Abstract
Cough is typically associated with physical activity in children with asthma, but the characteristics of the relationship between cough and exercise has not been established under physiological conditions. The aim of the study was to describe the effect of exercise on the reflex cough response elicited by a single breath of capsaicin in non-asthmatic children. A group of non-asthmatic adults was studied as reference. Thirty children and 29 adults were recruited. The cough reflex sensitivity to capsaicin was first determined to establish the dose that provokes 5 cough efforts (C5). The number of coughs elicited by C5 (NC5) was then compared at baseline and during a standardized submaximal treadmill exercise. Data are expressed as median (interquartile range). Children and adults showed a significant decrease in NC5 (respectively from 5.0 (4.0–6.0) to 2.5 (2.0–4.0), p < 0.0005 and from 6.0 (5.0–7.0) to 2.0 (0.0–3.0, p < 0.0005). During exercise, NC5 was observed to decrease in all adult subjects, but in only 24/30 children (80%, p = 0.02). A trend for a higher incidence of personal and familial atopy was observed in children that lacked cough down-regulation during exercise compared with other children. It is concluded that the cough reflex response to capsaicin is down regulated by exercise in both children and adults. The effect however is less consistently observed in the former. The difference may reflect maturation of descending inhibitory pathways of the cough reflex, but may also be associated to atopy. The data stress the importance of assessing the time relationship of cough and exercise in questionnaire studies of asthma.
Highlights
In children with respiratory disease, perception of dyspnoea may be difficult to estimate (Schweitzer and Marchal, 2009), wheeze may be missed, but cough appears at first hand identifiable from parental report
It is important to establish the characteristics of cough during exercise in children because the cough reflex changes during growth and important differences have been shown between children and adults (Chang, 2005, 2010)
The median capsaicin concentration that provoked at least 5 coughs during capsaicin challenge (C5) was 39.1 μmol/l (IQR: 9.8–156.3 μmol/l) in children and 23.4 μmol/l (IQR: 11.7–125.0 μmol/l; p = 0.4) in adults
Summary
In children with respiratory disease, perception of dyspnoea may be difficult to estimate (Schweitzer and Marchal, 2009), wheeze may be missed, but cough appears at first hand identifiable from parental report. Diagnostic of the respiratory condition may benefit identification of a particular trigger such as exercise that is sought by cough questionnaire studies (Suguikawa et al, 2009; Cichalewski et al, 2015; Boulet et al, 2017). It appears important to determine whether cough is down-regulated during exercise in childhood, especially in view of the fact that children spend much time of their every-day life in physical activities
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
