Improved lung function following dietary antioxidant supplementation in exercise-induced asthmatics.

INTRODUCTION: Oxidative stress is a characteristic of exercise-induced asthma (EIA), however antioxidant supplementation may attenuate EIA. The purpose of this study was to determine if ascorbic (AsA) and α-tocopherol supplementation would improve airway function in subjects with EIA. METHODS: A single-blind randomized crossover design with eight clinically diagnosed EIA subjects (22.0 ± 0.7 year) and five healthy control subjects (28.2 ± 1.4 year) was used. Subjects consumed vitamins (V) (AsA 500 mg; α-tocopherol 300 IU) or placebo (PLA) daily for three weeks, followed by a three week washout period and then three weeks of the alternative treatment. Ten-minute treadmill tests (90% VO2peak) were performed with pulmonary function testing (forced vital capacity (FVC), forced expiratory volume in one second (FEV1) and between 25 and 75% (FEF25-75%), and peak expiratory flow rates (PEFR)) measured pre-exercise and 1, 5, 15, and 30 min post-exercise. RESULTS: Supplementation led to significant improvements at minute 5 and minute 15 in FVC; FEV1; PERF; FEF25-75% and minute 30 in FEV1 and FEF25-75% post-exercise. CONCLUSION: AsA and α-tocopherol may aid the recovery of pulmonary function in subjects with EIA.

Does menstrual cycle phase affect lung diffusion capacity during exercise?

Resting lung diffusing capacity (DLCO) decreases during the early and late-follicular phases of the menstrual cycle presumably due to capillary blood volume (VC) changes; however, it is not known if these differences exist during exercise. We hypothesized that DLCO would increase during the mid-luteal phase of the menstrual cycle due to increases in VC. Eight normally menstruating females (21.4±0.7 yrs) were studied. Subjects completed a discontinuous treadmill V˙O2max test during the early-follicular (EF), late-follicular (LF), and mid-luteal (ML) phases of the menstrual cycle. Metabolic measurements were made from a breath-by-breath automated cart, and DLCO via the single-breath exhalation technique during exercise. During exercise, DLCO was lesser during EF compared to ML at 90% and 100%V˙O2max (p<0.05) (90%: 37.8±3.7 EF vs 41.6±4.0 ML, 100%: 37.7±3.7 EF vs 42.6±4.3 ML mL/mmHg/min). VC was significantly greater during the ML phase when compared to the EF at 80%, 90%, and 100%V˙O2max. These results demonstrate DLCO and VC are influenced by the menstrual cycle during heavy exercise.