Parasympathetic Activity and Bronchial Hyperresponsiveness in Athletes.
PURPOSE: High prevalence of asthma and bronchial hyperresponsiveness (BHR) are reported in swimmers and cross-country skiers. It has been suggested that increased parasympathetic nervous activity is involved in asthma development in endurance athletes. We aimed to assess the associations of BHR to parasympathetic activity in healthy and asthmatic swimmers and cross-country skiers, and healthy non-athletes.
METHODS: Parasympathetic activity was measured by pupillometry and heart rate variability (HRV) at the onset of exercise with the cardiac vagal index (CVI) calculated, in 28 cross-country skiers ([male sign]18/[female sign]10), 29 swimmers ([male sign]17/[female sign]12), and 30 healthy non-athletes controls ([male sign]14/[female sign]16) on two different days. All subjects performed a methacholine bronchial challenge with the provocation dose causing 20% decrease in the forced expiratory volume in one second (FEV1) calculated (PD20met). Data were analyzed by robust regression analysis and presented as [beta]-coefficients with 95% confidence intervals.
RESULTS: PD20met was negatively associated to CVI (-13.9 [-26.8, -1.0]) in all subjects. When adjusted to type of sport, this association was stronger in swimmers (-8.3 [-13.0, -3.6]) as compared to controls, and non-significant in cross-country skiers. Percent pupil constriction was significantly associated to PD20met in swimmers (-9.4 [-15.4, -3.4]) only after adjusting for type of sport. Fourteen swimmers (48%) and 16 cross-country skiers (57%) had doctor's diagnosed asthma in combination with current BHR and/or current use of asthma drugs. Seventy-two percent swimmers, 44% cross-country skiers and 39% controls had a PD20met <=8 [mu]mol (p=0.015). Fourteen swimmers had a PD20met <=2 [mu]mol as compared to one cross-country skier (p<0.001).
CONCLUSION: Parasympathetic activity measured in the heart is more closely related to BHR as compared to parasympathetic activity measured in the pupils. Type of sport influences BHR severity and its relationship to parasympathetic activity.
(C) 2016 American College of Sports Medicine
Autor / Fonte:Julie Stang, Trine Stensrud, Petter Mowinckel, Kai-Hakon Carlsen Medicine and Science in Sports and Exercise 2016 June 9