Trail Food

[AlanK]

Regarding electrolyte replacement: It has been known for a long time that a person loses electrolytes, especially sodium and potassium, along with water in sweating. Exercise can cause a lot of sweating. If you drink water, you can replenish much of what you lose. However, your electrolyte concentrations go down because you are diluting what was left. As Ellen said, that can be very bad. People have died in activities like marathon running from this cause. It's harder to kill yourself that way hiking, although I'm sure a determined person...

Nowadays, this is pretty well known and there are competing brands of electrolyte replacement drinks. They are a relatively recent phenomenon. Back in the 1960s, the University of Florida developed Gatorade for its football team. I believe it provided the University with lucrative patent income for a time. There were people who disdained Gatorade because it seemed originally to be flavored salt water. That led to other approaches.

Bill Gookin was a 40+ runner who competed for the San Diego Track Club. My dad used to run against him back in the day. Gookin was a chemist who analyzed his own sweat and formulated a drink to replace the electrolytes he found. Gookinade was originally ERG (Electrolyte Replacement with Glucose). We technically-inclined types thought this was a much better approach than Gatorade.

A bit of history from an imperfect memory of 40 years ago.

[FIGHT ON]

Alan. I heard that Gatoraid originally had huge amounts of electrolytes and was designed for people who were performing and sweating big time. But after it was made available for the general public they found that it was harmful for people who just drank it sitting on the couch or not doing much. So they reduced the amount of electrolytes in it so everyone could have it w/o any bad side effects. I don't know what the bad side effects are but gookinaid is supposed to have the same amount as the original gatoraid w/o the sugar. Did you hear anything like that?

[AlanK]

I should update my knowledge of the details before making any pronouncements. But Ellen is a better source of advice anyway. I know that Gookinade, Cytomax, etc. have instructions that made sense to me when I studied them. I never drink any of them exclusively. I alternate with plain water. I rarely drink anything but water on hikes of less than 6+ hours. Electrolytes are replenished in a normal diet.

[Hikin_Jim]

Regarding electrolyte replacement: It has been known for a long time that a person loses electrolytes, especially sodium and potassium, along with water in sweating. Exercise can cause a lot of sweating. If you drink water, you can replenish much of what you lose. However, your electrolyte concentrations go down because you are diluting what was left. As Ellen said, that can be very bad. People have died in activities like marathon running from this cause. It's harder to kill yourself that way hiking, although I'm sure a determined person...

I've always admired your determination, Alan.

On a more serious note, I drink electrolyte drinks because, based on just my personal experience, they work. When I was 21, I was stationed by the Army at Ft. Huachuca, AZ (think DRY). For whatever reason, I actually had a lot of my weekends off, which is not typical in the Army. I used to go hiking a lot in the Huachucas, Dragoons, etc. Now at 21 on active duty in the Army, I was probably in the best shape of my life, but in shape or no, I hurt at the end of a long hike. Just a weird achy feeling that I couldn't get to go away. I used to carry about a gallon and a half of water on a day hike, and I would drink extra water before the hike, when I got back to the car, and when I got back to base. Despite copius intake of water, I couldn't get the achy feeling go away. I don't think it was dehydration. I'm pretty sure that the real issue was electrolyte loss. I find that when I drink the electrolyte replacement drinks, I don't ache. I drink the drinks.

One item of note: The army used to issue salt tablets, a somewhat primitive way of replacing electrolytes. They stopped doing that in the 60's (70's?), reputedly due to side effects (blood pressure?), but I don't really know. Any body got some 411 on this?

Also, my dad would sprinkle salt into a glass of water when we got back from long hikes when I was a kid. I hated the taste, but maybe dad wasn't too far off with what he was doing.

Funny how the older I get, the smarter dad gets.

[Ellen]

Howdy Alan

The following information is from one of my continuing education courses.
If you have any trouble sleeping, read this prior to going to bed tonight


Muscle glycogen represents the major source of carbohydrate in the body (300 to 400 g or 1,200 to 1,600 kcal), followed by liver glycogen (75 to 100 g or 300 to 400 kcal) and, lastly, blood glucose (25 g or 100 kcal). These amounts vary widely among individuals, depending on factors such as dietary intake and state of training.

