Below which temperature human muscles don't work?

Below which temperature human muscles don't work?

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When one exposes theirs body parts to cold environment (especially foot and hands), they may be numb, with temporarily blocked both muscles.

What is typical body temperature below which human muscles don't work properly?

Moreover, what is the mechanism behind it?


Interested in case when muscles almost cease to work (e.g one is not able to grasp a cup), not just in small perturbations to strength.

If you dissect striated muscle out of most-any organism, the actual contractile apparatus works over a wide range of temperatures. So that's at the single-muscle-fiber scale. The muscle itself continues to work at all (thawed) temperatures below body temperature -- the problem comes with its regulation.

The shivering response -- a centrally controlled involuntary contractile pattern -- overwhelms voluntary muscle control. So the mechanism behind loss of muscle coordination in hypothermia is the same as the shivering mechanism. When the core temperature drops, the midbrain starts over-riding voluntary control of the muscles. When the core temperature drops far enough; around 32C, the shivering often slows down or stops. Voluntary movement becomes compromised probably because the brain simply isn't working; neuron firing rates are so slow that sensation, processing, and motor responses are all critically impaired.

The feeling of numbness does not actually directly accompany a loss of muscle contractility. You can walk pretty much indefinitely on frozen feet if you can keep your balance (and you keep your core temperature up.) Lots of people survive severe frostbite of their feet (their feet do not often survive, however.) The reason why it seems your hands don't work when they get cold is that you can't feel what you're doing (note; your hands can be much colder than your core body temperature.) But the muscles themselves work right up until they freeze solid.

UPDATE: Here's a paper that directly addresses the scenario posed by OP -- the decrease in grip strength with temperature. Figure 1 of that paper illustrates their experimental setup; they measure the contractile strength of the index finger while manipulating the temperature of the rest of the hand. They show that contractile function is impaired with temperature and look at temperatures as low as 12C.

They measure as much as a 50% impairment on twitch tension upon cooling to 12C. It's interesting that they review results suggesting that some of this effect is intrinsic to the muscle fiber (not neurological), showing that I should refine what is meant by "continuing to work" in my opening paragraph. (I meant having an ability to generate contractile force when equilibrated in solution containing sufficient ATP and Ca$^{2+}$, not the ability to contract optimally.) For fun, I linearly extrapolated the final arm of Figure 5 and found that the 'voluntary tension' approached 25% at 5C. This suggests that total failure of the voluntary contraction happens somewhere below the freezing point of water (muscle would freeze at a temperature lower than 0C because of colligative effects.)

This seems complicated, but I found a reference that might answer these questions (if its right).

Sports physiology common wisdom is that human muscles regularly work in the range of 37C to 40C which is basically body temperature. Since the muscles generate quite a bit of heath when they function, they are usually not functioning in colder temperatures and hyperthermia starts setting in.

Thomas et al. put this to the test by cooling down some muscles in volunteers! They say that the core body temperature is more important than the peripheral temperature in restoring muscle strength (torque produced). Hypothermia makes the victim weaker and weaker apparently and it sets in below 37C pretty quickly apparently. They speculate that the cooling might actually impair the nervous system from activating the muscles, which might be an answer to your question.

This is probably not the final word, but its as far as I got…

Understanding the IT band

The IT band runs along the outside of the thigh, from just above the hip to just below the knee, and is made up of fascia, an elastic connective tissue found throughout the body.

Image source:


How high is too high when it comes to your temperature? Anything above 100.4 F is considered a fever. You may feel terrible, but on the whole, a fever isn’t bad for you. It’s a sign your body is doing what it should when germs invade. It’s fighting them off.

However, if your temperature is 103 F or higher or if you’ve had a fever for more than 3 days, call your doctor. Also call if you have a fever with symptoms like severe throat swelling, vomiting, headache, chest pain, stiff neck or rash.

