Cardiovascular disease (CVD) is the major causes of death in industrialized countries such as the UK, Australia, and the United States. CVD includes medical conditions and diseases such as heart attacks, chronic chest pain, stroke, and heart failure.
Encouragingly, deaths attributable to CVD have declined over the last 10-15 years in these countries but, the overall costs of managing CVD are still extremely high. In 2011, the annual costs for CVD and stroke were estimated at approximately US$320 billion. (1)
What causes Cardiovascular disease?
The cardiovascular disease starts with damage, then inflammation to the lining inside blood vessels, the endothelium (2). This is often caused by high blood pressure, smoking or high cholesterol.
When bad cholesterol, or high-density lipoproteins (LDLs), reach the damaged endothelium, it amalgamates within the wall of the artery. White blood cells then try to ‘digest’ these LDLs. In time, this creates a bump-like plaque in the artery walls. If it gets big enough, it can create a blockage. This process, known as atherosclerosis, is not limited to the heart but the entire body.
What are the symptoms?
Vessels that are partially or fully blocked with plaque can impair blood flow. A partially blocked vessel causes chest pain with exertion, this is angina. These plaques can also rupture, causing a clot inside the vessel, completely cutting off the blood supply (3).
If the flow is not restored quickly, the heart muscle will be damaged and potentially die. This is a ‘heart attack’ or a myocardial infarction (MI). If the victim survives, the heart muscle will almost certainly be weakened. This can lead to heart failure of which shortness of breath, fatigue, and fluid retention are symptoms.
Risk factors associated with CVD
Lifestyle modifications, such as a healthy diet and regular physical activity have been proven to be extremely effective in CVD prevention and treatment (4) Risk factors fall broadly into 2 categories:
- Non-modifiable risk factors such as age, family history of CVD, race, and gender (men are at greater risk than women)
- Modifiable risk factors such as smoking, high blood pressure, high cholesterol, physical inactivity, obesity, excessive alcohol, stress, and diabetes (5)
Reducing alcohol intake, quitting smoking and reducing stress are all important strategies in managing the risk of CVD. However, positively changing one’s exercise and nutritional habits can significantly reduce one’s risk, improve fitness and even add on years to your life.
Poor nutrition is an absolute risk factor for high cholesterol, elevated blood pressure, and heart disease. The average Western diet increases the risk for all of these conditions. Generally, it is high in refined grains, added sugars, and red and processed meats. Taking a back seat are all-important vegetables, fruits, whole grains, and dairy (6).
Whole grains such as brown rice and cereals, first and foremost, are the cornerstone of any ‘healthy heart’ diet. Three servings a day is recommended. They are a great source of both soluble and insoluble fiber. Soluble fiber helps lower bad cholesterol or low-density lipoproteins (LDLs). Oats, fruits, vegetables, and legumes are great soluble fiber sources.
Total daily fiber intake should be in the range of 20 to 30 grams (7). Most people know that ‘5 servings a day’ is the recommendation for fruits and vegetables. The greater the variety in color, the better.
Protein is highly important for heart and musculoskeletal development and maintenance. The leaner the protein the better. Choose the leanest cuts of beef and pork (loin, leg, round, extra-lean ground beef), skinless poultry, fish, and game. Healthy, non-meat based protein sources include dried beans and peas, nuts and egg whites.
Dietary fat should be kept between 25 and 35% of your daily caloric intake. There are several types of dietary fats. Saturated fats are responsible for raising LDL levels. Research has shown that for every 1% increase in calories from saturated fats, LDL levels rise about 2%, in ‘high cholesterol’ individuals (7).
Animal products are the main sources of saturated fats. Meat and dairy products such as beef, lamb, pork, poultry with skin, cream, butter, and cheese are all examples (8). The American College of Cardiology recommends that less than 7% of your total daily calories are from saturated fats (4).
Similarly to saturated fats, trans-fats increase LDLs and should be consumed as little as possible (4). They also decrease ‘good fats’ or high-density lipoproteins (HDLs) (9). Seeing “hydrogenated” or “partially hydrogenated” on a foodstuff suggests that it contains trans-fats. Margarine, shortening, muffins, pies, and cakes are examples.
It goes without saying, the consumption of such items should be limited.
Conversely, unsaturated fats also known as monounsaturated or polyunsaturated fats, are recommended to make up the majority of the fat you consume. Monounsaturated fats are found in, amongst other things, canola, peanut, and olive oils. Polyunsaturated fats, including omega-3 fats, are found in vegetable oils, several types of fish including salmon, tuna, mackerel, herring, lake trout, tuna, and sardines. They’re also seen in canola and soybean oils.
