Cardiopulmonary Exercise Testing in the Very Young (4–6 Years): Feasibility of Outdoor Testing

Objectives: Cardiopulmonary exercise testing (CPET) in very young children (4–6 years) is challenging. Due to anatomic limitations, bicycle testing is not feasible. Requirements for a representative treadmill test (TM) are good motor skills and a high motivation, often not attained in this age group. Most studies investigating CPET have therefore been limited to older children (>8 years of age). Since cardiorespiratory fitness decreases over time and physical activity has declined especially in children over the last few years, better knowledge of these parameters in the very young is essential. This study strives to compare a standard indoor TM test with an outdoor incremental running test using a mobile CPET device.

Methods: A group of seven 4- to 6-year old healthy children was tested indoors using the modified Bruce protocol endorsed by the DGPK. The results were compared with a self-paced incremental running test, using a mobile CPET device in an outdoor park. The each step was 2-minute long. The first step involved walking at a normal pace, then slow running, motivated running in the third step, and then the highest possible speed in the last step as long as possible.

Result: The children were able to reach significantly higher values for most of the cardiopulmonary exercise variables during the outdoor test. Whereas six out of seven children did not reach a VT2 indoors, all of them reached a VT2 outdoors. One boy reached VT2 indoors due to exceptional motivation and was able to reach a true VO2max outdoors. The exercise time was significantly shorter outdoors compared with indoors (07:09 vs. 12:43 minutes). Still, mean VO2peak (out 51.71 ± 7.54/in 43.14 ± 8.07 mL/min/kg), mean peak velocity (out 7.98 ± 1.80/in 5.67 ± 0.68 km/h), mean RER (out 1.11 ± 0.04/in 0.97 ± 0.09), mean VEmax (out 39.66 ± 8.88/in 30.94 ± 10.00 L/min), and mean breath rate (out 69.14 ± 5.27/in 59.57 ± 8.36/min) were significantly higher when tested in the park. The heart rate, the O2pulse and the OUES were comparable between both tests.

Conclusion: Testing very young children outdoors by using a mobile CPET unit is a new alternative to standard exercise testing. With a significantly shorter test duration, significantly higher values for above listed cardiopulmonary variables were achieved, indicating a better cardiopulmonary workout. This allows for individualized exercise testing aiming for standardized test durations instead of standardized test protocols. The outdoor running speeds may be used to develop age-adapted test protocols for TM testing.

Publication History

Article published online:
21 February 2021