Asthma symptoms, mannitol reactivity and exercise-induced bronchoconstriction in adolescent swimmers versus tennis players

Abstract

Background: Strenuous physical activity at an elite level is associated with an increased risk for asthma and, in some sports, also prevalence of allergies. The aim of this study was to investigate the prevalence of asthma and allergy among elite swimmers and tennis players and compare airway hyperreactivity to mannitol and exercise.

Materials and methods: One hundred and one adolescent swimmers and 86 tennis players answered a questionnaire about respiratory symptoms and allergy and performed mannitol challenge and sport-specific exercise challenge. Atopy was assessed and fractional exhaled nitric oxide was measured. Mannitol positivity was defined as drop in FEV₁ ≥15% (ordinary criteria) and/or β₂-reversibility (≥15%) after provocation (extended criteria). A positive exercise test was defined as a drop in FEV₁ ≥10% (ordinary criteria) and/or β₂-reversibility (≥15%) after provocation (extended criteria). Club cell protein (CC16) was measured in urine before and after the challenges.

Results: Asthma symptoms were common in both groups. More swimmers had exercise-induced symptoms (77% versus 50%) and current asthma symptoms (56% versus 38%), compared to the tennis players. More swimmers also had a positive mannitol challenge test both using ordinary (26% versus 6%) and extended criteria (43% versus 17%), while the number of positive exercise tests did not differ. After exercise (but not mannitol) challenge, CC16 level was increased in both groups, but to a higher extent in tennis players. There were no differences in atopy, rhinitis or fractional exhaled nitric oxide.

Conclusion: We found a high prevalence of asthma among elite swimmers and tennis players and a higher frequency of current asthma and positive mannitol challenge tests among the swimmers. This indicates an unfavorable exercise environment.

Keywords: CC16 bronchial hyperreactivity; asthma; bronchial hyperreactivity test; exercise; mannitol; sport; swimming; tennis.

Figure 1

Respiratory symptoms in swimmers and tennis players in relation to a reference group. Notes: Asthma exacerbation was defined as emergency visit due to an asthma attack, not able to go to work or school due to asthma and/or substantial temporary change of medication due to deterioration in asthma. *p<0.05, **p<0.01, ***p<0.001. Abbreviation: AS, asthma symptoms.

Figure 2

Mannitol reactivity. Notes: Data presented are the number of swimmers and tennis players positive to mannitol provocation tests (ordinary criteria) grouped into mild (>155 mg), moderate (>35–≤155 mg) or severe (≤35 mg) airway HR. Abbreviation: HR, hyperreactivity.

Figure 3

Sensitivity and specificity of mannitol reactivity in relation to respiratory symptoms in swimmers (A, C, E, G) and tennis players (B, D, F, H). Notes: AS during the last 12 months. OC was defined as a drop in FEV₁ of ≥15%, compared to baseline. Reversibility was defined as an improvement of 15% after inhalation of 1 mg terbutaline, compared to the maximum fall in FEV₁. EC was defined as either a direct fall (OC) and/or a positive reversibility. Current AS (A, B)=report of symptoms such as wheezing and/or nocturnal symptoms without respiratory infection and/or asthma medication. Current AS exerc=wheezing, coughing and/or chest tightness adjacent to physical activity (C, D). Current AS allerg=wheezing, coughing and/or chest tightness adjacent to contact with airborne allergens (E, F). Exacerb=emergency room visits, sick leave due to asthma or periods with more accentuated symptoms that required an increase in medication (G, H). Abbreviations: AS, asthma symptoms; EC, extended criteria; OC, ordinary criteria.

Figure 4

Sensitivity and specificity of exercise challenge response in relation to respiratory symptoms in swimmers (A, C, E, G) and tennis players (B, D, F, H). Notes: AS during the last 12 months. OC was defined as a drop in FEV₁ of ≥15%, compared to baseline. Reversibility was defined as an improvement of 15% after inhalation of 1 mg terbutaline, compared to the maximum fall in FEV₁. EC was defined as either a direct fall (OC) and/or a positive reversibility. Current AS (A, B)=report of symptoms such as wheezing and/or nocturnal symptoms without respiratory infection and/or asthma medication. Current AS exerc=wheezing, coughing and/or chest tightness adjacent to physical activity (C, D). Current AS allerg=wheezing, coughing and/or chest tightness adjacent to contact with airborne allergens (E, F). Exacerb=emergency room visits, sick leave due to asthma or periods with more accentuated symptoms that required an increase in medication (G, H). Abbreviations: AS, asthma symptoms; EC, extended criteria; OC, ordinary criteria.

Figure 5

The relation between respiratory symptoms and positive provocation tests among swimmers and tennis players. Notes: AS were defined as asthma symptoms during the last 12 months. AHR was defined as any positive challenge test (ordinary criteria). Abbreviations: AHR, airway hyperreactivity; AS, asthma symptoms.

Figure 6

Urinary levels of CC16 in swimmers and tennis players before (pre) and 1 hour after (post) mannitol provocation and/or sport-specific exercise test. Note: Box plot with whiskers showing 5–95 percentile. **p<0.01, ***p<0.001.