Measuring heart performance under stress: the many values of the cardiopulmonary exercise test

The cardiopulmonary exercise test (or CPET in short) is a stress test included in the "second level" cardiac exams to check, in  both competitive and non-competitive athletes, young and master (over 40) ones alike, their exercise stress tolerance. However, this test is also performed to assess cardiac health, as well as to prevent and monitor the onset of cardiovascular diseases.

The CPET allows monitoring the state of the heart under physical stress. The system includes an electrocardiogram to monitor the heart and the use of fitness machinery with which to perform said physical exercise. The latter usually is either a treadmill or an indoor bike.

This test, also known as the graded exercise test (or GXT), is able to examine the reactions of the cardiovascular system during physical exercise and to highlight any changes that are not found at rest.

To guarantee both the sport medicine doctor and the athlete or patient an efficient cardiopulmonary exercise test, Technogym offers Run and Bike Med, two products from the larger Medical line. Both Run and Bike Med can interact with the commonest electrocardiograms on the market, through the following communication protocols: Trackmaster, Ergoline and C-Safe.

After connecting to the medical device, the practitioner can control both devices through the electrocardiogram reading program, adjusting the speed and inclination of the treadmill, or the gradual resistance of the bike. At the same time, both Run and Bike Med allow for the creation of pre-set protocols, with which the levels of resistance, speed and inclination increase gradually.

Analysing the cardiopulmonary exercise test

The CPET, as already said, is an examination frequently carried out in sports medicine as a "second level" examination. In fact, a normal exercise test, usually performed at rest, is not the ideal system for detecting any latent coronary artery disease, ischaemic heart disease or even obvious or latent arrhythmias, which could also involve major risks for sportsmen and ordinary people alike.

Exercise tests are continued until the maximum theoretical heart rate is reached. In addition to the electrocardiogram - carried out with adhesive electrodes placed on the chest - blood pressure is also recorded at certain intervals.

Thanks to the cardiopulmonary exercise test, the effort required of the patient leads to an increase in heart rate and blood pressure, and consequently to an increased demand for blood from the heart.

How to perform a cardiopulmonary exercise test

There are two cardiopulmonary exercise test protocols: incremental (step) protocol and constant (ramp) protocol. In the incremental "step" protocol, the workload increase is distributed in intervals, usually every minute. In the incremental "ramp" protocol, the amount of workload increase established per minute is "diluted" gradually -Watt per Watt in the case of the indoor bike - during each interval.

In both protocols, a warm-up phase is followed by the actual training phase, in which the resistance (in the case of the bike) or the inclination and speed (in the case of the treadmill) is increased at regular intervals of time. The protocol ends when a certain heart rate is reached or when the patient is unable to continue the exercise.

In both cases, data on heart rate, blood pressure and changes in the electrocardiogram are collected. The test ends with a recovery phase, in which the patient ends the exercise with low or zero-load exercises. Biometric data are associated with the patient's responses during the exercise, to determine the presence or to monitor existing cardiovascular diseases.

Why is the cardiopulmonary exercise test useful?

The cardiopulmonary exercise test is recommended for all athletes, with particular reference to athletes over 40 that do not present risk factors or with low risk and, regardless of gender and age, to agonists with intermediate or high cardiovascular risk factors. The CPET allows assessing possible disorders, as well as changes in the electrocardiogram of the patient while under stress.

This test is also indicated for subjects potentially affected by ischaemic heart disease, providing information on the blood flow through the coronary arteries, reducing the risk of coronary atherosclerosis.

Coronary atherosclerosis involves the accumulation of plaques inside the walls of the arteries. It is not a disease to be brushed off easily, because it is the main cause of ischaemic heart disease, and it can even cause strokes and heart attacks.

In practice, this heart disease reduces the blood supply in a body district, causing a decrease in the supply of oxygen and other nutrients and in the ability to eliminate waste substances.

For this reason, CPET is of fundamental importance: first, to detect the presence of atherosclerotic diseases and second, to monitor the physical condition of individuals affected by these diseases.

When to use and not to use the CPET

During his sporting activity, an athlete may face different cardiac risks depending on his age. Generally speaking, after the age of 40, the risk of coronary atherosclerotic diseases and ischaemic heart disease increases. Therefore, performing a cardiopulmonary exercise test is extremely effective for the detection of diseases at risk, which would not be evident with normal tests at rest.

However, the cardiopulmonary exercise test is not indicated in all conditions. If the patient shows severe cardiovascular instability, respiratory failures, episodes of embolism or recent heart attacks, it is not recommended to use CPET in favour of other tests, such as ECG at rest.