The study, “Sit-to-stand test in children with bronchiectasis: Does it measure functional exercise capacity?,” was published in the journal Heart & Lung.
Bronchiectasis causes respiratory symptoms that affect a person’s capacity for exercise.
Though tests of lung capacity may be helpful, limitations in exercise ability can be caused by a number of factors and may not be predicted by lung capacity alone.
Exercise capacity is best measured by having the patient perform a specific activities. Some involve the use of an exercise bike or treadmill, but others target sub-maximal activities to account for respiratory impairment.
The six-minute walk test, which records the distance that a patient can walk in that time, is a common sub-maximal exercise test. It can be used to evaluate exercise capacity in people with cardiopulmonary disorders, and has shown reliability with bronchiectasis patients as well.
Although no special equipment is required, this walk test does need a large open space — about 30 meters or 100 feet — in total, and testing time is often more than 10 minutes to allow for a pre- and post-test rest.
Clinicians, for these reasons, have begun using another sub-maximal and self-paced exercise capacity test, called the sit-to-stand test, as a time- and space-saving alternative for patients with respiratory conditions.
During the sit-to-stand test, a patient will be seated on a standard chair with no armrests, and asked to stand up and sit back down repeatedly over the course of either 30 seconds or one minute. Clinical assessments of exercise capacity can be made from the number of stands during tests of either time length.
Research has shown that he sit-to-stand test correlates well with the six-minute walk test in evaluating patients with respiratory conditions. But most studies have been conducted in adults with chronic obstructive pulmonary disease (COPD), and not in children.
Researchers in Turkey addressed this gap in children with bronchiectasis. They recruited 60 patients (age range 6-18) and 20 healthy, age-matched controls. To allow for broader representation of bronchiectasis severity, no clinical criterion of lung capacity was used to determine eligibility.
Children were asked to complete both tests, choosing which to undergo first. A 30-minute rest interval was given to avoid fatigue. Before and after each test, the researchers measured participants’ heart rate, oxygen saturation in the blood (SpO2), and the level of labored breathing as assessed with the Modified Borg Scale.
Results showed that the two tests were highly correlated, meaning that someone who did better on one test would likely have done better on the other test.
Researchers also determined that, in the bronchiectasis group, lung function and performance were not significantly correlated on either test.
Both tests were able to discriminate between bronchiectasis patients and controls, with patients showing a significant reduction in exercise capacity based on a shorter distance in the walk test and fewer sits and stands.
“Parallel to findings obtained from COPD patients, children with BE [bronchiectasis] performed significantly lower sit-to-stand repetitions compared to healthy individuals (21.66 vs 26.55),” the researchers wrote.
Children with bronchiectasis had larger fluctuations in oxygen saturation than their healthy peers when comparing pre- and post-test measures. Heart rate and labored breathing levels were similar for both groups.
All of these fluctuations were greater during the walk test, indicating that the six-minute walk test is more physically demanding than the sit-to-stand test, which might be “safer to perform” for this reason.
“In conclusion, 30s-STST [30 second sit-to-stand test] is found to be a valid, space- and time-saving alternative measurement for functional exercise capacity in children with bronchiectasis,” the researchers wrote.
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