Potato, good or bad for endurance?

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Crud, I had a big question posted in here and accidentally deleted it... :rolleyes:


Here it is again, in a nutshell:

I've got a buddy convinced that potatos are the only food for long endurance activities because of the starch. He states that the US army, in some crazy year like 1946, decided that the potato was the ultimate endurance food. They'd send guys into battle on diets of potatos and bread, etc.... to give them long term energy.

I think he's wacked out, based on the Glycemic Index, and more importantly the glycemic load. You might as well have a power bar.

What's the real deal?

I see no extra benefit from a baked potato. Because of the higher glycemic index number it may provide a better recovery food immediately after training, but other than that it is just another quickly absorbed carbohydrate. Almost as rapid as other simple sugars.

A good example for a test.
Take a baked potato (skin removed) fully cooked, place it in a bowl, smash it up a little and then add a 1/4 cup of water and smash it a little more.

What happens?

The potato almost disolves like cotton candy or like sugar desolves in water.
That is what happens once it enters our digestive system. It breaks down very quickly and triggers a larger insulin release. Where as a yam or sweet potato will digest much slower.

A baked potato can be useful for a quick recovery food to replenish glycogen levels or to replenish low glycogen levels before training if for some reason levels are low before training. Other than that I have not heard of any other special endurance values.

I don't care much for potatoes as you already pointed out are pretty empty food... but a sweet potato is cheap and easy recovery food. Wrap one in saran wrap nuke it for 4-5 minutes, then smother it in butter and honey/sugar. Mmmmm good and cheap as hell.

"I've got a buddy convinced that potatos are the only food for long endurance activities because of the starch. He states that the US army, in some crazy year like 1946, decided that the potato was the ultimate endurance food."

Could be... but that's not the rate-limiting step anyway... endurance is multi-faceted and it's only partially determined by calorie intake... let's back up a bit... I'll break up this discussion on endurance into two related systems, energy and muscular.

First, let's examine our energy stores in relation to endurance:

2000~2500 calories in muscle-glycogen
500~750 calories glycogen in liver and floating around bloodstream
400~600 calories in free proteins and amino acides in bloodstream
unlimited calories in fat-stores

Obviously the main limitation is the 2500 calories in our muscles as that's accessed first and its supply must be replenished from outside sources. The question here is a matter of HOW best to re-stock the muscle-glycogen stores.

Personally, I hate using the glycemic index as a proxy indicator of blood-glucose levels, and it's also not a good indicator of muscle-glycogen stores either. However, measuring insulin is easier than glucose concentrations but it's still a secondary indicator, kinda like using the cholesterol marker to track relative concentrations of HDL to LDL fats. But it's the best we've got to work with, so let's make the most we can of the glycemic index and its relation to measuring endurance factors.

Now the main rate-limiting step in endurance is getting the CHO molecules past intestinal lining into the bloodstream where it can be transported to the muscles to replace the spent muscular glycogen. The age-old idea of using slow-release carbs like complex starches that takes a long time to digest may be fine for dieters and people who don't want to drive up their glycemic-index and the resultant fat-storage, but for athletes, it's doesn't matter WHEN all the CHO gets through, it's a matter of HOW MUCH we can get RIGHT NOW!!!. The trick is getting the highest calories/hour of CHO into the bloodstream.

It does appear that training and an optimized nutrition mixture does affect the rate of CHO absorption. TDF and RAAM teams have seem to fine-tuned this process to about 400 cal/hr on the upper limit with 300-350 cal/hr to be easily obtainable, much higher than the 200-250 cal/hr rate for mere mortals like us. Now if we assume that the glycemic-index is an indicator of absorption-rate of various carbs, then yes we want a high GI CHO in order to get it from the intestines into the bloodstream as fast as possible. It appears medium-chain carbs work best, too big of a molecule takes too long to digest before its absorbed, to simple, like glucose, ends up being too dilute a mixture to get through a lot at once. The potato's high GI seem to indicate that it's a good balance in the middle and is a fast-absorbing CHO, good for performance.

