Week 9: The U-Shaped Relationship between Exercise and Health

Question 1

Who is considered the “pioneer of exercise physiology”?

Answer 1

Per-Olof Åstrand.
The first man to note the beneficial effects of exercise on the heart and the negative effects of pro-longed bed-rest.

Question 2

What are the beneficial effects of exercise (on a cardiovascular level)?

Answer 2

1. Improves blood lipid profile
2. Increases insulin sensitivity
3. Aids blood pressure control
4. Enables weight loss
5. Reduces risk of coronary artery disease (CAD)
6. Reduces risk of myocardial infarction

Question 3

How much does regular exercise reduce the risk of developing CHD (based on general population studies)?

Answer 3

30-50% reduction in risk of developing CHD.

Question 4

What effect does exercise have in heart failure patients?

Answer 4

Improves their functional capacity and well-being.

Question 5

What is AF?

Answer 5

Atrial fibrillation - happens when abnormal electrical impulses suddenly start firing in the atria.
- Overrides the hearts natural pacemaker
- Causes highly irregular pulse rates

Question 6

What is the effect of moderate PA on AF?

Answer 6

Moderate PA associated with a reduction in prevalence of AF, especially in older adults.

Question 7

What difference in longevity is seen in olympic athletes (compared to the general population)?

Answer 7

Longevity benefit of 3 years approx.

Question 8

What mix of PA do adults need to stay healthy?

Answer 8

Moderate intensity aerobic activity - at least 150 mins a week.

Muscle strengthening activity - at least 2 days a week.

(If you prefer to do vigorous intensity aerobic activities, like running, then aim for at least 75 mins a week)

Question 9

What is meant by the “U-shaped curve”?

Answer 9

Moderate exercise is better than no exercise, but extreme exercise may be harmful.

Question 10

Give an example of a study that exhibits this U-shaped curve.

Answer 10

A recent study showed…
- Light joggers had lower mortality than sedentary non-joggers
- Strenuous joggers had a mortality rate that was not statistically different to the sedentary group

Question 11

What did Kokkinos et al. show?

Answer 11

A 13% reduction in mortality per MET achieved between 4 and 10 METs, but no additional benefit after 10 METs.

Question 12

What do we need to be aware of when carrying out an athlete’s ECG?

Answer 12

Many physiological changes are at risk of being identified as abnormal.

Question 13

What are reasons for not mandating ECGs in athletes?

Answer 13

1. Financial cost (large number of tests that would be required)
2. Resources
3. Potential for false-positive results

Question 14

What does clinically effective interpretation in athletes require?

Answer 14

The ability to optimally distinguish between normal, training-related changes and pathological changes on the ECG.

Question 15

What are athletes with high body mass at increased risk of?

Answer 15

1. Elevated systolic blood pressure
2. Low-density lipoprotein and glucose
3. Cardiometabolic syndrome (CMS)

Question 16

What did Baron et al., (1994 and 2012) show in retired American football athletes?

Answer 16

46% reduction in all-cause mortality.
HOWEVER,
CVD was increased by 52% in linemen, primarily due to hypertensive heart disease and coronary heart disease.

Question 17

What did Pelliccia et al., (2017) show in Olympic athletes?

Answer 17

Reported an unexpected prevalence of cardiovascular risk factors in power, skill, and mixed discipline with endurance based athletes likely to be free from risk factors.

Question 18

What did Zemski et al., (2019) show in Polynesian rugby players?

Answer 18

Elevated risk factors, such as increased visceral fat and unfavourable lipid profiles in rugby athletes of Polynesian decent compared to athletes of Caucasian decent.

Question 19

What is CMS?

Answer 19

Cardiometabolic syndrome - a combination of metabolic dysfunctions mainly characterised by insulin resistance, impaired glucose tolerance, dyslipidemia, hypertension, and central adiposity.

Question 20

What is hypertension during adulthood a well-established independent risk factor for?

Answer 20

Later life CVD morbidity and mortality.

