Week 4 cradiac risks of exercise

Question 1

Albert et al (2002) examined the effect of habitual vigorous exercise on the risk of sudden death during and for 30 minutes after vigorous exercise compared with light and no exercise. What were the key findings?

Answer 1

Relative risk of sudden death during and up to 30 mins after vigorous exercise was 16.9.

Absolute risk of sudden death during vigorous exercise was very low (1 sudden death per 1.5million episodes of exercise).

Relative risk a lot higher in people who do not partake in vigorous exercise often.

Even if accustomed to vigorous exercise, risk is sill elevated but a lot less.

Question 2

Mittleman et al (1993)examined the triggering of acute myocardial infarction by heavy physical exertion and whether it could be protected against by regular exertion. What were the key findings?

Answer 2

Dose response - people who reported they normally did no vigorous exercise had a 100 fold increase in risk of onset of MI when exercising.

People who reported >5 vigorous exercise a week only had a 2 fold increase in risk.

Risk of MI increases when vigorous exercising. Absolute risk is low but relative risk depends on the amount of vigorous exercise an individual regularly undertakes.

Question 3

Kim et al (2012) assessed the incidence and outcomes of cardiac arrest associated with marathon and half marathon races in the US from Jan 2000 to May 2010. What were the key findings?

Answer 3

Incidence rate higher during marathons than half marathons.

Incidence rate higher in men and has increased in men in the last decade.

Question 4

What conclusions were drawn about death and cardiac arrest in US triathlon participants between 1985-2016?

Answer 4

Death and cardiac arrest during the triathlon are not rare

Most have occurred in middle aged men and older men.

Most sudden deaths happen during the swim stage

Clinically silent CVD was present in an unexpected proportion of descendants.

Question 5

What were the key points from the scientific statement form the American heart association council?

Answer 5

Habitual activity reduces CHD risk

Vigorous exercise transiently increases risk of sudden death and MI

Hereditary or congenital cardiovascular abnormalities are predominantly responsible for cardiac events among the young

Atherosclerotic disease is primarily responsible for these events in adults

The incidence of both acute MI and sudden death is greatest in habitually least active individuals.

Question 6

How many people in the UK die each day from sudden cardiac death?

Answer 6

20

Question 7

What did the Harvard Alumni Health study show about PA and mortality risk?

Answer 7

As PA increases, mortality risk decreases

Up to a certain point (>3499 Kcal/wk) then risk increases again but still lower than inactive.

Question 8

What is MET?

Answer 8

Metabolic equivalent of task

1MET is equivalent to energy expenditure at rest (3.5ml/kg/min).

Question 9

What did Church et al (2005) find was sufficient VO2 max to get optimal reduction in risk of death in men with diabetes?

Answer 9

40-45

Question 10

What did O’Keefe and Lavie (2012) suggest about running distance and all-cause mortality?

Answer 10

Between 5-20 miles per week is optimal for reduction in mortality risk but any more than 20miles and risk starts to increase again.

Question 11

What is cardiac dysrhythmia?

Answer 11

When cardiac rhythm is irregular during exertion (if in ventricles can cause a heart attack)

Question 12

What is hypertrophic cardiomyopathy?

Answer 12

An inherited disease of the heart muscle

Heart muscle walls are thickened which compromises cardiac function

Can also lead to dangerous cardiac arrhythmias

Affects approx. 1 in 500 people in the UK

Question 13

What is cardiac troponin?

Answer 13

A protein found in cardiac muscle (shouldn’t be in blood)

Its a standard biomarker for diagnosing MI - circulating concentrations are very low in healthy subjects but markedly increased after cardiac injury.

Question 14

What is collagen?

Answer 14

A structural protein found in connective tissue

Build up of collagen can lead to fibrosis

Question 15

What is fibrosis?

Answer 15

A thickening and scarring of connective tissue, usually as a result of injury. Fibrosis in the heart can lead to cardiac arrhythmia?

Question 16

Benito et al (2011) examined collagen deposition and fibrosis in exercise trained rats (rats ran for 60mins daily), what were the key findings?

Answer 16

Increased fibrosis on right ventricular free wall even after just 4 weeks (significant increase at 4 16 weeks - double than in sedentary group).

Question 17

What is thought to be the relationship between exercise and disability and life expectancy?

Answer 17

People who exercise regularly have lower rates of disability and a mean life expectancy 7 years longer than those who are physical inactive.

However, a safe upper dose limit potentially exists, beyond which the adverse effects of exercise may outweigh its benefits.

Question 18

What can chronic intense and sustained exercise cause?

Answer 18

Patchy myocardial fibrosis, particularly in the atria, interventricular septum, and right ventricle, creating a substrate for atrial and ventricular arrhythmias.

May also be associated with coronary artery calcification (build up of calcium in coronary artery - makes it harder to dilate), diastolic dysfunction, and large artery wall stiffening.

Question 19

Veteran endurance athletes have been noted to have what?

Answer 19

A five fold increase in the prevalence of atrial fibrillation.

Question 20

Intense endurance exercise often causes an increase in what?

Answer 20

Biomarkers of myocardial injury (e.g. troponin, and B-type natriuretic peptide) which were correlated with transient reductions in right ventricular ejection fraction.

Question 21

What is atrial fibrillation?

Answer 21

Chaotic electrical activity that replaces normal sinus rhythm and eliminates the contribution of atrial contraction to LV filling.

Left and right atrium not contracting in a rhythmic way, they’re just fibrillating (shaking).

If atria don’t empty properly, ventricles aren’t as full of blood so hence cardiac output is compromised.

Question 22

What is the danger of atrial fibrillation?

Answer 22

Not usually life threatening on its own (unlike ventricular fibrillation) but it can lead to a stroke, because blood clots can form in the atria because the blood stays in there (is stagnant).

Leads to a five fold increase in risk of stroke.

Question 23

What is the prevalence of atrial fibrillation in the UK?

Answer 23

2% of the population (1.5 million)

Between 100,00-200,000 diagnosed in the UK each year

One in four lifetime risk of developing AF.

Question 24

What is the relationship between atrial fibrillation and PA?

Answer 24

Moderate levels of exercise reduce risk of AF

Very high levels of PA increase risk of AF but the effect is modest and there is no effect on mortality

Question 25

what has been bought in in cycling?

Answer 25

heart scans

Question 26

after how long into vigorous exercise is there no benefit?

Answer 26

50 mins

Question 27

relationship between exercise in METS and relative risk of mortality

Answer 27

as exercise capacity (in METs) increases the relative risk of death decreases but beyond 12.9METs the risk increases