what you’ve heard, cold drinks aren’t absorbed into your body more quickly than warm ones. However, cold drinks are often more palatable than warm ones during exercise, so if coldness helps you to drink large quantities of fluid while you exert yourself, then keep your drinks cool.

Swilling drinks during exercise does NOT increase your risk of digestive-system problems. In actuality, most gut disorders that arise during exercise are caused by dehydration, not from taking in fluid. Dehydration induces nausea and discomfort by reducing blood flow to the digestive system, so by all means keep drinking!

Water Intoxication

Intracellular fluid and interstitial fluid have the same osmotic pressures under normal circumstances. The principal cation inside the cell is K+ (Potassium) , whereas the principal cation outside is Na+ (Sodium).

When a fluid imbalance between these two compartments occurs, it is usually caused by a change in the Na+ or K+ concentration. Sodium balance in the body normally is controlled by aldosterone and ADH (antidiuretic hormone) . ADH regulates extracellular fluid electrolyte concentration by adjusting the amount of water reabsorbed into the blood by the distal convoluted tubules and collecting tubules of the kidneys. Aldosterone regulates extracellular fluid volume by adjusting the amount of sodium reabsorbed by the blood from the kidneys which, in turn, directly affects the amount of water reabsorbed from the filtrate.

Certain conditions, however, may result in an eventual decrease in the sodium concentration in interstitial fluid. For instance, during sweating the skin excretes sodium as well as water. Coupled with replacement of fluid volume with plain water, these conditions can quickly produce a sodium deficit. The decrease in sodium concentration in the interstitial fluid lowers the interstitial fluid osmotic pressure and establishes an effective water concentration gradient between the interstitial fluid and the intracellular fluid. Water moves from the interstitial fluid into the cells, producing two results that can be quite serious:

The first result, an increase in intracellular water concentration, called overhydration, is particularly disruptive to nerve cell function. In fact, severe overhydration, or water intoxication, produces neurological symptoms ranging from disoriented behavior to convulsions, coma, and even death.

The second result of the fluid shift is a loss of interstitial fluid volume that leads to a decrease in the interstitial fluid hydrostatic pressure. As the interstitial hydrostatic pressure drops, water moves out of the plasma, resulting in a loss of blood volume that may lead to circulatory shock.

Growth spurts can be a big issue for some children.

They have a disorientating affect on their sporting activities and make them more susceptible to injury.

When do they strike?

Girls tend to have growth spurts between the ages of seven and 12, while boys typically experience growth spurts later – usually from 10 to 14, but every child is unique and develops at a different rate.

What’s happening?

During a growth spurt a child’s bones grow first and fast and their muscles and tendons become inflexible as they get stretched tight until they catch up.

The child’s longer limbs, bigger feet and lack of muscular structure can often lead to a loss in co-ordination.

And there’s a greater tendency to be injury-prone.

Useful precautions

• Make sure your child stretches before and AFTER sport (it’s a better stretch and improves flexibility quickly)
• Ease your child into new seasons or sports
• Keep ability levels as closely matched as possible
• Avoid explosive sports!

Where injuries hit

In particular watch out for nagging heel or knee injuries and inflammations.

Late developers

Some kids may be at a disadvantage physically if they are late maturers.

But keep up the words of encouragement.

Late developers can still go on to have excellent sporting experiences.

Regular trips to the shoe shop and trousers that rapidly become too short are common occurrences during puberty.

In their teens, children put on an amazing growth spurt to reach their final adult height. At their fastest, boys can grow taller by as much as 9cm a year and girls at a rate of 8cm a year. It’s no wonder teenagers are clumsy. Their body is shooting upwards at a speed their brain simply cannot keep up with.

Outside-in

This phenomenal growth starts at the outside of the body and works in. Hands and feet are the first to expand. Needing new shoes is the first sign of trouble.
teenagers shoot up so fast that their brains can’t keep up

Next, arms and legs grow longer, and even here the ‘outside-in’ rule applies. The shin bones lengthen before the thigh, and the forearm before the upper arm.

Finally the spine grows. The very last expansion is a broadening of the chest and shoulders in boys, and a widening of the hips and pelvis in girls.

Growing up and tripping over

Many teenagers shoot up so fast that their brains cannot keep up. As their height increases, their centre of gravity lifts. This happens so quickly that the brain does not get a chance to calculate the new rules for balancing. Clumsiness is often unavoidable.

The trigger

Rapidly increasing height is a sign that a teenager is experiencing puberty. Growth is triggered in both boys and girls by increased levels of the sex hormone testosterone. This chemical also triggers the sexual organs to develop. In fact, the relationship between growth of the skeleton and puberty is so strong that a teenager’s developmental age can be measured by looking at the maturity of the bones in their hand and wrist.

