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Rehydration: The Key to Peak Performance During and After Exercise

 

by Julie Hansen, M.S., R.D., C.D.

Proper fluid replacement before, during, and after exercise can positively influence how you feel and how you perform.  Most people do not realize how quickly water can be lost from our bodies when exercising.  The heat production rate in active, exercising muscles can be 100 times that of resting muscles.

On the average, the body loses more than two liters of water each day through perspiration, urine, feces and respiration.  During exercise, sweat losses of up to three liters/hour are common.  Technically, dehydration occurs when body water loss equals one percent of body mass (performance is affected at a fluid loss of two percent).  For example, a 150 pound person becomes dehydrated after losing one and one-half to three pounds of body weight.

Thirst is an unreliable indicator of fluid needs after exercising in hot weather, partly because the intake of water quickly dulls the thirst sensation.  Further, rehydration with plain water dilutes the blood rapidly and stimulates an increase in urine production that leads to greater dehydration.

Rehydration will occur more rapidly when beverages containing sodium (the major electrolyte lost in sweat), are consumed.  Ingesting a beverage containing sodium allows the plasma sodium to remain elevated during the rehydration period and helps maintain thirst while delaying stimulation of urine production.  The rehydration beverage should also contain glucose or sucrose because these carbohydrates provide a source of energy for working muscles, stimulate fluid absorption in the gut, and improve beverage taste.

 

The following guidelines will help athletes maintain proper hydration during practice and competition:

 

  • Weigh in without clothes before and after exercise, especially during hot     weather.  For each pound of body weight lost during exercise, drink 2   cups of fluid.
  • Consume a sports drink containing sodium to quickly replenish lost body fluids.  The beverage should contain 5-8% glucose or sucrose.
  • Drink 2.5 cups of fluid two hours before practice or competition.
  • Drink 1.5 cups of fluid 15 minutes before the event.
  • Drink at least 1 cup of fluid every 15-20 minutes during training and competition.
  • Limit beverages containing caffeine and alcohol because they increase urine production and add to dehydration.

 

Try your own homemade sports drink:

5% Carbohydrate:

4 Tbs. sugar

4 cups water

1/8 tsp. salt

2 Tbls. lemon juice

 

6.5% Carbohydrate:

5 Tbs. sugar

4 cups water

1/8 tsp. salt

2 Tbls. lemon juice

Julie Hansen

Julie Hansen, M.S., R.D., C.D. is a Registered Dietitian and Exercise Physiologist.  She has been running competitively in road races since 1980 and competing in triathlons since 2005.  Julie currently teaches a Sports Nutrition course for Weber State University and a Weight Management course for the University of Utah.  She is the dietitian for the Weber State Athletic department and works part time as a dietitian for Kimberly Clark Corporation in Ogden, Utah and for Solstice Residential Treatment Center in Layton, Utah.  Julie also has a private nutrition practice in Utah working with individuals who want to lose weight, improve performance, lower cholesterol or prevent disease.

Google Buzz

Fueling for workouts and races over 3 hours long.

There are alot of runners and triathletes out there who are learning how to take in some fuel during events and workouts over an hour and that is great news! The not so good news is that as some of those athletes start going longer than 2-3 hours problems start occurring that didn’t happen before.  So what is going on here? Isn’t 1-2 gel packs an hour enough? Do I absolutely have to have an electrolyte supplement? More water? What?  Well, the deal is that for events shorter than 3 hours, you can almost fake it on not doing enough. You may feel kind of lousy by the end, by you will survive even though you are running very low on energy, fluid and electrolytes. That is because you should have enough stores of all of those things to make through by doing only minimal amounts of eating and drinking. But…especially after the 3 hour mark…EVERYTHING CHANGES! You just can’t keep up with how much you are losing unless you make a SERIOUS effort to eat and drink more.

While it is true that you are hopefully getting about 50%-60% of your fuel from fat during longer,slower events, you are still blowing through quite a bit of carbohydrate. Most any runner or triathlete will still be using a MINIMUM of 125 grams of carbohydrate an hour. Then, in the case of  a Half-Ironman triathlon, the fastest athletes can burn over 200 grams.per.hour! And since we only have about 400-500 grams of carb stored in our muscle tissue and liver, it is easy to see how quickly you will start running out even if you are eating some fuel.  Yeah, do that math for a second.  ”Let’s see…I take 2 gels an hour or one pack of Clif blocks so that is about 50 grams of carbs I eat in a hour. Okay, well if I am blowing through at least 125 grams, but probably more like 150-175, then I am running an hourly deficit of about 100-125 grams. So by the 3 hour mark, I will have used 300-375 grams of carb and running very very low in fuel and by the 4 hour mark, I will be done!”  Yep, all those feelings of being light-headed, sick to the stomach, heavy legged, cranky, crampy, slowing down and feeling like you have been hit by a bus  somewhere between the 2 and 3 hour mark does not always have to be the case. Does this ring true to anyone? Is it worth trying more? (Notice here the picture of Mirinda Carfree holding 2 gel flasks full of 100 grams carb each while on her way to running a 2:56 marathon at the end of Ironman Hawaii 2009)

Read More….

Google Buzz

Training Schedule Adjustments for Running Multiple Marathons

Question:

“How do i need to adjust my training schedule for running multiple marathons (one a month for 4 months). i haven’t been able to find training schedules for this kind of running. I don’t know when to taper, how to do speed workouts, etc. i am trying to get under 3:30 for one or all of the races. I also want to know how often i should do gu or gels during the race. i have run more than a dozen marathons, yet i still can’t figure it out. If you have any advice that would be great!

Oh ya, if you know of any running studies i could be a part of that would be awesome too.
thanks,”
Sherrie Wayment LOVE2RUN

Answer:

Hi Sherrie,

The short answer is yes, you would want to adjust your training based on the number of races you plan to run and the frequency with which you plan to run them. The marathon distance takes a toll on your body and without adequate recovery you will not be properly, rested, refueled and ready for the next one. That said, I would think seriously about running one per month, especially if you are trying to set a personal best. I am a pretty firm believer that you can only really “race” 2-3 marathons per year – the incredible effort it takes to do well in a marathon (training: including mileage and speed work as well as recovering adequately) is quite taxing. Not knowing your current training schedule, it is difficult to make specific suggestions or comments – I am also not a coach, and consulting with one would be a great place to start. Paul Pilkington [Lora Erickson, and Janae Richardson], [members] of UtahRunning.com’s expert panel [offer] coaching services and may be a great resource for you to develop a training plan specific to your needs.

Read More….

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