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1
Exercise response Exercise response in the presence of in the presence of
respiratory and cardiac respiratory and cardiac diseasesdiseases
Fang LouFang Lou
2
By the end of this session and appropriate reading, successful students should be able to:
Learning Outcomes
Describe the response to exercise in the presence of cardiac disease and respiratory disease
Explain the principle of exercise prescription in the presence of cardiac and respiratory disease
Appreciate basic concepts of nutrition and energy supply
3
Exercise training
Part of a rehabilitation programme
Focus on secondary prevention for MI
recovery; early stage benefit from low-
intensity aerobic exercise programme,
also facilitate both compliance and safety
Patients with chronic heart failure also
included
Effects lost on cessation of exercise
4
Who would benefit?
Traditionally available to post-MI and
coronary artery bypass graft patients
Patients with angina
Chronic heart failure
Following angioplasty
Cardiac transplantation
5
Central of the cardiovascular disease
A steady build-up of atherosclerotic plaques in the coronary arteries, leading to reduced blood flow
angina, arrhythmias (not totally blocked)
myocardium infarct (heart attack, totally blocked)
Prevention of CAD development
Rehabilitation of CAD patients (exercise therapy)
Coronary artery disease (CAD)
6
What are the benefits (1)?
Improvement in VO2max (peak performance)
Improving endurance (delay onset of fatigue)
Central: cardiovascular adaptation Increased left ventricular mass & chamber size
Increased total blood volume
Reduced TPR at maximal exercise
Peripheral: adaptive changes in the trained skeletal muscles (muscle oxidative capacity- extraction and utilisation of oxygen)
7
Exercise may have an important secondary
prevention role (risk factor modification):
A raised post-exercise metabolic rate
HDL (high-density-lipoprotein)
Improved insulin sensitivity
Decreased blood pressure
What are the benefits (2)?
8
VO2: rate of oxygen consumption
Metabolic equivalent (1 MET): the basal VO2 at
rest (3.5 ml/min/kg; ~250 ml/min in a standard 70kg man)
VO2max: The maximal rate at which an individual
can consume oxygen (normally 35-55 ml/min/kg (10-15 METs); ultra-fit athletes 70-80 ml/min/kg; cardiac patients much lower ~ 15-30 ml/min/kg)
Oxygen uptake and VO2max
9Modified from Bethell,1996, Fig. 4.1
Work load against oxygen uptakeO
xyg
en u
pta
ke (
VO
2)
(l/m
in)
1
2
3
4
50 100 150 200 250 300Work load (W)
5
0
Fit
Unfit
1 MET
10
UnfitVO
2 (
l/m
in)
1
2
3
4
50 70 90 110 130 150Heart rate
Modified from Bethell,1996, Fig. 4.2
Fit
Heart rate against VO2
170 190
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VO2max aerobic capacity; starting point
Training effect in normal subjects
Modified from Bethell,1996, Fig. 5.1
VO
2 m
ax (
ml/m
in/k
g)
Before Training
AfterTraining
40
50
30
60
20
Unfit
Fit
12
Oxygen consumption by the myocardium
Factors contributing to VO2max: Heart rate Stroke volume Arterio-venous oxygen difference
Oxygen difference at rest: 70% in myocardium (very little to improve) 20% the rest of the body
The main factor to increase oxygen supply is to increase coronary blood flow (SV x HR)
13
Changes in SV for MI patients
Stroke Volume (SV) = EDV - ESV
Ejection Fraction (EF) = SV / EDV
In normal subject, EF > 60% at rest; it is much lower in patients with heart disease - as low as 10% in severe heart failure
During exercise, the increase in SV is greatly reduced with the increase in size of myocardial infarct, therefore increase in heart rate becomes the main factor
14
Heart rate against stroke volume
Normal
L infarctM infarct
S infarct
SV
(m
l)S
V (
ml)
120
120
100
100
80
60
60
80
90 11070 150 170130 90 11070 150 170130Heart rate Heart rate
Modified from Bethell,1996, Fig. 4.3
15
Effects of physical training on coronary patients
Natural recovery: ~ 3 months after MI, physical work capacity and VO2max , marked by HR at given load, stroke volume
Improvements in MI patients > healthy individuals (enhanced effect for programme started during natural recovery process)
Remember FITT
Effects are comparable with that of unfit subjects
16
Principle of exercise prescription
Frequency of training F
Intensity I
Duration / time T
Mode / type T
17Modified from Bethell,1996, Fig. 5.3
Exercise frequency
Time per week
Increase VO2 max
63 5 71 2 4
Orthopaediccomplication
Optimalfrequencyrange
18Modified from Bethell,1996, Fig. 5.5
Exercise intensity
Risk of cardiac complications
OptimalIntensityrangeIncrease
VO2 max
10070
% of max heart rate8550
Be aware of individual conditions!
