• Hot Topic: Beat the Heat - Combat Dehydration
    Recognizing basic signs of dehydration before, during, and after bouts of activity are important to prevent heat-related illness. This article will review three methods to assess hydration levels, signs and symptoms of heat illness, and proper hydration guidelines to maximize performance and prevent illness.
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  • Man dowsing himself with waterWith summer in full swing, it is important to know the warning signs of heat-related illness and dehydration and how to prevent it. Proper hydration is vital for optimal performance and recovery. The National Athletic Trainers Association (NATA) and the American College of Sports Medicine (ACSM) have released guidelines for fluid replacement (1,2).

    Proper hydration is an important part of our training programs. Our first step in combating dehydration is to measure an athlete’s hydration levels. There are several methods for measuring an athlete’s hydration levels. In this article, we will discuss weight/water loss, urine color, and the specific gravity of urine.

    When exercising vigorously, it is a good idea to record your bodyweight before and after exercise. When monitoring bodyweight, it is important to be consistent with several factors such as the time of day that you measure, the clothes you wear, and having a precisely calibrated scale. I recommend to athletes that they wear minimal clothes such as underwear or compressions shorts and/or sports bra. This will minimize added weight from clothes or absorbed moisture.

    Hydration needs can vary from athlete to athlete based on factors such as environmental conditions, age of the athlete, and demands of various activities. Dehydration provokes changes in blood volume, which can affect cardiovascular, thermoregulatory, metabolic, and central nervous function that become increasingly greater as dehydration worsens. Weight loss greater than 1 percent can adversely affect performance, and weight loss of 3 percent of bodyweight or more after activity greatly increases the risk of heat illnesses such as heat cramps, heat exhaustion, or even heat stroke, which can be life threatening (2,9).

    In addition to recording bodyweight, hydration levels can be monitored by simple urine color measurements. When optimally hydrated, urine color will appear clear or very lightly yellowed. As dehydration settles in, an athlete’s urine color will become dark yellow or even brown. The darker, more concentrated the urine appears the more the athlete is dehydrated. Thirst, irritability, headaches, weakness, dizziness, cramps, nausea, and decreased performance are all common signs of dehydration. Recognizing these basic signs of dehydration before, during, and after bouts of activity are important to prevent illness. We must keep in mind that certain vitamins, minerals, and supplements can also affect the color of urine, and this is completely normal as the kidneys filter out these substances. One of the more common examples is high doses of vitamin B which can cause our urine to appear neon yellow to green. Vitamin C, riboflavin, and supplements that contain carotene can also produce dark yellow to orange urine.

    A third method to measure hydration levels is to have an athlete’s urine checked for specific gravity. This method is typically done in a clinical setting, but it will give you a very precise measure of hydration levels. In this test, urine is compared to the density of water. The higher the density, or specific gravity, the more dehydrated the athlete is. The normal ranges for youth athletes are between 1.000-1.019. For adults the normal ranges are between 1.010 and 1.025. Anything above those numbers would be considered dehydrated (6,8).

    Prevention and recognition are the keys to staying hydrated and maximizing exercise performance and benefits. Follow these guidelines to help prevent possible heat and hydration-related illnesses.

    Before Exercise
    Fluids should be consumed several hours before exercise or athletic events to allow for proper absorption. About two to three hours before exercise, athletes should drink 17 to 20 oz of water. Then, again, 10 to 20 min before exercise, athletes should drink another 7 to 10 oz of water (1).

    During Exercise
    Drink 7 to 10 oz of water every 10 to 20 min (or 28 to 40 oz of water per hour of activity). Drink beyond your thirst. If you are feeling thirsty, you are already dehydrated. It is important for an athlete to include these fluid replacement habits into their regular training to build up tolerance to this amount of water. Some athletes have trouble consuming fluids during activity (1).

    After Exercise
    Individuals should drink approximately 20 to 24 oz of water or sports drink per pound of weight loss within two hours of exercise or athletic events (1). Athletes should drink enough water to replace any weight loss from exercise. Water is recommended for shorter bouts of normal exercise since it is unlikely that your body’s electrolyte stores have been depleted to a level where a sports drink in necessary. Sports drinks containing electrolytes, such as sodium or potassium, may be necessary after prolonged bouts of exercises. Events such as marathons, ultra marathons, ironman events, or any event that last longer than 3-5 hr may require electrolyte replacement throughout the day following these events. Electrolytes can be replaced by various sports drinks or even with a well-planned meal after exercise.

    Special Considerations
    Older athletes (i.e., 50 years old or older) have a decreased ability to maintain an adequate plasma volume and osmolality during exercise, which may predispose them to dehydration. The ability of an older athlete to adapt is partly a function of age but also depends on functional capacity and physiological health (3).

    All the hard work and training will all be for nothing if dehydration and heat illness kicks in and you cannot perform or recover properly. Like many things, prevention is the key. It is our jobs as strength coaches and certified personal trainers to educate our clients and athletes on the warning signs of potential heat and hydration-related illness.

  • Larkin_bio

    About the Author:

    Scott Larkin, ATC, CSCS

    Scott Larkin is the Director of Personal Training at Gainesville Health and Fitness with over 15 years of experience in the health and fitness industry. Larkin’s experience as a certified athletic trainer and certified strength and conditioning specialist, combined with his post-rehab strength and conditioning experience adds tremendous value in developing world-class personal trainers. Larkin specializes is post-rehabilitation training, sports performance training, and periodized programming for the “everyday” athlete.

    REFERENCES →

    1. Binkley, HM, Beckett, J, Casa, DJ, Kleiner, DM, and Plummer, PE. National Athletic Trainers’ Association Position Statement: Fluid Replacement for Athletes. Journal of Athletic Training 35(2):212-224, 2000.
    2. Medicine & Science in Sports & Exercise: February 2007 - Volume 39 - Issue 2 - pp 377-390doi: 10.1249/mss.0b013e31802ca597 SPECIAL COMMUNICATIONS: Position Stand: Exercise and Fluid Replacement. Retrieved from http://journals.lww.com/acsmmsse/Fulltext/2007/02000/Exercise_and_Fluid_Replacement.22.aspx
    3. Kenney WL, and Hodgson JL. Heat tolerance, thermoregulation, and ageing. Sports Med 4: 446–456, 1987
    4. Zappe, DH, Bell, GW, Swartzentruber, H, Wideman, RF, and Kenney, WL. Age and regulation of fluid and electrolyte balance during repeated exercise sessions. Am J Physiol 207(1 Pt 2): R71–R79, 1996
    5. Inoue, Y, Shibasaki, M, Ueda, H, and Ishizashi, H. Mechanisms underlying the age-related decrement in the human sweating response. Eur J Appl Physiol Occup Physiol 79:121–126, 1999.
    6. Terris, MK. The Significance of Abnormal Urine Color: http://urology.stanford.edu/about/articles/abnormal_urine.html
    7. Mayo Clinic. Urine Color Causes. www.mayoclinic.com
    8. Murray, B. Hydration and Physical Performance: J Am Coll Nutr 26(suppl 5): 542S-548S, 2007.
     

  • Disclaimer: The National Strength and Conditioning Association (NSCA) encourages the exchange of diverse opinions. The ideas, comments, and materials presented herein do not necessarily reflect the NSCA’s official position on an issue. The NSCA assumes no responsibility for any statements made by authors, whether as fact, opinion, or otherwise. 
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