Energy vs. Sport Drinks

May 27, 2011 By Leave a Comment

Summer is here and with it the necessity to maintain adequate hydration. However, an article recently published in Athletic Business suggests energy drinks may be harmfully replacing water and sport drinks as a source of rehydration, particularly in young athletes. The reason proposed for this trend is thought to result from individuals looking to maximize energy and thus performance.

Caffeine, a common main ingredient in energy drinks, often combined with an assortment of herbal stimulants may cause an individual’s heart rate to increase. However, heart rate naturally increases in response to physical activity. Therefore, a combination of caffeine and exercise will result in an abnormally elevated heart rate response. Furthermore, heart rate will increase when blood volume decreases secondary to sweat loss and inadequate rehydration as well as rising environmental temperatures.

Energy drinks contain a very high concentration of natural and/or artificial sweeteners that reduces the amount of fluid absorption into the blood. Sport drinks, however, have a small concentration of sweeteners and common electrolytes such as sodium (Na), potassium (K), and magnesium (Mg) that allow for adequate absorption and hydration. As suggested above, reduced fluid absorption will lower blood volume and increase heart rate. Additionally, reduced absorption will lead to intestinal cramping, discomfort and ultimately reduce performance.

The concern of an abnormally elevated heart rate during physical activity is that the high rate may lead to an unhealthy arrhythmia which was indicated by Michael Popke to have already resulted in the death of two Virginia high school athletes. The American College of Sports Medicine (ACSM) has established a position stand for hydration during physical activity. Current guidelines suggest drinking approximately 2 cups of water (16oz) about 1 ½ – 2 hours prior to activity, ¼ cup of water every 10-20 minutes of light to moderate activity or ½ cup of water every 10-20 minutes for more vigorous activity, and 2 cups of water per pound of weight lost following activity. Additionally, if activity exceeds 90 minutes, the use of sport drinks is recommended.

Stay hydrated, stay safe and have fun.

Written by:
Adam Reece, MS CSCS, NSCA-CPT

References:

Popke, Michael. Buzz Kill. Athletic Business October 2010. Volume 34 (10): 68-70.

ACSM Position Stand: Exercise and Fluid Replacement. Volume 39(2): 377-390.

Hydration

June 22, 2010 By Leave a Comment

Importance of Hydration

While the majority of the general public understands that water plays many key roles in our day-to-day activities, many may not realize that our bodies are composed of nearly seventy percent water!  It may not seem necessary to always be aware of how much water we put into our bodies, but even a two percent decrease in water mass can begin to have detrimental effects on the human body’s performance capabilities.

It is be especially important in the blistering Arizona sun to keep yourself well-hydrated, as your body needs a continuous source of water to keep its core temperature down.  Heat is shuttled form the core and brain to the capillaries of the arms ands legs which are located closer to the surface of the body, allowing the blood to cool. This helps regulate the amount of heat that that our vital organs must endure during exercise, or even just daily living in over 100-degree weather. The well-know “rule” of drinking eight glasses of water per day actually only accounts for the amount needed to maintain the water content of a normally functioning body. Water is constantly being excreted form the body whether through regular urination, sweat, or even saliva being expelled from the mouth. So, although eight 8-ounce cups of water a day is a perfect baseline, if you are exercising or live in an extreme environment, it is always beneficial (if not necessary) to ingest a few extra cups of water.

Some simple signs of dehydration include thirst, decreased sweat accumulation, slight to severe light-headedness, and it is usually accepted that if you feel the need for a drink you are already slightly dehydrated!  Maintaining ample water intake helps the body run more efficiently just as oil in a cars engine helps the car run more smoothly. Proper hydration can also assist your metabolism immensely, as water is required in order to break down fat and glucose molecules during exercise. While everyone is prone to dehydration, children are especially susceptible when they are exercising. Although their bodies do not produce the same amount of sweat as an adult, they are already working at a higher capacity of their maximal effort. So, a child that is even slightly dehydrated is adding a great deal more stress to their body than an adult at the same level of hydration. Most of the time children do not know the importance of ingesting water, and are not conscious of their need for it even while exercising. The trainers at the H.I.T Center in Mesa can help explain the importance of hydration to children and anyone who is looking to become more knowledgeable in these hot summer months.

Basic guidelines for water intake:

http://www.thebeverageinstitute.com/hydration/hydration_guidelines.shtml

Jacob R