Its officially SUMMER!  For those of us in the Houston area, I think its been summer since about March.  Here, it went from pleasant to HOT in a matter of days without any time to acclimate to the change in temperature.  This means that our bodies don’t quite know what do to as far as sweating.  You’ll probably find that you sweat more than usual until your body gets used to it.

During the summer it is particularly important to pay attention to how much you are sweating when you are exercising outside or even working in your yard.  Studies have shown that as little as a 1 to 2% drop in body weight can impact your athletic performance.  Or, you can swing the other way and over-hydrate.  Studies have also shown that we can be pretty good at estimating how much we are drinking but we can’t estimate how much fluid we are losing through sweat.  Personally, when I’m doing triathlons I find that I tend to under-hydrate on the bike and over-hydrate on the run.  The result – a sloshy stomach accompanied by stomach cramps.  Not a fun way to do the run.

Most people are also spending time outdoors gardening, working on their house, etc.  Don’t forget the importance of hydrating when you are outside in the heat (regardless of activity type) for a period of time.

How can you monitor your hydration?  One of the easiest things you can do is to weigh yourself before and after you workout or before and after you work outside in the heat.  Both times you weigh, you should be nude (or in the same dry clothes) and dry (take a minute to towel off before stepping on the scale – don’t forget to towel off your hair, too).  For every pound you’ve lost, you should drink 16 – 24 oz of fluid over the next couple of hours.  Two pounds or so lost, I’m not concerned.  More than three pounds lost and I start to get concerned about dehydration.  Going in the other direction, if you find you are gaining weight, you could be running the risk of being over-hydrated and should consume a little less fluids.

For the athletes out there, you may have read that some studies have shown that high performance/professional runners are dehydrated when they finish a race.  I’ve heard people use this data to argue that you should finish a run dehydrated.  However, keep in mind that each person is different, but most people I know can tell a performance difference if they are dehydrated in the form of headache and/or just not feeling right.  To me, there is quite a difference between those professionals whose job is to run and those of us mere mortals who run/train in addition to our other jobs.  As people train, their bodies adapt to that training.  I’ve had the opportunity to run with Jeff Galloway a couple of times in 2000 and 2001.  I asked him about what he drinks before and during runs since he didn’t have any fluids with him.  At that time, he would drink a couple of cups of coffee before a long run and would be OK without other fluids on the run.  Now, how many marathons had Jeff run at that point?  More than I have fingers and toes I believe.  Therefore, for professionals and highly trained people (like Jeff), that may mean their bodies can handle performing in a dehydrated state.  For most others who are not training for hours every day, I’m not sure this is a good idea.

Finally, if you are exercising outdoors consistently, I’d recommend conducting a sweat trial every month or so.  A sweat trial can help you figure out how much you should be drinking and can help you figure out a starting point for salt/electrolyte intake. You want to do it on a shorter workout so you don’t have to also account for urine output. Here’s the steps (get out those calculators again):

1) weigh yourself nude/dry before your workout
2) weigh yourself nude/dry after your workout
3) multiply the amount of weight you lost by both 16 and 24 (it takes about 16 – 24 oz, maybe more to replace every pound of fluid lost)
4) To the two numbers you got in #3, add the oz you drank (both water and sports drink). Again, you get two answers.
5) Divide the numbers you got in step 4 by the hours of your workout. This gives you an oz per hour to shoot for. Then, you can break this into 4, 15 minute or 6 10 minute drinking intervals. Some people find that marking their water bottle every 2 to 4 oz helps them track how much they are drinking and when.  If the numbers you get are unrealistic (e.g. 80 oz per hour), then you need to determine how much you can realistically drink without negatively impacting your performance.

Second, is to look at electrolyte needs.  For every 4 cups (32 oz) the guideline is you need to take between 500 and 1000 milligrams of sodium. Some people need more, some less. This is a starting point. If you are crusty when you finish working out, you need to be on the higher end or perhaps even more.  You can and should get this during your workout through sports drink/salt tablets/etc.

Also, you should do sweat trials several times through out the year because we sweat differently in the spring than in the summer and fall.

Each of us needs a certain number of calories in a day to maintain our weight.  Eat less than that magic number over a period of days and you should lose weight.  Eat more over a period of days and you gain weight.  One way that helps people get their heads around this concept is to think about your daily calorie allotment as a “calorie bank account.”  At the beginning of each day, you have a certain number of calories to “spend” through the food and beverages you choose to consume.  How you spend those calories are up to you.  Do you really want to spend your calories on a Snickers bar or would you rather have an apple and save them for dessert later?