Lecture 10 - Nutrition & Immune Function in Athletes Flashcards
what does the immune system do?
- recognizes, attacks and destroys things that are foreign to the body
- protects the body against infections caused by bacteria, viruses, fungi, and parasites
two broad functions of the immune functions
Innate and Adaptive immunity
Innate Immunity
- the body’s first line of defense
- the attempt of an infectious agent to enter the body immediately activates the innate immune system
- it comprises three general mechanisms that have the common goal of restricting microorganisms entry into the body
three general mechanisms of the innate immune system
- physical or structural barriers (skin, epithelial linings, mucosal secretions)
- chemical barriers (pH of bodily fluids i.e. saliva and soluble factors)
- phagocytic cells (neutrophils, monocytes and macrophages)
Adaptive Immunity
- failure of the innate system and the resulting infection activates the adaptive immune system to help recover from infection
- adaptive immunity is helped greatly by T-lymphocyte acquisition of receptors that recognize the foreign molecules (called antigens)
- causes memory that enables the immune system to mount an augmented response when the host is reinfected by the same pathogen
- THIS IS THE BASIS OF VACCINATION WITH AN ATTENUATED VIRUS
acute inflammation
the introduction of an infection agent to the body initiates an inflammatory response, which augments the response of the immune system.
Acute inflammation causes:
- increase local BF in the infected area
- increases permeability of blood capillaries
- facilitates the entry of leukocytes and plasma proteins into the infected tissue
- produces symptoms of redness, swelling, and soreness
how are immune responses triggered
the immune response itself varies according to the nature of the infection agent (parasitic, bacterial, fungal, or viral) but a general response pattern is evident
- the key player is the macrophage which expresses toll like receptors (TLRs) on its surface
- TLRss initiate an immune response
- the macrophage ingests the foreign material and presents antigens on its cell surface that in turn activate T and B lymphocytes specific for that antigen
TLRs
Toll-like receptors
- TLRs detect the presence of certain molecules that are present on the surface of microorganisms and initiate an immune response to destroy potentially harmful invaders
other things that infection agents can activate
- phagocytic cells
- NK cells
factors that can increase an athletes susceptibility to URI symptoms
- too much stress for the athlete (physiological, psych, environmental, poor sleep, inadequate diet) can lead to depressed immune function that leads to an increased suscep……
- allergy or inflammation of airways
- increased exposure to pathogens (lung ventilation, skin abrasions, foreign travel, crowds, bad hygiene)
how can exercise impact immune defences
athletes that engage in heavy endurance training programs often have depressed immune function and suffer from increased incidents of URTIs
- training and competitive surroundings may increase the athletes exposure to pathogens and provide optimal conditions of pathogen transmission
- heavy, prolonged exertion is associated with numerous hormonal and biochemical changes, many of which potentially have detrimental effects on immune function
- increases in temperature depresses white blood cell which depresses immune response
open window theory
THEORETICAL
- short term suppression of the immune system following an acute bout of endurance exercise
- window of opporitunity to get sick
- so if this occurs and they are already at risk for URTIs then their risk increases
Exercise and infection J curve
GO TO SL. 10
- the dotted line is what the new literature is saying
most common illness in athletes (and general pop)
Upper respiratory tract infections
- caused by virus (i.e. the common cold, influenza)
- more common in winter months
- adults typically experience 2-4 URTI episodes per year
- athletes can also develop similar symptoms from an allergy or inflammation affecting the mucosal lining of the upper respiratory tract caused by the inhalation of cold, dry, or polluted air
- risk is higher for females in cold environments, when usually men are at higher risk of everything
consequences of URTIs in athlete
URTI symptoms are generally not severe but no matter whether the symptoms and inflammation are caused by an infection, allergy, or an adverse reaction, they can cause an athlete to:
- miss training
- underperform
- be unable to participate in an important competition
- be a danger to other team members
- be isolated from other team members
