Lung Function Responses to Cold Water Ingestion: A Randomised Controlled Crossover Trial.

This study tested the hypothesis that cold water ingestion would reduce lung function and thereby confound its measurement in a way that is mediated by both temperature and volume. In a randomised crossover trial, 10 healthy adults performed spirometry before and 5, 10, 15, and 30-minutes after consuming one-of-four drinks: 500mL or 1000mL refrigerated water (~2°C); identical water volumes at ambient temperature (~18 °C). Ingesting 1000mL cold water significantly reduced forced vital capacity (FVC) for at least 10minutes (mean difference =0.28L, p<0.05, d=1.19) and forced expiratory volume in 1second (FEV) for at least 15minutes (0.20-0.30L, p<0.05, d=1.01). Ingesting 500mL cold water reduced FEV for 5minutes (0.09L, p<0.05, d=1.05). Room-temperature water had no influence on lung function. To avoid confounding the measurement of lung function, we conclude that individuals should avoid drinking cold water, especially in large volumes, immediately prior to a given test.