For children, fevers are a bit more complicated. Call your pediatrician if your child is:

  • Under 3 months and has a rectal temperatures of 100.4 F or higher
  • Between 3 months and 3 years and has a rectal temperature over 102 F
  • Older than 3 years and has an oral temperatures above 103 F
  • Between 3 and 6 months and -- along with a fever -- is fussier or more uncomfortable than usual, or doesn’t seem alert
  • Sick enough for you to be concerned, regardless of what the thermometer says

There are two types of cells in your brain, neurons and glial cells (glia - Greek word for glue). For a long time biologists have thought that the neurons were the only cells that controlled our bodies and were also where our memories are kept. Glial cells were just in the brain to support neurons, insulate them, provide nutrition, and do basic housekeeping. New research is beginning to show that glial cells are doing more than these jobs.

Support: Glia cells act as a physical support and protection for neurons. They also help keep the blood-brain barrier which prevents toxic chemicals in the blood from entering the brain.

Nutrition: Glia cells help keep the environment around neurons in balance and make sure the right nutrients are available for neurons.

Insulation: Glia cells can create myelin , a fatty substance that helps insulate the axons of neurons. This helps keep electrical signals inside the neuron and helps them move faster.

Housekeeping: Glia cells can prevent the buildup of toxic chemicals, help destroy viruses and bacteria, and get rid of dead neurons.

Biologist Dennis McDaniel used a confocal laser scanning microscope (CLSM) to see inside the brain. The rotating image shows many glial cells called astrocytes .

What is a normal body temperature range?

Normal body temperatures vary depending on many factors, including a person’s age, sex, and activity levels.

The normal body temperature for an adult is around 98.6°F (37°C) , but every person’s baseline body temperature is slightly different, and may consistently be a little higher or lower.

In this article, we discuss the normal ranges of temperature for adults, children, and babies. We also consider factors affecting body temperature, and when to call a doctor.

Body temperature readings vary depending on where on the body a person takes the measurements. Rectal readings are higher than oral readings, while armpit readings tend to be lower.

The table below gives the normal ranges of body temperature for adults and children according to a thermometer manufacturer:

Type of reading0–2 years3–10 years11–65 yearsOver 65 years
Oral95.9–99.5°F (35.5–37.5°C)95.9–99.5°F (35.5–37.5°C)97.6–99.6°F (36.4–37.6°C)96.4–98.5°F (35.8–36.9°C)
Rectal97.9–100.4°F (36.6–38°C)97.9–100.4°F (36.6–38°C)98.6–100.6°F (37.0–38.1°C)97.1–99.2°F (36.2–37.3°C)
Armpit94.5–99.1°F (34.7–37.3°C)96.6–98.0°F (35.9–36.7°C)95.3–98.4°F (35.2–36.9°C)96.0–97.4°F (35.6–36.3°C)
Ear97.5–100.4°F (36.4–38°C)97.0–100.0°F (36.1–37.8°C)96.6–99.7°F (35.9–37.6°C)96.4–99.5°F (35.8–37.5°C)

Normal body temperature readings will vary within these ranges depending on the following factors:

An electrolyte imbalance can be caused by:

  • Losing fluids as a result of persistent vomiting or diarrhea, sweating or fever.
  • Not drinking or eating enough.
  • Chronic respiratory problems, such as emphysema.
  • Higher-than-normal blood pH (a condition called metabolic alkalosis).
  • Medications such as steroids, diuretics and laxatives.

To ensure that you have enough electrolytes, stay hydrated and eat foods rich in electrolytes, including spinach, turkey, potatoes, beans, avocados, oranges, soybeans (edamame), strawberries and bananas.

With the exception of sodium * , it's not likely that you'll get too many of any electrolytes from your diet. (The risk may be higher if your kidneys are not working well.) However, supplements can cause problems — for example, too much calcium can increase your risk of kidney stones — so always talk to your doctor before you start to take them.

* Processed foods and restaurant meals can be very high in sodium.

Older folks with chronic illness who have low sodium will have more symptoms than younger, healthy people with the same low sodium level.

Chloride Cl -

May not have symptoms unless level changes are severe. Since it is closely tied to sodium, some people have symptoms of hyponatremia (low sodium levels in the blood).

Potassium K +

Works with sodium to maintain water balance and acid/base balance. With calcium, it regulates nerve and muscle activity.

Magnesium Mg +2

Mostly in bones, with about 1% in extracellular fluid (body fluid outside the cells). Important for enzyme reactions.