You also want to avoid fructose like the plague, so that leaves out dried fruits, fruit-juices and sodas sweetened with high-fructose corn-syrup (that's an evil requiring another dissertation altogether). On reason the GI isn't affected by fructose is that fructose is useless to the body. It cannot be converted to glycogen and cannot be used in ATP-production by the muscles, it cannot be converted to fat either. All fructose must be metabolised in the liver first and coverted into glucose and returned to the bloodstream before it can be used, not like the liver doesn't have enough to do already... so avoid fructose.

The insulin-response to the absorbed CHO on the other hand, doesn't appear to affect endurance in any way. Typically insulin is to signal body cells to absorb free-floating blood-glucose into muscle-tissue glycogen. When those are well-stocked, it also triggers the conversion to fat in adipose tissues as well. However, when you're running a glycogen defecit in the muscle tissues, regardless of insulin levels, the digested CHO is headed straight for your muscles anyway. Experiments, primarily on race-horses, show that pre-race meals and their resultant insulin levels doesn't affect performance whether or not you're well-fed. What matters in endurance is replacing all the glycogen that you burn up later.

Another factor that affect CHO absorption aside from GI is concentration in the stomach. The RAAM teams have found it's best to keep CHO concentrations high and limit the water used. This is to get as much carbs past the stomach into the intestines and too much water dilutes the mix and limits how many CHO molecules makes in in each "squirt" out of the stomach. The RAAM riders that end up dehydrated at the end of the day seems to have better endurance than those who take in water 1:1 with their expenditures. Plus too much water tends to cause gastrointestinal cramps and other distractions from performance.

Another factor is adequate electrolyte consumption along with the CHO. Seems about 1000mb of sodium salt per hour is what the RAAM teams use and it balances out what's lost from perspiration. Magnesium and potassium salts are also vital for managing smooth muscle contractions and avoiding cramps. Again, another area where the potato comes in handy.

One little known factoid in maintaining electrolytes is in absorption of CHO into the intestions. Each and every single glucose molecule that's absorbed through the intestine requires an exchange with a sodium. With low sodium levels, you can't absorb the carbs you're consuming, a vicious cycle when you're bonking, eh? You're going crazy and desperately looking around on the ground for scraps of carbs to eat and the body's refusing to absorb it... heh, heh :(

So, the nutrition side to endurance is easy. While getting 300 cal/hr may not be able to completely supply a 200-mile ride, but I've found that there's some other factors other than the energy system that help made those rides easier. One of them, the muscular system, really impacts endurance and improved my average speed on a 200-mile ride... more on that in another paper.. :)

You also want to avoid fructose like the plague, so that leaves out dried fruits, fruit-juices and sodas sweetened with high-fructose corn-syrup (that's an evil requiring another dissertation altogether). On reason the GI isn't affected by fructose is that fructose is useless to the body. It cannot be converted to glycogen and cannot be used in ATP-production by the muscles, it cannot be converted to fat either. All fructose must be metabolised in the liver first and coverted into glucose and returned to the bloodstream before it can be used, not like the liver doesn't have enough to do already... so avoid fructose.


Although fructose does follow a different metabolic pathway to other sugars, there is evidence that making use of this pathway by ingesting small amounts of fructose during exercise increases total CHO uptake and metabolism. I wouldn't avoid it like the plague, so much as take care not to overdo it (especially as this can lead to gastro-intestinal upset).

Although fructose does follow a different metabolic pathway to other sugars, there is evidence that making use of this pathway by ingesting small amounts of fructose during exercise increases total CHO uptake and metabolism. I wouldn't avoid it like the plague, so much as take care not to overdo it (especially as this can lead to gastro-intestinal upset).

References to supplement this post:

Lots of stuff on pubmed from Asker Jeukendrup - searching for his last name and fructose, glucose or CHO oxidation yields a lot of information.

