Cardiovascular disease and its syndromes: Why exercise?

METABOLIC SYNDROME: What is it?

• A condition in which several coronary heart disease risk factors are grouped together

• According to ACSM: Diagnosis is made when 3 or more of the risk determinants are present

• Abdominal obesity – a central feature of this syndrome

Risk factors of metabolic syndrome

Risk factor Defining level

Abdominal obesity

Men:

Women:

>102 cm

>88cm

Triglycerides ≥150mg/dL

HDL cholesterol <1.03mmol/dL

Blood pressure ≥130/85

Fasting glucose ≥110mg/dL

Risk factor 1: Obesity

• According to WHO:

– 29% men and– 56% women in South Africa are overweight or

obese– Much higher than other African countries– 1.3 billion people worldwide

Risk factor 1: Obesity• Can be caused by interplay between genetic and

environmental factors.• In the end: A positive energy balance = obesity

↓

calories consumed is greater than calories used• Abdominal fat or apple-shaped body type = highest risk

Determining obesity: BMI

WEIGHT CLASS BMI (body mass index)

Underweight <18.5

Normal 18.5-24.9

Overweight 25.0-29.9

Obesity:

Class 1 30.0-34.9

Class 2 35.0-39.9

Class 3 ≥40

Problem with BMI

• Does not take muscle mass or bone density into consideration

• Study was done on women with a BMI near 30: Still not of major concern if weight is distributed in the pelvis and not the abdomen

• When trying to lose weight: A decrease in body weight due to a loss of skeletal muscle or bone mass – does not improve a person’s risk levels for cardiovascular diseases.

• Rather use ‘Waist-to-hip ratio’

Waist-to-hip ratio

• Circumference of waist ∕ circumference of hips• How to measure:

Waist: Abdomen relaxed, horizontal measure at narrowest part of torso

Hip: Horizontal measure at maximal circumference of buttocks

• Risk stratification:• For people 60yrs and older high risk = • Men: WHR > 1.03• Women: WHR > 0.90

Exercise and obesity

• Many weight loss programmes available.• Key components:

1. GRADUAL weight loss of 0.5 to 1kg per week.2. More emphasis placed on frequency and duration, rather than intensity of exercise3. Primary mode should be large muscle group aerobic

activities4. However, combine with resistance exercise

Exercise and obesity

• NB not to lose hope if weight reduction is minimal:

• According to research, it is not necessary to achieve an OPTIMAL body weight to experience the health benefits.

• Even slight levels of weight loss ( 5 – 10% reduction in body weight) results in:

1. Significant reductions in blood pressure

2. Increases in insulin sensitivity

3. Improvements in lipid concentrations

Risk factor 2: Insulin resistance

• In a normal person: Stomach breaks down sugars into glucose which then enters the bloodstream

• Insulin is secreted by the pancreas • Insulin binds to glucose and allows it to enter cells

throughout the body

Insulin resistance• Insulin resistance occurs when the body cells no longer responds to

insulin • Pancreas reacts by producing more insulin – hyperinsulinemia –

causing other problems such as making it difficult for the body to use stored fat for energy

• Glucose is therefore not taken up by the cells and remains in the bloodstream

Insulin resistance: Causes

• Genetics• Lack of physical activity• Obesity• Pregnancy• Infection or severe illness• Stress• Prolonged steroid use

Insulin resistance and exercise

• Exercise assists with glucose control since it has an insulin-like effect

• Enhances glucose uptake even when insulin levels are low

• Increases insulin sensitivity

• Decreased insulin requirements

Risk factor 3: High blood pressure

Blood pressure classification

Systolic blood pressure (mmHg)

Diastolic blood pressure (mmHg)

Normal <120 And <80

Pre-hypertension 120-139 Or 80-90

Stage 1 Hypertension

140-159 Or 90-99

Stage 2 Hypertension

≥160 Or ≥100

Blood pressure=silent killer• The relationship between blood pressure and the risk of

developing cardiovascular disease is continuous, consistent and independent of other risk factors.

• For people aged 40 – 70yrs: Each increase of 20mmHg in systolic BP or 10mmHg in diastolic BP, the risk of cardiovascular disease or having another cardiovascular event …. DOUBLES

Blood pressure and exercise

* Aerobic exercise has an impressive blood pressure reduction effect: 3.84mmHg for systolic BP

2.58mmHg for diastolic BP• Studies show: • Mean blood pressure reduction is not significantly linked

to mean change in body weight – instead blood pressure will lower even in people who did not lose weight at all.