Calcium Ca +2

99% in teeth and bones. Calcium in blood is ionized (carries an electrical charge) and helps regulate cell function, heart rate and blood clotting. The body needs vitamin D to absorb calcium. (Ionized calcium level range is 4.7-5.28.)

Phosphate/Phosphorus PO4 -

Blood tests measure inorganic phosphate. About 85% is in bones most of the rest is inside cells. Phosphate helps build/repair bones and teeth, stores energy, contracts muscles and enables nerve function. The body needs vitamin D to absorb phosphorus.

Below which temperature human muscles don't work? - Biology

  • Primary function is to obtain oxygen for use by body's cells & eliminate carbon dioxide that cells produce
  • Includes respiratory airways leading into (& out of) lungs plus the lungs themselves
  • Pathway of air: nasal cavities (or oral cavity) > pharynx > trachea > primary bronchi (right & left) > secondary bronchi > tertiary bronchi > bronchioles > alveoli (site of gas exchange)

The exchange of gases (O 2 & CO 2 ) between the alveoli & the blood occurs by simple diffusion: O 2 diffusing from the alveoli into the blood & CO 2 from the blood into the alveoli. Diffusion requires a concentration gradient. So, the concentration (or pressure) of O 2 in the alveoli must be kept at a higher level than in the blood & the concentration (or pressure) of CO 2 in the alveoli must be kept at a lower lever than in the blood. We do this, of course, by breathing - continuously bringing fresh air (with lots of O 2 & little CO 2 ) into the lungs & the alveoli.

Breathing is an active process - requiring the contraction of skeletal muscles. The primary muscles of respiration include the external intercostal muscles (located between the ribs) and the diaphragm (a sheet of muscle located between the thoracic & abdominal cavities).

  • Contraction of external intercostal muscles > elevation of ribs & sternum > increased front- to-back dimension of thoracic cavity > lowers air pressure in lungs > air moves into lungs
  • Contraction of diaphragm > diaphragm moves downward > increases vertical dimension of thoracic cavity > lowers air pressure in lungs > air moves into lungs:

  • relaxation of external intercostal muscles & diaphragm > return of diaphragm, ribs, & sternum to resting position > restores thoracic cavity to preinspiratory volume > increases pressure in lungs > air is exhaled

As the external intercostals & diaphragm contract, the lungs expand. The expansion of the lungs causes the pressure in the lungs (and alveoli) to become slightly negative relative to atmospheric pressure. As a result, air moves from an area of higher pressure (the air) to an area of lower pressure (our lungs & alveoli). During expiration, the respiration muscles relax & lung volume descreases. This causes pressure in the lungs (and alveoli) to become slight positive relative to atmospheric pressure. As a result, air leaves the lungs (check this animation by McGraw-Hill).

The walls of alveoli are coated with a thin film of water & this creates a potential problem. Water molecules, including those on the alveolar walls, are more attracted to each other than to air, and this attraction creates a force called surface tension. This surface tension increases as water molecules come closer together, which is what happens when we exhale & our alveoli become smaller (like air leaving a balloon). Potentially, surface tension could cause alveoli to collapse and, in addition, would make it more difficult to 're-expand' the alveoli (when you inhaled). Both of these would represent serious problems: if alveoli collapsed they would contain no air & no oxygen to diffuse into the blood &, if 're-expansion' was more difficult, inhalation would be very, very difficult if not impossible. Fortunately, our alveoli do not collapse & inhalation is relatively easy because the lungs produce a substance called surfactant that reduces surface tension.

