Purpose: To determine whether changes in lung function are associated with exercise-related transient abdominal pain (ETAP). Methods: Twenty-eight subjects susceptible to ETAP performed a flow-volume loop before (pre) and after (post) treadmill exercise. Fourteen of the subjects developed symptoms of ETAP during the exercise and completed the flow-volume loop while the pain was present. The remaining 14 subjects reported no symptoms of ETAP. Results: Forced inspiratory vital capacity was essentially unchanged from pre to post in both groups (ETAP group –0.8% ± 5.1%, comparison group –0.9% ± 6.5%). Peak inspiratory-flow rate increased in both the ETAP group (12.4% ± 16.2%) and the comparison group (17.9% ± 16.6%), but the difference between groups (–4.6%, standardized effect size [EF] = –0.17) was trivial. Forced expiratory vital capacity decreased by approximately 4% in both groups (ETAP group –3.9% ± 3.3%, comparison group –4.0% ± 5.1%). Small differences in the mean change from pre to post between groups were recorded for peak expiratory-flow rate (–7.4%, EF = –0.28) and the forced expiratory volume in the first second of the test (–4.4%, EF = –0.44). Conclusions: ETAP does not appear to be associated with reduced inspiratory performance, suggesting that the diaphragm is not implicated directly in the etiology of ETAP. Expiratory power might be slightly reduced during an episode of ETAP, but the magnitude of this effect is unlikely to compromise exercise performance.