Exercise intensity self-regulation using the OMNI scale in children with cystic fibrosis

Prescribing exercise at intensities that improve fitness is difficult in children with cystic fibrosis (CF) due to ventilatory limitations and fluctuating health status. Our aim was to determine if children with CF could regulate the intensity of cycle ergometer and treadmill exercise using target ratings of perceived exertion (RPE) derived from the Children's OMNI Scale. We examined prescription congruence (similar oxygen consumption [VO₂] and heart rate [HR] for target RPE) and intensity discrimination (different VO₂ and HR for different RPEs), from cycle to cycle and cycle to treadmill. Subjects were 24 children (12 male, 12 female), aged 10-17 years with varying disease severity. Each child participated in one orientation, one estimation trial (graded maximal exercise test), and two production trials (cycle and treadmill, alternating between RPE 4 and 7). At RPE 4, congruence was evident for both VO₂ and HR on the treadmill. On the cycle at RPE 4, VO₂ was significantly higher only in the first production trial, although HRs tended to be higher in the production trials than the estimation trial. Prescription congruence was also supported at RPE 7, with no significant differences in VO₂ or HR between estimation and production trials on cycle or treadmill. Results fully supported intensity discrimination, with significant differences between VO₂ and HR at RPE 4 and 7 (P < 0.0001). Children with CF appear capable of using the OMNI Scale to regulate cycle and treadmill exercise intensity. Training using this methodology has the potential to promote fitness in children with CF of varying severity.