Environmental physiologist Dr. Stephen Cheung explores the question of whether you should drink according to a fixed schedule—for example, a bottle every 30 minutes—or if you should rely on your sense of thirst to dictate how much you drink.
First, however, he takes a step back to explore an important underlying question: Is there a performance impact from mild dehydration? The evidence suggests that, while some physiological attributes may change due to mild dehydration—for example, heart rate and core temperature—the impact is not catastrophic and performance does not significantly decline.
Dr. Cheung addresses the most recent research comparing “programmed” drinking to using thirst as an indicator of an athlete’s need to hydrate. Based on the evidence, he makes recommendations as to when it is preferable to stick to a schedule or program, and when thirst is enough to avoid what he calls “hydration obsession.”
References
- Cheung, S. S., McGarr, G. W., Mallette, M. M., Wallace, P. J., Watson, C. L., Kim, I. M., & Greenway, M. J. (2015). Separate and combined effects of dehydration and thirst sensation on exercise performance in the heat. Scandinavian Journal of Medicine & Science in Sports, 25, 104–111. https://doi.org/10.1111/sms.12343
- Ebert, T. R., Martin, D. T., Bullock, N., Mujika, I., Quod, M. J., Farthing, L. A., Burke, L. M., & Withers, R. T. (2007). Influence of hydration status on thermoregulation and cycling hill climbing. Medicine & Science in Sports & Exercise, 39(2), 323–329. https://doi.org/10.1249/01.mss.0000247000.86847.de
- Goulet, E. D. B., & Hoffman, M. D. (2019). Impact of Ad Libitum Versus Programmed Drinking on Endurance Performance: A Systematic Review with Meta-Analysis. Sports Medicine, 49(2), 221–232. https://doi.org/10.1007/s40279-018-01051-z
