Preventative Hydration Protocols for Heat Stress Management: Applications from Sport Science

Personalized hydration protocols, informed by sports science, are essential for preventing heat stress and ensuring the safety and performance of industrial workers exposed to extreme heat.

• By Matt Marrapode
• Aug 05, 2024

Imagine running 135 miles in California’s Death Valley, with temperatures soaring to 130 degrees Fahrenheit under the blazing sun, while maintaining a pace of 10 kilometers per hour. Elite athletes tackle this challenge in the Badwater Ultramarathon in under 22 hours. What crucial lessons can industrial workers draw from these extraordinary athletes to perform safely and efficiently in similarly extreme conditions? 

Proper hydration is key. While heat acclimation is crucial, dehydration can negate its benefits, underscoring the need for effective hydration strategies to ensure worker safety and performance.

As the climate crisis escalates, industrial workers are on the frontlines, battling extreme heat that jeopardizes their health and productivity. Like athletes, industrial athletes are exposed to high temperatures and demanding physical work and are particularly vulnerable to heat stress. Thirty-five percent of American PDO workers experience occupational heat strain, significantly impacting productivity and health. 

In this challenging landscape, proper hydration emerges as a critical defense. The Occupational Safety and Health Administration (OSHA) calls out hydration as key to heat illness prevention in its recent bulletin, but one-size-fits-all guidelines fall short. Enter the realm of sports science, where personalized hydration strategies and advanced monitoring technologies offer promising solutions for heat stress management in industrial settings. 

The National Institute for Occupational Safety and Health (NIOSH) recommends that workers consume one cup (8 oz or 250 mL) of water every 15-20 minutes. Robust individual variability exists in exercise-related fluid losses. So workers should consider individual needs based on environmental conditions, work intensity and heat exposure duration.

Personalized Hydration Protocols

Personalized hydration protocols, informed by sports science, provide a tailored approach to combat heat stress. Athletes use individualized hydration strategies to optimize performance and prevent heat-related illnesses. Sports science has long recognized the importance of tailored hydration, which can significantly enhance safety and performance. Maintaining hydration status with minimal variation (+1 percent to –1 percent of body weight lost in fluid) allows the body to optimally thermoregulate and maintain cardiovascular function.

Normative Sweat Dynamics in Athletes

The amount of water and electrolytes (primarily sodium, Na+) lost due to thermoregulatory sweating during exercise can vary considerably within and among athletes. Even for the same individual, losses can vary greatly day to day. The reported range in sweating rate and sweat Na+ concentration ([Na+]) is ~0.5 to 2.0 L/h and ~10-90 mmol/L, respectively. Extrapolated for workers throughout a workday, this could result in multiple U.S. gallons of fluid lost in a day on the high end.

Effects of Dehydration

Proper hydration is essential, as even mild dehydration can decrease physical performance by 2-3 percent and cognitive performance by up to 10 percent.

Dehydration elevates core temperature responses and negates the thermoregulatory advantages conferred by heat acclimatization. When dehydrated, similar core temperature responses were observed for both unacclimated and acclimated states. 

The capacity to perform high-intensity exercise, which results in exhaustion within a few minutes, is reduced by as much as 45 percent by prior dehydration corresponding to a loss of only 2.5 percent of body weight.

Exercise performance is impaired when an individual is dehydrated by as little as 2 percent of body weight. Losses of more than 5 percent of body weight can decrease the capacity for work by about 30 percent.

Fluid & Electrolyte Replenishment Guidelines

Appropriate fluid intake before, during and after exercise is important for health and optimal performance. Before exercise, athletes may achieve euhydration prior to exercise by consuming a fluid volume equivalent to 5–10 ml/kg BW (∼2–4 ml/lb) in the two to four hours before exercise to achieve urine that is pale yellow while allowing for sufficient time for excess fluid to be voided. Sodium consumed in pre-exercise fluids and foods may help with fluid retention. Drinking during exercise aims to address sweat losses that occur to assist thermoregulation. After exercise, the fluid should be restored by drinking a volume of fluid that is equivalent to ∼125-150 percent of the remaining fluid deficit (e.g., 1.25–1.5 L fluid for every 1 kg BW lost).

Some, but not all, sodium should be replaced when sweat sodium losses are high, which may occur when there is some combination of moderate to prolonged duration exercise in the heat (>1–2 h), moderate-to-high sweating rates (>1.5 L/h) and/or moderate-to-high sweat sodium concentrations (>60 mmol/L).

 Athletes who sweat profusely, especially when overlaid with a high sweat sodium concentration, may be at greater risk for cramping, particularly when not acclimatized to the heat and environment.

Over-drinking fluids in excess of sweat and urinary losses is the primary cause of hyponatremia (blood sodium <135 mmol/L), also known as water intoxication, although this can be exacerbated in cases where there are excessive losses of sodium in sweat and fluid replacement involving low-sodium beverages.

Conclusion and Future Outlook

As global temperatures rise, the need for innovative heat stress management solutions becomes urgent. Wearable technologies and personalized hydration strategies can safeguard industrial workers' health and boost productivity. Implementing effective hydration protocols requires education, training, management support, and advanced monitoring technologies. Embracing these advancements ensures a safer and more resilient workforce, offering practical and effective solutions to heat stress challenges. Continued investment can create a healthier and more productive work environment for all industrial athletes.

Pre-Hydration Strategies:

• Fluid intake. Consume 5–10 ml/kg body weight (2–4 ml/lb) 2 to 4 hours before work. Ensure urine is pale yellow and include sodium in fluids and foods to enhance retention.
• Fluid balance. Check hydration status by monitoring urine color and volume and/or sweat loss and volume. Drink small amounts consistently and use electrolyte solutions containing sodium and potassium.

Post-Hydration Strategies:

• Fluid replacement. Drink 125-150 percent of the remaining fluid deficit (1.25–1.5 L for every 1 kg lost) immediately after work and gradually over the next few hours. Use electrolyte solutions.

Monitoring. Monitor urine color and volume, aiming for pale yellow urine. Use real-time sweat loss technology or pre/post-body-weight assessments to determine fluid loss.

This article originally appeared in the September 2024 issue of Occupational Health & Safety.