RESULTS
A total of 147 children and adolescents were recruited (healthy n = 48, asthmatic n = 48, and CF = 51). Table 1 presents the baseline characteristics of the study sample. Participants were homogeneous in age (11.8 ± 3.0 years) and sex distribution. As expected, there were significant differences between asthmatics and CF children when compared to their healthy peers for anthropometric and lung function measurements. Asthma and CF groups presented lower FEV1when compared to healthy controls, although there was no difference between asthmatics and CF patients in lung function.
As for cardiorespiratory fitness, significant differences were found for both VO2peak (F(2,144)=16.992,p <0.0001) and BR (F(2,144)=12.067,p <0.0001) (Figure 1). Asthmatics showed lower VO2peak when compared to both healthy and CF subjects. On the other hand, no differences in VO2peak between healthy and CF patients were described. Although patients with CF had no decrease in VO2peak, a lower BR was found when compared to both healthy and asthmatic groups. Comparison between asthmatic and healthy children revealed no differences in the BR (Figure 1).
The main cardiopulmonary exercise testing variables at VT1 and peak exercise are presented in Table 2. Significant differences between groups were observed for both VE/VO2 (F(2,143)=15.384,p <0.0001) and VE/VCO2(F(2,143)=15.194, p <0.0001) at VT1 (Figure 2A and 2B). For the VE/VO2 at VT1, patients with CF reported the highest values when compared to both asthma and healthy individuals. In addition, asthmatic patients also presented higher VE/VO2 at VT1when compared to healthy subjects (Figure 2A). As for VE/VCO2 at VT1 both asthmatic and CF patients showed higher values when compared to healthy participants, while no differences between asthma and CF groups were revealed (Figure 2B). There were also differences for both VE/VO2 (F(2,139)=7.895,p =0.001) and VE/VCO2(F(2,144)=6.802, p =0.002) at peak exercise, indicating that CF patients presented higher values for both variables when compared to healthy individuals (Figures 2C and 2D).