Maximal cardiopulmonary exercise testing (CPET) involves a person exercising up to the point when they can no longer continue, whilst monitoring heart and lung function. We wanted to determine if this is a reliable assessment tool in young patients with CF.
Why is this important?
CPET is considered the ‘gold-standard’ test to measure the fitness of patients with mild-to-moderate CF. The maximum rate of oxygen that a person consumes is particularly important, since it has been shown to relate to better health. Although the European CF Society recently promoted CPET as the exercise test of choice where possible, very few UK clinics use it.
What did you do?
The CPET involved a cycling test, which was increasingly difficult until the patient said they could not continue. Our earlier work investigated how well this exercise test worked in determining maximum exercise. This study determined how much variability there was for the same people in a short period of time. Thirteen patients, aged 7-18, completed three CPETs. After the first CPET, subsequent testing took place at 48 hours and 4-6 weeks.
What did you find?
The main finding of this study was that CPET was reliable over the short- and medium-term. The present study demonstrates that CPET is an acceptable test for use in clinical practice when monitoring fitness.
What does this mean and reasons for caution?
This is the first study to provide the CPET outcomes which can be used to check disease progression, the effect of therapeutic interventions, and decide ‘meaningful’ clinical changes in young people with CF. Knowing the reliability of a test is crucial when evaluating the effectiveness of treatment, which may accrue over weeks or months. The present study provides a reliable CPET protocol and establishes the methods for clinicians to plan clinical trials that use aerobic fitness as an outcome measure. Of course, this study shows the reliability under our expert care, and other teams need to develop their own reliability.
We plan to complete a series of studies examining CPET and assessing the effectiveness of exercise training in clinical studies. We would be interested in hearing of young patients’ experiences of exercise and sports training.