Refuting Myth of Non-Response and Exercise Amount Flashcards
What is the strong evidence regarding individual differences in response to physical activity?
- Considerable heterogeneity in the responsiveness to physical activity
What was found to not be a major determinant of human responses to regular physical activity?
- Age
- Sex
- Ancestral Background
What was found to have a considerable impact on human response to regular physical activity?
- Pre-training phenotype
What is habitual employment or leisure time physical activity associated with?
- Reduced Cardiovascular Disease Risk
What do recent studies suggest about lifelong endurance activity?
- Might increase cardiovascular disease risk
What does regular, intense exercise cause regarding the heart?
- Structural, functional, electrical cardiac adaptations
What is more commonly found in older athletes compared to their inactive peers?
- Atrial fibrillation
- Myocardial fibrosis
- Coronary Artery Calcification
Describe Athlete’s Heart
- Increase in Heart Mass & Volume
- Greater LVEDV during rest/exercise
- Myocardial cell enlargement
- Increased LV cavity (eccentric hypertrophy)
- Modest Thickening of walls (concentric hypertrophy)
What can increase the risk of sudden cardiac death?
- Vigorous exercise
What was the overall occurrence of cardiac arrest during long distance running?
- 1 in 184k participants
What is the initial response of the cardiovascular system to exercise?
- Withdrawal of parasympathetic vagal tone
What is subsequently activated when the parasympathetic vagal tone is withdrawn during the cardiac response to exercise?
- Sympathetic Nervous System
What is the evidence that the sympathetic nervous system is subsequently activated when the parasympathetic system withdrawals in a cardiac response to exercise?
- Catecholamine release at nerve endings
- Spill Over of epi- and norepinephrine into the systemic circulation
What do epinephrine and norepinephrine do following sympathetic activation following cardiac response to exercise?
- Increase heart rate
- Increase cardiac contractility
- Increase stroke volume
- Increase cardiac output
When does cardiac output increase during endurance exercise?
- Initial phases
What is cardiac fatigue in endurance exercise?
- Reduced cardiac output during prolonged endurance exercise
- no decrease in blood plasma
What are the two subunits of Creatine Kinase (CK)? What do they reflect?
M
- Muscle Predominance
B
- Brain Predominance
What does an increase in blood concentration of CK indicate?
- Cell damage with membrane injury
Why cant CK exit the cell?
- Their size
What does the evidence on elevated CK-MB levels following endurance exercise suggest?
- Originate from skeletal muscle damage
- Does not represent acute myocardial injury
What is the troponin complex composed of?
- Subunits
- Troponin C
- Troponin T
- Troponin I
What subunit of troponin are identical in skeletal and cardiac muscles?
- Troponin C
What subunits of troponin are specific for either cardiac or skeletal muscle?
- Troponin I
- Troponin T
What does the specificity in cardiac Troponin I and T make them suitable for?
- Detecting Cardiac Damage
What activity types have studies observed exceeding levels of cardiac troponin compared to those used to diagnose acute myocardial infarction?
- Marathons
- Triathlons
- Endurance Cycling
- Ultra-endurance races
Why might there be increases in cardiac troponin following endurance activity?
- Increased cardiomyocyte membrane permeability by mechanical stress
- Production of oxidative radicals
- Cardiac ischemia could cause proteolysis of Troponin complex, permitting troponin degrading products to pass through the cellular membrane
Describe the remodeling of left and right ventricles due to endurance training
- Mild/moderate eccentric LVH and RV dilation
- Biatrial enlargement
- Normal to slightly reduced resting LVEF
- Normal/Enhanced Early LV Diastolic Function
- Normal/Enhanced LV twisting/untwisting
What remodeling of left and right ventricle occur from strength training?
- Mild concentric LVH/ No RV remodeling
- Normal/Mild enlarged Left atrial size
- Normal/hyperdynamic resting LVEF
- Normal/Slight reduced Early LV Diastolic Function
- Compensatory Increase in late LV diastolic function
What is myocardial fibrosis characterized by?
- Accumulation of collagen in the extracellular matrix of the heart
When does myocardial fibrosis most commonly occur?
- After Myocyte injury from ischemia
- But can have nonischemic causes
What is myocardial fibrosis divided into?
- Reactive interstitial fibrosis
- Infiltrative Interstitial fibrosis
- Replacement fibrosis
What studies are needed regarding fibrosis and athletes?
- determine if it is reversible with exercise cessation
- Determine clinical significance of persistent fibrosis in athletes
What did the rats who did endurance training equivalent to 10 human years develop?
- eccentric cardiac hypertrophy
- Diastolic dysfunction
- Atrial dilation
- Collagen deposition at right ventricle and both atria
What biochemical evidence suggests myocardial fibrosis in elite middle-aged endurance athletes?
- Increased plasma markers of collagen syntheses and degradation
What is the QT interval?
- electrocardiographic measurement of the time between depolarization and repolarization of cardiac ventricles
What is the QT interval generated by?
- Passage of calcium, potassium, and sodium ions through cardiac ion channels
What leads to Long QT Syndrome? What can that lead to?
Abnormal increase in QT interval
- Lead to sudden cardiac death
What gene defect is most prevalent for producing Long QT syndrome?
- KCNQ
What type of gene defects produce LQTS?
- Cardiac ion channel genes
- 10 Identified
What percentage of LQTS - 1 individuals cardiac events occur during exercise?
75%
What percentage of LQTS 2&3 individuals’ cardiac events occur during exercise?
5%
What do studies suggest increase the risk of ventricular tachycardia and sudden cardiac death in LQTS - 1 patients?
- Enhanced Vagal Tone
How does exercise training reduce heart rate?
- Increasing parasympathetic or vagal tone
What do studies suggest the increases in vagal tone from exercise training could do?
- Increase arrhythmia risk in individuals with genetic predilection for LQTS-1.
What are the potential acute cardiovascular risks to acute and chronic endurance exercise?
Increased
- Risk of Sudden Cardiac Death
- Risk for Acute Myocardial Infarction
Decreased
- Ventricular Function of the Heart
What potential acute myocardial injury could occur from acute and chronic endurance exercise?
list biomarkers
- CK and CK-MB Concentrations
-membrane damage - Cardiac Troponin Concentration
-oxidative stress
-mechanical stress
-ischemia - BNP and NT-proBNP concentration
-membrane damage
What potential cardiac remodeling occurs from acute and chronic endurance exercise?
Increased
- Dimensions of right and left ventricle
- Dimensions of right and left atria
- Wall thickness
What Potential Cardiac Maladaptations could occur from acute and chronic endurance exercise?
Increased
- Prevalence of myocardial fibrosis
- Risk for atrial fibrillation
- Risk for Bradycardia
- Aortic Diameter
- Progression of ARVC
Decreased
- Carotid Intima-Media Thickening
Increased or Decreased
- Coronary Artery Calcification
What potential longevity effects occur from acute and chronic endurance exercise?
- Increased life expectancy
- Decreased risk for cardiovascular mortality
What did the comparisons between the Dallas Bedrest and Training Study + the 30 yrs study observe?
- A more profound impact on cardiovascular capacity observed in bedrest than 30 yrs of aging