Question 21

What is essential (primary) hypertension?

Answer 21

Abnormally high blood pressure that is not as a result of a medical condition.

Question 22

Where is essential hypertension most commonly seen?

Answer 22

Essential hypertension is the most prevalent cause of high blood pressure in athletes.
- Participation in certain sports may be associated with an increased risk of developing hypertension
- E.g., American football

Question 23

What might strenuous static training induce?

Answer 23

Unfavourable blood pressure profile.

Question 24

What is hypertension a result on?

Answer 24

Complex interplay between genetic determinants and behavioural characteristics.

Question 25

What behavioural characteristics contribute to increased hypertension risk?

Answer 25

1. Dietary habits
2. Beverages rich in salt and energy drinks
3. Overuse of dietary supplements
4. Prohibited substances
5. Frequent use of NSAIDs
6. Fatigue, poor sleep
7. Psychological stress, competitive sport

Question 26

What is SCD?

Answer 26

Sudden cardiac death - the abrupt loss of heart function, breathing and consciousness.

Question 27

When does the ESC use the term sudden cardiac death?

Answer 27

1. A congenital/acquired potentially fatal cardiac condition is known to be present during life.
2. Autopsy has identified a cardiac/vascular anomaly as a cause of death.
3. No obvious extra-cardiac causes have been identified by post-mortem exam and therefore an arrhythmic event is a likely cause of death.

Question 28

What is SCD in older athletes predominantly due to?

Answer 28

Atherosclerotic coronary artery disease.

Question 29

Who in the athletic population are most at risk of SCD?

Answer 29

Middle-aged recreational athletes.

Question 30

What have recent studies identified in the muscles after prolonged exercise?

Answer 30

A rise in the concentration of biomarkers of myocyte damage.

Note!
- Myocytes = smallest unit of muscular tissues and organs.

Question 31

50% endurance athletes have an elevated
troponin response after exercise. What can such elevations result in?

Answer 31

May eventually lead to myocardial fibrosis that manifests as cardiac dysfunction and arrhythmias.

Question 32

What can repeated bouts of endurance exercise lead to?

Answer 32

Myocyte necrosis.

Question 33

What is the consequence of increased cardiac damage (occurring as a result of too much vigorous endurance exercise)?

Answer 33

Development of arrhythmogenic substrate (forms a prerequisite for the induction of arrhythmia) through adverse myocardial remodelling and myocardial fibrosis.

Question 34

What has been uncovered regarding the prevalence of AF in endurance athletes?

Answer 34

High prevalence of AF in middle-aged endurance athletes.
- Athletes engaged in chronic exercises experience a 5-fold risk of AF compared to sedentary population

Question 35

What are the cardiac consequences of using steroids (such as androgen-anabolic steroids, used to increase muscle mass and strength)?

Answer 35

They are implicated in adverse lipid and blood pressure profiles, myocardial infarction, arrhythmias, LV (left ventricle) dysfunction, and SCD.

Question 36

What can the use of human growth hormone (used to increase skeletal muscle) lead to?

Answer 36

Can cause myocardial hypertension and fibrosis.

Question 37

What can the use of erythropoietin EPO (usually utilised to increase red cell concentration and improve oxygen delivery to tissues) cause?

Answer 37

The accompanying rise in haematocrit and dangerous blood viscosity levels may predispose to spontaneous thrombosis and systemic thromboembolism as well as hypertension due to the elevated afterload.

Question 38

What is thrombosis?

Answer 38

Local coagulation or clotting of blood within a vein or arteries.
- Results in an embolism
- Can results from use of EPO

Question 39

What is an embolism?

Answer 39

A blocked vein or artery caused by a foreign body, such as a blood clot or air bubble.

Question 40

What is systematic thromboembolism?

Answer 40

An embolism which travel through the systemic arterial circulatory system.
- Vast majority arise within the heart secondary to atrial fibrillation (altered flow) or thrombus formation over an area of myocardial infarction (altered wall)