Perfect timing?

Timing is everything. No teenager wants to be developing too quickly, or lagging behind. In reality, many of them grow up much earlier or later than the average and this is perfectly normal.

The average boy is growing fastest between 14 and 15. Girls start earlier, growing fastest when 12 and 13. Girls also end their growth spurt earlier at 18, while boys need another two years before they finish growing aged 20.

Youth soccer coaches have to be careful not to allow matches to go ahead on unsuitable pitches.

There can often be pressure to allow the game to go ahead from your own team (who are usually keen to play no matter what the conditions) and the opposition (who may have travelled a considerable distance). However, this must be resisted. The health and safety of the players has to come first.

The article below was written by an experienced referee and offers some advice for coaches who are about to inspect a hard, frosty pitch.

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There is no scientific measure that can be used to deem a frosty ice covered field to be safe.

Nevertheless, any experienced Referee will take the following into consideration before making a decision.

It is the Referee’s responsibility to make the decision and nobody else’s.

The whole of the field of play surface MUST be safe. There is a great danger that if 99 percent of the field of play surface is OK, and the game is allowed to be played, players will assume that 100 percent is OK, and play normally, and not compensate for any hard surface areas. In other words, playing on a hard field of play, which is partially 99% OK, is just as dangerous (if not more so) than on a field of play, which is totally hard. Neither game should be played.

The Referee should not be influenced by the teams’ opinion. If an accident happens, it is the Referee who cops it.

The teams will deny any responsibility! Therefore, when a field of play inspection is carried out, the Referee should not do so in company of team managers or Club Officials, as they will try to influence the Referee’s decision.

When the weather is doubtful, the Referee should aim to arrive at the ground as early as he can to make an inspection. This may allow time for travelling teams to be warned of a cancellation.

When the weather is doubtful, a check on the local weather forecast can help. For example, although a field of play may be frozen in the early hours of the morning, a prediction of sunshine, will give the Referee a good idea of the possibility that the field may become playable later in the day. If the forecast is for snow or frost or freezing temperatures, then the chances are, that the game will not proceed.

At lower level football, it can be useful for a local Referee to be contacted, to make an early inspection on behalf of the match Referee who lives some distance away from the ground. This can prevent unnecessary travelling.

When completing the field of play inspection, a good indicator of the suitability of the surface, can be ascertained by inspecting the goalmouth areas and the centre circle area first. These are the areas that get more use, and are more likely to be rutted and hard due to frost.

When completing the field of play inspection, other areas for close inspection, are places covered in shadow from buildings or trees. They are more likely to be frost bound, rather than those areas basked in sunshine.

When completing the field of play inspection, if it is not immediately clear that the game cannot be played (i.e. the goalmouth areas are completely solid with frost and the game is definitely cancelled), the whole of the field of play surface MUST must be inspected to eliminate any hidden areas of danger.

A referee, who is seen to be completing a thorough field of play inspection, will have greater credibility when he decides to call off the game, than a Referee who only spends a few minutes making his inspection.

The position of the sun and its path as the game progresses must also be taken into consideration. For example, if a field of play is ‘just about playable’, but the path of the sun means that its rays will disappear behind the trees or over the horizon, then the field of play surface on a cold frosty day, will get worse, not better.

At local level, if it is clear, that waiting an extra 30 minutes or possibly up to an hour, will allow the sun to melt the frost, then play could be delayed with the agreement of both teams. But this depends very much on the weather forecast, the time of day and the team’s agreement. Generally, it is better to make a decision quickly, based on the surface suitability at the time of the scheduled kick-off.

The referee should wear a set of studded boots when inspecting the field of play, as this will give the best indication of the suitability of the playing surface.

A surface which does not yield any purchase to studded boots, is dangerous, and the game should not be sanctioned. This includes, any part of the surface that does not yield, no matter how small an area.

A field of play with hard deep frosted ruts and divots (a legacy of a muddy game played the day before) is less likely to be playable than a completely flat field with only crusty surface-frost to contend with.

When the Referee has made his decision, it should be communicated to the teams as soon as possible. When a Referee is communicating his decision to the teams, that in his opinion, the field of play is not safe, the decision should be made confidently. If teams suspect any doubt in the Referee’s decision, they will try and persuade the Referee to change his mind. In short, when a Referee makes his decision, he should not back down, and he should make it abundantly clear that the decision is his to make, and the game will not be played under his authority.

The inspection of a field of play covered in frost, and whether to sanction a game or not, is not a difficult decision to make for a Referee. It is fairly obvious to identify dangerous area that could potentially cause an injury. Common sense should be used.

Young players are more likely to get injured on hard surfaces. Therefore, even greater care must be taken when making a decision to allow the game to be played or not.

If there is any doubt (no matter how small), then the game must not be played.