Chapter 8 - Cardiovascular Disease and Aerobic Endurance Training Flashcards
What is the recommended weekly energy expenditure for physical activity in people with CVD?
1,500-2,100 kcal
Outline the Cardiovascular response to exercise
- Increases in proportion to exercise intensity
- Maintains in steady state however increases slightly with CV drift
Describe the stroke volume change in response to exercise and what are the 2 causes of this?
- Increases up until 40-50%
1) Increased sympathetic activity increases contractility of the heart muscle and subsequent emptying of the left ventricle
2) Greater volume of blood returned from the veins increases preload and subsequent SV (Frank-Starling mechanism)
Outline the changes in Cardiac Output and Blood Pressure
- CO increases up to 4x
- BP:
1) Systolic: Increases in proportion to exercise intensity potentially up to over 200 in average 120 individual
2) Diastolic blood pressure sees little to no change
What is rate pressure product and the significance of this in relation to the muscle being trained
- Rate Pressure Product = HR x SBP and is a measure of myocardial workload - indirect measure of myocardial oxygen consumption
- Smaller muscle mass requires less vasodilation and therefore less drop in TPR and a increase in blood pressure
How does the redistribution of blood flow change with exercise?
How does the 02 changes translate into movement?
- Cardiac Output: 15-20% at rest, 80-85% during exercise goes to skeletal muscle
How is energy produced in the human body and what implications does this have for the CV system?
- 20% of energy expended is used to produce mechanical work
- 80% produces heat leading to sweating and redistribution of blood flow to the skin reducing venous return
- Venous return is therefore diminished and heart rate must increase to maintain cardiac output - Cardiovascular drift (CO = HR x SV)
How does O2 extraction and plasma volume change during exercise?
- Increases from 5ml O2 per 100ml blood to 15-20ml
- Plasma volume is reduced: Increases BP increases interstitial fluid and sweating reduces BP
- Can be reduced 10-20%
What are the 3 mechanisms by which coronary blood flow increases during exercise via vasodilation? Why is this significant?
1) Increased in adenosine, hydrogen and potassium ions from increased metabolic activity
2) Vascular endothelium dilates in response to nitric oxide
3) Sympathetic activity increases: Coronary vessels have proportionally more bets receptors then alpha receptors compared to other arterioles
- Myocardium already extracts around 70% oxygen so needs increased blood flow to meet demand
What are the 6 considerations that should be made with heart failure patients in regard to aerobic exercise
1) LV function impaired, HR increases to compensate increasing rate pressure product
2) Vascular endothelium damage is less responsive requiring a longer warm-up
3) SBP may not increase and possibly decrease
4) SBP if higher than normal will require HR to be reduced so that RPP is not too high
5) Medication that blunts HR response and therefore potential for postural hypotension
6) Reduction in plasma volume particularly with diuretics means fluid intake should be kept adequate
Outline the 4 principles of exercise training adaptations
1) Individuality: No two individuals will adapt the same to the same program
2) Progressive overload: Greater demands must be placed on the body
3) Regression: Adaptation are only kept to a level required to meet the demands placed upon them
4) Specificity: The adaptation conferred by training are highly specific to the volume, type and intensity of training (FITT principle)
What are the typical changes seen in VO2 max in those with and without CVD? What are the reasons for this?
3-6 months
10-55% following MI
15-65% following Coronary Artey Bypass Graft
10-25% in the general population
Poor initial fitness levels and the natural recovery process that occurs
What are the peripheral and central changes that occur with aerobic training?
Central: Increased stroke volume through improved left ventricular mass
Peripheral:
- Improved capillarisation
- Increased myoglobin concentration
- Increased number and size of mitochondria
- Increased oxidative enzyme capacity in mitochondria
- Increased O2 extraction
What are the most common improvements seen in cardiac patients and why is this?
Peripheral - Time and intensity of rehab programs doesn’t allow for great changes in LVM
How does submaximal training specifically produce improvements for cardiac patients
- Less physiological stress at a given intensity
- VO2 max 2.5 litres, exercise at 1.25 - 50% comparatively less for someone with VO2 max 80%
