A fitness stress test is an important medical technique for revealing heart problems. Stress tests are sometimes called exercise stress tests, exercise electrocardiograms (ECG or EKG), or treadmill tests, among other names.
Stress testing allows doctors to collect important data about heart performance while it works hard. During typical stress testing, the individual being tested will walk or run on a treadmill, pedal a stationary bike, or engage in some other rhythmic exercise to make their heart work harder than it does at rest.
A fitness assessment, by comparison, has a different purpose than, and is not a replacement for, a stress test. Fitness assessments can be done without specific medical training to make non-medical interpretations.
A fitness assessment might measure
- the maximum amount of oxygen one can consume during exercise (VO2 max),
- blood lactate during anaerobic metabolism (i.e., lactic acid in the blood when oxygen delivery to muscle tissue falls short of demand), and
- heart rate.
The information gathered from a fitness assessment will help a coach or trainer determine, for example, the best exercise intensity for their athlete or trainee. A fitness assessment is not an equivalent substitute for a fitness stress test.
Types
A stress test via exercise involves attachment of electrodes to the body that measure electrical signals in the heart which are sent to an electrocardiograph for a display of heart activity. The individual might also be required to breathe into a tube connected to equipment measuring oxygen consumption and waste gases. While the test starts very easy, it incrementally gets harder/faster until the individual under test reaches their anaerobic/speed zone (80-90 percent of their maximum heart rate) or “quit point” (i.e., when you decline to continue from fatigue or discomfort), whichever comes first. The test also might be terminated if warning signals – like irregular heart rate, dizziness, or nausea – present themselves to the physician.
A stress test via imaging is a pharmacological option for individuals not able to exercise due to known preconditions, risk factors or physical limitations from arthritis to heart surgery. In this method, injectable drugs induce the heart to work harder and put exercise-like stress on it; the individual under test is basically at rest during the test. Imaging equipment gives a look at the heart’s response to the drug. Imaging may come from recording the echo of sound waves detailing heart chambers and valves at work. Imaging could also come from injecting radioactive dye into the bloodstream with pictures taken of the amount of dye reaching parts of the heart.
Imaging stress tests have some advantages over exercise stress tests such as more effective detection of coronary artery/heart disease (CHD), revealing heart valve problems, and better prediction of future heart attacks. Some stress tests blend mild exercise and drugs. Images can be taken of the exercising heart for comparison of blood flow and pumping with the same heart at rest.
Why Stress Test?
Stress testing is often used as an evaluation for certain people before they embark on an exercise regime. Under the conditions of pumping hard and beating fast, some heart problems – like coronary heart disease – are easier to diagnose or cannot be diagnosed with a resting ECG. A resting ECG might conclude the heart is receiving enough oxygenated blood whereas an exercise ECG could show a shortfall, perhaps from plaque buildup in coronary arteries (i.e., the two big blood pipes connected to your heart effectively get narrower), when any amount of work is involved. A person might not otherwise discover such a problem until they experienced chest pain or even suffer a heart attack while exercising.
A fitness stress test can detect
- a low VO2 max during mild exercise (i.e., shortness of breath) and
- abnormal changes in heart rhythm (steadiness), electrical activity (strength and timing of signals), heart rate (beats per unit time) and/or blood pressure.
An imaging stress test can detect
- areas of poor blood flow,
- dead heart muscle tissue, and
- parts of the heart not contracting.
Based on the results of the test, a qualified physician may determine their patient is suffering from CHD, has damage from a prior heart attack, lung disease, or is just plain out of shape. Your doctor may either give their blessing to your exercise intentions or advise you on an alternate course.
Should You Be Tested?
A stress test isn’t a must for everyone; but, if you have a mind to start a change in your life that involves regular exercise and any of the following apply to you, it is something you should consider, especially if you’re over 40 years old:
- Sedentary lifestyle (e.g., you spend a lot of time on the sofa or at a desk)
- Overweight
- Smoking
- Irregular heart beat (arrhythmia)
- High blood pressure (hypertension)
- High cholesterol
- Diabetes
- Previous heart attack(s)
- Chest pain
- Shortness of breath resultant of minimal or non-strenuous activity
- Dizziness and loss of balance
Being younger than forty doesn’t necessarily mean you’re in the clear. If, for instance, you’re obese in your thirties, there are no guarantees. Smokers, for instance, experiencing shortness of breath absent chest pain might have a lung problem and not a heart problem; but, then again, maybe not. The shortness of breath could just be a consequence of being out of shape. Wouldn’t you like to be sure?
Sedentary and/or overweight individuals that go right into unusually high physical activity can get a heart attack. Just about everyone has heard of the so-called silent killers of high blood pressure and coronary artery disease because the first sign is often the worst: a heart attack. Chest pain might be symptomatic of clogged arteries but arteries can be clogged without pain. With or without pain, the plaque clogging arteries can be dislodged by unusually high physical activity, causing arterial blockage.
Of course, if doctors have diagnosed you as having CHD or you have just had a heart attack, starting an exercise program without having a stress test would be foolish as you might be biting off more than you can handle. Stress testing will also be revealing of the efficacy of surgical procedures – like stent placements and bypasses – to treat CHD.
For appropriate individuals, getting a stress test is important. However, a fitness stress test isn’t urgent or a presumptive necessity for those under 40 years old in good health without apparent risk factors and with no family history of CHD. You might, instead, opt for a fitness assessment.
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