Lung function and cytokine levels in professional athletes

Abstract

Objective: Previous studies have demonstrated that exercise-induced asthma and bronchial hyperresponsiveness commonly occur in athletes. The present study investigates pulmonary function and cytokine levels in professional athletes to explore the impact of various sports on respiratory system function and to evaluate the possible role of systemic anaphylaxis.

Methods: Lung function was measured at rest in professional athletes without a history of smoking. Athletes were recruited from 10 different sports including swimming, water ballet, shooting, volleyball, softball, football, kickboxing, fencing, judo, and track and field. Measurements included forced vital capacity (FVC), forced expiratory volume in one second (FEV(1)), vital capacity (VC), peak expiratory flow (PEF), maximal mid-expiratory flow curve (MMEF), and forced expiratory flow rate (FEF(25-75)%). In addition, the medical history of all athletes was recorded. Correlations between lung function measurements and the different sports, age, gender, height and weight were analyzed. In some athletes, serum was sampled to detect IL-4 and IL-10 concentrations. In these subjects, the correlation between pulmonary function and cytokine levels was analyzed.

Results: A total of 147 professional athletes and 30 healthy volunteers were enrolled in the study. Allergic rhinitis and asthma were detected only in swimmers with an incidence of 56.52% (13/23) and 8.70% (2/23), respectively. Lung function measures were significantly correlated with sport, age, gender, height, and weight. Ventilation functions (including FVC, FEV(1), FEV(1)/FVC, and MMV) in male athletes were superior to those in females, and the ventilation functions in swimmers were superior to those in others. However, the small airway functions (MMEF, FEF(50), FEF(75)) in swimmers and in track and field athletes were lower than predicted (swimmers: 72%, 70%, and 78%, respectively; track and field athletes: 79%, 75%, and 99%, respectively). Serum analyses for IL-4 and IL-10 revealed that IL-4 concentrations were higher in swimmers 69.34 +/- 22.4 pg/mL relative to non-swimmers (p = 0.000). By contrast IL-10 concentrations were lower in swimmers 34.94 +/- 9.71 pg/mL than that in the static group (44.69 +/- 16.32 pg/mL; p = 0.027). IL-4 levels were negatively correlated with FEV(1)%, FEF(25)%, FEF(50)%, and MMEF%. By contrast, IL-10 levels were not correlated with any of these measures.

Conclusions: The lung function measurements were correlated with sport, age, gender, height, and weight in the various athletes. The lung capacity of swimmers was greater than that of other athletes. Small airway dysfunction was observed in some swimmers and endurance athletes. We observed an association between systemic anaphylaxis and small airway dysfunction after prolonged regular training, particularly following swimming and endurance training.