Show With the hot weather upon us in the northern hemisphere, this marks a time for many to get outdoors and enjoy the warm weather, but caution should always be exercised given the potential risks for dehydration. Fluid is perhaps the most important, but least recognized nutrient/compound we need to ingest, given how the body cannot survive more than a few days without it in comparison to food where the body can survive without it for much longer. Before discussing effective methods by which we can monitor hydration, take a brief moment to reflect upon the existing strategies you utilize to verify hydration for yourself and your clients (as a Nutrition Professional. Do you rely upon the sensation of thirst as your guide, daily weight fluctuations or perhaps urine color to monitor fluid needs? Considering how the sensation of thirst generally kicks in only when the body reaches about one percent dehydration (i.e., 1 % loss of normal body weight), and the fact that performance is negatively impacted at two percent dehydration, this approach alone may be inadequate (1, 2). It does not provide much of a buffer for individuals exercising in the heat who may be susceptible to compromised performance. Read also: Foods to Replace Electrolytes For example, a 180 lb. (81.8 Kg) man need only lose 1.8 lbs. (0.82 Kg), to initiate the sensation of thirst (1 % dehydration), and 3.6 lbs. (1.64 Kg) to reach 2 % of body weight. Given how sweat rates range between 0.5 and 1.5 L per hour (1.06 – 2.13 lb. / hour) during light-to-moderate intensity exercise, but can increase to 3.0 to 4.0 L per hour (6.25 – 8.5 lb. / hour) in well-conditioned, large male athletes who have acclimatized to hot environments, the loss of two percent of body weight can happen very easily (3). Body weight and urine specific gravity (USG) are two common methods by which euhydration (maintaining normal total body water content) can be monitored (1, 4 – 6):
Although urine color is oftentimes used as a marker of hydration where we follow the guideline of maintaining a clear-to-lemonade color while avoiding darker, apple-juice urine colors, we need to exercise caution with such generalized guidelines given how various factors can influence urine color and volume that are discussed subsequently. Consistent urine colors between one and three indicate well-hydrated levels equivalent to less than 1 % loss in body weight; scores between four and five indicate minimal dehydration levels equivalent to 1 – 3 % loss in body weight that merit ingestion of 7 – 10 oz. (200 – 300 mL) of fluid within the next 60 minutes; scores between six and seven indicate significant dehydration levels equivalent to 3 – 5 % loss in body weight that merit ingestion of 7 – 10 oz. (200 – 300 mL) of fluid immediately; and a score of eight indicates severe dehydration, equivalent to > 5 % loss in body weight that requires medical attention (8). Consistent, larger volumes excreted during the first morning void with a lemonade color (scale of 1 – 3 ) usually indicate euhydration, whereas consistent, smaller volumes excreted during the first morning void with darker colors (4+ on the scale - apple juice-to-ice tea color) usually indicate levels of dehydration. Exceptions do exist however, and should always be considered – they include:
Lastly, pre- and post-exercise weight differences represent another method to assess total body water, albeit it a method used more appropriately to determine rehydration needs following exercise. Implement a practice of collecting pre-exercise weight (voided), either naked or in light clothing and again following exercise to determine fluid needs to rehydrate. The efficacy of this method however is contingent upon an individual being in a state of euhydration before exercise. Fluid Requirement = Pre-exercise Weight - Post-exercise Weight For example, if a female weighs 145 lbs. (65.9 Kg) before exercise (voided, dry) and then weighs 142 lbs. (64.5 Kg) following exercise, even after drinking during exercise, she needs to replace 3 lbs. (48 oz. or 1.36 L) of fluid. This does not imply that she only needs to drink 48 oz. of fluid. She will probably need to consume more as a portion will be lost to urine. The quantities needed vary between beverage choice (i.e., water or sports drink). **Be sure to check out this blog on heat and heat syptoms to look out for. References:
Which assessment would be most appropriate for monitoring a client's state of hydration?Changes in body weight, haematological and urine parameters, bioelectrical impedance, skinfold thickness, heart rate and blood pressure changes are among these indices. Plasma osmolality, urine osmolality and urine specific gravity are the most widely used markers of hydration.
What is the best way to monitor hydration status?One of the easiest ways to test your hydration is through bathroom frequency and urine color. Your urine should be light yellow and you should be emptying your bladder on average 5-8 times per day. Another way to determine hydration levels (especially after a run) is a sweat test.
What technique can be used to assess the hydration of a patient?Urinalysis is a frequently used clinical measure to distinguish between normal and pathological conditions. Urinary markers for dehydration include a reduced urine volume, a high urine specific gravity (USG), a high urine osmolality (UOsm), and a dark urine color (UCol).
What are two recommended methods for athletes monitoring hydration status?Athletes who are not sure how much fluid to drink can monitor hydration using two helpful techniques: Weighing themselves before and after practice. For every kilogram (pound) lost during the workout, drink ~1.5 liters (~three cups) of fluid in order to rehydrate the body. Checking urine color.
|