Exercise: Benefits vs. Risks

Question 1

Exercise has been proven to have a positive effect in

Answer 1

insulin resistance, obesity, dislipidaemia, and hypertension - i.e. metabolic syndrome

Question 2

T/F Higher insulin sensitivity is associated with higher glucose infusion rates

Answer 2

True; the more glucose that has to be infused, the more insulin-sensitive the tissues are

Question 3

T/F Trained individuals have lower insulin sensitivity

Answer 3

False; trained individuals have higher insulin sensitivity marked by higher glucose infusion rates

Question 4

What is thought to be the reason for increased insulin sensitivity in trained individuals?

Answer 4

At the level of Akt and AS160 - something to do with GLUT4 translocation; increase in hexokinase activity (phosphorylates glucose to G6P to enter the glycolytic pathway); increased mitochondria; increased insulin stimulated blood flow enhances glucose disposal into muscle

Question 5

T/F GLUT4 expression is increased by exercise

Answer 5

True; in both muscle and adipose tissue

Question 6

Regular exercise depletes muscle glycogen; what effect does this have on subsequently ingested CHO?

Answer 6

CHO is converted back to muscle glycogen rather than being converted to fat

Question 7

With regular exercise, capacity to re-synthesize muscle glycogen is increased which has what beneficial effect?

Answer 7

increases insulin sensitivity

Question 8

How does increased mitochondria with exercise training affect insulin action?

Answer 8

increased mitochondria increases capacity for fat oxidation in addition to glucose oxidation; TG clearance from the circulation is higher in trained individuals bc they have more lipoprotein lipase in muscle and greater oxidation capacity - tf it is oxidized rather than being deposited in adipose tissue

Question 9

What is the effect of exercise on insulin-stimulated blood flow?

Answer 9

smooth muscle of resistance arterioles becomes more sensitive to insulin effects with training - partially due to increased capillary density and NO/NOS activity which mediates vasoD by insulin - this enhances glucose disposal into muscle

Question 10

What is the significance of adipose tissue GLUT4 in diabetes?

Answer 10

Its expression on adipose tissue is decreased in T2D which dysregulates adipokines; can be increased with exercise

Question 11

What is the effect of increased insulin sensitivity with exercise on the liver?

Answer 11

more efficient at turning glucose into glycogen - tf get less lipogenesis in the liver, lower risk of elevated TGs, dislipidaemia, and NAFLD

Question 12

What is the effect of training on cholesterol?

Answer 12

increase in lipoprotein lipase in muscle = increased chylomicron, VLDL, TG uptake and metabolism to HDL; tf higher circulating HDL

Question 13

T/F Exercise reduces accumulation of visceral abdominal fat

Answer 13

True

Question 14

T/F Exercise can reduce BP to a similar extent as beta blockers, diuretics, ECE inhibitors, etc.

Answer 14

True

Question 15

What is the role of IL-6 in exercise?

Answer 15

Increases without an increase in TNF (non-inflammatory response); thought to be a myokine that has effects on lipolysis in fat and glycogenolysis in liver, on the CV system

Question 16

What are the risks associated with exercise?

Answer 16

Sudden cardiac death (arrythmia, diastolic dysfunction with training); exercise-induced bronchospasm; MSK injury; DOMS; exertional rhabdomylosis (muscle breakdown); exertional hyper or hypothermia; proteinuria with altered glomerular membrane permeability, sometimes myoglobin or haemoglobinuria

Question 17

What aspects of acute exercise stress contribute to a risk of CV events?

Answer 17

increased sympathetic activity, reduced vagal stimulation, Na/K imbalance w/hyperkalaemia that changes myocardial excitability, icnreased catecholamines, increased HR and BP, increased O2 requirement of cardiac muscle which may cause ischaemia if CVD is present, altered excitability and ECG changes that predispose to MI

Question 18

What factors immediately post-exercise may contribute to risk of CV events?

Answer 18

decreased venous return, decreased CO, tf decreased BP and decreased coronary perfusion all while musculature and arteries are all vasodilated