Cold

IR Monkey

09/17/14
To Do Today:

  • PT – Cardio – 1hr cross train // Strength – c/j / dead / squat / tire flip / chest to bar pull-ups.
  • Describe the “Rule of 3’s.”
  • Begin/update your personal medical file. Plan/schedule a comprehensive physical if more than 12 months from your previous medical examination.
  • Begin/update your personal dental file. Plan/schedule a dental appointment if more than 6 months from your previous dental cleaning/exam.
  • Begin/update your personal vision file. Plan/schedule a vision health appointment if more than 12 months from your previous vision examination.

FIVE WAYS THE BODY LOSES HEAT

Radiation. Radiation is direct heat loss from the body to its surroundings. If the surrounding temperature is colder than the body, the net result is body heat loss. Without clothing, you will lose about 60% of your total body heat by radiation (vis-à-vis the other methods listed below). Specifically, heat is lost in the form of infrared radiation. Infrared targeting devices work by detecting radiant heat loss.

Conduction. Conduction is the direct transfer of heat from one object in contact with a colder object. Most commonly conduction occurs when an individual sits or rests directly upon a cold object, such as the ground, a rock, or snow. Without an insulating layer between you and the object (such as leaves, an isopor mat, etc.), you will quickly begin to lose heat. This is why it’s important to not sit or sleep directly on cold ground or snow without vegetation, a mat, or a pack acting as insulation.

Convection. Convection is heat loss to the atmosphere or a liquid. Air and water can both be thought of as “liquids” running over the surface of the body. Water or air, which is in contact with the body, attempts to absorb heat from the body until the body and air or water is both the same temperatures. However, if the air or water is continuously moving over the body, the  temperatures can never equalize and the body keeps losing heat.

Evaporation. Heat loss from evaporation occurs when water (sweat) on the surface of the skin is turned into water vapor. This process requires energy in the form of heat and this heat comes from the body. This is the major method the body uses to cool itself down. This is why you sweat when you work hard or PT. One quart of sweat, which you can easily produce in an hour of hard PT, will take about 600 calories of heat away from the body when it evaporates.

Respiration. When you inhale, the air you breathe in is warmed by the body and saturated with water vapor. Then when you exhale, that heat is lost. That is why breath can be seen in cold air. Respiration is really a combination of convection (heat being transferred to moving air by the lungs) and evaporation, with both processes occurring inside the body.

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