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How Hydration at Work Affects Performance Strategy

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How Hydration at Work Affects Performance Strategy

In 2004 Dianne Staal Wästerlund, Janet Chaseling and Lage Burström published an interesting study entitled The Effect of Fluid Consumption on the Forest Workers’ Performance Strategy. The aim of the study was to assess the effect of different hydration levels on the mental approach and physical ability of four Zimbabwean forest workers who were assigned with manually felling and processing marked trees into stem sections 2.4 m long. While the notion of hydration at work might not conjure up images of the forest floor for most of us (more’s the pity), it is worth drawing a parallel between how different hydration levels affect ability and performance and how that impacts on all of us – regardless of profession.

The method implemented in the Wästerlund, Chaseling and Burström paper was to study each worker over a period of eight consecutive work days – the men were tasked with producing 2.4 m³ of pulpwood every day. The subjects were randomly assigned (for two four-day periods) to one of two fluid schemes: reduced water intake during the work day where they were given only 0.17 litres of water to drink every 30 minutes leading to mild dehydration; or greater water intake where they were given 0.6 litres of water every 30 minutes leading to full hydration throughout the work day. Interesting to note was that at the start of every study day, each test person was given 0.5 litres of water to drink to ensure that all four men began their work day hydrated – despite this equal-footing starting point, performance still deteriorated on the days they drank less and were mildly dehydrated. This is pertinent, because a previous study, examined in Assessing Hydration Status in the Workplace, showed that the majority of workers across a variety of different professions began their work day already dehydrated, which when coupled with limited hydration during the day only served to further exacerbate cognitive and mental performance.

That aside, all the forest workers in the Wästerlund, Chaseling and Burström study applied the same strategy when tackling their allocated area of work – all chose to harvest large trees at the start of the working day leaving smaller trees for the end of the day. But while their starting strategy may have been the same, their ability, when mildly dehydrated, was not.

The time to perform the task of producing 2.4 m³ of pulpwood … was also found to be significantly higher during the days on the dehydrating fluid consumption scheme compared with days on the full hydration regime (234 min versus 209 min).

In short it took the men 25 minutes longer to do the same task on the days they were drinking less water. It is also important to remember that the study only aimed to achieve mild dehydration – this is typically considered to be around a 1% loss in body mass – it never aimed for more severe levels of dehydration in which the adverse effects are known to be even more egregious.

The Forest Workers study proves that mild dehydration affects performance, and while the majority of us won’t be felling and stripping trees anytime soon, the fact remains that mild dehydration slows us down, both physically and mentally. Similar results can be seen in The Impact of ‘Voluntary Dehydration’  where mild dehydration was shown to lead to detrimental changes in mood, along with negative changes in working memory and executive processing. So while being fully hydrated remains important for all forms of optimal functioning, sufficient hydration at work remains crucial where productivity and mental performance demands are at their greatest.



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