Pulmonary function is thought to be influenced by a variety of dietary factors and more recently the ingestion of fluids. Specifically, recent evidence suggests that the ingestion of a large volume of fluid (~750 mL) decreased resting pulmonary function However, it is unknown whether factors other than volume (i.e. drink temperature) influenced the effect of fluid ingestion on airway function.
PURPOSE: Therefore, the purpose of the study was to investigate the effect of both the volume and temperature of fluid ingestion on pulmonary function in recreationally active individuals.
METHODS: Eight, healthy, recreationally active individuals completed a randomised, crossover study design consisting of four experimental trials. On separate occasions (separated by ≥2 d) participants visited the laboratory after an overnight fast to complete an experimental trial consisting of the ingestion of: 500 mL cold-temperature [CT] (~2°C) water, 500 mL room-temperature [RT] (~18°C) water, 1000 mL CT (~2°C) water or 1000 ml RT (~18°C) water. Pulmonary function (FEV1, FVC, FEF25-75%) was assessed pre-ingestion and at 1, 5, 10 and 15 min post-ingestion. The maximum percentage fall in forced expiratory volume (FEV1) from the pre-ingestion to the post-ingestion value was calculated to provide an index of airway narrowing.
RESULTS: The ingestion of 1000 mL of CT water resulted in a group mean decrease in FEV1 of 7 ± 3% which was significantly reduced compared to 500 mL CT water (2 ± 1%, p=0.005), 500 mL RT water (1 ± 2%, p=0.002) and 1000 mL RT water (3 ± 3%, p=0.002). The maximum reduction in FEV1 following the ingestion of 1000 ml CT was 9 ± 3% and was significantly decreased compared to the 500 mL CT (3 ± 2%, p=0.036) and RT (3 ± 2%, p=0.004) drink. The ingestion of 1000 mL of CT water caused a significant reduction in FVC (7 ± 4%) compared to 500 mL CT water (2 ± 2%, p=0.006), 500 mL RT water (2 ± 2%, p=0.025) and 1000 mL RT water (4 ± 4%, p=0.031).
CONCLUSION: The ingestion of a cold, large drink decreased pulmonary function in healthy, active individuals compared to both small volumes of cold and room temperature drinks and a large room temperature drink. These findings suggest an important link between temperature and volume of fluid intake on airway function and should be considered in relation to fluid intake strategies pre-, during, and post-exercise.