August is well underway which means many individuals are involved in various outdoor activities. This is great for both mental and physical health, though the increase in activity and warm temperatures can make it a bit more challenging to ensure we are consuming the proper amount of fluids to support both health and physical performance.
Inadequate fluid consumption can lead to hypo-hydration, commonly called dehydration. Even at small relative levels of dehydration (2-3% body weight loss) many individuals will experience negative effects such as early fatigue, cognitive and mood impairment, trouble tolerating heat, headaches, and nausea. Limiting net fluid losses to less than 2% of body weight is recommended to help minimize the risk of these negative effects.
Exercise is commonly associated with dehydration but did you know it is possible to consume too many fluids as well? Over-hydration (hyponatremia) is not nearly as common as dehydration but can be every bit as serious. It is caused, quite simply, by drinking too much fluid—and at it’s most extreme can cause death. Hyponatremia is more likely to take place during low-intensity endurance exercise where individuals may be making concerted efforts to ‘stay hydrated’, unaware that they are drinking too much.
So how much fluid do you need to maintain balance during activity? This is not as straightforward as you might think. Everyone sweats at a different rate, and this is highly dependent on the environment (temperature, humidity, etc.), individual fitness level, as well as the intensity of the activity.
Standard recommendations emphasize the importance of beginning your activity hydrated and consuming fluids regularly during activity to replace what is lost in sweat. Consuming 16-32 ounces of fluid each hour is typically adequate, though strenuous activity in hot environments can result in sweat losses nearing 64 ounces each hour!
The best way to determine your individual fluid needs is to weigh yourself before and after exercise. Try to drink enough fluids to maintain your weight. Thirst usually does a pretty good job of keeping us properly hydrated but may fall behind when sweat rates are high. The color of your urine (aim for pale yellow) is another good indicator of how well you’re keeping up with hydration.
Water is the best fluid choice throughout the day and for most activities lasting less than one hour. If your activity is greater than one hour duration you may benefit from a sports drink that will provide you with carbohydrates (sugar) needed for energy in addition to helping you replace some of the electrolytes (salt, primarily) that are lost in sweat. Look for sports drinks that provide 20~40g carbohydrate and 200~400mg sodium per 16 ounces of fluid. If you are a very heavy sweater or have a ‘salty’ sweat you may need to make an effort to consume additional salt to replace losses. Energy drinks and shots are NOT good substitutes for sports drinks.
Whether you are a competitive athlete or simply enjoy being active you will quickly experience the benefits of proper hydration. Listen carefully to your body and be aware of your individual fluid needs to maintain your hydration. To read more about nourishing health and performance please take a look at our summer edition of the Eating on the Run newsletter.