Influence of sympatho-vagal balance on airway responsiveness in athletes |
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Authors: | Jean-Bruno Langdeau Hélène Turcotte Pierre Desgagné Jean Jobin Louis-Philippe Boulet |
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Institution: | Centre de Recherche de l'H?pital Laval, Institut Universitaire de Cardiologie et de Pneumologie, Université Laval, Sainte-Foy, Québec, Canada, CA H?pital Laval, 2725, Chemin Sainte-Foy, Sainte-Foy, Québec, Canada, GlV 4G5 e-mail: lpboulet@med.ulaval.ca Tel.: +1-418-6564747; Fax: +1-418-6564762, CA
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Abstract: | The increased prevalence of airway hyper-responsiveness (AHR) observed among athletes suggests that high-level training may
contribute to the development of AHR. We investigated the possible influence of the sympatho-vagal balance on this phenomenon
in 40 athletes and 10 sedentary controls. Each subject filled out a respiratory questionnaire, had a methacholine challenge,
and measurements were made of their baseline plasma catecholamines epinephrine (E), norepinephrine (NE) and dopamine (DA)]
as a reflection of sympathetic tone, and their heart rate variability (SDNN: standard deviation of all normal-to-normal intervals)
as an indicator of parasympathetic tone. The athletes had a 45% prevalence of AHR (defined as PC20 < 16 mg/ml, where PC20 is the concentration of methacholine inducing a 20% fall in the forced expiratory volume in 1 s, FEV1) with a mean PC20 of 21.2 mg/ml compared with 10% prevalence (mean PC20: 74.4 mg/ml) in sedentary subjects (P < 0.01). Plasma catecholamine values were not significantly different between the two groups (all P > 0.05), but the estimated parasympathetic tone was higher in athletes (P=0.01). When data from all subjects were analyzed together, plasma E and NE correlated with PC20 (r=0.39, P=0.005 and r=0.29, P < 0.005) but DA and SDNN did not (both P > 0.05). However, the ratios E/SDNN, NE/SDNN and DA/SDNN showed significant correlations with PC20 (r=0.42, P < 0.01; r=0.33, P < 0.005 and r=0.31, P < 0.05, respectively). This study suggests that the sympatho-vagal balance may contribute to the increased AHR in the population
studied but this influence alone cannot explain the higher prevalence of AHR in athletes.
Accepted: 26 July 2000 |
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Keywords: | Airway hyper-responsiveness Athletes Plasma catecholamines Parasympathetic tone |
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