The Immune System

The immune system is network of cells (white blood cells or leukocytes; e.g. monocytes, macrophages, neutrophils, lymphocytes-B and T) stored in different organs, such as the thymus, spleen, bone marrow, lymph nodes that encounter pathogens, such as viruses, parasites or bacteria and fight against infection. 

A healthy immune system can recognize the body’s own cells as well as pathogens by detecting proteins found on the surface of all cells. White blood cells are on constant patrol, looking for pathogens. Pathogens are agents that can cause disease within the body, and on the surface of each pathogen are proteins known as antigen, which are specific to each pathogen. Upon entering the body, antigens are capable of inducing an immune response. When white blood cells spot a target they begin to multiply, sending signals to other cells to follow suit. They produce antibodies and proteins that lock onto specific pathogen, inducing an immune response. Once an antibody has been produced, a copy remains in the body to deal with the antigen in case it appears again. The adaptive process strengthens immunity allowing antibodies to fight pathogen with more efficiency. 

Innate & Adaptive Immune Responses


The Innate immune response is the first line of physical, chemical and cellular defense against pathogens. These responses immediately prevent the spread of pathogens throughout the body. Within this response, there are physical (such as skin and gut) and cellular defenses (macrophages and neutrophil) against pathogen.  

The adaptive immune response is specific to the pathogen. Pathogens induce a rapid increase of T and B lymphocytes, the major cellular components of the adaptive immune response. The effect of this type of immune response is long lasting, highly specific and is sustained long-term by memory T cells.  

The Immune System & Exercise  


Research has shown that frequent exercise is beneficial for the immune system. A weakened immune system is more susceptible to infection and is generally caused by several external factors, such as poor sleep, poor nutrition, lifestyle habits, chronic conditions, diseases, and so on.  

Immune System and Stress (Acute and Chronic)


Stress is a broad concept in which an individual experiences challenging or difficult circumstances (stressors) or the physiological or psychological response to such circumstances, also known as a stress response. In humans one of the systems that responds to challenging circumstances is the immune system. The immune system comprises cells, proteins, organs, and tissues that work together to provide protection against bodily disease and damage.  

Acute stress (or the “flight or fight” response) can last a matter of minutes or hours. Certain kinds of cells are mobilized into the bloodstream, potentially preparing the body for injury or infection during “fight or flight”. Acute stress also increases levels of pro-inflammatory cytokines, which are proteins that coordinate immune responses. Some cytokines, such as IL-5 and IL-10, primarily control and contain immune responses. Others, such as IL-6 and tumor necrosis factor-α (TNF-α), induce inflammation. Short-term stress is one of nature’s fundamental survival mechanisms that enhance immune protection. Short-term stress experienced during immune activation enhances innate/primary and adaptive/secondary immune responses.  

Mechanisms of immuno-enhancement include changes in different types of immune cells (dendritic cell, neutrophil, macrophage, and lymphocyte), trafficking, maturation, and function as well as local and systemic production of cytokines. Short-term stress may also enhance mental/cognitive and physical performance through effects on brain, muscle- skeletal, and cardiovascular function, reappraisal of threat/anxiety, and training-induced stress-optimization. Therefore, short-term stress psychology/physiology could be harnessed to enhance immuno-protection, as well as mental and physical performance. 

Chronic stress or term stress, lasts from days to years and is associated with higher levels of pro-inflammatory cytokines, but with potentially different health consequences. Inflammation is a necessary short-term response for eliminating pathogens and initiating healing, but chronic, systemic inflammation represents dysregulation of the immune system and increases risk for chronic diseases. Another consequence of chronic stress is activation of latent viruses which can reflect the loss of immunological control over the virus, and frequent activation can cause wear-and-tear on the immune system. Long-term stress suppresses or dysregulates innate and adaptive immune responses by altering cytokine balance, inducing low-grade chronic inflammation, and suppressing numbers and function of immune protective cells. Chronic stress can suppress protective immune responses (wound healing, anti-infectious and anti-tumor agents) and/or exacerbate pathological pro-inflammatory, immune responses. 

The Immune System & Post-Exercise Recovery Methods 

  • Whole Body Cryotherapy (WBC) 

Increases number of white blood cells (leukocytes, monocytes,), antibodies or immunoglobulins (IgA, IgG, IgM), C3 and C4 protein levels 

Increases levels of anti-inflammatory cytokines, groups of proteins that regulate immune response and inflammation such as IL-6, IL-10, IL-12  

Decreases levels of pro-inflammatory cytokines, such as TNF- α, IL-1α, IL-2, IL-8 

 Increases norepinephrine levels: Even one single bout of WBC exposure stimulates norepinephrine, a hormone and neurotransmitter that increases brain arousal, memory, focus and attention. Norepinephrine also has powerful anti-inflammatory effects through inhibiting the production of TNF- α, pro- inflammatory marker linked to cases of Type 2 Diabetes, Alzheimer’s and cancer. Frequent WBC also increases norepinephrine level in blood plasma, protein rich fluid part of the blood that protects body against illness and infection. 

Increased levels of antioxidants: One of side effects of everything that happens within the body is production of oxidants: free radicalsReactive Oxygen Species (ROS) and creating oxidative stress. To fight oxidative stress body needs antioxidants. Antioxidants can be produced within the body itself or ingested through diet. WBC stimulates body to produce antioxidants and “fight” cold exposure (oxidative) stress. Oxidants damage proteins, lipid and DNA, which is a process linked to aging, as well as age-related diseases. Antioxidants are molecules that react with oxidants, minimizing their action and delaying oxidative stress. The exposure to cold temperatures activates very potent antioxidant systems, by increasing levels of antioxidants: glutathione reductase (GPx) and superoxide dismutase (SOD). 

  • Infrared (IR) Sauna  

Oxidative stress reduction: Each bodily function, from metabolism to immune system creates by-products known as oxidants that damage proteins, DNA and cell membrane lipids. As mentioned before, Oxidative stress is a condition in which concentration of oxidants is high, which the body tries to fight through decreasing the amounts of oxidants. Heat exposure by sauna use increases production of heat shock proteins (HSPs) that reduce, and repair damage caused by oxidants. 

Increases white blood cells count: such as lymphocytes, monocytes, neutrophils, basophils.  

Stimulation of innate and adaptive immunity response: HSPs stimulate the maturation and activation of dendritic and Natural Killer Cells (NK), white blood cells responsible for controlling viral infections. These are integral to the body’s innate ability to fight off new diseases it has never been exposed to.  Once activated, HSPs remain active for up to 48 hours. 

Decreases pro-inflammatory markers: CRP (c-reactive protein) and IL-6 (interleukin 6). 

Increase levels of anti-inflammatory marker: IL-10 (interleukin 10). 

Improving lung function: Recent studies show that regular sauna use significantly decreases cases of common colds and the risk of developing certain chronic or acute respiratory illnesses, including pneumonia (14)(15)(16). Frequent sauna use may also decrease pulmonary congestion and improve lung function such as vital capacity, tidal volume, minute ventilation and forced expiratory volume 



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