Just Breathe

With summer fast approaching and warmer days in store for us, runners need to take more caution in monitoring their hydration. While dehydration can occur during the winter months just from sweating and running in the cold, chances of heat injury increase in the spring and summer months with the onset of higher temperatures and humidity. Here is some useful information to help you prevent dehydration.

Sweatrate

Athletes can sweat at much as 2-3 liters and hour. Two liters of sweat is equal to 4.4 pounds (1 liter = 1 kg= 2.2 pounds) which can mean a loss of 3% in body weight an hour in a 150 pound runner (4.4/150= .03; .03X100 = 3%. To make matters more difficult, even if one hydrates properly, the rate of fluid absorption is slower than the sweat rate, so the runner is always battling some dehydration. Dehydration is the ultimate opposition in distance running as it leads immediately to fatigue and slower times.

Here’s how dehydration affects the body. Our blood has a fluid part called plasma and when we sweat, we lower our plasma levels. This in turn changes our blood from a easy flowing fluid into a very thick sluggish fluid making our heart have to work harder to pump this thick blood around. Eventually if dehydration is not countered with fluid intake and rest, the body can loss enough fluid to get heat illness which could lead to death.

One of the easiest ways to determine your sweat rate and how much fluid you have lost is to do the following: Weigh yourself before and after a run. Measure any fluid consumed during exercise (and any urine excreted which hopefully won’t happen during the exercise). Subtract your end of the run weight from your beginning weight, add in any fluid you drank and subtract any fluid you excreted and divide that remaining amount by time to get sweat rate per minute. Here is an example:

A body weight in kilograms before run 70.5 kg (1 kg = 2.2 pounds)

B body weight in kilograms after run 68.9 kg

C is change in weight A-B = 1.6 kg

D any fluid you drank add in +300 ml

E urine volume 100 ml

F sweat loss 1.6 kg +300 ml – 100 ml = 1800 ml sweat loss

Exercise time 60 min

Sweat rate 30ml/min

Knowing the amount of sweat you lost in a workout also helps you hydrate properly.

Pre-Workout Hydration

Keep in mind that fitness also helps in heat tolerance so if you have not trained much it is best not to try a race until you are fit. Also children and the elderly have less heat tolerance so these individuals even if well trained need to be more cautious in the heat.

1. Hydrate the day before exercise, a general rule of thumb is to take your body weight in pounds and divide it in half and that is the number of ounces of water to drink a day. Add in more ounces according to your sweat rate to account for sweat loss in training

2. Prior to competition, hyperhydrate with about 10-17 ounces of cold water 15-30 minutes prior to running. For events over 50 minutes, you can ingest a carbohydrate drink but make sure it is only 6-8% concentrated as higher concentrations can delay gastric emptying of fluids and cause stomach distress.

3. Avoid caffeine and alcohol the night before.

Hydrating During Your Run

1. Cold water is best if available and if the endurance event is less than 50-60 minutes.

2. If your event is longer, carbohydrate intake during competition can be a good energy source in delaying fatigue. The solution should still be only 6-8% concentrated to ensure rapid gastric emptying.

3. The fluid should also have small amounts of electrolytes if your event is greater than 4-5 hours in duration. This length of time can lead to excessive electrolyte losses. Gisolfi recommends 460-690 mg of sodium per liter and another group recommended 120-225 mg of potassium per liter, many of the sports drinks available during marathons and long races have these amounts in them.

4. Rehydrate with 6-8 ounces of cold fluid ever 10-15 minutes if available. A normal mouthful is about 1 ounce. This amount can offset moderate sweating but heaving sweating will exceed this however if one tries to drink more it can become too uncomfortable, so it is a delicate balance to play.

5. Drink at water stops before you feel thirsty as our thirst does not develop until about 1-2% of our body weight has been dehydrated and by that time, performance will be dropping.

Post Workout Hydration

1. Ideally weight yourself before and after the race or have an idea of what our weight loss is and try to consume about 24 ounces of fluid for every 16 ounces lost during the race.

2. Ingesting carbohydrate drinks within 1 hour of finishing also helps replenish your glycogen stores faster. If you wait longer then the effect is lost

Caution:
Keep in mind your own body and during training, try out energy drinks that you know are going to be available during your race and see how they agree with you. Some runners make up their own fluids and put them in bottles and ask the race director to have them out on the course for them.

Also too much water ingestion, especially in long races where electrolyte losses can occur, may lead to a dangerous condition known as hyptonatremia or subnormal levels of sodium in the bloods. Small female runners have been especially at risk. Signs are dizziness and light headedness and head ache and if untreated can lead to death.

Signs of Heat Illness

It’s important when exercising in the warm months to not only hydrate correctly but to know the signs of heat illness.

Early signs:

Early signs are goosebumps, this indicates dehydration. Fatigue and light headedness and dizziness can occur. Immediately stop, go into a cool area and get fluids.

If early signs are ignored, one can appear intoxicated and start stumbling and loss consciousness. Never give fluids to an unconscious person and get them immediate attention. Many races have IVs set up along courses and can get runners rehydrated immediately. Do not hesitate to stop and get help rather than try to finish your race.

If you listen to your body, know your sweat rate, consume adequate fluids and pay attention to heat warnings, you can have a safe enjoyable running experience in the heat.