Dehydration is a serious problem, especially when talking about athletic performance. Your body needs water in order to operate on the most basic of levels. Without proper hydration your body can suffer mild to severe physiologic compromise. Weight loss of 1-2% of your total body weight can signify dehydration and will show signs of decreased performance. At a 3% loss you will start to experience heat cramps and a moderate to severe decrease in performance. Anything over a 5% loss puts you at risk for heat stroke. Dehydration actually occurs before the onset of thirst. Therefore, if you feel thirsty you are already dehydrated! Dark urine (which is more concentrated that light urine) is a sign that you are on the way to dehydration. Other signs of dehydration include headache, nausea, and light headedness. You are in trouble if your body stops sweating and you display signs of dry/hot skin. This may indicate that you are showing signs of heat stroke and should cease activity and seek medical attention immediately. A general guideline for daily fluid consumption is eight cups per day (8x250ml). Don’t forget you get water from other sources than just the tap. Food actually accounts for 20% of most people’s daily water intake. A handy online calculator for hydration needs can be found at www.eload.net
The world of athletic hydration can be confusing. There are many different companies that recommend a specific product before, a different product during, and another product after exercise or sport. But what does the evidence say? Dr. Lawrence Spriet, a well known researcher from the University Of Guelph, outlines three important components of sport drinks.
You must maintain periodic fluid consumption before, during, and after exercise. Letting yourself go to a state of thirst may decrease performance
Your body needs carbohydrates to perform at peak levels. A sports drink that is approximately 6% carbohydrates is about the maximum amount your stomach can handle quickly. Therefore don’t bother putting the extra scoop of Gatorade in your water bottle. Also consider how carbohydrates affect calorie intake. A drink loaded with carbohydrates is usually high in calories. It is important to individualize your carbohydrate intake based on your weight and calorie requirements. One study indicated that even swishing your mouth with a carbohydrate loaded drink may improve performance because of the stimulation of certain centers in your brain!
Alex Hutchinson, Ph.d and sports columnist for the Globe and Mail, reports that electrolyte replenishment is only necessary for people who exert themselves at high levels for durations of over an hour. Your body does not need extra salts or electrolytes during an athletic event unless the event is longer than an hour. However, recovery blood volume (how much blood you have to go to your muscles after exercise) was improved with drinking an electrolyte beverage after exercising. This may help improve oxygen and nutrient transport to muscles.
It is important to select your drink wisely, do some research and see what works best for you. It is also crucial to train the way to race or play sports and this includes training your stomach to use fluids, carbohydrates and electrolytes during activity. Don’t wait until game day to properly hydrate. Start now and enjoy the benefits of a well working system to help you make the best of all your hard work training. Good luck and drink up!
E.S Chambers et al. Carbohydrate sensing in the human mouth: Effects of exercise performance and brain activity. Journal of Physiology. (2009). 587 (8), 1779-1794
Dolhmann, B., Knudsen, B., Nielsen, B., Sjogaard, G., Ugelvig, J. (1986). Fluid balance in exercise dehydration and rehydration with different glucose-electrolyte drinks. Journal of applied Physiology. 55: 318-325
Hutchinson, Alex. (2011). Which comes first, cardio or weights? Toronto, Canada: McClelland and Stewart.
Riley, C.O., Wein, D. (2011). Measuring hydration status in athletes. NSCA performance training journal. Vol 9, issue 5