19Modified from Bethell,1996, Fig. 5.4
Exercise duration
Optimaldurationrange
Orthopaediccomplication
Increase VO2 max
20 40Duration (min)
10 30
20Modified from Bethell,1996, Fig. 5.2
Recovery of SV with time after MIS
V a
t s
ub
-ma
x e
xerc
ise
(%
of
No
rmal
)
1 2 3 4
50
75
25
100
Time (month)Infarct
The larger the infarct, the longer the recovery will continue
21
Four stages for CR case
Phase II: immediate post-discharge (2-6 weeks)
Phase I: in-hospital (average 5-7 days)
Phase III: supervised outpatient exercise programme (6-12 weeks)
Phase IV: Long-term maintenance programme in the community
22
Exercise programme for MI patients
Phase II: immediate post-discharge (2-6 weeks)
Phase I: in-hospital (5-7 days) 2-3 times daily rHR + 20-30bpm 5-20 mins Sitting/standing, walking
Phase III: supervised outpatient exercise programme (6-12 weeks) 2-4 times weekly 60-75% MHR 20-30 mins Aerobic/endurance training involving large muscle
groups
23
Guideline of monitoring
Heart rate
Rating of perceived exertion
Metabolic cost (multiples of METs - metabolic equivalent )
ECG (for high-risk patients only)
(high-risk patients: functional capacity < 6 MET;
left ventricle ejection fraction <35%; exercise-induced hypotension)
24
Post-exercise hypotension
Following exercise:
Resting blood pressure < baseline
Epinephrine, dopamine and cortisol
Sympathetic nerve activity
Secretion of endogenous opioids and serotonin
25
Hypertension
Mechanisms: primary and secondary
Clinical intervention: For those not at high risk of CHD: SP>160, DP>90
Individuals with CHD/CVD: SP>140, DP>85
Diabetes: SP>130, DP>80
Factors contributing
Consequences if untreated (inc CAD)
Treatment (-blocker among the drugs, exercise)
26
Hypertension and exercise
Use FITT principles, but adopt lower intensity and longer duration
Adopt lower resistance/higher repetitions for resistance work; avoid high-intensity arm work and overgripping of equipment (e.g. cycle handlebars)
Avoid Valsalva manoeuvre
Warm-up is very important (acute BP is dangerous)
Consider drug side effects
27
Valsalva manoeuvre
Contraction of abdominal & thoracic wall muscles; attempted expiration against a closed glottis
1. Intrathoracic P, arterial P, small HR2. Vena cava being pressed, venous return, CO,
arterial P, baroreceptor------tachycardia
3. When the straining ends, intrathoracic P, arterial P, small HR
4. Vena cava recovered, blood surges back to heart, CO, arterial P, bradycardia, then normal
HR is good indicator, provided ANS is intact
28
With
bet
a blo
ck
VO
2 (
l/m
in)
1
2
3
4
50 70 90 110 130 150Heart rate
Modified from Bethell,1996, Fig. 5.7
Without b
eta block
Heart rate against VO2 vs. -blockade
29
Effect of -blockade on responses to exercise
Basic effects of -blockers: Heart rate and force Blood pressure In susceptible individuals, may precipitate asthma
Response to exercise: BP ; HR ; VO2max The linear relationship between % of VO2max and % of
MHR is unchanged Exercise alone can SP & DP by 10-20 mmHg
(intensity related, overtraining resting BP) Difficult to calculate MHR (has to be tested)
30
Sense of well-being (confidence) Anxiety and depression Exercise capacity ST segment depression on the ECG Blood pressure at rest Heart rate at rest Levels of serum cholesterol and triglycerides Elevated levels of HDL Perhaps mortality
Long-term effects of exercise therapy
31
COPD
Leg fatigue & muscle weakness
Caused by metabolic abnormality or
inactivity?
Reduction in cross-sectional area
Marked decrease in type I (endurance) and
type IIb (maximum strength) muscle fibres
Increased in endurance fibres of respiratory
accessory muscles
32
Pulmonary rehabilitation
Recognised long time ago (1895) that
exercise to be beneficial in the management
of respiratory disorder – dyspnoea in COPD
Multidisciplinary intervention including
physiotherapist
Aim at reducing the work of breathing and
improving disability
To aid the removal of secretions
Assessment of patient is important
33
COPD
Predominant symptom in COPD (Chronic
Obstructive Pulmonary Disease) is dyspnoea
Increased resistance in the airway
Associated with anxiety and fear
Patients report significant limitation in daily life
Previous experience could help reduce the
symptom
34
COPD
Is a disease with systemic effects
Muscle function further impaired by systemic
inflammatory agents
Peripheral muscle in COPD respond to
training in a similar manner to muscles in
healthy individuals
Other factors – nutritional status, hypoxia,
hypercapnia, inflammatory mediators,
circulating hormones – also contribute
35
Aims of pulmonary rehabilitation
Reduce dyspnoea
Increase muscle endurance
Improve muscle strength
Ensure long-term commitment to exercise
Help allay fear and anxiety
Increase knowledge of lung condition and
promote self-management
36
Exercise prescription
Same principle: FITT
Endurance or strength training?
40 to 60 min
Daily/x2 week/x3 week
Assessment
Symptom related (short of breath?)
