Treadmill Stress Test at Cooper Clinic
Did you know that more than 100,000 patients have done the treadmill stress test at Cooper Clinic? A few weeks ago we began a blog series to dive into each of the six components of Cooper Clinic’s comprehensive preventive exam. To get caught up, read about the first two components.
- Medical Exam & Counseling
- Laboratory Analysis
- Cardiovascular Screening
- Multidetector Computed Tomography (MDCT) Scan
- Skin Cancer Screening
- Nutrition Consultation
Component #3: Cardiovascular Screening
Since Cooper Clinic opened in 1970, we have used the treadmill stress test to help detect heart artery blockages and assess patients’ overall risk of developing heart disease in the future. Dr. Cooper was the first physician in Dallas to routinely use the treadmill stress test for this purpose. And since then our research has proven the importance of having this test done annually.
The stress test is a standardized walking or cycling test used to determine cardiovascular fitness, assess functional capacity and the conduction system of the heart and identify possible underlying coronary artery disease. Before, during and after the stress test, the electrocardiogram (EKG) is monitored continuously and blood pressure is measured frequently to assess the cardiovascular response to exercise.
On the Treadmill
At Cooper Clinic we use a modified Balke treadmill protocol for the treadmill stress test. With this protocol, the treadmill speed remains at 3.3 mph. We increase the work of the heart by adding elevation.
- First minute—Zero percent elevation
- Second minute—Two percent elevation
- Third minute—Three percent elevation
After the second minute, we increase the elevation by one percent for each minute up to a maximal incline of 25 percent. As you can imagine, that is a pretty steep hill! For those few individuals who can exercise beyond 25 minutes, the incline stays at 25 percent and then the speed increases 0.2 mph/minute until exhaustion. We use this protocol rather than the Bruce protocol, which is used in most cardiology offices for the diagnosis of coronary blockages. Why? Because the Balke treadmill protocol has a more gradual increase in cardiac workload so that even our most unfit patients can participate to provide the data to write an exercise prescription.
How Performance Provides Results
Patients will often ask, ‘how long do I need to walk on the treadmill?’ In order to obtain an adequate test for the diagnosis of coronary blockages, a patient should reach a heart rate of at least 85 percent of their predicted maximal heart rate. The predicted maximal heart rate is estimated using the equation “220 minus age”. For example, if you are 50 years old, your predicted maximal heart rate is 220-50 or 170 beats per minute. However, we often exercise patients beyond this threshold value of 85 percent of predicted maximal heart rate because we stop the treadmill based on the patient’s exertion level rather than a predetermined heart rate. For many of our very fit patients, if we stopped the test when their heart rate reached 85 percent of their predicted maximal heart rate, we would have a result that didn’t reflect how hard they work when they exercise and we couldn’t create a realistic exercise prescription for them.
A recent study from Cooper Clinic involving 25,642 individuals followed for 7.2 years, showed that in addition to assessing changes on the EKG during a stress test, other non-EKG measures helped predict the risk of death from all causes or from cardiovascular disease. Including:
- Functional capacity (how long you exercised on the treadmill)
- Resting heart rate
- If the heart rate increased appropriately during exercise
- How fast the heart rate recovered after exercise
Unlike its use in other settings, the treadmill stress test at Cooper Clinic is used as an objective way to measure fitness. Sure, we can ask you how often you exercise; we can ask you how hard you work during exercise, but nothing provides a real measure of fitness like your performance on the treadmill.
In 1989, a landmark paper from The Cooper Institute 501(c)(3) nonprofit examined 10,224 men and 3,120 women who had undergone fitness (treadmill) testing. After a follow-up of slightly more than eight years, research showed the risk of death from any cause decreased as fitness increased in both men and women. In addition, cardiovascular and cancer death rates were lower among the higher fit individuals.
Since that time, numerous scientific publications from The Cooper Institute have demonstrated the benefits of being fit and the risks of being unfit:
- Men who maintained or improved their fitness were less likely to die from anything or from cardiovascular disease versus the unfit men who remained unfit over time.
- The health benefits of fitness include reduced risk for developing risk factors for heart disease including diabetes, high blood pressure and high cholesterol.
- The risk of low fitness approaches the risk of smoking.
- Being fit reduces the risk of stroke and depression.
- Being fit reduces the risk of dying from lung and gastrointestinal cancers.
Most recently, The Cooper Institute has shown that fitness at mid-life (average age in the upper 40s) impacts health—including the development of heart disease, stroke, diabetes mellitus, Alzheimer’s disease—and is a predictor of health care costs in later life. The average follow-up was between 24-26 years.
Given the proven health benefits of fitness, most experts recommend that a fitness evaluation should be part of routine preventive care as an independent “vital sign” that can be directly modified by routine physical activity. At Cooper Clinic, we do exactly that. Once we measure your fitness, we can use that information to create an individualized exercise prescription to improve your fitness or keep you fit.
To learn more about the treadmill stress test at Cooper Clinic, click here.