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This article was provided by AccuWeather.com.
Temperatures are dropping to dangerous levels across the northern tier of the U.S. this week. Lower temperatures bring forth new hurdles for the human body to conquer.
Similar to how the body reacts to heat during the summer months, the body naturally reacts and attempts to acclimate itself to cold.
The most important factor in effectively battling and surviving in the cold is the body's ability to maintain its internal core temperature around 98.6 degrees.
A cold and wet environment is the most dangerous because this scenario causes the most heat to escape the body and makes it more difficult for the body to replace lost heat.
Regardless of weather conditions, the body will first exert its three major defense mechanisms in order to battle the cold.
How the Body Adjusts to the Cold:
1. Your Energy Expenditure Decreases
The body will inherently source and spend its energy levels differently in order to keep itself warm. During this process, the body will reduce some of its muscle contractions and reallocate the amount of carbohydrates used.
"As temperatures get a lot colder, your nervous system slows down a little bit and the impulses that move your muscles slow down a little bit," Founder and Head Coach at Runner Academy Matt Johnson said.
Simultaneously, the body will use more carbohydrates to produce lactic acid.
This lactic acid combined with the deceleration of the nervous system will force the body to slow down, so that it can retain heat.
2. Your Blood Flow Reduces
"Cold increases cause blood vessels to constrict and blood flow resistance to increase," Ph.D Research Physiologist for the US Army Research Institute of Environmental Science John Castellani said.
Blood flow is first reduced to the skin and the peripheries including, the fingers, hands and feet. This is why these areas of the body tend to get coldest the fastest.
"We try to limit how much blood we send out there, so it limits how much heat we put into the environment," Castellani said.
The more heat the body can conserve, the more successful the body is at keeping its core temperature in a healthy range.
However, it is this defense mechanism that can actually be detrimental to those with cardiac issues.
The restriction of blood flow also increases blood pressure which in turn influences how blood is received by the heart. This can influence how hard the heart has to work and in colder temperatures may make the heart work even harder than normal.
3. You Start to Shiver
In a venture to bring the body's temperature back up, the body will strive to generate heat itself by allowing muscles and organs to shake within the body, more commonly known as shivering.
While this method uses more energy and is quite inefficient, according to Johnson, it usually begins when skin temperatures begin to fall.
When the Body Hits its Limit:
In extreme cases, during prolonged exposure to the cold, the body will be unable to naturally conserve heat and maintain its internal core temperature. This is when more serious and potentially life-threatening injuries can set in such as frostbite and hypothermia.
Every winter people die from cold-related illnesses. In 2012, eight people lost their lives due to extreme cold.
However, while everyone can experience symptoms of the cold, some people are slightly more likely to run into problems.
Due to the muscle to fat ratio in children, kids can have a moderately higher risk of developing cold injuries. Similarly, the constriction of blood flow in the body may not be as efficient in older adults so they can be at higher risk too.
Nevertheless, "many of the injuries that we see are in the younger people who are out and doing things in the cold," Castellani said.
Have questions, comments, or a story to share? Email Kristen Rodman at Kristen.Rodman@accuweather.com, follow her on Twitter @Accu_Kristen or Google+. Follow us @breakingweather, or on Facebook and Google+.