[Comparative study of the pulmonary function equipment and Douglas-bag in the energy consumption measurement of Chinese healthy youth].

Objective: To determine the validity of the pulmonary function equipment.
Methods: 12 young students (including six males and six females) were enrolled as our research subjects. And the values of oxygen consumption (VO(2)), carbon dioxide production (VCO(2)) and energy expenditures (EE) of the subjects under three typical activity intensities: resting, moderate intensity (on a treadmill with grade 10% and speed 2.7 km/h) and hard intensity (on a treadmill with grade 10% and speed 5.8 km/h) were measured using the pulmonary function equipment (K4b(2)) and Douglas-bag respectively. And the Douglas-bag method was used as reference and the results were compared with the other method.
Results: The measured VO(2) values by using the Douglas-bag and the pulmonary function equipment under three typical activity intensities were: at rest (0.22 ± 0.03), (0.22 ± 0.05) L/min (t = 0.120, P > 0.05); moderate intensity condition (0.95 ± 0.12), (0.96 ± 0.14) L/min (t = 0.240, P > 0.05); hard intensity condition (1.63 ± 0.28), (1.54 ± 0.35) L/min (t = 1.487, P > 0.05). For VCO(2) values: at rest (0.18 ± 0.02), (0.18 ± 0.04) L/min (t = 0.425, P > 0.05); moderate intensity (0.82 ± 0.11), (0.83 ± 0.13) L/min (t = 0.579, P > 0.05); hard intensity (1.64 ± 0.27), (1.52 ± 0.39) L/min (t = 2.330, P < 0.05). And for EE values, at rest (269.40 ± 35.70), (267.02 ± 55.39) kJ/h (t = 0.200, P > 0.05); moderate intensity (1165.76 ± 148.06), (1185.91 ± 161.89) kJ/h (t = 0.326, P > 0.05); hard intensity (2062.91 ± 341.97), (1912.27 ± 483.88) kJ/h (t = 1.718, P > 0.05) respectively. The results showed that there were no significant differences between the two methods except the VCO(2) values under high intensity condition was underestimated by the pulmonary function equipment. Bland-Altman test showed that the difference of the two methods was evenly distributed by the mean and standard error of the system was 24.7 kJ/h. Our data showed the results from the Douglas-bag and the pulmonary function equipment were consistent.
Conclusion: Pulmonary function equipment had good validity in assessing the energy expenditure in Chinese adults.