Some selected highlights from him and others:
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=15946410&query_hl=5
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=8005840&query_hl=1
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=15741841&query_hl=7

Try clicking on 'related articles' for more.

Just for clarity sake (perhaps for my own sanity) the above replies are regarding CHO uptake I feel are accurate enough, but I suppose I read the original question as if there was some special attribute of the potato over other like carbohydrates.

However, it has always been my understanding that other carbohydrates like white quick cooked rice can achieve the same results as can other low fiber and simple sugars that can be considered as useful as a potato.

http://www.medicdirectsport.com/athletictraining/default.asp?step=4&pid=57

Does this mean that a very high GI food like rice will be good for an energy boost whilst on a long ride?

A potato is a zip file of sugar but more importantly for us old guys it helps your body make hyaluronic acid (you make less with age) a water holding molecule that is good for your tendons.

Crud, I had a big question posted in here and accidentally deleted it... :rolleyes:


Here it is again, in a nutshell:

I've got a buddy convinced that potatos are the only food for long endurance activities because of the starch. He states that the US army, in some crazy year like 1946, decided that the potato was the ultimate endurance food. They'd send guys into battle on diets of potatos and bread, etc.... to give them long term energy.

I think he's wacked out, based on the Glycemic Index, and more importantly the glycemic load. You might as well have a power bar.

What's the real deal?

I don't care much for potatoes as you already pointed out are pretty empty food... but a sweet potato is cheap and easy recovery food. Wrap one in saran wrap nuke it for 4-5 minutes, then smother it in butter and honey/sugar. Mmmmm good and cheap as hell.

Sweet potatoe are great food. I just about lived on them for weeks on end in Zambia and Tanzania years ago because I can't eat wheat.

High GI foods are great while you are exercising and immediately after because of their easily available glucose. They are not good immediately before exercise due to the impact of rebound hypoglycaemia on some people.

I don't care much for potatoes as you already pointed out are pretty empty food... but a sweet potato is cheap and easy recovery food. Wrap one in saran wrap nuke it for 4-5 minutes, then smother it in butter and honey/sugar. Mmmmm good and cheap as hell.Never put plastic in the microwave.

Never put plastic in the microwave.

Urban myth :rolleyes:

Potatoes have potassium and a fairly complete protein profile. They have not a small amount of protein especially if you eat them with the skins.

Never put plastic in the microwave.
Never put anything in the microwave. ;)

Would you say that because a potato is a rapidly metabolized sugar that it would provide quick energy, but also leave a person short of energy? ind of like how eating a candy bar supposedly makes a person "crash"? If that is true, would the same thing happen when drinking something like gatorade?

Back in the day I would stop at a Jiffy store and buy one of the economy size fig bars to get through the last of an eight hour ride. It actually worked for me, unless it was only a placebo effect. Occasionally now I will get cramps in my legs on the last five miles of one of my rides. Would that be due to improper nutrition or to something like dehydration? It seems somewhere I heard or read that dehydration would cause cramps, but I could be mistaken.

I always thought the fat that was on my body would supply the energy that my muscles needed whilst riding. Burning this fat was better than keeping this fat and using an external source of calories. That is the logic I have followed. Was that wrong, just an old wive's tale? Somebody I know told me that carbs burn in a sea of fat (like what is around my gut) so I made it a point to take in carbs and use the fat from my body to burn them. If that makes any sense.

alas. last few years I have only drank bottles of gatorade on what amount to an average of about forty mile rides. Only very seldomly have I had a difficult ride home (noticed only on really hot days in the summer). I never have felt the need to eat anything at home to recover immediately afterwards. What negative effects on my body did this have, if any- not having a recovery meal?

I suppose everybody is different, but the principles of nitrition should apply the same to all humans. Do any of you really have much of an appetite when you're done with a ride?

Oh,and what happens if you put plastic in the microwave?