 Ask an inSHAPE personal trainer. I'm training for a marathon coming up in four weeks, and read an article last week about over hydration. I'm worried about drinking too much or not drinking enough, and was hoping you could provide some insight into proper hydration for a marathon.
When you consider that 60% of our body is made up of water, it is easy to recognize how essential hydration is to our survival. Beyond the basic maintenance of bodily functions, when we exercise, body temperature and heart rate rise, and the body requires additional hydration to maintain equilibrium. However, as this critical need for hydration entered the national consciousness, with most people aware of the 8-glasses-a-day rule of thumb, in recent years there has been a growing number of cases in which athletes OVER hydrate for performance. And as marathon season moves in with the cooler fall weather, the risk of over hydration is even more prevalent.
Hyponatremia
Over hydration (hyponatremia or water intoxication) occurs when you ingest more fluid than you lose through sweating and urination and dilute your blood's sodium levels. As cells draw water from the blood in an attempt to equalize the sodium level, they can swell. Unfortunately, symptoms of early water intoxication are similar to those of dehydration: muscle weakness, fatigue, dizziness, and nausea. Also, if this cellular bloating occurs in the brain, it can be fatal. On the other hand, with a level of exercise as long and grueling as running a marathon, it is important to keep the body properly hydrated so that the cardio-respiratory system can effectively pump the blood around the body and deliver sufficient oxygen to the working muscles.
Marathon day is NOT the time to figure out this balance. With four weeks remaining, you have one last long run, so read on to learn how to gauge your body's hydration levels during long-term exercise.
Hourly Sweat Rate
So the question is: How can you be sure that you're drinking enough to keep the body functioning at top level, while avoiding the risk of flooding your cells? A good basis for your hydration plan should be focused on avoiding weight gain or loss from fluid intake. You can figure this out by determining an hourly sweat rate. One way to gauge your hourly sweat rate is to figure out the difference in body weight plus your drink volume during exercise.
1. Wake up early, fuel and hydrate as usual. Just before you run your last long run, take off all of your clothes and weigh yourself. Write down the weight.
2. Run your 18-20 miles (and yes, if your race is in 4 weeks, you should be running that far this weekend), which will take you roughly three hours.
3. Hydrate as usual during your run but do your best to keep track of how much you take in.
3. When you return, take off all of your clothes and weigh yourself again.
Depending on how much post-run fluid you take in before you weigh in again, you want to finish up just under your starting weight by about a lb. Faster runners who poorly hydrate can lose as much as 3% of their body weight during the marathon (4-6 lbs). This is largely fluid loss, which is why experts suggest that you replenish fluids every 15-20 minutes with about 8 oz. If you have lost more than roughly 1 lb, which we can attribute to fat loss during a run this long, you need to bump up your fluid intake, remembering that 1 lb = 16 oz of fluid.
If you gained weight - you are definitely drinking too much during your runs. Speak to your coach asap or let us know if you would like help from our team.
Electrolytes and Carbohydrates
Finally, don't forget that replacement of electrolytes and carbohydrates is just as important in keeping you going. When you sweat, in addition to the water lost, you also lose crucial electrolytes, including sodium, potassium, calcium, and magnesium. You therefore want to include fuel sources which digest easily, including bars, fruit, bread, and/or sports-specific food products as suggested by your training team. They will fuel your active muscles with carbohydrate energy, and the electrolytes will help replace some of what is lost in sweat.
A steady combination of drinking water in direct relation to how much you sweat out and replacing essential electrolytes and carbohydrates should keep you fueled throughout the race. Be sure to pay attetion to the signs, come up with a plan and stick to it. Oh, and a big CONGRATULATIONS on making it through your training. Race day is so much easier than the final couple of months of marathon training, and three weeks out, you start to taper your runs. This means that you run fewer miles, allowing the body to fully recover from all of the wear and tear you've put it through to prepare. Remember to eat smart, sleep well, and practice your mental preparedness in these last weeks.
If it's NYC Marathon you're running, we'll be out there. inSHAPE Owner, Kim Watkins, coaches the NYRR Team for Kids charity group, and will be at the start line if you need any last minute tips.
 Tip of the Week: GO for Something That You Don't Know!
Our nutritional angle is pretty straightforward: eat real food and try to ensure that most of it comes from plant sources. At inSHAPE, we constantly try to drive home the notion that the simplest solutions often work the best. By eating mainly the items that grow in the ground, you are far more likely to fill up on nutrient rich, fibrous food. Most Americans rely on boxed or otherwise processed foods that spike insulin levels and make the body feel unsatisfied, in turn, causing them to eat more.
These food products also cook down the fresh ingredients that purport to offer health benefits to the point where they offer very little in the way of nutrition. What the manufacturers do, instead, is fortify the product so that you get the nutrients the box says you get, but no matter what they write, the box of organic cereal is likely still just a box of cereal.
This week's tip is super easy - we aren't telling you that every single thing that you eat needs to be completely fresh and whole. The real world dictates that we cut some corners sometimes, but do this one thing. When you hit the market this week, pick up something fresh that you do not know. The fall is a great time for root veggies in all shapes and colors, there are exotic tropical fruits that look like cartoon characters, and greens of all shades are stuffed in the produce aisles. Pick something. Write down its name, do a little diligence on it, and let us know how it goes. Have fun.
inSHAPE is committed to your successfully active lifestyle, and if you need any assistance getting started with a fitness program or nutritional regimen, please let us know. Give us a call (212.362.1001) or send an email (info@inshapellc.com) so that we can help you and your heart stay fit and healthy. Click here for last week's edition, and check out our blog for a new in home workout each week.
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