Down-Regulation of Cough during Exercise Is Less Frequent in Healthy Children than Adults. Role of the Development and/or Atopy?

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.

Effect of Capsaicin Atomization–Induced Cough on Sputum Excretion in Tracheotomized Patients After Hemorrhagic Stroke: A Randomized Controlled Trial

“…Capsaicin nebulization was used as an intervention method in our study and was shown to be more effective in removing sputum and preventing infection compared to conventional airway management procedures. Capsaicin nebulization-induced cough has been used in healthy adults, children, and the elderly (Brandimore et al, 2017;Demoulin-Alexikova et al, 2017), as well as in patients with pathological cough, hypertension, and cervical marrow injury. It has also been used to induce reflexive coughing in stroke patients (Hegland et al, 2016;Kulnik et al, 2015).…”

“…Capsaicin is a component extracted from cayenne pepper (Sharma et al, 2013), which is commonly used as a non-acid-tussive agent to experimentally induce cough (Morice et al, 2007). Capsaicin nebulization to induce cough has been used in healthy adults (Brandimore et al, 2017;Demoulin-Alexikova et al, 2017) and patients (Duricek et al, 2018;Ferenc et al, 2018). Similarly, citric acid, a representative of acid tussives, could also be used to stimulate cough .…”

Global Physiology and Pathophysiology of Cough

“…One study examined the capsaicin cough sensitivity and found that exercise reduced cough sensitivity in all healthy adults but only in approximately 80% of healthy children. 10 Although the reason for this difference is not known, a higher incidence of personal and familial atopy may be present in children who did not show a reduction in cough during exercise compared with children who did. 10 Another aspect in cough-specific physiological maturation influence is the age-and sex-related differences in cough sensitivity.…”

“…10 Although the reason for this difference is not known, a higher incidence of personal and familial atopy may be present in children who did not show a reduction in cough during exercise compared with children who did. 10 Another aspect in cough-specific physiological maturation influence is the age-and sex-related differences in cough sensitivity. In prepubertal children, cough sensitivity is similar in boys and girls and therefore not influenced by sex.…”

Desensitization of the Cough Reflex Induced by Corticosteroids in Ovalbumin-Sensitized Rabbits During Artificial Limb Exercise

“…The pathophysiology of cough during exercise remains unclear but undoubtedly involves numerous mechanisms suggesting that cough exhibits plasticity at both peripheral and central levels (Bonham et al, 2004;Widdicombe and Singh, 2006;Aggarwal et al, 2018). Previous studies have proven that CR is decreased during exercise in healthy subjects (Lavorini et al, 2010;Demoulin-Alexikova et al, 2017) as well as in animal models (Poussel et al, 2014), even the precise underlying mechanisms are still debated. In contrast, CR sensitivity during exercise was unchanged (i.e., lack of downregulation) in ovalbumin (OVA)-sensitized rabbits (eosinophilic bronchial inflammation mimicking classical asthmatic inflammation) (Tiotiu et al, 2017), suggesting the contribution of bronchial eosinophilic inflammation in the modulation of CR in asthmatics during exercise.…”