The Difference Between Whole-Body and Full-Body Cryotherapy
Whole-body cryotherapy (WBC) and full-body cryotherapy (FBC) are two types of cryotherapy chambers.
While both types involve exposing the body to extremely cold temperatures, the main difference between them lies in the fact that FBC machines also expose the head, while WBC machines do not.
This raises the question of whether exposing the head in FBC triggers a “better” physiological response than WBC.
What happens when our body is exposed to cold temperatures?
By understanding how our body reacts to cold, we can better evaluate the efficiency of WBC and FBC machines and draw a conclusion on whether exposing the head in FBC provides any additional benefits.
Understanding the Relationship Between the Body and Temperatures
When exposed to cold temperatures, our body enters a state of vasoconstriction, which reduces blood flow to the extremities and redirects it to the core. This triggers a series of physiological responses, such as the release of endorphins and anti-inflammatory cytokines, which are thought to have therapeutic benefits.
Being a warm-blooded (or homeothermic) animal, we humans have a built-in sensory process called thermo-reception. This is how we detect different levels of temperatures in the environment and the body.
This process helps us to maintain considerable inner physiological stability (e.g., body temperature and metabolism) under changing environmental conditions.
How Do We Perceive Temperature?
Different sensors perceive different temperatures. We perceive external temperature via thermoreceptors in our skin, which, in response to temperature stimuli, fires a specific neural pathway that carries a representation of thermosensory activity to the cerebral cortex in our forebrain.
These receptors are, as you guessed, specific places in our skin that are selectively sensitive to warm or cold stimuli.
What Temperature Range Can We Sense?
The cold spots on our skin fire when temperatures go below the neutral skin temperature (~34 °C [93 °F]). Likewise, the warm spots have increased activity at temperatures warmer than neutral skin temperature.
The sensitivity of these receptors extends across a continuum of thresholds and response maxima. The static activity of many cold receptors reaches a peak at temperatures around 20–30 °C (68–86 °F).
Some receptors have lower thresholds (i.e., less than 30 °C [86 °F]) and maximal activity at colder temperatures (i.e., less than 20 °C [68 °F]).
Warm receptors are continuously active at constant temperatures above neutral skin temperature and have response maxima around 41–46 °C (106–115 °F), although, in many cases, warm receptors are inactive at temperatures above 45 °C (113 °F).
Pain receptors called thermal nociceptors fire signals when the temperature is over 45 °C and less than five °C (these values change slightly depending on the source). These signals are what we experience as pain.
What Are Our Temperature Receptors?
The sensory system involved in perceiving the changes in skin temperature begins with the free nerve endings found in the dermal and epidermal layers of skin that can be functionally classified as cold and warm thermoreceptors.
Warm and cold receptors respond similarly to radiant and conducted thermal energy and are involved in perceiving innocuous (harmless) temperatures.
The molecular mechanisms underlying temperature sensation have been extensively studied over the past decade. As a result, several temperature-sensitive ion channels of the transient receptor potential (TRP) family have been identified as candidate temperature sensors.
These thermos TRP channels are expressed in sensory nerve endings and are active at specific temperatures ranging from noxious cold to burning heat.
As far as cryotherapy goes, pain does NOT mean gain
Our cold receptors are more profound in our skin than our heat receptors, and they stop registering temperatures a few degrees before sub-zero levels are reached. As temperatures decrease below +4 °C, cold receptors stop recording temperature and our pain receptors take over.
E.g., if a person is submerged into +4 °C water, the feeling of pain and thermal shock are imminent. However, this does not result in a similar therapeutic effect as WBC, partly because the length of exposure is usually very short.
Using a full-body over a whole-body cryotherapy machine doesn’t impact the efficiency of the treatment.
The efficiency of cryotherapy treatment depends on exposure to extremely cold temperatures at the cellular level. The higher the number of cells exposed to low temperatures, the better.
More receptors triggered means more SOS signals to our brain, signaling our body to produce the maximum output of life-supporting enzymes and hormones.
Simultaneously, the more evenly distributed supercooled air, the less discomfort we experience. However, the receptors exposed to life-threatening temperature levels will signal the brain via our central nervous system that all available life support is needed.
This is the essence of a successful cryotherapy session rather than the level of discomfort in our conscious mind. Some clients may also find whole-body machines more comfortable than full-body machines.
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