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

Figures & data

Table 1 Study population

	Reference group, n=1626		Swimmers, n=101		Tennis players, n=86		p-value*
	n	%	n	%	n	%
Male/female	828/798	51/49	55/46	55/46	54/32	63/37	N.S.
Age, yearsa	16	15–17	16	14–17	16	15–18	N.S.
Training >6 years	514	31.6	88	87.1	75	87.2	N.S.
Weekly training, hoursa	4	0–7	18	15–20	12	11–15	<0.0001
Doctor-diagnosed asthma	275	16.9	37	36.6	21	25.0	0.089
Any asthma medication	205	12.6	31	30.7	18	21.4	N.S.
Regular inhalation of corticosteroids	79	4.9	17	16.8	5	6.0	0.023
Eczema ever	678	41.7	57	56.4	28	33.3	0.002
FVC, % predicteda	n.a.	n.a.	116	109–122	105	96–111	<0.0001
FEV1, % predicteda	n.a.	n.a.	112	104–118	104	96–112	<0.0001
Atopy (positive skin prick test)	n.a.	n.a.	54	53.5	38	46.9	N.S.
FENO, ppba	n.a.	n.a.	13	9–18	14	11–18	N.S
FENO ≥20 ppb	n.a.	n.a.	21	20.8	15	18.5	N.S.

Notes: Descriptive data from elite aspiring swimmers and tennis players.

* p=statistical significance between swimmers and tennis players with Pearson’s chi-square test.

a Median and IQR.

Abbreviations: F_ENO, fractional exhaled nitric oxide; FVC, forced vital capacity; IQR, interquartile range; n.a., not applicable; N.S., not significant.

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.

Table 2 Results from mannitol challenge and field exercise challenge in swimmers versus tennis players

	Swimmers, n=101		Tennis players, n=86		p-value*
	n	%	n	%
Positive mannitol challenge ordinary criteria	26/101	25.7	5/79	6.3	0.001
Positive mannitol challenge extended criteria	43/101	42.6	12/79	15.2	<0.0001
Positive exercise challenge ordinary criteria	14/97	14.4	16/67	23.9	N.S.
Positive exercise challenge extended criteria	24/97	24.7	19/67	28.4	N.S.
Positive reversibility in any test	47/101	46.5	21/86	25.0	0.002
Any positive provocation test ordinary criteria	33/101	32.7	20/86	23.3	N.S
Any positive provocation test extended criteria	51/101	50.5	26/86	30.2	0.005

Notes:

* Statistical comparison between the two groups was conducted using Pearson’s chi-square test. n=number of subjects with positive tests/total number of subjects who have undergone the tests. Positive mannitol challenge ordinary criteria defined as a drop in FEV₁ ≥15%, compared to baseline. Positive exercise challenge ordinary criteria defined as a drop in FEV₁ ≥10% from the baseline. Positive reversibility defined as an improvement of 15% after terbutaline inhalation, compared to maximum fall in FEV₁. Positive mannitol challenge extended criteria defined as either a direct fall (ordinary criteria) and/or a positive reversibility. Positive exercise challenge extended criteria defined as either a direct fall (ordinary criteria) and/or a positive reversibility.

Abbreviation: N.S., not significant.

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.