Somebody told me yesterday about the concept of Bikram Yoga. I am not an expert and I do not want to discourage people that support it, but, based on my knowledge, I believe that the side effects and the risks of it outweigh the possible benefits. The main reasons I believe that are the following:
As in other mammals, thermoregulation is an important aspect of human homeostasis. Most body heat is generated in the deep organs, especially the liver, brain, and heart, and in contraction of skeletal muscles. Humans have been able to adapt to a great diversity of climates, including hot humid and hot arid. High temperatures pose serious stresses for the human body, placing it in great danger of injury or even death. For humans, adaptation to varying climatic conditions includes both physiological mechanisms resulting from evolution and behavioural mechanisms resulting from conscious cultural adaptations.
- Exhaustion of body temperature control mechanisms
- Unnecessary heart overload
- Unhealthy temperature for the skin and hyperthermia
- Oversweating and dehydration
- Possible instability of joints due to excess mobility under high temperature
As in other mammals, thermoregulation is an important aspect of human homeostasis. Most body heat is generated in the deep organs, especially the liver, brain, and heart, and in contraction of skeletal muscles. Humans have been able to adapt to a great diversity of climates, including hot humid and hot arid. High temperatures pose serious stresses for the human body, placing it in great danger of injury or even death. For humans, adaptation to varying climatic conditions includes both physiological mechanisms resulting from evolution and behavioural mechanisms resulting from conscious cultural adaptations.
In hot conditions
- Eccrine sweat glands under the skin secrete sweat (a fluid containing mostly water with some dissolved ions) which travels up the sweat duct, through the sweat pore and onto the surface of the skin. This causes heat loss via evaporative cooling; however, a lot of essential water is lost.
- The hairs on the skin lie flat, preventing heat from being trapped by the layer of still air between the hairs. This is caused by tiny muscles under the surface of the skin called arrector pili muscles relaxing so that their attached hair follicles are not erect. These flat hairs increase the flow of air next to the skin increasing heat loss by convection. When environmental temperature is above core body temperature, sweating is the only physiological way for humans to lose heat.
- Arteriolar vasodilation occurs. The smooth muscle walls of the arterioles relax allowing increased blood flow through the artery. This redirects blood into the superficial capillaries in the skin increasing heat loss by convection and conduction.
In cold conditions
- Sweat stops being produced.
- The minute muscles under the surface of the skin called arrector pili muscles (attached to an individual hair follicle) contract (piloerection), lifting the hair follicle upright. This makes the hairs stand on end which acts as an insulating layer, trapping heat. This is what also causes goose bumps since humans don't have very much hair and the contracted muscles can easily be seen.
- Arterioles carrying blood to superficial capillaries under the surface of the skin can shrink (constrict), thereby rerouting blood away from the skin and towards the warmer core of the body. This prevents blood from losing heat to the surroundings and also prevents the core temperature dropping further. This process is called vasoconstriction. It is impossible to prevent all heat loss from the blood, only to reduce it. In extremely cold conditions excessive vasoconstriction leads to numbness and pale skin. Frostbite only occurs when water within the cells begins to freeze, this destroys the cell causing damage.
- Muscles can also receive messages from the thermo-regulatory center of the brain (the hypothalamus) to cause shivering. This increases heat production as respiration is an exothermic reaction in muscle cells. Shivering is more effective than exercise at producing heat because the animal remains still. This means that less heat is lost to the environment via convection. There are two types of shivering: low intensity and high intensity. During low intensity shivering animals shiver constantly at a low level for months during cold conditions. During high intensity shivering animals shiver violently for a relatively short time. Both processes consume energy although high intensity shivering uses glucose as a fuel source and low intensity tends to use fats. This is a primary reason why animals store up food in the winter.[citation needed]
- Mitochondria can convert fat directly into heat energy, increasing the temperature of all cells in the body. Brown fat is specialized for this purpose, and is abundant in newborns and animals that hibernate.
What is happening during exercise?