  • Surfactant decreases surface tension which:
    • increases pulmonary compliance (reducing the effort needed to expand the lungs)
    • reduces tendency for alveoli to collapse
    • External respiration:
      • exchange of O 2 & CO 2 between external environment & the cells of the body
      • efficient because alveoli and capillaries have very thin walls & are very abundant (your lungs have about 300 million alveoli with a total surface area of about 75 square meters)
      • it's the individual pressure exerted independently by a particular gas within a mixture of gasses. The air we breath is a mixture of gasses: primarily nitrogen, oxygen, & carbon dioxide. So, the air you blow into a balloon creates pressure that causes the balloon to expand (& this pressure is generated as all the molecules of nitrogen, oxygen, & carbon dioxide move about & collide with the walls of the balloon). However, the total pressure generated by the air is due in part to nitrogen, in part to oxygen, & in part to carbon dioxide. That part of the total pressure generated by oxygen is the 'partial pressure' of oxygen, while that generated by carbon dioxide is the 'partial pressure' of carbon dioxide. A gas's partial pressure, therefore, is a measure of how much of that gas is present (e.g., in the blood or alveoli).
      • the partial pressure exerted by each gas in a mixture equals the total pressure times the fractional composition of the gas in the mixture. So, given that total atmospheric pressure (at sea level) is about 760 mm Hg and, further, that air is about 21% oxygen, then the partial pressure of oxygen in the air is 0.21 times 760 mm Hg or 160 mm Hg.
      • Alveoli
        • PO 2 = 100 mm Hg
        • PCO 2 = 40 mm Hg
        • Entering the alveolar capillaries
          • PO 2 = 40 mm Hg (relatively low because this blood has just returned from the systemic circulation & has lost much of its oxygen)
          • PCO 2 = 45 mm Hg (relatively high because the blood returning from the systemic circulation has picked up carbon dioxide)

            • Leaving the alveolar capillaries
              • PO 2 = 100 mm Hg
              • PCO 2 = 40 mm Hg
                • Entering the systemic capillaries
                  • PO 2 = 100 mm Hg
                  • PCO 2 = 40 mm Hg
                  • PO 2 = 40 mm Hg
                  • PCO 2 = 45 mm Hg
                    • Leaving the systemic capillaries
                      • PO 2 = 40 mm Hg
                      • PCO 2 = 45 mm Hg

                      Because almost all oxygen in the blood is transported by hemoglobin, the relationship between the concentration (partial pressure) of oxygen and hemoglobin saturation (the % of hemoglobin molecules carrying oxygen) is an important one.

                      • extent to which the hemoglobin in blood is combined with O 2
                      • depends on PO 2 of the blood:

                      The relationship between oxygen levels and hemoglobin saturation is indicated by the oxygen-hemoglobin dissociation (saturation) curve (in the graph above). You can see that at high partial pressures of O 2 (above about 40 mm Hg), hemoglobin saturation remains rather high (typically about 75 - 80%). This rather flat section of the oxygen-hemoglobin dissociation curve is called the 'plateau.'

                      Recall that 40 mm Hg is the typical partial pressure of oxygen in the cells of the body. Examination of the oxygen-hemoglobin dissociation curve reveals that, under resting conditions, only about 20 - 25% of hemoglobin molecules give up oxygen in the systemic capillaries. This is significant (in other words, the 'plateau' is significant) because it means that you have a substantial reserve of oxygen. In other words, if you become more active, & your cells need more oxygen, the blood (hemoglobin molecules) has lots of oxygen to provide

                      When you do become more active, partial pressures of oxygen in your (active) cells may drop well below 40 mm Hg. A look at the oxygen-hemoglobin dissociation curve reveals that as oxygen levels decline, hemoglobin saturation also declines - and declines precipitously. This means that the blood (hemoglobin) 'unloads' lots of oxygen to active cells - cells that, of course, need more oxygen.

                      Factors that affect the Oxygen-Hemoglobin Dissociation Curve:

                      • lower pH
                      • increased temperature
                      • more 2,3-diphosphoglycerate (DPG)
                      • increased levels of CO 2

