Hydration and nutrition are vital components of training for a marathon or half-marathon in any location. But in South Florida’s heat and humidity, it’s even more crucial to replenish your body’s carbohydrates and fluids during long-distance events.
Even with the cooler temperatures forecast for this Sunday’s 2015 Miami Marathon and Half Marathon, proper hydration is essential.
Many of the runners at Sunday’s event have trained for months, compiling hundreds of miles and conditioning their bodies to restore the key nutritional elements lost during and after running. But during the actual event, both amateur and professional athletes tend to work even harder, with additional adrenaline pumping when the starting gun fires for the long-anticipated race.
Fluid needs are highly dependent on an individual’s physical conditioning, as is the need for digesting anything stronger, such as those widely-available “energy” or “power” gels that carry about 100 calories of carbs, with sodium, potassium and sometimes caffeine.
Occasionally, first-time marathoners tend to overdo it, drinking too much and creating stomach upset. Research has found that most runners’ stomachs can empty only about 6 to 7 ounces (180 to 210 ml) of fluid every 15 minutes. That’s about 24 to 28 ounces (720 to 840 ml) per hour.
“By the time you get to the event, you should know what you can tolerate in terms of fluid intake,” says Osnat Shmueli, M.D., a Board-certified family practitioner, with the Baptist Health Medical Group. “Since the Miami Marathon is in January, local runners most likely trained in the heat and humidity going back to the summer months.”
Dr. Shmueli says it’s important to drink sports drinks, not just water. The carbs in sports drinks help restock the body’s spent energy. Most of these drinks will also replace the electrolytes lost to sweat, helping prevent hyponatremia (low blood-sodium level caused by excessive water intake). Sports drinks could also diminish the need for gels, which are more likely to cause stomach upset.
Here are five general hydration/nutrition tips for long-distance runners, keeping in mind that all runners have individual needs, depending on their conditioning and overall health:
Pre-Race Hydration
On the morning of the marathon, make sure to drink about 8 to 16 ounces of fluid to properly prepare. But you probably should stop drinking about one hour before the start to avoid early stops along the course.
A Cup Every Other Mile
A general guideline for marathoners is to drink 3 to 6 ounces of fluid every 15 to 20 minutes. This averages out to grabbing a cup of water or a sports drink every other mile. This depends on how crowded those water stops are during the race. Additionally, you may need to drink more if the weather is hotter than usual.
Know Your ‘Sweat Rate’
The most accurate way for figuring out your fluid need is to take a sweat-rate [1] test during your training. Weigh yourself without clothes before and after a one-hour run. Convert the amount of weight lost to ounces to figure out your sweat rate per hour. A loss of one pound means you sweated about 16 ounces of fluid (assuming you didn’t drink any fluids during the run. Otherwise, you would take into account any fluids taken). You should try to replenish fluids at a rate of about 16 ounces per hour.
Chase Your Energy Gels with Water
If you take those “energy” gels with a sports drink, then you risk ingesting too much sugar, which can cause stomach cramps or even diarrhea. If you take gels, chase them down with water. Remember that sports drinks generally provide the same electrolytes that are in gels.
Make a Plan for Race-Day Hydration, Nutrition
Most runners carry with them water, sports drinks or gels in case the volunteers along the course run out of cups or those stops get too crowded. Develop a plan so you know what and when you’ll eat and drink. Make sure that includes drinking and consuming calories within 30 minutes to an hour after the start. You shouldn’t wait too long before starting to hydrate properly.