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Training Camp

posted Sep 15, 2008 to Featured Articles by FLmx
from the Sep 2008 issue

Column Name: Training Camp

Column Title: Quenched! Part 2

Written by: Kirk Layfield, MS, EMT-P

Ok, Lets pick up where we left off last month. How do you maintain hydration during training and competition? Let’s take a look at how to maintain fluid and electrolyte balance. At high exercise intensities in warm environments, it’s common for athletes to achieve sweating rates of .5-2 liters per hour. Unfortunately, although measurable decrements in performance will begin to manifest at as little as 1% dehydration, we generally do not “feel thirsty” until we are approximately 2% dehydrated. This fact alone suggests that an aggressive approach to hydration during vigorous exercise would measurably improve athletic performance.

However, in order to implement a suitable proactive fluid replacement schedule, you must first obtain a reasonably accurate estimate of fluid losses. The simplest way to do this is to weigh yourself before and after activity, and keep track of how much you drink during the activity.

Post exercise decreases in body weight (grams, ounces or pounds) will reflect uncompensated sweat losses. This number can be used to calculate additional fluid-replacement requirements that should be met over the course of a typical training session. He’s an example: if your post exercise weight loss was 100grams, you would need to replace 100ml of fluid, if your weight loss was 1oz, you would want to replace 30ml and if your weight loss was 1 pound, your fluid replacement would be ½ liter.

Obviously, if you engage in a variety of exercises or activities within a range of different environments, you need to repeat this procedure so that you can better customize a fluid-replacement schedule to accommodate the spectrum of training conditions.

Replacing fluids after exercise or re-hydration is vital to your success as an athlete. Complete post exercise recovery is strongly tied to food and fluid intake. In fact, at least one study suggests that eating prior to drinking water after exercise significantly enhances plasma volume and hydration status.

As with pre-hydration, eating foods containing sodium during the re-hydration period will help stimulate thirst and increase fluid retention. However, although humans appear to require proactive intervention to prevent dehydration during physical activity, we do not seem to need an aggressive approach to re-hydration after exercise if you have properly hydrated prior to training or your event. In most cases access to foods and fluids is all that most athletes will need to re-establish euhydration and electrolyte balance.

How about sports drinks? I am a firm believer that water is by far the most important thing we can drink but there are times when a sports drink can be beneficial. Even with liberal access to water, the longer we exercise, train or ride the higher the risk of both becoming dehydrated and developing dilution hyponatremia, an electrolyte imbalance that contributes to muscle cramping and gastrointestinal upset. If you plan to train at high intensities for at least 45 minutes to one hour, or at moderate intensities for longer periods, sports drinks are recommended fro minimizing fluid and electrolyte imbalances, as well as sustaining energy output.

The ergogenic advantage of carb-containing beverages over water is well documented for endurance events, and emerging research now supports their use in power sports. Further, the benefits of using sports drinks may be more far reaching than simply enhancing muscle-fiber performance. Exciting new studies in the area of neuropsychology suggest that as little as 1 or 2% dehydration during intense physical activity measurably hampers visual motor tracking, training focus and reaction time. These are decrements that can manifest even before the athlete feels thirsty.

Because exercising individuals tend to prefer taste, sports drinks have actually been shown to encourage fluid intake and help prevent exert ional dehydration better than water. It stands to reason that the use of sports drinks could also help to prevent the cognitive dysfunction and performance decrements that precede thirst. Lastly, for optimal results your sports drink should contain 20-30 mill equivalents of sodium chloride per liter, 2-5 mill equivalents of potassium per liter and 6-8% carbohydrates (high concentrations can slow gastric emptying, causing gastrointestinal upset).

Questions, comments or ideas for topics you would like to see covered in training camp, send them my way. Klayfield@yahoo.com