                      CO 2 + H 2 0 -----> H 2 CO 3 -----> HCO 3 - + H +

                      & more hydrogen ions = a lower (more acidic) pH. So, in active tissues, there are higher levels of CO2, a lower pH, and higher temperatures. In addition, at lower PO 2 levels, red blood cells increase production of a substance called 2,3-diphosphoglycerate. These changing conditions (more CO 2 , lower pH, higher temperature, & more 2,3-diphosphoglycerate) in active tissues cause an alteration in the structure of hemoglobin, which, in turn, causes hemoglobin to give up its oxygen. In other words, in active tissues, more hemoglobin molecules give up their oxygen. Another way of saying this is that the oxygen-hemoglobin dissociation curve 'shifts to the right' (as shown with the light blue curve in the graph below). This means that at a given partial pressure of oxygen, the percent saturation for hemoglobin with be lower. For example, in the graph below, extrapolate up to the 'normal' curve (green curve) from a PO 2 of 40, then over, & the hemoglobin saturation is about 75%. Then, extrapolate up to the 'right-shifted' (light blue) curve from a PO 2 of 40, then over, & the hemoglobin saturation is about 60%. So, a 'shift to the right' in the oxygen-hemoglobin dissociation curve (shown above) means that more oxygen is being released by hemoglobin - just what's needed by the cells in an active tissue!

                        1 - bicarbonate (HCO 3 ) - 60%
                        • formed when CO 2 (released by cells making ATP) combines with H 2 O (due to the enzyme in red blood cells called carbonic anhydrase) as shown in the diagram below
                        • formed when CO 2 combines with hemoglobin (hemoglobin molecules that have given up their oxygen)

                        Control of Respiration

                        Your respiratory rate changes. When active, for example, your respiratory rate goes up when less active, or sleeping, the rate goes down. Also, even though the respiratory muscles are voluntary, you can't consciously control them when you're sleeping. So, how is respiratory rate altered & how is respiration controlled when you're not consciously thinking about respiration?

                        • controls automatic breathing
                        • consists of interacting neurons that fire either during inspiration (I neurons) or expiration (E neurons)
                          • I neurons - stimulate neurons that innervate respiratory muscles (to bring about inspiration)
                          • E neurons - inhibit I neurons (to 'shut down' the I neurons & bring about expiration)

                          Pneumotaxic center (also located in the pons) - inhibits apneustic center & inhibits inspiration

                          How Does the Body Regulate Temperature

                          Thermoregulation is an important aspect of homeostasis in humans. Humans, as well as other mammals, are capable of adapting to a wide range of climate conditions such as cold, hot, and humid conditions Most of the bodily heat is produced by deep organs such as liver, brain, and heart and, the contraction of skeletal muscles. The physiological control of the body core temperature primarily occurs through the hypothalamus. Hypothalamus is assumed as the body’s ‘thermostat’. Two types of thermoreceptors are involved in the sensation of temperature. They are the receptors sensitive to the cold and the receptors sensitive to warm temperatures. Nerves transmit the impulses from those two types of receptors to the hypothalamus. Negative feedback mechanisms that are controlled by the hypothalamus are involved in maintaining a constant core temperature. Thermoregulation by the hypothalamus is shown in figure 1.

                          Figure 1: Thermoregulation

                          The Danger of High Humidity

                          High humidity makes us feel hotter and uncomfortable, but it also causes our core temperature to rise, causing our bodies to compensate by working harder and harder to cool us down. When sweating doesn’t work to cool us down and our bodies continue to heat up, it can result in overheating, which causes loss of the water, salt, and chemicals that the body needs. Overheating, or as it is more commonly known as, heat exhaustion, can lead to dehydration, chemical imbalances within the body, or in severe cases, death. As expressed on The Weather Doctor,

                          “And overheating can cause discomfort at the very least and death at the very worst. Continued loss of water and a variety of dissolved chemicals such as sodium chloride — salt — from the body, if not replenished, can cause dehydration and chemical imbalances. Dehydration depletes the body of water needed for sweating and thickens the blood, requiring more pressure to pump it through the body, thus straining the heart and blood vessels.”

