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Hydration Measurement Methods for Athletes

Cristina Vulpe provides three user-friendly ways to check your level of hydration.

It is common knowledge that daily fluid intake significantly impacts any athlete's training success. Whether a coach has shared this information or not, the fact is that the amount of water and other fluids consumed in a day can vary vastly from one type of sportsperson to the next. Besides, it can be influenced by the individual's age, gender, health status, and various other factors.

Given that not all athletes can test their hydration levels, it is a good idea to consider several simple hydration testing methods that can be performed conveniently and efficiently.

Urine specific gravity

While analyzing urine-specific gravity is the most sophisticated method of measuring hydration, it requires the use of a refractometer. While the broad array of scientific gear destined for urinalysis calls for a set of skills or knowledge on the part of the user that athletes might not possess, utilizing a refractometer is not all that difficult.

A simple handheld version can measure urine density in several minutes, letting sportspeople know whether they should drink more fluids. The athlete collects his or her urine, calibrates the refractometer with distilled water, and performs the urinalysis. Results range from 1.000 to 1.035, with the second number signalling severe dehydration.

The core advantage of this method is that it is easy to perform, even by athletes who have no prior experience using a refractometer. However, the cost of the equipment and the fact that the urine has to be collected by the actual user could be drawbacks.

Nonetheless, using a refractometer is beneficial both for coaches and for athletes. A standard practice among professional and amateur boxers is to perform weight-manipulating techniques that involve dehydration [1]. When performed correctly, this method offers accurate results, although there have been cases where the consumption of certain medicines and vitamins has influenced the readings. Calibration of the refractometer is necessary before testing.

Urine colour

Another method of testing hydration involves assessing the athlete's urine colour. The urine has to be collected and tested first thing in the morning or stored for several hours. It should be noted that collecting samples before and after a training session is a beneficial practice as it can underline the effect of the exercise on the sportsperson's hydration status.

Unlike the measurement involving a refractometer, assessing the colour of the collected urine is far more manageable. It can be done by any athlete, regardless of their background or technical expertise. However, it does require using a colour rating chart whose scale might vary depending on the publication that has made it available [2] [3].

There is no cost involved in performing this method. As such, a chart can be downloaded and printed from the internet for free. The test can be done on the spot or using samples preserved in a refrigerator. As for the accuracy of the technique, it is worth mentioning that medicines and vitamins have affected the correctness of the results over time. In addition, consuming certain vegetables, such as carrots and fruits, such as blackberries, might modify the colour of the urine. Fava beans, rhubarb, asparagus, and beetroot can also influence the findings.

Athletes interested in measuring their hydration levels using this technique are advised to avoid using a chart displayed on a computer or laptop screen as there may be differences in colour correctness.

Sweat analysis

Sweat patches can be applied to the athlete's skin to determine whether their hydration levels are on par. There are two kinds of patches available nowadays. Some are disposable, and others can be used time and again. Recently, several companies have developed a design that enables users to connect sweat monitors to a mobile app and analyse the results using their smartphones.

Instead of measuring the amount of fluid in the urine as a refractometer or the formerly mentioned colour analysis, such patches measure the electrolyte content of the athlete's sweat. Some of the expected electrolyte levels revealed with a sweat patch are sodium, magnesium, and potassium. Given that muscle cramping has been connected to low sodium, it is crucial for an athlete training for a competition to be aware of such figures to make the necessary adjustments to their dietary habits.

Laboratories can perform sweat analysis if the use of such a patch is impossible. The sweat has to be collected and shipped to the laboratory for further study in situations like this.

This method should be chosen by people who know how to eliminate more sodium during exercise than others. The technique can assist them in defining their nutritional requirements to replace any sodium deficits. Fluid supplementation is required to avoid the negative effects of hypohydration on performance and health alike.

Furthermore, it has been suggested that specific exercises and fitness routines can lead to sodium depletion more quickly than others, so they should be avoided or practiced after the athlete has hydrated using sports drinks.

The reliability of these patches is still a matter of debate. On the one hand, the results vary mainly because the patches are placed; they need to be set in sites such as the athlete's forehead, chest, or forearm, where the body perspires more heavily than in other areas. The results must be correlated with the intensity of the exercise, its duration, and the type of clothing worn by the user.

When it comes to ease of use, the sweat monitor is the most user-friendly one. It allows owners to utilize the product repeatedly and transmits the results to a mobile app via Bluetooth or Wireless. Some traditional sweat patches still have to be placed in a centrifuge to be collected and only then analysed. Such equipment limits athletes significantly, as such gear might not be readily available. Furthermore, sending the perspiration sample to a laboratory for further analysis might be less cost-effective. This last method may be better suited for research purposes.

Developing wearable multi-sensing patches for continuous sweat monitoring [5]could solve these user-related issues. These patches could measure both electrolytes and metabolites and transmit the levels they detect wirelessly to collect and store the data easily.

Conclusion

Even though two other methods can be used to test hydration, meaning sweat loss and sweat rate measurement, they are less preferred by actual sportspeople. The first involves measuring the athlete's body weight, which is why the accuracy of the results is lower when compared to the techniques described above.The sweat rate can be measured only in certain body parts, so the patches must be placed accurately and might fail to assess the loss of electrolytes efficiently.

Sportspeople can measure urine specific gravity and urine colour and perform a sweat analysis relatively quickly, avoiding expensive laboratory services. Furthermore, such tests can be done alone or with the assistance of a coach, which means that they are, above all, convenient.

The cost of portable refractometers can range from just under thirty dollars to a couple of hundred dollars, but auto refractometers used for research and scientific purposes can cost as much as four thousand dollars.

Printing a urine colour chart costs little to nothing, so it is the most cost-effective method of measuring hydration. Smart patches like Kenzen's ECHO are still in development, so it is difficult to tell just how economical or unreasonably priced they might be.


References

  1. ZUBAC, D. et al. (2016) Hydration status assessment among elite youth amateur boxers. J Sports Med Phys Fitness, 56 (6), p. 731-6
  2. ARMSTRONG, L.E. et al. (1998) Urinary indices during dehydration, exercise, and rehydration. Int J Sport Nutr., 8 (4), p. 345-55
  3. ARMSTRONG, L.E. et al. (1994) Urinary indices of hydration status. Int J Sport Nutr., 4 (3), p. 265-79
  4. REHRER, N.J. et al. (1994) The maintenance of fluid balance during exercise. Int J Sports Med, 15 (3), p. 122-125
  5. ANASTASOVA, S. et al. (2017) A wearable multisensing patch for continuous sweat monitoring. Biosens Bioelectron, 15 (93), p. 139-145

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About the Author

With a Ph.D. in veterinary oncology, Cristina VulpeĀ loves helping amateurs better understand the daunting terminology depicting current gear and equipment employed for scientific purposes. As an avid reader and tech enthusiast, she spends most of her spare moments in the company of a good book or checking on the latest advances in various scientific domains.