Understanding Hydration & Why It’s Not Just About Thirst
Proper hydration is fundamental for performance. Water is necessary for thermoregulation (cooling via sweating), maintaining blood volume (thus oxygen & nutrient delivery to muscles), joint lubrication, and even cognitive function. Small deficits in hydration already start to impair these systems.
Effects of Dehydration on Performance
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Reduced endurance: Even mild dehydration (≈2% loss of body mass) can reduce endurance‐capacity and increase perceived exertion. Athletes will fatigue earlier. Gatorade Sports Science Institute+3askerjeukendrup+3ScienceDirect+3
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Cardiovascular strain: With less fluid, blood volume is lower, meaning the heart needs to work harder to maintain output. Heat further compounds this strain. ScienceDirect+2Gatorade Sports Science Institute+2
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Thermoregulation & heat stress: As you dehydrate, your ability to sweat and dissipate heat reduces; you overheat more easily. That can degrade performance and increase risk of heat illness. SpringerLink+1
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Cognitive and perceptual effects: Dehydration can reduce your ability to focus, decision making, reaction time. Especially in endurance events where fatigue + dehydration combine. SpringerLink+2ScienceDirect+2
Thresholds & Practical Impacts
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2% body mass loss is often used as a benchmark: beyond that, negative effects tend to show up. askerjeukendrup+1
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Greater losses (3–5% or more) lead to larger decrements: strength, power, endurance, heat regulation, etc. Frontiers+2ScienceDirect+2
Strategies to Stay Hydrated
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Pre‐hydrate before training/racing; monitor signs of dehydration (urine colour, weight changes, thirst).
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Drink during exercise: fluids with electrolytes help, especially in hot/humid conditions.
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Rehydrate afterwards, replacing both fluids and electrolytes lost in sweat.
Key References
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“Influence of sustained mild dehydration on thermoregulatory and cognitive functions during prolonged moderate exercise.” Watanabe et al. (2024) – examines perturbations in functions under mild dehydration. SpringerLink
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“Does dehydration really impair endurance performance? Recent methodological advances.” GSSI Sports Science Exchange. Gatorade Sports Science Institute
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“Dehydration and its impact on physical performance: A critical review.” ScienceDirect article. ScienceDirect
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“Dehydration and exercise‐induced muscle damage: Implications for recovery.” GSSI. Gatorade Sports Science Institute