Omega-3 fats are important as they have been shown has shown to decrease your risk of heart disease.
The American Heart Association (AHA) recommends adding two servings of baked or grilled fish (about 100 grams) to your diet each week to compliment your intake of these healthy fats (10). Fish oil supplements are a recommended alternative source of good fats. The AHA suggests that people with heart disease get 1 gram of omega-3 fatty acids, from any source, daily (11).
Research has shown blood pressure is reduced with decreased dietary sodium (11,12). In the US, the average daily intake is 3,300 milligrams (6). The Dietary Guidelines for Americans recommends less than 2,300 milligrams of sodium per day. Those with established high blood pressure (hypertensives) should restrict themselves to 1,500 milligrams per day (6). 75% of people’s sodium intake comes from processed, pre-packaged, and restaurant foods. Label reading is therefore highly recommended.
Speculation is rife about the benefits of alcohol provides in relation to heart health. The AHA recommends moderate consumption i.e. 1-2 drinks per day for men and 1 drink per day for women (13).
Interestingly, excessive alcohol consumption can increase the presence of unwanted fats in the blood. Alcohol intake can also influence one’s blood pressure. Reducing alcohol intake has been shown to reduce resting blood pressure.
Finally, and probably most obviously, weight control is key in decreasing your risk for CVD and lowering blood pressure (13). Overweight persons should aim for a ‘calorie deficit’ ie. burning more calories than those consumed. This is most readily achieved through moderate calorie restriction and moderate intensity exercise (discussed in the next section).
Studies have consistently shown that weight loss can lower blood pressure and improve overall cardiovascular health.
Understandably, those living with CVD or, at risk of CVD, are worrying about what might happen if they commence a program of exercise. Naturally, we can see increased risk when sedentary people or, those with CVD, jump straight into vigorous exercise. With regular physical activity, of course, this risk reduces (14). It’s prudent therefore to start with a low to moderate exercise program, progressing gradually and safely, in-line with improvements in health and fitness.
When commencing an exercise program, screening is a must for anyone with CVD or several risk factors associated with CVD. Ideally, you should seek medical clearance. This clearance should ideally include a medical exam and an exercise test (14). In terms of the program itself, aerobic exercise and resistance training should be included.
You should perform aerobic exercise on at least 3, but preferably most, days of the week. The American College of Sports Medicine (ACSM) recommends a minimum of 5 days per week to help maximize caloric expenditure, for weight loss, as well as cardiovascular benefit. According to studies, blood pressure is lower for several hours after exercise, so exercising more frequently is beneficial for those with hypertension (14).
Aerobic exercise should be moderate in intensity exercise. On a Rate of Perceived Exertion (RPE) scale of 1-10 (where ‘1’ is extremely light and ’10’ is maximal known exertion), this would equate to a 5 or 6 (15). On a side note, if one has angina, the recommendation is to keep your heart rate 10 beats below the chest discomfort threshold (14).
Beta-blockers and other heart rate lowering medications will reduce your heart rate response to exercise. Heart rate as a guide to intensity is therefore of little value. Using the aforementioned RPE scale is the way to go (16).
20 and 60 min is the recommended duration for these aerobic sessions. Starting with only 5 to 10 minutes then gradually building up to this level is fine. We encourage it for those sedentary or higher risk persons (14).
The majority of one’s exercise routine should be aerobic exercise. Expending around 1,000 calories (kcal) per week with the aerobic exercise program is a recommended goal. If weight loss is a goal, this, of course, should be higher.
The rate of progression for intensity and duration be should gradual to avoid injury (14). Warming-up reduces the risk of injury and should simply consist of the activity to be undertaken at a low intensity for 5 to 10 minutes. The cool-down should be the same. You can also include stretching in the warm-up or cool-down preceding the low-intensity activity.
Resistance exercise training is important for increased muscle strength. With that said, you should avoid isometric exercises (exercises in which a contraction is maintained or held in position). Testing has shown massive increases in blood pressure during these contractions. Again, just as with aerobic exercise, intensity should be moderate. People with high cholesterol or high blood pressure should do 2-4 sets of 8 to 12 repetitions for each of the major muscles groups (14).
Aerobic and resistance exercise whilst important, shouldn’t detract from a physically active lifestyle in general. Being sedentary can be detrimental, even for regular exercisers.
The advent and easy access to pedometers help promote and encourage regular physical activity, and most guidelines suggest a goal of between 5,400 to 7,900 steps per day (14).