Airway obstruction during exercise in asthma.

Abstract

Airway obstruction (AO) in exercise-induced asthma (EIA) is considered a postexercise phenomenon. However, many with EIA complain of respiratory distress during exercise. We evaluated AO in six asthmatic subjects during a short (SX = 6 min) and a long (LX = 20 min) exercise session. We measured peak expiratory flow (PEF) rate, forced expiratory volume in one second (FEV1), and forced expiratory flow at 50% of vital capacity (Vmax50) and calculated expiratory and inspiratory pulmonary resistance (RLe and RLi). Rated perceived exertion (RPE) was evaluated as a measure of dyspnea. All three indices of airflow significantly decreased following SX and LX, but RLi and RLe increased. During SX, PEF, FEV1, and Vmax50 did not decrease, but RLi decreased. During LX, PEF, FEV1, and Vmax50 decreased (20.0, 26.0, and 17.7%, respectively), whereas RLi and RLe significantly increased (74.0 and 53.0%). Rated perceived exertion correlated highly with RLi during exercise (r = 0.95). In summary, there was little or no AO during SX but a frank AO during LX in asthmatic subjects. We conclude that AO occurs during LX and that the manifestation of dyspnea is associated with AO during exercise, as well as in recovery.

Mechanisms of dyspnoea and its language in patients with asthma

“…Indirect evidence suggests that hyperinflation is not the sole mechanism of dyspnoea: some patients with chronic asthma have a minimal increase in lung volume but are quite symptomatic. Previous studies have found that there is no airway obstruction or dynamic hyperinflation (DH) during short-term intense exercise sessions in mild-to-moderate asthma [13,14]. SUMAN et al [13] reported that there was little or no airway obstruction during short-term exercise, with obstruction and mild DH only evident during the late stage of long-term exercise sessions in patients with exercise-induced asthma.…”

“…Previous studies have found that there is no airway obstruction or dynamic hyperinflation (DH) during short-term intense exercise sessions in mild-to-moderate asthma [13,14]. SUMAN et al [13] reported that there was little or no airway obstruction during short-term exercise, with obstruction and mild DH only evident during the late stage of long-term exercise sessions in patients with exercise-induced asthma. Moreover, no relationship was found between dyspnoea and DH during short-or long-term exercise sessions [13].…”

“…SUMAN et al [13] reported that there was little or no airway obstruction during short-term exercise, with obstruction and mild DH only evident during the late stage of long-term exercise sessions in patients with exercise-induced asthma. Moreover, no relationship was found between dyspnoea and DH during short-or long-term exercise sessions [13]. Likewise, BARREIRO et al [14] demonstrated that an exerciseinduced increase in lung volume did not appear to be a crucial contributor to both exercise limitation and dyspnoea intensity in patients with severe asthma, as shown by the fact that: 1) correlation coefficients were reported to be similar to those obtained with resting IC; and 2) the decrease in IC during exercise was not statistically significant in patient the subgroup with the greatest peak Borg score during exercise [14].…”

“…During the first visit, patients performed a baseline pulmonary function test. At the second and third visit, each patient was randomly administered either an Mch aerosol inhalation test or a cardiopulmonary exercise test, tailored according to SUMAN et al [13].…”

“…KILLIAN et al [12] stated that asthmatics who rate the intensity of dyspnoea as high during bronchoconstriction also tend to report that dyspnoea is high during exercise. However, this opinion is perhaps questionable if the role of obstruction and hyperinflation on dyspnoea during Mchinduced bronchoconstriction is considered [11] and, conversely, if little or unreported airway obstruction during a short exercise session, as opposed to a long-term session, in patients with exercise-induced asthma is taken into account [13]. To the best of the current authors' knowledge, in studies on the language of dyspnoea, asthmatics were asked to recall their experience of breathlessness provoked by activity [4] or exercise [3], but not to describe what they experienced during exercise.…”