Physiological test (VO2max)
Intensity (age and severity)
37
Nutrition (for your interest)
Nutrients: a substance in food that is used by the body to promote normal growth, maintenance, and repair
Food Building blocks and repair Form ATP Pleasure
Essential nutrients: those molecules can not be made (converted from other molecules) by the body so must be provided by the diet
38
Major nutrients
Carbohydrates
Fat
Protein
Vitamins
Minor (but equally crucial)
Minerals
39
The food guide pyramid
Fats, oils and sweetsuse sparingly
Milk, yogurt and cheese2-3 servings
Meat, poultry, fish dry beans, eggs and nuts group, 2-3 servings
Fruit group2-4 servings
Vegetable group3-5 servings
Grain products 6-11 servings
Modified from Marieb, Fig. 24.1
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Serving sizeGrain products group
• 1 slice bread• 0.5 cup cooked cereal, rice or pasta
For details, see McArdle 1999 Sports & exercise nutrition, p189
Vegetable group• 1 cup raw leafy vegetable• 0.5 cup other vegetables cooked or chopped raw
Fruit group• 1 medium apple, banana, orange• 0.75 cup fruit juice
Milk group• 1 cup milk or yogurt• 2 oz processed cheese
Meat and beans group• 2-3 oz cooked lean meat, poultry or fish; • 0.5 cup cooked dry beans counts as 1 cup lean meat
41
One calorie: the quantity of heat to raise the temperature of 1 g (1mL) of water 1°C; kilocalorie (kcal) is used more
The joule (J) is the SI unit for energy; conversion of kcal to kJ: multiply the kcal value by 4.184
Calories contained in food: the potential energy trapped within the foods’ chemical structure; it can be measured in laboratory using a ‘bomb calorimeter’ (the heat liberated as food burns completely)
It depends on the structure of foods; average values: Carbohydrates: 4.2 kcal / g Lipids: 9.4 kcal / g Proteins: 5.65 kcal / g
The calorie - a unit of food energy
Modified from McArdle 1999 Sports & exercise nutrition, p166-7
42
Comparison of intake of middle-aged runners and sedentary controls
Males
Females
Runners %
Calories (kcal/day) 2959.0 2361.0
Seden.C. %
Proteins (g/day) 102.1 13.8 93.6 15.8
Lipids (g/day) 134.4 40.8 109.0 41.5
Carbohyd. (g/day) 294.6 39.8 225.7 38.6
Fat (g/1000 kcal) 25.2 25.3
Calories (kcal/day) 2386.0 1871.0
Proteins (g/day) 82.2 14.2 76.7 17.4
Lipids (g/day) 110.7 41.1 83.0 40.3
Carbohyd. (g/day) 234.3 39.5 174.7 39.1
Fat (g/1000 kcal) 25.3 24.4
Modified from McArdle Sports & exercise nutrition
43
Nutrition for exercise
Only carbohydrates, fat, and proteins can yield energy for muscular exercise. Protein is not used as a fuel as long as the energy supply is adequate.
The % of the two major fuels depends on, eg.:
Type of muscular exercise
State of physical training
The diet
State of health
44
Nutrition for exercise
At rest and during moderate exercise for a normal diet person, fats and carbohydrates contribute about equally
With increasing intensity of exercise, there is a gradual change toward a proportionally greater share of energy yield from carbohydrates (key point: oxygen supply)
Physical training can increase individual’s facility for fat utilisation
45
Type of performance (weight control for long-distance runners and high-jumpers)
Same proportion of fat intake for runner and weight lifter
Duration of performance Regular and well-balanced diet except the days proceeding
the event and the day itself
Events lasting less than 1hr: no special diet; no heavy meal; no meal <2.5hr before exercise
Events lasting between 1hr and 2 hrs: high-carbohydrate diet several days prior to exercise
Events lasting for several hours: same as above, plus ingestion of carbohydrates during the actual event
Nutrition for exercise
46
Effect of diet
47
Extreme high-fat diet (<5% from carbohydrates) for several days: duration of exercise is short (1hr); 70 to 99% use fat
Extreme high-carbohydrate diet (>90% from carbohydrates) for several days: duration of exercise is much longer (4hr); 20-30 to 60% use fat
Certain pathological conditions (diabetes) affecting the organism’s choice of fuel
Effects of diet
48
Bethell, H. (1996). Exercise-Based Cardiac Rehabilitation. Publishing Initiatives. Kent.
Brooks G.A., Fahey, T.D., White, T.P. & Baldwin, K.M. (2000). Exercise Physiology (Human Bioenergetics and Its Applications). 3rd ed. Mayfield Publishing Company. California.
Plowman, S. & Smith, D.L. (2003). Exercise Physiology. Benjamin Cummings. San Francisco
Pryor, JA & Prasad, SA (2002,) Physiotherapy for repiratory and cardiac problems. Churchill Livingstone.
Thompson, D. Bowman G.S., de Bono, D.P. & Hopkins, A. (1997). Cardiac Rehabilitation. Royal College of Physicians of London. London
References