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Hydration is often underplayed in the discourse of athletic performance. However, the profound implications of hydration on an athlete’s physical and cognitive abilities can’t be overstated. This article will delve into the science behind hydration, its impact on an athlete’s performance, and practical strategies for maintaining optimal hydration before, during, and after physical activities.
Why Hydration Matters to Athletes
The human body comprises approximately 60% water1. This vital fluid plays numerous roles, from maintaining blood volume and regulating body temperature to facilitating muscle contractions1. Yet, many athletes, regardless of their skill level, overlook the importance of staying adequately hydrated.
During intense physical activity, the body sweats to maintain optimal body temperature1, and this leads to fluid loss. Replenishing these lost fluids is crucial for preserving normal muscle function, preventing a decrease in physical performance, and reducing the risk of heat stress1.
The consequences of dehydration can be severe, with symptoms including tachycardia, hypotension, hyperventilation, vomiting, diarrhea, seizures, and even coma in extreme cases2.
The Physiological Impact of Dehydration
Dehydration can lead to a reduction in blood volume, decreased skin blood flow, reduced sweat rate, increased core temperature, and an accelerated rate of muscle glycogen use4.
These changes can decrease the amount of blood entering the heart during diastole (the phase in the cardiac cycle where the heart relaxes and fills with blood), thereby reducing the amount of blood that leaves the heart during systole (the phase where the heart contracts), consequently leading to a decrease in cardiac output4.
An increased core temperature during a dehydrated state can also trigger a larger aromatic amine response, possibly leading to an increased rate of glycogen breakdown in muscles4.
This can contribute to an increased level of muscle fatigue. Moreover, the breakdown of glycogen during exercise leads to an intracellular increase of acids, principally lactic acid, which in turn causes skeletal muscle fatigue5.
Hydration and Muscle Growth
Not only does dehydration affect an athlete’s immediate performance, but it can also impact muscle growth. Research from the University of Connecticut showed that athletes in a dehydrated state had an increased level of cortisol, which competes for certain enzymatic receptors in the body, reducing the level of testosterone, the primary hormone required for muscle growth6.
Additionally, increased cortisol concentration reduces the amount of testosterone released as a response to resistance-specific weight training6.
How Much Water Should You Drink?
While the importance of hydration is clear, the question of how much water should be consumed remains a subject of debate. The Institute of Medicine suggests that adult males above the age of 18 should consume about 4 liters of water daily, while adult females should drink about 3 liters1.
However, athletes, due to their higher level of physical activity, may require more than these estimated amounts. It’s also crucial to note that hydration needs can vary based on factors such as body size, sweat rate, exercise intensity, and environmental conditions.
Recognizing the Signs of Dehydration
Identifying dehydration early is of paramount importance in preventing its adverse effects on athletic performance. Common signs of dehydration include dry mouth and tongue, thirst, headache, lethargy, dry skin, muscle weakness, dark urine, and/or dizziness4. It’s essential for athletes to be in tune with their bodies and seek immediate hydration at the first sign of these symptoms.
Maintaining Hydration: Before, During, and After Exercise
Maintaining optimal hydration levels involves strategies that extend beyond just drinking water during exercise. It entails a comprehensive approach that considers hydration before, during, and after physical activities.
Hydration Before Exercise
Starting exercise in a euhydrated state is critical for optimal performance. This requires good hydration practices throughout the day, including consuming high water content foods such as fruits and vegetables6.
If you’ve lost a significant amount of fluid and haven’t adequately replenished it, an aggressive pre-exercise hydration protocol is recommended6.
This involves consuming approximately 5 to 7 ml of fluid per kilogram of body weight at least 4 hours before exercise and an additional 3 to 5 ml/kg body weight 2 hours before exercise if you’re not urinating frequently or if your urine is dark6. Consuming sodium-rich foods during this time can stimulate thirst and help retain fluids.
Hydration During Exercise
During exercise, the aim is to prevent excessive dehydration and drastic changes in electrolyte balance6. A good rule of thumb for athletes is to aim for 3 to 8 ounces (90 to 240 ml) of a 6% to 8% carbohydrate-electrolyte beverage every 10 to 20 minutes during exercise lasting longer than 60 to 90 minutes6.
Hydration After Exercise
Post-exercise hydration aims to replenish any fluid and electrolyte deficit from the exercise bout. To achieve normal hydration within 6 hours after exercise, athletes should consume 150% of the lost weight6. Therefore, practically speaking, the recommendation is to ingest 20 to 24 ounces (600 to 720 ml) of fluids for every pound of body weight lost during training6. Consuming sodium-rich foods and beverages with water after exercise can help replace electrolyte losses6.
Hydration plays an instrumental role in athletic performance. By understanding the science behind hydration, recognizing the signs of dehydration, and adopting effective hydration strategies before, during, and after exercise, athletes can optimize their performance and safeguard their health.
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1. “Fluids and Electrolytes.” SpringerReference (2011): n. pag. June 2009. Web. 22 June 2015.
2. Shaheen, Naila A, et al. “Public Knowledge of Dehydration and Fluid Intake Practices: Variation by Participants’ Characteristics.” BMC Public Health, BioMed Central, 5 Dec. 2018, www.ncbi.nlm.nih.gov/pmc/articles/PMC6282244/
3. McDermott, Brendon P, et al. “National Athletic Trainers’ Association Position Statement: Fluid Replacement for the Physically Active.” Journal of Athletic Training, National Athletic Trainers Association, Sept. 2017, www.ncbi.nlm.nih.gov/pmc/articles/PMC5634236/
4. Binkley, Helen M. et al. “National Athletic Trainers’ Association Position Statement: Exertional Heat Illnesses.” Journal of Athletic Training 37.3 (2002): 329-343. Print.
5. Westerblad, Hakan, David G. Allen, and Jan Lannergren. “Muscle Fatigue: Lactic Acid or Inorganic Phosphate the Major Cause?” American Journal of Physiology 17.1 (2002): 17-21. Web. 10 July 2015.
6. Jeukendrup, Asker, and Michael Gleeson. “Dehydration and Its Effects on Performance.” Humankinetics. N.p., n.d. Web. 29 July 2015.
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- Binkley, Helen M. et al. “National Athletic Trainers’ Association Position Statement: Exertional Heat Illnesses.” Journal of Athletic Training 37.3 (2002): 329-343. Print. ↩
- Jeukendrup, Asker, and Michael Gleeson. “Dehydration and Its Effects on Performance.” Humankinetics. N.p., n.d. Web. 29 July 2015. ↩ ↩2
- Jeukendrup, Asker E., and Michael Gleeson. Sport Nutrition: An Introduction to Energy Production and Performance. Champaign, IL: Human Kinetics, 2010. N. pag. Print. ↩ ↩2 ↩3 ↩4
- Westerblad, Hakan, David G. Allen, and Jan Lannergren. “Muscle Fatigue: Lactic Acid or Inorganic Phosphate the Major Cause?” American Journal of Physiology 17.1 (2002): 17-21. Web. 10 July 2015. ↩
- Brown, Jordana. “SimplyShredded.com.” SimplyShredded.com. Weider Publications, n.d. Web. 22 June 2015. ↩ ↩2 ↩3 ↩4 ↩5 ↩6 ↩7 ↩8 ↩9 ↩10