Humans are very physical beings and the role of physical activity in promoting health has deep evolutionary roots. We have evolved over millions of years as hunter, gatherers doing a lot of physical work every day just to survive. We are anatomically and metabolically designed for physical activity.
However, modern life has allowed us to live a much more sedentary life with cars, motorbikes, escalators, lifts or elevators and a myriad of labour saving devices.
We rarely need to break a sweat these days as many jobs do not require physical activity. Personally, I live by the old adage, ‘use it or lose it’. If we don’t use it, we’ll find that our fitness levels diminish and our muscles shrink over time. We are designed to be physically active so it is not a normal state to do little or no exercise. Every single component of the body benefits from some form of exercise and physical activity. There is a direct relationship between physical inactivity and cardiovascular associated mortality. In addition, the lack of physical activity is a major risk factor for the development of cardiovascular disease.(1) Exercise improves your heart condition because the heart is a muscle just like any other so it needs exercise to keep it working optimally and to make it stronger. If we don’t do any exercise, it will weaken over time and this can lead to a whole raft of negative health outcomes. Lets take an analogy. If you were to just drive your car around town on short journeys, without doing any servicing or maintenance, never changing the oil, spark plugs filters etc, using cheap, low quality fuel, then it wouldn’t be long before the engine is choked up and performing poorly. Ultimately, it will breakdown. A car needs a good run to burn off all the carbon deposits. It needs regular servicing to keep it in good condition. It is the same with humans. We are designed for physical activity and therefore need regular exercise as well as putting high quality food into our systems to prevent us from ‘clogging’ up.
Exercise will get the heart pumping at a faster rate and pump blood into the circulatory system more efficiently. This leads to increased perfusion of nutrient loaded blood into the tissues and organs as well as increased oxygen delivery. Over time, the heart becomes stronger, just like any muscle and its myocardial contractions become more efficient. Research has revealed that being fit or active is associated with greater than a 50% reduction of risk of death from any cause and from cardiovascular disease.(2)
A systematic review of the literature regarding primary prevention in women revealed there was a graded inverse relationship between physical activity and the risk of cardiovascular health, with the most active women having the least risk. These protective effects were seen with as little as 1 hour of walking per week.(3) Both of these observational studies as well as many other studies provide compelling evidence that regular physical activity and a good level of fitness are associated with a reduced risk of premature death from any cause and from cardiovascular disease. There also appears to be a dose dependent relationship here too in that people with the highest levels of fitness have the lowest risk. However, this relationship can only go so far, as too much intense physical exercise can put excessive stress on the body and we become over-trained, which can lead to negative health outcomes. The key to this is balance.
There are also many studies that investigate the relationship between exercise and disease in situations where the disease is already present and the patient is undergoing treatment and rehabilitation. Several systematic reviews show the importance of undertaking regular exercise to reduce the disease state or even reverse the disease process in patients with cardiovascular disease. For example, a meta-analysis of 48 clinical trials revealed that, compared with the usual treatment and care, cardiac rehabilitation significantly reduced the incidence of premature death from any cause and from cardiovascular disease in particular.(4) This intuitively makes sense to us as we know that exercise is good for us.
Research shows that an energy expenditure of about 1600 kcal per week doing physical activity has been found to be effective in halting the progression of coronary heart disease. Furthermore, an energy expenditure of about 2200 kcal per week doing physical exercise has been shown to be associated with plaque reduction in patients with heart disease. Aerobic capacity serves as an independent predictor of all cause and cardiovascular mortality in patients referred to an outpatient cardiac rehabilitation program, with each 1 metabolic equivalent increase in aerobic fitness conferring an approximate 10% reduction in mortality.(5)
What is a metabolic equivalent? One metabolic equivalent otherwise known as Metabolic Equivalent of Task or MET is a physiological measure expressing the energy cost of physical activities. It is defined as the ratio of metabolic rate and therefore the rate of energy consumption) during a specific physical activity to a reference metabolic rate. This reference metabolic rate is defined as the amount of oxygen consumed while sitting at rest and is equal to 3.5 ml O2 per kg body weight.
The MET concept provides a way to express the cost of physical activities as a multiple of the resting metabolic rate. MET can be thought of as a measure of the intensity of an activity. For example, an activity with a MET value of 2, such as walking at a slow pace requires twice the energy that an average person consumes at rest.
How much exercise do we need?
The American Heart Association recommends the following exercise for overall cardiovascular health:
At least 30 minutes of moderate-intensity aerobic activity at least 5 days per week for a total of 150 minutes.
At least 25 minutes of vigorous aerobic activity at least 3 days per week for a total of 75 minutes – or a combination of moderate and vigorous intensity aerobic exercise.
Moderate to high intensity muscle strengthening activity at least 2 days per week for additional health benefits.
What are the best exercises for cardiovascular health?
Interval training, also known as burst cardio is great exercise for preventing heart disease and diabetes, losing weight, and improving fitness. This type of exercise calls for short bursts of high-intensity exercise with slightly longer periods of active recovery. Continuously raising and lowering your heart rate improves vascular function, increases metabolism, burns calories, and makes the body more efficient at burning fat.
Weight training is another form of exercise that is similar in many ways to interval training as you are increasing your heart rate as to rep out on a particular exercise and you recover between sets. This type of training builds strength and muscle as well as the heart. With stronger muscles, you’ll ease the demands placed on the heart.
In fact, any type of exercise that you enjoy is good for your heart. Some are more effective than others, but the key to this is that you enjoy the exercise or it won’t be sustainable. There is no point going to the gym and working out with weights if that is not your thing and it feels more like a form of torture. Perhaps cycling is more your thing, or maybe swimming? In fact, research shows that swimming is one of the best exercises you can do, and that is great if you really like swimming. I’m not really into swimming so for me, it wouldn’t work so I’ll keep going to the gym as I enjoy this. It also fits into my lifestyle and I can get more sessions in a week.
If you have had a fairly sedentary lifestyle, then the easiest thing to do, that will have have a positive impact on your health is to start walking. It's free, it's easy and its great exercise. I really enjoy brisk walking out in the countryside on my days off from the gym. Its a convenient way to get some additional exercise that actively promotes recovery from intense gym sessions and also has the added benefit of getting some fresh air, clearing my head of the daily hassles and improving my mood.
It is clear that exercise has significant health benefits for reducing the risk of cardiovascular disease. We are designed for physical activity and therefore need regular exercise to keep everything working optimally and in good shape. Of course, we need to consider diet as part of our health and well-being strategy and you can find more articles on this in the nutrition section to keep up to date with this. In the next article in this series, we’ll take a more detailed look at high intensity interval training and the latest research on this.
1.Physical Activity and Cardiovascular Health. Circulation. 2010;122:743-752
2.Fitness versus physical activity patterns in predicting mortality in men.
Am J Med. 2004 Dec 15; 117(12):912-8.
3.Physical activity decreases cardiovascular disease risk in women: review and meta-analysis.
Am J Prev Med. 2004 Jun; 26(5):407-18.
4.Exercise-based rehabilitation for patients with coronary heart disease: systematic review and meta-analysis of randomized controlled trials. Am J Med. 2004 May 15; 116(10):682-92
5. New insights in the prescription of exercise for coronary patients.
J Cardiovasc Nurs. 2003 Apr-Jun; 18(2):116-23.
Sports & fitness nutritionist, researcher and author on a mission to improve the human condition. Focusing on evidence-based and outcome-based nutrition, training, mindset & environment