• The blood pressure reduction is also not directly linked to frequency or intensity of aerobic exercise, therefore all forms of exercise seems to be effective in lowering blood pressure

Risk factor 4: Low HDL & exercise

• Low HDL levels are strongly related to risk for cardiovascular diseases

• For every 1ml/dl decrease in HDL-cholesterol, the risk for CAD increases by 2 – 3%

• Most research studies are consistent:• HDL levels in endurance athletes are 20 to 30% higher

than in sedentary individuals

HDL & exercise

• If there is no significant change in body weight and composition, increased exercise has little effect on HDL levels

• THEREFORE:• If the exercise programme is prolonged and there is

associated weight loss, loss of body fat and increased muscle mass, HDL levels can rise significantly.

Risk factor 5: High triglycerides

• What are triglycerides?

• The most common form of fat which are the main ingredient in vegetable oils and animal fats

• The body uses it for energy, however if triglyceride levels are elevated, even with no other risk factors = at risk for CAD

Causes of high triglycerides:

• Lifestyle factors: overweight, inactivity, smoking, excessive alcohol use, eating a high carbohydrate diet

• Certain medications: Corticosteroids, estrogens, retinoids( used to treat acne, etc), high doses of beta-adrenergic blocking agents

• Certain conditions: Type 2 diabetes, some kidney diseases, hereditary factors.

Exercise and triglycerides

• Study showed: Aerobic exercise training in the presence or absence of weight loss reduces fasting and postprandial triglycerides.

• Sessions of low-to-moderate intensity aerobic exercise of about 30-90 min decreased postprandial triglyceride levels by 15 – 50%.

I had a Cardiac event: How do I exercise?

Component of fitness

Frequency Intensity Time Type

Cardiovascular Minimum of 3 times per week

60-75% of HR max

40-60% HRR

RPE: 12-15

20-60min Aerobic

Muscle strength

2-3 times per week

To moderate fatigue

One set of 10-15 reps

8-10 different exercises involving major muscle groups

Flexibility Minimum of 2-3 days per week

Stretch to tightness but not pain

Hold 15-30sec, 2-3 times

Static stretching

Calculating your heart rate at which you should exercise

• Heart rate reserve:

• Step 1: HRR = Maximum heart rate – resting heart rate• (If you do not know your maximum heart rate, use 220-

age)• Step 2: Training intensity is selected: 40-60%• Step 3: Add resting heart rate

• NB: If you are on a beta-blocker, you must subtract 20-30 beats from the first step eg. 220-age-30

Example of calculating your heart rate

• Tom is a 70 year old man who had a heart attack in February 2011. He is keen to start a healthy lifestyle beginning with exercise. He has a resting pulse of 84. His Biokineticist worked out his heart rate reserve

• Maximum heart rate: 220 – 70 = 150• Max HR – Resting HR: 150 – 84 = 66• 40% of above: 0.4 x 66 = 26.4• 60% of above: 0.6 x 66 = 39.6• Add Heart rate rest: 26.4 + 84 = 110• 39.6 + 84 = 123.6

• Therefore, Tom should exercise between 110 and 124 beats per minute

RPE scale• This is a scale of an individual’s subjective perception of effort• Borg RPE scale: Ranges from 6 – 20

• 6 = No exertion at all• 7-8 = Extremely light• 9-10 = Very light• 11-12= Light• 12-13 = Somewhat hard• 14-16 = Hard• 17-18 = Very hard• 19 = Extremely hard• 20 = Maximal exertion

RPE should not be used individually if you are not 100% sure that you can reliably match your perceived exercise intensity to objective measures such as HR.

Warm-up and cool down

• Very important for starting and ending exercise programmes.

• Why the warm-up is important:• 1. It raises the pulse rate in a graduating and safe way,

thereby preparing the body• 2. Redistributes blood to active tissues.• 3. Increases muscle temperature which may speed the

muscle action & relaxation.• 4. Stimulates the release of synovial fluid

Cool down

• Should have at least 10min of cool down in which exercises of reduced intensity and passive stretches are incorporated

• The cool down:• Reduces the risk of hypotension after an exercise

session• Helps the heart rate to gradually return to resting levels• Allows circulating catecholamines (which increases the

risk of arrhythmias following exercise) to drop to resting levels

• After the cool-down the heart rate should have dropped to 10 beats per minute of resting levels

Let’s get … MOVING!!