                          Such effects are more pronounced and can be more dangerous depending on your age and overall physical condition. However, young people that aren’t aware that their physical activity or exercise could be dangerous in humid conditions, are also at risk. Overheating is a serious condition, and can result in the following (courtesy of USA Today):

                          • Heat cramps: Exercising in hot weather can lead to muscle cramps, especially in the legs, because of brief imbalances in body salts. Cramps become less frequent as a person becomes used to the heat.
                          • Heat syncope or fainting: Anyone not used to exercising in the heat can experience a quick drop in blood pressure that can lead to fainting. As with heat cramps, the cure is to take it easy.
                          • Heat exhaustion: Losing fluid and salt through perspiration or replacing them in an imbalanced way can lead to dizziness and weakness. Body temperature might rise, but not above 102°. In some cases victims, especially the elderly, should be hospitalized. Heat exhaustion is more likely after a few days of a heat wave than when one is just beginning. The best defense is to take it easy and drink plenty of water. Don’t take salt tablets without consulting a physician.
                          • Heatstroke: In some cases extreme heat can upset the body’s thermostat, causing body temperature to rise to 105° or higher. Symptoms are lethargy, confusion and unconsciousness. Even a suspicion that someone might be suffering from heatstroke requires immediate medical aid. Heatstroke can kill.

                          There are a number of ways to avoid overheating. First, you need to be aware of not only the temperature, but of the heat index, too. Be sure to drink plenty of water and to take it easy, slow down and cool off if you notice any signs of fatigue, headache or an increased pulse.

                          Keeping your indoor air at a comfortable and healthy humidity level is also very important—you can do this by running a dehumidifier in your home. While an air conditioner may remove some of the moisture from the air inside of your home, a dehumidifier is built specifically for that purpose. Often times a dehumidifier enables you to control both the humidity and the temperature inside of your home. The drier the air, the quicker you will cool down and the cooler your body will feel. In addition to creating a more comfortable living environment, a dehumidifier also works to reduce allergens that often thrive in warmer, more humid conditions.

                          The Water in You: Water and the Human Body

                          Water is indeed essential for all life on, in, and above the Earth. This is important to you because you are made up mostly of water. Find out what water does for the human body.

                          The Water in You: Water and the Human Body

                          ​​​​​​​Water serves a number of essential functions to keep us all going

                          Think of what you need to survive, really just survive. Food? Water? Air? Facebook? Naturally, I'm going to concentrate on water here. Water is of major importance to all living things in some organisms, up to 90% of their body weight comes from water. Up to 60% of the human adult body is water.

                          According to H.H. Mitchell, Journal of Biological Chemistry 158, the brain and heart are composed of 73% water, and the lungs are about 83% water. The skin contains 64% water, muscles and kidneys are 79%, and even the bones are watery: 31%.

                          Each day humans must consume a certain amount of water to survive. Of course, this varies according to age and gender, and also by where someone lives. Generally, an adult male needs about 3 liters (3.2 quarts) per day while an adult female needs about 2.2 liters (2.3 quarts) per day. All of the water a person needs does not have to come from drinking liquids, as some of this water is contained in the food we eat.

                          Water serves a number of essential functions to keep us all going

                          • A vital nutrient to the life of every cell, acts first as a building material.
                          • It regulates our internal body temperature by sweating and respiration
                          • The carbohydrates and proteins that our bodies use as food are metabolized and transported by water in the bloodstream
                          • It assists in flushing waste mainly through urination
                          • acts as a shock absorber for brain, spinal cord, and fetus
                          • forms saliva
                          • lubricates joints

                          According to Dr. Jeffrey Utz, Neuroscience, pediatrics, Allegheny University, different people have different percentages of their bodies made up of water. Babies have the most, being born at about 78%. By one year of age, that amount drops to about 65%. In adult men, about 60% of their bodies are water. However, fat tissue does not have as much water as lean tissue. In adult women, fat makes up more of the body than men, so they have about 55% of their bodies made of water. Thus:

                          • Babies and kids have more water (as a percentage) than adults.
                          • Women have less water than men (as a percentage).
                          • People with more fatty tissue have less water than people with less fatty tissue (as a percentage).

                          There just wouldn't be any you, me, or Fido the dog without the existence of an ample liquid water supply on Earth. The unique qualities and properties of water are what make it so important and basic to life. The cells in our bodies are full of water. The excellent ability of water to dissolve so many substances allows our cells to use valuable nutrients, minerals, and chemicals in biological processes.

                          Water's "stickiness" (from surface tension) plays a part in our body's ability to transport these materials all through ourselves. The carbohydrates and proteins that our bodies use as food are metabolized and transported by water in the bloodstream. No less important is the ability of water to transport waste material out of our bodies.