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Injuries Chronic & Acute

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Old 03-12-2007, 05:01 PM   #1
Bobbi Beglau Salvini
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We are entering that time of year again, at least here in California, where we have some hot days to contend with. Heat prostration and heat stroke can be deadly, and so I will take on this dry topic so we all stay safe.

What to Watch For Heat Stress: The stages

Vasomotor control: As the heat stress increases, more blood is pumped to the skin and less to the visceral organs and brain. There is cardiovascular stress and tachycardia. Muscular work is reduced since it produces more heat. Heat exhaustion is manifested by headaches, dizziness, sleepiness, lack of concentration and anorexia.

Evaporative cooling: The body starts to sweat with the amount of related to the degree of stress and acclimatization. Loss of sodium chloride (salt) through sweating causes heat cramps (painful cramps starting in the working muscles and spreading to other muscles) and dehydration which aggravates cardiovascular problems. The volume of urine is reduced. High air velocity and low relative humidity help cooling through the evaporation of sweat.

Heat Stroke: If sweating is not sufficient to keep the body temperature within the physiological range, the heat regulating centre fails, sweating stops, the skin is flushed and the person is said to suffer from heat stroke. Unconsciousness and death may follow. It is an emergency situation where rapid cooling, rehydration and replacement of electrolytes are needed.

Excessive sweating can also cause electrolytes to be thrown off changing the bodies pH and transfer of water from the body into the intestine making the dehydration worse. Hypovolaemic shock (bicarbonate concentration is less than 10 mmol/l; ) can also cause excessive production of lactic acid which can cause vomiting also making the dehydration worse.
• Breathing becomes deep and rapid, which helps to raise arterial pH by causing a compensating respiratory alkalosis.

Potassium Depletion
The signs of hypokalaemia may include:
• general muscular weakness;
• cardiac arrhythmias;
• paralyticileus, especially when drugs are taken that also affect peristalsis (such as opiates).
When metabolic acidosis is corrected by giving Bicarbonate a potassium-deficiency can be created causing hypokalaemia. This can be prevented by replacing potassium and Bicarbonate at the same time.

WHAT TO DO?

Hydration: It is important to remember to keep hydrated before, during and after exercise. It can take the body as long as twelve hours to become properly re-hydrated after exercise.
Generally, try to drink enough fluid, preferably water, that your urine is always straw colored or pale yellow. Don’t wait on hot days to start drinking right before exercise. Drink lots of water!

How much water?
The amount of water/fluid you need to consume everyday depends on your age, sex, size, metabolism and exertion. The water requirement may be calculated based on caloric requirement for the day or using body weight. In general, an adult living in general conditions (in terms of environmental exposure and how much energy is expended requires approximately 1 ml of water per calorie consumed Therefore, if the average caloric requirement for the day is 2000 cal then that person needs 2 liters of fluid a day. The requirement is higher for children by up to 1.5 times.

The fluid requirements increase if you are exposed to high temperatures, high humidity, or high altitudes. You also need more fluids if your diet is high in fiber and you consume a lot of alcohol or caffeine or you take a medication that is a diuretic. For Crossfiter, a gallon is good.

Have on hand a good electrolyte sport drink or a pediatric anti diarrhea drink such as Pedialite that approximates the below specs. Heath food stores have some dry mixes that are good that can be added to water. I keep one in my sports bag. The reason I recommend pre packaged mixes is the first time I had uncontrolled heat cramps, I later found out it was because I did not have enough sodium, the second time I forgot to eat glucose. When you are in that much pain you may not be thinking clearly. And as you read below, if you don’t do this right you can actually make things worse.

Eat a well balanced diet.

Pay attention to the risk factors, and stop and recover if you need to. Because heat illness can affect your brain and judgment, have a work out buddy that will keep and eye out for you if temperatures and or humidity is up.

Give your body time to adjust to hot weather. A gradual exposure over time to a hot environment under work conditions results in acclimatization and better tolerance. This is why most laborers that die from heat exposure are new employees.

Save your anaerobic work outs for the early morning or evening or air conditioned space. Swimming in cool water is also a good choice. As you can see from above, lactic acid which is a by-produced of anaerobic work outs of high intensity is also associated with heat illness.

Pick a spot out of the sun that is well ventilated. Cross ventilation and fans are a good choice.

REHYDRATION THERAPY
The goal in managing dehydration is rapidly to correct fluid and electrolyte deficits. Oral rehydration therapy (ORT)
Sucrose or cooked starches are a good way to enhance the absorption of electrolytes and water. In fact without a source of glucose or amino acids, sodium is not absorbed and the fluid remains in the gut. However, when an isotonic solution of glucose and salt is given, glucose-linked sodium absorption occurs and this is accompanied by the absorption of water and other electrolytes.
Oral rehydration salts (ORS)
A balanced mixture of salts of potassium and citrate (or bicarbonate), in addition to sodium chloride and glucose to form an oral rehydration salt (ORS) is used in treating and preventing dehydration, potassium depletion, and base (pH) deficit due to dehydration. The following guidelines were used in developing the WHO/UNICEF-recommended ORS solution:
• the solution should have an osmolarity similar to, or less than that of plasma, i.e., about 300 mOsmol/l or less;
• the ratio of glucose to sodium (in mmol/l) should be at least 1:1 to achieve maximum sodium absorption;
• the concentration of potassium should be about 20 mmol/l in order adequately to replace potassium losses;
• the concentration of base should be 10 mmol/l for citrate or 30 mmol/l for bicarbonate, which is satisfactory for correcting base-deficit acidosis. The use of trisodium citrate, dihydrate, is preferred, since this gives ORS packets a longer shelf life.
References from the World Health Organization
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Old 03-12-2007, 05:25 PM   #2
Adam Noble
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Good post. It was seriously hot here in L.A. yesterday. I went snowboarding and encountered the heat on the way home. It seemed worse as I drove home in my pants (not expecting it to be 95), and the ac in my car isn't working. Been rehydrating since yesterday.
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Old 03-12-2007, 05:44 PM   #3
Lynne Pitts
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Old 03-15-2007, 02:45 AM   #4
Samuel Redwine
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I spent mid May to mid July last summer out at 29 Palms in CA. It was routinely 90%F overnight. During the day was 110-130%. Let me tell you something we were told. Drink water, gatorade, etc. Drink lots and often. If you do not have to urinate every 1-2 hours you're awake, you are not drinking enough. We routinely drank 64oz/1.892liters upon waking in the mornings.
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Old 03-15-2007, 05:38 PM   #5
David Aguasca
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it doesn't get as hot in the hudson valley as it does in the desert, but the humidity here is the killer. this past summer, there were many days where it was above 95F but also so humid you could swim your way to your car and back.

great post!

(Message edited by david_aguasca on March 15, 2007)
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Old 03-17-2007, 09:36 PM   #6
Bobbi Beglau Salvini
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I talk to my MD about this topic yesterday and he recommended a product called Gookinaid Hydralyte. He said it was developed by a man looking for an ideal formula, while he was stationed in Iraq. I purchased some at REI, and I understand you can get most of their products through the internet if you cant find it local. I tried it today, and I felt great through my whole workout.

Adam, I bet you looked like the polar bear in your avitar. Don’t you just love California, ski in the snow and roast in the sun all on the same day!

David: Dang I hate humidity. I used to work out with a private boxing coach mid day in the summer in San Diego. It didn’t seam all that hot but the humidity was a killer. I have been blessed by many coaches that make you push through. You got to love it!
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