Matt Poe uses an existing client, "Ned The Golfer", to explain the considerations and fluid requirements for athletes with comments about Gatorade’s new “Endurance Formula”.

A Discussion On Fluid Intake and Gatorade's New Endurance Formula

By Matt Poe, MS

Matt Poe > Let’s pose three questions for this discussion! 

First let's look at the profile of "Ned The Golfer"
 

Beginning weight: 146.5 (66.59kg)

Ending weight: 145 (65.91kg)

Fluid loss: 2.5 pounds (1.14kg) weight loss (consumed 16 oz of fluid)

Sweat rate: 40 oz/hour
 

PART 1:   Based on the recommendations in the literature what is the average amount of fluid you estimate that Ned requires each day?  How would you recommend Ned obtain this fluid (type of fluid(s), consumed in one sitting/multiple sitting, etc). 

THEN, consider the results of the sweat loss test- do your estimates change?  (in other words is Ned a typical sweater, a heavy sweater of a light sweater?

Ned lost 1.18 liters (40 oz) of fluid in an hour of exercise.  Based on current research, I would recommend that Ned consume from 5-8 liters of water each day (1).  During golf tournaments in warmer climates I would even recommend 8-10 liters/day as his losses would tend to be higher.   This may seem a bit high but keep in mind that he is outside for prolonged periods in humid and hot conditions both for practice time and during competitions.  Consuming much more than 1.2L/hr can be quite difficult thus consumption before and after practices and competitions is vital (1,2,3).  A 16 oz drink would be perfect prior to exercise as that would meet the 6-8 ml per kg of bodyweight recommendation (2). 

Ned appears to be a typical sweater thus my estimates for fluid intake are not affected by this single variable (2).  The main variables that will affect Ned’s loss of fluid are the temperature and humidity and the level of exercise.  More strenuous golf courses/tournaments would require higher levels of consumption.  The research states that negative effects begin to occur after a 2% body mass loss due to sweat loss (2,3,5,7).  Much of the research recommends between 1.2 and 1.6 L/hr as that is close to the gastric emptying rate and much more would cause GI discomfort (3,4).  I would recommend Ned reach these consumption goals via sports drinks that contain the proper electrolyte balance or water while consuming granola, trail mix, or the like (6).

PART 2: Ned decides to spend the next 6 weeks in Miami Florida, and do all of the exercise outside between 8am and 12pm each day.  Again based on research how, if at all, would your recommendations from #1 differ? 

According to The Weather Channel website the average temperatures for Miami, FL and Nashville, TN are relatively close during the golf season(8).  The average humidity of those same two cities are relatively close as well over that same time period(9).  The good news here is that Ned will be used to the humidity which is a gigantic hurdle for those who are not acclimatized to the heat and humidity. Considering my original recommendations, if Ned were to encounter warmer days and higher average temperatures in Miami in comparison to Nashville, I would make Ned aware that he might consider an increase in his consumption of fluids by a liter or so to combat these changes. Practicing earlier or later in the day is not a viable option as he will most likely be competing in the hottest parts of the day.

PART 3: Gatorade now markets Gatorade Endurance.  Powerade plans to bring a similar product to the market (it is currently available in some markets).  Is this just marketing hype, or is there actually a physiological benefit for active individuals to utilize these beverages compared to “traditional” Gatorade/Powerade/Cytomax/etc? 

Gatorade and Gatorade Endurance do differ in the amount of sodium and potassium.  Gatorade original has 110 mg of sodium and 30 mg of potassium; whereas, the endurance formula has 200 mg of sodium and 90 mg of potassium and 6 mg of calcium and 3 mg of magnesium (10).  These increased levels of nutrients are important during longer, more intense exercise (6).  Based on this information, I would tend to say that there is a physiological benefit from these beverages as opposed to solely being “hype”, but more research seems  to be needed in this area.  There are less expensive options and more expensive options to maximize recovery.  One’s body must be “trained” to utilize the increased nutrients in the endurance formula.

References

1. Sawka MN, Cheuvront SN, Carter R. Human water needs. Nutr Rev.  2005:63;30-39.

2. Shirreffs SM, Sawka MN, Stone M. Water and electrolyte needs forfootball training and match-play. J Sport Sci. 2006:24;699-707.

3. Kovacs MS. A review of fluid and hydration in competitive tennis. Int J Sport Physiol Perf. 2008:3;413-423.

4. Maughan RJ, Watson P, Evans GH, Broad N, Shirreffs SM. Water balance and salt losses in competitive football. Int J Sport Nutr Ex Metab. 2007:17;583-594.

5. Palmer MS,  Spriet LL. Sweat rate, salt loss, and fluid intake during an intense on-ice practice in elite Canadian male junior hockey players. Appl Physiol Nutr Metab. 2008:33;263-271.

6. Shirreffs SM, Aragon-Vargas LF, Keil M, Love TD, Phillips S.  Rehydration after exercise in the heat:A comparison of 4 commonly used drinks. Int J Sport Nutr Ex Metab.2007:17;244-258.

7. Maughan RJ, Shirreffs SM. Development of individual hydration strategies for athletes. Int J Sport Nutr Ex Metab. 2008:18;457-472.

8. Average Temperatures for Miami, FL and Nashville, TN. The Weather Channel. www.weather.com. Accessed June 15^th, 2010.

9. Average Humidity for Miami, FL and Nashville, TN. National Climatic Data Center. http://ggweather.com. Accessed June 15^th, 2010.

10. Nutritional information Gatorade and Gatorade Endurance.  Gatorade.  www.gatorade.com. Accessed June 18, 2010.