During the exercise test (see above), expiratory flow limitation was assessed as previously described. Spontaneous tidal flowvolume loops were collected and followed by a maximal inspiratory capacity maneuver twice during the eighth, 10th, 12th, and 14th min of the exercise test (SensorMedics; Yorba Linda, CA) [Fig 1]. When > 30% of the tidal volume was expiratory flow-limited (ie, the expiratory part of the spontaneous exercise tidal flow-volume loops met the boundaries of the maximal flow-volume envelope collected immediately at the end of exercise), the subject was considered as having expiratory airflow limitation during intense exercise (ie, a positive diagnosis of VL [VL+]).
Statistical Analysis
Results are expressed as the mean ± SD. For continuous variables, comparisons between the control and athlete groups were performed using either analysis of variance with unpaired t test or Kruskal-Wa]]is test with Mann-Whitney U test. The differences in atopy, BHR diagnosis, and VL between groups were assessed by x2 test with Fisher two-tailed exact test. Correlations were assessed by calculation of Spearman correlation coefficients. A value of p < 0.05 was considered to be statistically significant.
Results
Skiers and triathletes showed similar ages, competitive experience, spirometric values, and number of self-reported symptoms (p > 0.05). The prevalence of BHR (skiers, 41%; triathletes, 40%), airflow limitation Canadian Health Care Mall during exercise (skiers, 24%; triathletes, 10%), and airway inflammation characteristics were not significantly different between each type of athlete (p > 0.05). Hence, skier and triathlete results were combined.
BHR
Mean values for heart rate and ventilation output during the last 5 min of the exercise test were 171 ± 12 beats/min (ie, 88 ± 5% of the theoretical maximum heart rate) and 96.7 ± 18.2 L/min (67 ± 8% of the theoretical maximum voluntary ventilation), respectively. Fifteen athletes (38%; 11 skiers and 4 triathletes) demonstrated BHR to methacholine (n = 7), exercise (n = 5), or both (n = 3). No sedentary control subject had BHR.
