A stress test is a very useful diagnostic and prognostic tool in Cardiology. The purpose of this test is to assess a patient’s risk on exertion. However, there are other types of more complete stress tests that allow the analysis of exercise capacity and pulmonary pathologies.
How do we perform it?
Once the type of stress test to be performed has been decided, the sensors are placed on the patient and we start by measuring the resting time to know the patient’s baseline condition.
Then we will ask the patient to get on the treadmill or exercise bike to start the exercise protocol, which will gradually and progressively increase the effort load.
The stress test must be designed specifically for each patient, to reach a maximum effort after at least 8 minutes, and not to last longer than 12 minutes, because otherwise resistance, not effort, would be assessed.
Treadmill or exercise bike?
It is essential to adjust and adapt the protocol to each patient, since not all of us have the same capacity for effort.
For this reason, it is important to have different exercise modalities. In our practice, Cardio 2 MAX, we have the treadmill and the cycloergometer or exercise bike.
The treadmill is useful for walking protocols with or without ramp, indicated for active patients, or for running protocols (with little ramp for regular runners) or with some ramp for mountain runners or elite athletes.
On the other hand, the cycloergometer is used in sedentary patients with little habit of exertion and in athletes whose sport is cycling. The cycloergometer has the advantage that the patient is always in control of the effort, which generates less anxiety. However, the treadmill accelerates gradually, requiring the patient to maintain the pace.
Types of stress test
- Conventional stress test or Ergometry
- Cardiopulmonary stress test or Ergospirometry, also called gas stress test or oxygen consumption test (VO2Max).
- Oxygen consumption test or VO2 Max
What are the differences between the different tests?
- Conventional stress test: the patient is monitored with a continuous electrocardiogram and serial blood pressure measurements are taken. This test is useful above all for assessing cardiovascular risk, being able to detect problems such as arrhythmias, ischemic heart disease, pathological responses of blood pressure to exertion, as well as to estimate the exertional capacity of each person. The conventional stress test is used for diagnosis and prognosis.
- Cardiopulmonary stress test: the patient is monitored in the same way as in the conventional stress test, but this time we must add a mask to measure the volume of each breath of the patient. In this way, samples are taken to determine how much oxygen is consumed and how much CO2 is produced during each moment of exertion to detect pulmonary causes of exertion problems, such as exertion-induced asthma. In addition, oxygen consumption provides a more accurate measure of exertional capacity, known as VO2 Max.
- Oxygen consumption test or VO2 Max: this is a simpler test oriented to measure sport capacities. In this case, risk cannot be assessed, because neither blood pressure nor electrocardiogram is monitored. For this reason, it is only indicated for patients without risk or regular athletes. To perform this test, a heart rate monitor and the mask are used. In this way, we will be able to know our maximum effort capacity, our training zones by heart rate, our FAT Max zone.