The immune system and exercise Flashcards
increased URTI following marathon
Started from anecdotal evidence
Control – didn’t compete in particular event
Those who did marathon experienced minor illnesses
URTI incidence and activity: moderate activity protects
1.5h day – moderate
40min 5x week – low
Moderate activity protects you
Slightly older women
Sedentary – 50% had infections
how do we defend against pathogens: innate
what you are born with – first line of defence – activated as soon as you get ill
Anatomical barriers
Chemicals barriers
Immune cells
how do we defend our body against pathogens: acquired
Specific
Previous exposure required
Develops with age
Cells
immune cells
All WBCs
Phagocytosis – engulf foreign cells – destroy them from within
exercise and circulating immune cells
Biphasic leukocytosis
- Neutrophils and lymphocytes
- Neutrophils
Lymphocytes below rest – open window for infection
Lymphocytopenia
• Fall in lymphocytes
why does this happen during exercise? (changes in circulating immune cells)
Demargination – WBCs stuck to side of blood vessels during rest – increase in sheer stress – decrease likelihood of WBCs sticking to vessel wall
Increase in catecholamines – decrease likelihood of adherence
More immune cells in the blood
CO = cardiac output
Cortisol may not reach peak until after ex
Cortisol increases getting neutrophils from bone marrow – takes time to transport them – peak occurs later on
open window hypothesis
More susceptible to infection
neutrophil function
Phagocytosis –> de-granulation –> respiratory burst – markers of how well neutrophil functioning
response to acute exercise: neutrophils
More but not as good at their job
measure of do neutrophils work (training)
Before
Normal
Intense
Rest
Depletion of mature neutrophils – naïve neutrophils released – increase in number but reduction in how well they work
acute exercise and neutrophils
Increase
Inhibit function
immunity
Addition of cortisol prevents t cell proliferation
Start with naïve t helper cells
Where they go depends on infection type – virus/bacterial
cell-mediated immunity after severe exercise
Acute severe activity (3km swim, 130km bike, 21km run) suppresses cell-mediated immunity
cycling to fatigue: stimulate cytokine production
IFN-y production reduced following intense exercise
stress hormones
More susceptible to infection when stressed
practical advice
Minimise potential of transmission – avoid sick people
Don’t share water bottles
Avoid getting dry mouth – saliva good mucosal barrier
Be aware during training more at risk of getting ill – intense
Minimise risks of immunosuppression during intense training
Avoid too many long training sessions back-to-back
Monitor mood and emotions
Get adequate sleep
exercising during infection
Ex tolerance reduced
Ex with infection may increase severity/duration of illness
Don’t train with fever with symptoms below neck (swollen glands, muscle/joint aches/cough) – create passage for infection to get around whole body
Don’t resume training at same level
Isolate infected team members from others
what is a URTI?
Upper Respiratory Tract Infection
innate response - anatomical barriers
Mucosal
Skin
Low pH of stomach
innate response - immune cells
Granulocytes
Monocytes
Natural killer
- Destroy infection – kill host cells
- Responses non-specific – anything foreign
cells in the acquired response
Cell-mediated
- Cytotoxic t-cells
Humoral
- Antibodies (B-lymphocytes)
chronic exercise and neutrophils
Reduce function
Deplete bone marrow reserves – due to rise in cortisol
eosinophil function
destroy parasites
