Medical Advice

THE HYDRATION PENDULUM

Many areas of performance training in athletics go through a progressive change of beliefs regarding best practices for training that simulate the back-and-forth pattern of a pendulum.

A belief is formed about an area of training.

This belief in the method of training is popularized designating the lift of the pendulum to one side.

The belief is challenged either through popular media or through research (often both) and the belief in how to best train changes swinging the pendulum toward its’ opposite peak.

Often this shift in beliefs on training methods is exaggerated or inaccurate and a further change is instigated by research and/or by popular media. The pendulum swings back toward the original starting position.

Sometimes the pendulum settles in the middle, sometimes it swings all the way back to the initial training concept, and sometimes it swings toward a third completely different belief regarding training methods. Frequently these initial swings of the pendulum will be to extremes of difference and as the pendulum continues to swing it will eventually settle into a particular area.

The beliefs regarding hydration methods of distance runners have followed this pendulum model during the recent past. Only a few decades ago the importance of proper hydration was not fully realized. The degree to which dehydration affected performance and the rate at which heat illnesses were caused by dehydration were largely overlooked. You were thought to be ‘tough’ if you went without fluids and were a ‘weak’ athlete if you had to constantly have water breaks. With the significant rate of problems caused by the dehydration of athletes, recommendations shifted dramatically.

The principle that distance runners should hydrate as often as possible and should never reach a state of thirst was proponed based on research regarding performance training, hydration, and heat illnesses. What followed was a drop in heat illnesses but a rise in a previously rare athletic illness, hyponatremia (overhydration or, more accurately, dilution of electrolytes due to excessive fluid retention). Where runners were once not hydrating enough, now some runners were drinking fluids to excess.

A closer examination revealed that those susceptible to hyponatremia were those on the course for approximately four hours or more and were drinking significant amounts of fluid along the way. Further, women were found to be more susceptible than men as women typically have a lower sweat rate than do men. The constant consumption of fluids over a significant amount of time combined with the inability to dispel the fluids at the same rate as consumption caused an elevation of fluid levels within the body leading to illness.

So what should a runner do?

According to the International Marathon Medical Directors Association (IMMDA) it is far simpler than you might expect. Trust your body and drink when it tells you that you need fluid. Drink fluids when you are thirsty.

There are traditional training methods that teach you when you are thirsty you are already dehydrated. That is not necessarily true. Certainly you can be thirsty and be dehydrated but with the initial onset of thirst you are well within the boundaries of peak performance levels. Your running times will be unaffected if you are consuming fluids near the onset of thirst.

To truly get a better grasp on your fluid use and your potential fluid intake needs it is possible to get an estimate to help you formulate a running hydration plan. (It is important to note that during running not only fluid is lost but electrolytes are lost as well. The consumption of sports drinks, fruits, and possibly gel for events lasting greater than 1 hour should be incorporated into your plan.)

Weigh yourself nude immediately before a run.

Run at pace for one hour keeping track of how much fluid you drink.

After the run undress, towel yourself off so that you are dry, and weigh yourself again.

Subtract your after-run weight from your pre-run weight and convert this number into ounces (1 pound equals 16 ounces). Take this number and add the weight of fluid you drank.

Take this total and divide by four to estimate your fluid loss rate for every 15 minutes. This will provide you an estimate on how much fluid you may need to drink every 15 minutes during your run.

Example:
188 pounds pre-run weight. Consumed 16 ounces of fluid during the 1 hour run. 187 pounds post-run weight.

188-187=1 pound lost during run. 1 pound =16 ounces. 16ounces lost weight +16 ounces of fluid consumed = 32 ounces.

Sweat rate per hour = 32 ounces.

32 Ounces divided by 4 = 8 ounces. Sweat rate per 15 minutes is 8 ounces.

Approximately 8 ounces per 15 minutes would be consumed to maintain fluids lost.

Note that this estimate can vary depending on the weather conditions, running conditions (hilly versus flat), and choice of clothing. Simulate race conditions as closely as possible for the most accurate estimate.

With this strategy in mind, remember that current recommendations and best practice for hydration during extended running events is to consume fluids when you are thirsty.

Be sure to practice your hydration and calorie intake plan as everyone is different and have slightly different fluid and caloric demands during long distance running events. Have a running plan and practice it, adjust it as needed during your practice/training runs, and prepare yourself to have the best day of running on race day.

Happy training!