Cardiovascular risk assessment prior to commencing moderate to high intensity exercise

The P.N.G government in recent times has devoted billions into the construction of huge sporting venues with the aim of promoting sports and exercise in the community.  This is commendable however in Port Moresby as is the case in all the major urban areas in PNG there is still a very limited number of affordable and family safe venues for people to participate in structured or unstructured exercise.

Exercise has always been recognised as something that is good for health.  Two major studies give overwhelming evidence that exercise is good for both the prevention of diabetes and the optimising of blood glucose levels in people with diabetes.

In the Finnish diabetes prevention study  Jaana Lindström et al (2003) showed that people who participated in an intensive lifestyle intervention program involving exercise and diet show significantly better outcomes in terms of anthropometric measures (body mass index, waist circumference and central abdominal obesity), diabetes incidence and also in the biochemical parameters like blood glucose and lipids level.

The US diabetes prevention program (DPP) also showed similar benefits of exercise, National Institute of health (2008):

The DPP’s results indicate that millions of high-risk people can delay or avoid                         developing type 2 diabetes by losing weight through regular physical activity and                   a diet low in fat and calories. Weight loss and physical activity lower the risk of                       diabetes by improving the body’s ability to use insulin and process glucose.

For someone wishing to embark on an exercise program that is more intense then say brisk walking it is recommended they they undergo a health check by a suitably qualified health care practitioner.  This assessment is important to identify any pre-existing condition that may cause harm or at worse be fatal if they are not identified and appropriate precautions taken.

Mitigating the risk of heart attacks.

One issue that is of particular concern and should be assessed in high risk individuals is the risk of having a heart attack during moderate to high intensity exercise.

Heart attacks are caused by the narrowing and eventual blocking of the coronary arteries, the arteries that supply oxygen and nutrients to the heart muscle. Major risk factors for this narrowing and blockage include: cigarette smoking, high blood pressure, diabetes and high cholesterol.  These risk factors are termed modifiable risk factors because they can be modified in order to reduce their contribution to the overall risk.  Exercise along with a healthy diet and when indicated specific medication has been shown to be effective in reducing these modifiable risk factors.

A number of very well validated cardiovascular risk calculator tools have been developed that can allow the determination of an individual’s risk of developing a heart attack over the next 10 years.  By plugging in the individual’s value for blood pressure, total and HDL cholesterol, their sex and whether or not they have diabetes or whether or not they smoke, a percentage risk of developing a heart attack in the next 10 years can be determined.

An example of this is the Australian absolute cardiovascular disease calculator that can be found here

The individual may already have a pre-existing narrowed coronary artery the extent of which determine the symptoms and risk of having a heart attack.  If a pre-existing narrowing of coronary artery is left undetected (through an appropriate health assessment) and that person commences a medium to high intensity exercise program it may precipitate a heart attack.

One way of determining whether a person has narrowing of their coronary arteries is by doing an exercise stress test.  An exercise stress test involves connecting a patient to an electrocardiogram (ECG) while they perform some physical exercise of progressively increasing intensity either on a treadmill or an exercise bike.  The patients is monitored for signs and symptoms of cardiac ischemia (low oxygen delivery to the heart) and changes in the ECG that suggest ischemia.  If the person shows changes in his or her ECG during the test they have narrowing of their coronary arteries and it is recommended for them to undergo further more invasive test to assess the severity of this narrowing.

The exercise stress test does not need to be done on every person who wishes to commence an exercise program, this would be too costly and subject people to unnecessary testing.

The American Diabetes Association recommends that an individual should have an exercise stress test to identify an underlying coronary artery occlusion if their 10 year cardiovascular risk is greater or equal to 10% or 1% per year using the

In Papua New Guinea even this relatively simple test,  (the ECG stress test) is not readily available and therefore in a patient who has a 10 year cardiovascular risk of equal to or greater than 10% I will always suggest light to moderate exercise, like regular  brisk walking, until they undergo an exercise stress test after which they can undertake exercise of higher intensity if the stress test turns out negative

To the best of my knowledge only the Port Moresby General Hospital and the Pacific International Hospital are the only two health facilities that do exercise stress testing.

My recommendation would be for every adult (especially those living in urban areas) to have a cardiovascular risk assessment every 1 to 2 years and if indicated from this initial assessment they should undergo a stress test.

 

References

  1. National Institute of health (2008), ‘Diabetes Prevention Program (DPP)’ available at https://www.niddk.nih.gov/about-niddk/research-areas/diabetes/diabetes-prevention-program-dpp/Documents/DPP_508.pdf, accessed 16/02/2017.
  2. Jaana Lindström et al (2003), ‘The Finnish Diabetes Prevention Study (DPS) Lifestyle intervention and 3-year results on diet and physical activity’ DIABETES CARE, VOLUME 26, NUMBER 12, DECEMBER 2003.
  3. Sheri R. Colberg (2010), ‘Exercise and Type 2 Diabetes – The American College of Sports Medicine and the American Diabetes Association: joint position statement’ Diabetes Care 2010 Dec; 33(12): e147-e167

 

About Dr. Poyap J Rooney

Dr. Rooney is a medical doctor who has gained both his undergraduate medical degree and more recently his post graduate masters degree in clinical biochemistry at the University of Papua New Guinea.
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