Untrained individuals have muscle glycogen stores that are roughly 80 to 90 mmol/kg of wet muscle weight. Endurance athletes have muscle glycogen stores of 130 to 135 mmol/kg of wet muscle weight. Carbohydrate loading increases muscle glycogen stores to 210 to 230 mmol/kg of wet muscle weight.

Exercise energetics dictate that carbohydrate is the predominant fuel for exercise intensities at and above 65% of VO2max—the levels at which most athletes train and compete. Although both carbohydrate and fat contribute to energy production during exercise, fat oxidation alone cannot supply adenosine triphosphate (ATP) rapidly enough to support such high-intensity exercise. While it is possible to exercise at light to moderate levels (<60% of VO2max) with low levels of muscle glycogen and blood glucose, it is impossible to meet the ATP requirements necessary for high intensity, high power output exercise when these fuels are depleted.

Utilization of muscle glycogen is most rapid during the early stages of exercise and is exponentially related to exercise intensity. There is a strong relationship between the pre-exercise muscle glycogen content and the length of time that exercise can be performed at 70% of VO2max. The greater the pre-exercise glycogen content, the greater the endurance potential.

Bergstrom et al measured muscle glycogen content and compared the exercise time to exhaustion at 75% of VO2max after 3 days of three diets varying in carbohydrate content. A low-carbohydrate diet (less than 5% of calories from carbohydrate) produced a muscle glycogen content of 38 mmol/kg and supported only 1 hour of exercise. A mixed diet (50% calories from carbohydrate) produced a muscle glycogen content of 106 mmol/kg and enabled the subjects to exercise 115 minutes. However, a high-carbohydrate diet (82% of calories from carbohydrate) provided 204 mmol/kg of muscle glycogen and enabled the subjects to exercise for 170 minutes.

Liver glycogen stores maintain blood glucose levels both at rest and during exercise. At rest, the brain and central nervous system (CNS) utilize most of the blood glucose, and the muscle accounts for less than 20% of blood glucose utilization. During exercise, however, muscle glucose uptake can increase 30-fold, depending on exercise intensity and duration. Initially, the majority of hepatic glucose output comes from glycogenolysis; however, as the exercise duration increases and liver glycogen declines, the contribution of glucose from gluconeogenesis increases.

At the beginning of exercise, hepatic glucose output matches the increased muscle glucose uptake so that blood glucose levels remain near resting levels. Although muscle glycogen is the primary source of carbohydrate during exercise intensities above 65% of VO2max, blood glucose becomes an increasingly important source of carbohydrate as muscle glycogen stores decline. When hepatic glucose output can no longer keep up with muscle glucose uptake during prolonged exercise, the blood glucose drops. While a few athletes experience central nervous system symptoms typical of hypoglycemia, most athletes note local muscular fatigue and have to reduce their exercise intensity (3).

Liver glycogen stores can be emptied by a 15-hour fast and can fall from a typical level of 490 mmol on a mixed diet to 60 mmol on a low-carbohydrate diet. A high-carbohydrate diet can increase liver glycogen content to about 900 mmol.

Miles of smiles,
Ellen

[FIGHT ON]

What about caffeine?

[lipbiter]

Huh?? Ellen, you had me at chocolate milk.

I totally trust your opinion. You did, after all, write the book on the subject. I really appreciated learning what you, the expert, carries. And found your second post very helpful and informative. But I found myself completely LOST after reading your last post. Somebody call SAR

[FIGHT ON]

ya me too. what about caffeine?

[AlanK]

Ellen -- thanks a million. I will attempt to cure any insomnia by reading the whole thing late tonight, but I realized my error in the first paragraph. It's muscle plus liver glycogen that totals around 2000 Calories (or kcal, if you prefer). I had the right number but forgot, over 30 years or so, where it's located. So, your post makes complete sense rather than only 90+% sense. Not bad!

For the others -- caffeine is a stimulant, not a source of energy. It can affect performance, but the important stuff is carbohydrates.

[FIGHT ON]

Ellen, Why do you eat stuff with caffeine in it on your hikes?