Is Sodium Supplementation Necessary in the Heat?


A common question asked of us by workers relates to electrolytes and specifically, sodium

(the salty part of salt), while working in the heat. Some workers report that sodium supplementation is necessary to replace sodium excreted in sweat, thereby preventing muscle or 'heat' cramps. As for outdoor and/or heat-exposed manual workers, ultramarathon runners endure long periods of exposure and physical activity, albeit at a higher work rate. It was interesting to read the recently published work of Hoffman and White (2020) that reported the majority of the 1152 ultrarunners sampled indicated that sodium supplements should be available during races and ~60% reported that they prevent muscle cramping. This was despite Hoffman et al. (2015) reporting that the


majority of sodium for ultrarunners was generally sourced from their food and fluid consumption. Importantly, Hoffman and co also reported that there was no difference in sodium consumption between those that cramped (or 'near-cramped') compared to the non-crampers. Note that this analysis is from relatively small groups (total n=23, 9v14). For this sample, sodium consumption was also not related to the incidence of nausea.


So, what does this mean for heat exposed workers with high sweat rates? Hoffman's work provides more evidence that food and fluid consumption are likely to provide ample sodium and that supplementation may not be warranted for most workers. For excessive sweaters and those with confirmed (by medical staff) electrolyte deficiency, supplementation may be advised, that could be as simple as adding salt to the post-shift meal. We provide workers with the numbers regarding sodium content of common foods v electrolyte-containing beverages to demonstrate why food consumption during the hot work shift is important in spite of the loss of appetite reported by approximately 1 in 4 workers across Northern Australia (Carter et al., 2020). Most are surprised to learn that the 'electrolyte-containing' beverages are relatively low in electrolytes when compared to commonly consumed sandwiches.


References

Carter S, Field E, Oppermann E, Brearley M (2020). The impact of perceived heat stress symptoms on work-related tasks and social factors: A cross-sectional survey of Australia's Monsoonal North. Applied Ergonomics. 82:102918


Hoffman MD, Stuempfle KJ, Valentino T (2015). Sodium Intake During an Ultramarathon Does Not Prevent Muscle Cramping, Dehydration, Hyponatremia, or Nausea. Sports Med Open. 1(1):39


Hoffman MD, White MD (2020). Belief in the Need for Sodium Supplementation During Ultramarathons Remains Strong: Findings from the Ultrarunners Longitudinal TRAcking (ULTRA) Study. Appl Physiol Nutr Metab. 45(2):118-22

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