Effects of Inspiratory Muscle Training on Heart Rate Variability in Children with Cystic Fibrosis: A Pilot Study

Abstract

Abstract Purpose Cystic Fibrosis (CF) is a multisystem disease associated with symptoms such as dyspnoea, tachycardia and tachypnea that may be related to changes in autonomic function and sensitive to improvement following inspiratory muscle training (IMT). The aim of the present study was to investigate the effect of IMT on heart rate variability (HRV) and respiratory function in children. Methods Five CF and five matched controls (40% boys) performed a 4-weeks IMT programme, involving 30 breaths, twice a day. Weeks 1–2 of training were set at 40% of a participant’s maximal strength index (S.Index), with week’s 3–4 set at 50%. Participants wore an ActiHeart for three consecutive days at baseline and post-intervention and indices of HRV were derived. Standard measures of lung function were obtained along with health-related quality of life (HRQoL) using the CF-specific questionnaire (CFQ-R). Results IMT elicited clinically meaningful increases in respiratory muscle strength and respiratory symptom domain scores, but no improvements in respiratory volume, irrespective of group. Similarly, no significant improvements were found in HRQoL despite 62.5% of the population increased their HRQoL score. Post-intervention, CF participants showed a clinically meaningful decrease in the very low frequency (VLF) domain. Conclusion These results may indicate clinically meaningful changes in HRV and inspiratory muscle strength following a 4-week IMT intervention, although a more powerful study is required to draw further conclusions. Indeed, the trends for improved HRQoL support the need for such studies to ascertain the potential therapeutic role of IMT in those with CF.