Addressing Sweat and Electrolyte Loss with Dr. Robert Kenefick

We discuss sweat rates, sodium losses, general guidelines, and how everyone's sweat rates vary with Dr. Robert Kenefick.

When our bodies need to cool down, evaporative cooling is often the best method to beat the heat. While we lose fluids and electrolytes through urine production and breathing, it’s the sweat we create to fuel our evaporative cooling that is our biggest source of fluid and electrolyte loss.  

Some of us are efficient, sweating just enough to evaporate the heat away. Others will leave intricate patterns on our shirts and puddles on the ground; neither of which are overly helpful in cooling our bodies and more importantly, it pushes us closer to dehydration.  

To make it more complicated, not only do sweat rates differ from person to person, but your individual sweat rates can vary every day. Hydration levels, environmental conditions, acclimatization, clothing; all of these can alter both your volume of sweat and its composition, making it difficult to determine your fluid and electrolyte needs. 

On today’s episode, we are joined by Dr Robert Kenefick of Research and Development at Entrinsic Bioscience. Previously, as a researcher at the US Army Institute of Environmental Medicine, hydration and sweat rates were important topics for Dr. Kenefick, who is now considered one of the top experts in the country.  

He will take us through an understanding of the physiology behind sweat and why our bodies are willing to give up both fluid and electrolytes. We will also discuss our replacement needs and how to determine your own rehydration strategies. 

Joining Dr. Kenefick, we will talk with two exercise physiologists, Jared Berg, and Dr. Stephen Cheung. Jared Berg is a coach and exercise physiologist who used to work side by side with Rob Pickels at the Boulder Center for Sports Medicine. He will discuss his recommendations on what we need to replace as we sweat. We will also touch base with Dr. Stephen Cheung, one of the top experts in the world on exercising in environmental extremes, like hot weather.  

So, grab your towel and favorite sports drink, and let’s make you fast! 

REFERENCES

Baker, L. B. (2017). Sweating Rate and Sweat Sodium Concentration in Athletes: A Review of Methodology and Intra/Interindividual Variability. Sports Medicine, 47(Suppl 1), 111–128. Retrieved from https://doi.org/10.1007/s40279-017-0691-5 

Barnes, K. A., Anderson, M. L., Stofan, J. R., Dalrymple, K. J., Reimel, A. J., Roberts, T. J., … Baker, L. B. (2019). Normative data for sweating rate, sweat sodium concentration, and sweat sodium loss in athletes: An update and analysis by sport. Journal of Sports Sciences, 37(20), 1–11. Retrieved from https://doi.org/10.1080/02640414.2019.1633159 

Bio-sensing textile based patch with integrated optical detection system for sweat monitoring. (n.d.). 

Buono, M. J., Ball, K. D., & Kolkhorst, F. W. (2007). Sodium ion concentration vs. sweat rate relationship in humans. Journal of Applied Physiology, 103(3), 990–994. Retrieved from https://doi.org/10.1152/japplphysiol.00015.2007 

Cheung, S. S., & McLellan, T. M. (1998). Heat acclimation, aerobic fitness, and hydration effects on tolerance during uncompensable heat stress. Journal of Applied Physiology, 84(5), 1731–1739. Retrieved from https://doi.org/10.1152/jappl.1998.84.5.1731 

Duvillard, S. P. von, Braun, W. A., Markofski, M., Beneke, R., & Leithäuser, R. (2004). Fluids and hydration in prolonged endurance performance. Nutrition, 20(7–8), 651–656. Retrieved from https://doi.org/10.1016/j.nut.2004.04.011 

Kenefick, R. W., & Cheuvront, S. N. (2012). Hydration for recreational sport and physical activity. Nutrition Reviews, 70(s2), S137–S142. Retrieved from https://doi.org/10.1111/j.1753-4887.2012.00523.x 

SAWKA, M. N. (1992). Physiological consequences of hypohydration: exercise performance and thermoregulation. Medicine & Science in Sports & Exercise, 24(6), 657. Retrieved from https://doi.org/10.1249/00005768-199206000-00008 

Smith, J. W., Bello, M. L., & Price, F. G. (2021). A Case-Series Observation of Sweat Rate Variability in Endurance-Trained Athletes. Nutrients, 13(6), 1807. Retrieved from https://doi.org/10.3390/nu13061807 

Episode Transcript

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