During strenuous exercise the body's heat production may exceed 1000 W. Some of the heat produced is stored, raising body core temperature by a few degrees. Rises in body temperature are sensed by central and skin thermoreceptors and this sensory information is processed by the hypothalamus to trigger appropriate effector responses. Other sensory inputs from baroreceptors and osmoreceptors can modify these responses. Evaporation of sweat and increased skin blood flow are effective mechanisms for the dissipation of heat from the body but dehydration impairs the capacity to sweat and lose body heat. Hot, humid environments or inappropriate clothing may compromise the ability to lose heat from the body. Exercise training improves tolerance to exercise in the heat by increasing the sensitivity of the sweat rate/core temperature relationship, decreasing the core temperature threshold for sweating and increasing total blood volume.
How does cold temperature affect heart rate?
Unless you are starting to dye or get severe hypothermia your blood pressure increases. Because your muscles are tensing to confiscate for the cold weather. thats why you shiver. Since your body is doing that your organs demand for more blood and since your body works together the heart pumps out more blood to fulfill the need, therefore increasing your blood pressure.
How does hot temperature affect heart rate?
The blood vessels of the body, particularly the peripheral blood vessels, i.e those of the skin; can dilate or contract depending on body temperature. When the temperature of the body drops, the peripheral blood vessels contract to conserve heat. When the body's temperature increases above normal, the peripheral blood vessels dilate to allow more heat to escape. The blood vessels dilating lowers the blood pressure in the body, because the blood distribution has increased to areas which previously had less distribution. The body now has to compensate, because of the change in pressure less blood is being pumped to the vital organs of the body. It does this by increasing the cardiac output, the amount of blood pumped out of the heart per given time. Cardiac output can be increased by increasing the heart rate. Thus an increase in temperature, through the vasodilation of blood vessels causes a drop in blood pressure, which is compensated for by increasing the cardiac output, which can be achieved through increasing the heart rate. Therefore heart rate increases when temperature increases.
How does sweating help us to cool down?
When we sweat, our skin and clothing become covered with water. If the atmospheric humidity is low, this water evaporates easily. The heat energy needed to evaporate the water comes from our bodies. So this evaporation cools our bodies, which have too much heat. For the same reason splashing water on ourselves when it is hot feels good. Being wet during cold weather, however can excessively chill us because of this same evaporation effect.
Sweating is therefore the human body's primary cooling mechanism. Because this mechanism uses water, we need to replace lost fluids by drinking more fluids in hot weather. This is especially true after exercising or working in hot weather.
Does sweating help you lose weight?
Sweat happens. Throughout every day of your life, you exude a watery blend of urea, salts, sugars and ammonia from your pores. Most people presume that when you sweat, you lose weight. It's true that when you sweat, you shed some weight. However, most of the weight you lose is water weight, and you regain that as soon as you rehydrate. Any real weight loss that occurs when you sweat happens because of what you are doing that makes you sweat, and not because of the sweating.
Does sweat remove toxins from the body?
Does sweating help you lose weight?
Sweat happens. Throughout every day of your life, you exude a watery blend of urea, salts, sugars and ammonia from your pores. Most people presume that when you sweat, you lose weight. It's true that when you sweat, you shed some weight. However, most of the weight you lose is water weight, and you regain that as soon as you rehydrate. Any real weight loss that occurs when you sweat happens because of what you are doing that makes you sweat, and not because of the sweating.
Does sweat remove toxins from the body?
Toxins in the body include heavy metals and various chemicals such as pesticides, pollutants, and food additives. Drugs and alcohol have toxic effects in the body. Toxins are produced as normal by-products in the intestines by the bacteria that break down food. The digestion of protein also creates toxic by-products in the body.
The body has natural methods of detoxification. Individual cells get detoxified in the lymph and circulatory system. The liver is the principle organ of detoxification, assisted by the kidneys and intestines. Toxins can be excreted from the body by the kidneys, bowels, skin, and lungs. Detoxification treatments become necessary when the body's natural detoxification systems become overwhelmed. This can be caused by long-term effects of improper diet, stress, overeating, sedentary lifestyles, illness, and poor health habits in general.
Sweat does contain trace amounts of toxins but definitely won't help clear the body of mercury or other metals. Almost all toxic metals in the body are excreted through urine or feces. Less than 1% are lost through sweat. Sweating for the sake of sweating (e.g. sauna "treatments") has no benefits. In fact, heavy sweating can impair your body's natural detoxification system due to dehydration.
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