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
basophil function
inflammation
lymphocyte function
immune response
monocyte function
phagocytosis
immediate response from the CNS
sympathetic nerves
increases noradrenaline and adrenaline
decreases neutrophil-endothelial adherence
increases HR and CO
increases blood flow through muscles and pulmonary circulation
increases release of leukocytes from spleen
increase in circulating neutrophils and lymphocytes
delayed response from the CNS
hypothalamus
(CRF)
anterior pituitary
(ACTH)
adrenal cortex
(cortisol)
mobilisation of neutrophils from bone marrow
