Table 2.
Median pre-exercise breath pH values for selected sample characteristics (n = 144 observations from 16 subjects).
| Variable | Obs (n) | Median (IQR) (p value)† |
| Age, yr | ||
| 14 | 59 | 7.56 (7.05–7.87) |
| 15 | 59 | 7.70 (7.34–7.86) |
| 16–17 | 26 | 7.22 (5.12–7.58) |
| (0.01) | ||
| BMI, kg/m2 | ||
| <20 | 90 | 7.68 (7.06–7.87) |
| ≥20 | 54 | 7.41 (6.05–7.77) |
| (0.17) | ||
| Sex | ||
| Male | 86 | 7.58 (7.05–7.85) |
| Female | 58 | 7.56 (6.37–7.86) |
| (0.71) | ||
| Race | ||
| White | 103 | 7.60 (7.10–7.87) |
| Nonwhite | 41 | 7.44 (5.49–7.78) |
| (0.13) | ||
| Asthma | ||
| Yes | 13 | 7.41 (5.00–7.51) |
| No | 131 | 7.60 (7.05–7.86) |
| (0.10) | ||
| Allergy | ||
| Yes | 40 | 7.51 (7.27–7.82) |
| No | 104 | 7.60 (6.01–7.86) |
| (0.20) | ||
| Wheeze or cough in past month | ||
| Yes | 33 | 7.51 (7.25–7.78) |
| No | 111 | 7.59 (6.37–7.86) |
| (0.68) | ||
| Number of symptoms in past 24 hours* | ||
| 0 | 116 | 7.55 (6.83–7.86) |
| 1 | 22 | 7.68 (5.96–7.87) |
| 2 or more | 6 | 7.57 (7.27–7.66) |
| (0.58) | ||
| Home ETS exposure | ||
| Yes | 20 | 7.06 (4.99–7.74) |
| No | 124 | 7.60 (7.10–7.86) |
| (0.009) | ||
| Running style | ||
| Sprinter | 21 | 6.05 (5.12–7.59) |
| Distance | 123 | 7.64 (7.10–7.86) |
| (0.0004) |
* Symptoms included wheeze, cough, scratchy or itchy throat, runny nose, sneezing, and watery eyes.
IQR = interquartile range.
† Nonparametric Wilcoxon rank-sum tests used to examine differences in raw breath pH between groups.