200317 Fluid replacement-Water and the body-why we need it (2/3)

200317 Fluid replacement-Water and the body-why we need it 

In the book Essentials of Strength Training and Conditioning (page 247), it states that a fluid loss of around 1% of body weight will increase core temperature with a disproportionate rise in heart rate. These increases in temperature causes further fluid loss and the cycle repeats itself.

Plasma volume becomes reduced when sweating causes a fluid loss of 2-3% body mass. The blood thickens, which makes the heart work harder at pumping it through out the body. As dehydration progresses and plasma volume decreases, peripheral blood flow and sweating rate are reduced and thermo regulation becomes progressively more difficult. (Page 509 reference #1)

A 5% dehydration of the body mass significantly increases rectal temperature and decreases sweating rate. There is 25-30% decrease in stroke volume from the heart that is not off set by a higher heart rate so the system output and arterial blood pressure decline. For each liter of sweat loss, the heart rate increases by about eight beats per minute, with a corresponding decrease in cardiac output. “The primary aim of fluid replacement is to maintain plasma volume so that circulation and sweating progress at optimal levels”.

In Essentials of Strength and Conditioning, it (page 247) states that at 7% body weight loss a collapse is likely. Obviously, this is a serious condition if left unchecked.

Ultimately, the strain on the circulatory system impairs the thermo regulation of the body. (Page 507 reference #1)

Thirst is not a good indicator of hydration level as it normally lags behind the body’s needs. Each adult requires from 2-3 quarts of water/fluid daily, less than that, will gradually result in a dehydrated state over a period.

Indicators of the need for more fluid in the body that are relatively simple to monitor are (Page 247 reference #2)

  • Dark yellow urine (unless excessive vitamin intake has occurred)
  • Strong smelling urine
  • Decrease times of having to urinate
  • A rapid resting heart rate
  • Muscle soreness that lingers longer than normal

Normal urine loss for an adult is about 4 times per day for a total of about 1.2 quarts. This means the elimination of 8-10 fluid ounces about 4 times per day. If a person is drinking over and above the normal requirements bathroom breaks could occur more often. If this is not the case, and you are not drinking excessively, perhaps a check for diabetes is in order.

180317 Fluid replacement-Water and the body-why we need it (1/3)

180317 Fluid replacement-Water and the body-why we need it

Background information

Water “serves as the body’s transport and reactive medium: Diffusion of gasses always takes place across surfaces moistened with water. (Page 53 reference # 1)

  • Nutrients and gases are transported in aqueous solution.
  • Waste products leave the body in urine and feces
  • Water has tremendous heat-stabilizing qualities because it can absorb considerable heat with only a small change in temperature.
  • Water lubricates joints
  • And finally because it is essentially incompressible it helps give structure and form to the body through the turgor (the normal fullness of the blood vessels and capillaries) it provides for body tissues.”
  • Dehydration and its effects on the body.

Most studies relating to dehydration have been conducted for sports or military related reasons, but the results are the same; the body has to have fluids to run efficiently. It needs to replace these lost fluids in order to remain cool enough to properly function. If not, then heat builds up. The body attempts to lessen this raising of the core temperature by various mechanisms such as breathing faster or sweating more. If enough sweat is produced, dehydration cannot be far behind.

Sweat causes the body to lose electrolytes specifically sodium, potassium, chloride and magnesium. Each one of these electrolytes has an impact on, and is crucial to muscle and nerve activity. (Page 246 reference #2)

Therefore, lots of sweating over long periods can, and will, affect your ability and level of mental and physical performance. In fact, if sweating is heavy enough for an extended time (several hours) sweat fatigue may result. Sweat gland fatigue can cause an inability of the sweat glands to regulate core temperature. This is the body’s main mechanism for heat dissipation; should it be disrupted serious consequences result. (Page 408 reference #1)

Our body mass consists of 40-60% water, with muscle containing about 65-75% water, and fat having about 50% water. Excessive water/electrolyte losses impair heat tolerance and physical performance. This can lead to severe dysfunction in the form of heat cramps, heat exhaustion and finally heat stroke, which can be life threatening. (Page, 51-reference #1)

Much of the fluid loss is called extra cellular, meaning fluids that surround and bathe the cells (blood plasma, lymph, saliva, fluid in the eyes, fluid secreted by the glands, fluid that bathes the spinal cord and fluid excreted from the skin and kidneys). Blood plasma accounts for 20% of the extra cellular fluid (between 3 and 4 liters). (Page 53 reference #1)

Continued next week.