Objectives: Cardiopulmonary exercise testing in young children or children with limited cardiopulmonary capacity represents an exceptional challenge. Both test modalities, the bicycle (CE), as well as the treadmill (TM), face problems due to insufficient muscular development in the knee extensors, limited motivation and difficult size adaptation of the test equipment. Based on the wide range of problems to effectively perform cardiopulmonary testing in young children, this study strives to develop a new cardiopulmonary exercise test for children using a mobile testing device worn in a backpack to test children during their natural movement habits, namely, running in the park.
Methods: A standard cardiopulmonary exercise ramp test on a stationary bicycle was performed by a group of 20 7- to 10-year-old children. The results were compared with an incremental step test performed using the same mobile cardiopulmonary exercise measuring device as during the bicycle test but in an outdoor park. The children were instructed to run four steps of 2-minute lengths. The first step consisted of slow walking, the second of slow running and then faster running, finishing with maximal running. An age-adapted picture scale was used to simplify the four speeds and an experienced researcher accompanied each test.
Result: The children were able to reach significantly higher values for almost all cardiopulmonary exercise variables during the outdoor test. Whereas a true VO2 max was reached by 25% of the children during the outdoor test, only 75% were able to reach a reasonable VT2 during the bicycle test. The heart rate at VT1, the O2pulse, and the OUES (oxygen uptake efficiency slope) were comparable between both tests. OUES was also positively correlated with VO2 peak in both tests.
Conclusion: Testing children outdoors using a mobile cardiopulmonary exercise unit represents an alternative to standard exercise testing but with a higher probability of achieving maximum exertion in contrast to CE testing. The development of test protocols for TM testing with comparable test lengths instead of comparable test profiles might allow for a better comparability of cardiopulmonary exercise parameters.
