Week 4 readings summary Flashcards
what conditions appear more common in older athletes compared with their inactive peers ??????????
atrial fibrillation
myocardial fibrosis
coronary artery calcification
what did Morris study on buses show?
Morris - conductors on London’s double-decker buses had a lower risk of sudden cardiac death (SCD) than the physically inactive bus drivers
PA recommendations
Recommendation - recommend that adults perform moderate-intensity exercise for a minimum of 30 min daily at least 5 days a week, or vigorous intensity exercise for a minimum of 20 min daily at least 3 days a week
what does SCD stand for?
sudden cardiac death
what is SCD?
There is general consensus that vigorous exercise acutely, albeit transiently (Short term), increases the risk of SCD, but only in individuals with underlying cardiac disease, either occult or manifest
conclusion about SCD
The observations that the risk of SCD increases during moderate or vigorous exercise, but that habitual exercise also decreases the SCD risk again suggests, as in PHS, that exercise acutely increases, but ultimately decreases, the risk of SCD
why may young die?
Young individuals may die during exercise due to inherited or congenital cardiac conditions e.g. hypertrophic cardiomyopathy, coronary artery anomalies and RV cardiomyopathy
why may old die?
Older individuals due during exercise primarily from coronary artery disease (CAD). Acute atherosclerotic plaque erosion or rupture leading to acute coronary thrombosis is detected in most, but not all, previously asymptomatic individuals who die or suffer a myocardial infarction during exercise.
following endurance exercise there is a decrease in LV ejection fraction, why does this occur?
Decrease in blood volume reducing cardiac preload reducing ventricular performance without directly altering cardiac contractility
Exercise producing myocardial dysfunction independent of volume changes
Cardiac damage
what indicates cardiac dysfunction?
Decreases in LV systolic strain
Absolute peak systolic twist post exercise
examples of biomarkers
creatine kinase
cardiac troponins
BNP and NT-proBNP
role of creatine kinase
Catalyses the transfer of a phosphate group from creatine phosphate to ADP producing ATP, composed of 2 sub units creating three isoforms
who has increased CK?
marathon runners
what do high levels of cardiac troponin indicate?
High troponin levels can indicate a problem with the heart. The heart releases troponin into the blood following an injury, such as a heart attack. Very high troponin levels usually mean that a person has recently had a heart attack. The medical term for this attack is myocardial infarction
when are levels of CT elevated?
Endurance exercise
when are levels of CT greater?
with age presence of CV risk factors running experience increase exercise duration exercise intensity dehydration
what is the strongest single predictor of cardiac troponin release?
intensity
mechanisms behind increase in cardiac troponins
Increase in cardiomyocyte membrane permeability
Production of oxidative radicals
Preload-induced increases in stretch responsive integrins
what are BNP and NT-proBNP?
Hormones produced in the hearts ventricles constantly in response to cardiomyocyte stress produced by volume or pressure overload
what do increased levels of BNP and NT-proBNP indicate?
cardiac dysfunction
magnitude of increase of BNP and NT-proBNP depends on what?
duration
cardiac adaptations due to long term exercise training
increases in parasympathetic tone and sympathetic tone
enlargement of all 4 chambers
implications of cardiac adaptation from long term exercise on cardiac dimensions and function
The possibility that increased LV and RV dimensions from exercise training contribute to cardiac disease in a minority of susceptible individuals
other possible maladaptation’s of lifelong exercise
bradycardia
long QT
aortic size and root dilation
risk factors of atrial fibrillation
age
increased LA size/pressure e.g. hypertension
what is long QT?
Longer interval between depolarization and repolarization of cardiac ventricles
what is aortic size and root dilation?
Aortic dissection and rupture are rare, but can cause sudden death and the risk of this increases with increase aortic size and root dilation
