Friday, January 14, 2005


Hydration Puzzle??

Some good reminders and suggestions from on the issue of hydration. As endurance athletes we know full well how this can alter your race and training performance.

Ask the Tri Doc: optimal hydrationBy Dr. Jeff SankoffDear Tri Doc,
I just finished a marathon and all went well, expect I had to make two pit stops in the first half. I drank 16 ounces when I got up three hours before the marathon and 12 ounces more the hour before.
Should I skip the 12 ounces the hour before and just make sure I drink during the marathon?

The short answer: Your body will not store excess fluids for later use. What goes in over and above what you need will most definitely come out.

The long answer: One of the fundamental errors that many athletes make irrespective of their level of experience is poor fluid management. More often than not, the problem involves inadequate fluid replacement. Fluid and electrolytes are lost via increased sweat production and excess respiratory losses during strenuous exercise. Athletes who fear losing time will frequently choose to skip aid stations, which can lead to dehydartion.
Unfortunately, with dehydration comes a dramatic reduction in exercise efficiency, and so any time saved by skipping that water stop is ultimately lost.

In order to avoid dehydration, the best strategy while racing is to hydrate adequately such that fluid intake closely matches fluid losses. The amount ingested can be slightly less or slightly more than the actual losses, but if the amount is starkly different one way or the other, problems will ensue. Too little fluid replacement results in the aforementioned dehydration, while too much can cause electrolyte imbalances and gastrointestinal distress.
A complementary strategy espoused by many coaches and athletes is to maximize hydration status in the days before an event. This theory has athletes drinking copious amounts of fluid and ingesting larger-than-normal amounts of salt for several days leading up to an event. While in essence this strategy is a good one, it is misunderstood by many. The goal of this exercise is to arrive at the start completely hydrated. But many have mistakenly come to believe that the goal is actually to arrive over-hydrated, with an excess store of fluid that will carry them through the race with less fluid intake required. As a result, it is not uncommon to see athletes gulping down large quantities of fluid in the hours before a race start, only to see them soon after jumping in and out of porta-potties as you pass them by.

The fact of the matter is our bodies prefer to be in a normal state. Any deviations from this state will bring about various mechanisms to restore the norm: a process called normostasis. If we become too hot, we have systems to cool us down. Too cold and there are systems to warm us up. When we eat, the chemistry of our blood is altered: glucose, protein and fat levels all rise so several systems kick into action to restore the natural order.
When any of these systems fails to work properly, disease ensues. For example, if our pancreas fails to secrete insulin, glucose levels remain higher than normal, and the complications of diabetes will arise over time.

The same can be said for both water and sodium balance. Our kidneys are finely tuned machines, which in conjunction with various other organs, constantly work to maintain sodium and water normostasis. Unlike with fats, sugars and proteins, our bodies cannot store excess amounts of either water or sodium, and so the kidneys must maintain balance. Thus, when we drink too much our kidneys rapidly eliminate the excess. If we ingest too much salt they do the same (note: higher-than-normal levels of water or salt are toxic and can cause organ dysfunction, specifically of the heart and brain). On the flip side, since we cannot store water or salt, if we lose too much of either the kidneys cannot produce more nor can they liberate any from some stockpiled quantity restore normostasis. In this case the kidneys act to conserve both water and salt in an attempt to limit further losses. However, losses through the skin and lungs will continue unabated. The only solution is to ingest more.

What does this mean for Jim and other athletes who try to maximize their hydration status prior to a race? There is no question that it is ideal to toe the start line in a state of maximal hydration and sodium balance. For this reason, the conventional wisdom of taking on fluids and salt in the days before a race is valid. Furthermore, drinking several hours before the race start is also advisable. The mild dehydrated state that occurs overnight during sleep will be remedied, and any excess fluid will be simply eliminated prior to the race start. However, taking in excess fluid in the hour before the race start will confer no advantage whatsoever. It will simply be eliminated before it is actually needed. Thus, Jim should continue to drink the 16 ounces of fluid several hours before the race (more than this is unnecessary), but he should reconsider the 12 ounces in the hour just before. Instead, regular fluid intake during the race should begin early and should be continued right until the end.

Train hard, train healthy,Dr. Jeff Sankoff

Dr. Jeffrey Sankoff, MD, FRCP(C), is a triathlete, a member of the Leukemia and Lymphoma society's Team in Training and ER physician based in Denver, Colorado. To learn more, or to make a donation to the Team in Training, visit Sankoff’s Web site.

Comments: Post a Comment

<< Home

This page is powered by Blogger. Isn't yours?