Hydration: A Cornerstone of Peak Performance
Brandon Hyatt, MS, CSCS
July 15, 2024 • 3 min read
Proper hydration grows even more critical with the onset of summer heat, increased outdoor activity, and longer days. Whether you engage in weightlifting, endurance training, or outdoor pursuits, recognizing dehydration signs and implementing a hydration strategy is essential to optimizing performance. Even moderate dehydration can detrimentally impact both physical and cognitive function.
Beyond performance benefits, lifelong consistent hydration has been linked to favorable medical outcomes—including a biologically younger age, longer lifespan, and freedom from chronic diseases (2).
Symptoms of Dehydration
Dehydration occurs when the body loses more water than it consumes, disrupting physiological processes like heart rate regulation and thermoregulation. Recognizing its symptoms is vital to timely rehydration:
Thirst or dry mouth
Infrequent or dark-colored urine
Fatigue or irritability
Elevated heart rate
Muscle cramps
Factors Influencing Hydration
Hydration is not a one-size-fits-all practice—multiple variables shape fluid needs. Older adults are prone to rapid dehydration, men typically require more water than women, and larger-bodied individuals dehydrate more easily. Beyond these biological factors, interindividual sweat rate variations accelerate dehydration:
Age
Biological sex
Body size
Sweat rate
Environmental factors also compromise hydration status. These should guide fluid planning, with additional intake needed if present:
High temperature and/or humidity
Limited or no shade availability
Significant elevation gain
Heavy load carriage
Peak sun exposure times
Hydration and Performance
Dehydration—defined as 2–4% body weight loss—impairs endurance capacity and muscle force production. Cognitive performance (e.g., attention, executive function, motor coordination) declines at 2% sweat-induced body mass loss (3, 5, 6). Mood is adversely affected at 3–5% weight loss (3, 6).
Escalating dehydration also increases risk of heat-related illnesses (overheating, heat exhaustion, heat stroke), posing a medical hazard (4). Risk varies by activity: low- to moderate-intensity, prolonged events (e.g., running >1 hour) carry higher risk than short-duration, high-intensity activities (e.g., weightlifting) (4).
Hydration Guidelines
Before Exercise
The American Council on Exercise (ACE) recommends pre-exercise fluid intake of ~0.1 oz/lb (6 mL/kg) at least 4 hours prior to activity—allowing absorption time (e.g., 20 oz for a 200-lb individual) (1). Sodium-containing beverages/snacks enhance fluid retention. Avoid exercising thirsty, but do not overhydrate (this may cause unexpected restroom breaks).
During Exercise
Most research shows performance declines when weight loss exceeds 2%—aim to limit loss to ≤2%. To monitor sweat loss:
Weigh yourself pre- and post-exercise.
Account for urine output and fluid intake (if applicable).
Replace 1 oz of sweat with 1 oz of fluid.
If weighing is impractical, drink 8–16 oz of water per hour—adjust upward for factors like high temperatures. For activities >2 hours, use electrolyte-containing beverages.
After Exercise
If ≥12 hours separate sessions, rehydrate via regular eating/drinking (1). If <12 hours remain, consume 0.70 L of fluid per pound of sweat-induced weight loss (1).
General Hydration Tips
Invest in a high-quality, appealing water bottle—you’ll use it more frequently (similar to a child choosing a helmet they like).
Keep water visible throughout the day to support consistent intake and reduce dehydration risk.
Enhance water palatability with tea bags, supplements, or preferred flavorings.
When planning activity fluid intake, factor in environmental (humidity, shade, elevation) and physiological (body size, sweat rate) variables.
References
Bryant, C. X., Jo, S., Dalleck, L., Gagliardi, C. S., & Green, D. J. (2020). The Exercise Professional’s Guide to Personal Training: A Client-Centered Approach to Inspire Active Lifestyles.
Dmitrieva NI, Gagarin A, Liu D, Wu CO, Boehm M. Middle-age high normal serum sodium as a risk factor for accelerated biological aging, chronic diseases, and premature mortality. EBioMedicine. 2023 Jan;87:104404.
Dube, A., Gouws, C., & Breukelman, G. (2022). Effects of hypohydration and fluid balance in athletes' cognitive performance: a systematic review. African Health Sciences, 22(1), 367–376.
National Strength and Conditioning Association. (n.d.). Hydration and Performance.
Judge, L. W., Bellar, D. M., Popp, J. K., Craig, B. W., Schoeff, M. A., Hoover, D. L., Fox, B., Kistler, B. M., & Al-Nawaiseh, A. M. (2021). Hydration to Maximize Performance and Recovery: Knowledge, Attitudes, and Behaviors Among Collegiate Track and Field Throwers. Journal of Human Kinetics, 79, 111–122.
Wittbrodt, M. T., & Millard-Stafford, M. (2018). Dehydration Impairs Cognitive Performance: A Meta-analysis. Medicine and Science in Sports and Exercise, 50(11), 2360–2368.
