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Abstract
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This article was featured on Last Week Tonight with John Oliver: Scientific Studies (HBO) [https://www.youtube.com/watch?v=0Rnq1NpHdmw]. The British National Health Service issued statements of caution about this research because, although the methodology was flawed, the results had been prominently featured on TV newscasts throughout the world; the study was funded by the European Hydration Institute with primary funding by the CocaCola company.
Authors' summary:
The aim of the present study was to examine the effect of mild hypohydration on performance during a prolonged, monotonous driving task.
Methods
Eleven healthy males (age 22 ± 4 y) were instructed to consume a volume of fluid in line with published guidelines (HYD trial) or 25% of this intake (FR trial) in a crossover manner. Participants came to the laboratory the following morning after an overnight fast. One hour following a standard breakfast, a 120 min driving simulation task began. Driver errors, including instances of lane drifting or late breaking, EEG and heart rate were recorded throughout the driving task
Results
Pre-trial body mass (P = 0.692), urine osmolality (P = 0.838) and serum osmolality (P = 0.574) were the same on both trials. FR resulted in a 1.1 ± 0.7% reduction in body mass, compared to − 0.1 ± 0.6% in the HYD trial (P = 0.002). Urine and serum osmolality were both increased following FR (P < 0.05). There was a progressive increase in the total number of driver errors observed during both the HYD and FR trials, but significantly more incidents were recorded throughout the FR trial (HYD 47 ± 44, FR 101 ± 84; ES = 0.81; P = 0.006)
Conclusions
The results of the present study suggest that mild hypohydration, produced a significant increase in minor driving errors during a prolonged, monotonous drive, compared to that observed while performing the same task in a hydrated condition. The magnitude of decrement reported, was similar to that observed following the ingestion of an alcoholic beverage resulting in a blood alcohol content of approximately 0.08% (the current UK legal driving limit), or while sleep deprived.
Keywords
Cognitive function; Dehydration; Fluid balance; Road traffic accident
Language: en |