When marathon training, are GU or other solids helpful or detrimental during long training runs?

I have often wondered about this question. Until someone does a study on this I will recommend that the marathoners I coach do not take any sweets during long training runs but do so during races.

Maybe there is a training effect to taking sugar during training runs but we would need an experiment to show that.

Surely lots of investigators would accept grant money to do such a study.

I wonder who might put up the money? I wouldn't trust results of a study funded by companies that produce these running energy products. Who would fund it who doesn't have a product to sell?

Tom

I strongly believe that the training effect of long runs are better if few to no calories are consumed on the run. A major reason for running that long is to teach your body to store more glycogen. The limiting factor to marathon type races IS glycogen storage. If we could somehow have an endless supply of glycogen in the body, we could go on and on at LT. So really, doesn't it make sense to challenge your body's storage? Perhaps the same with water storage.

For training effect it might be better to forgo the GU, but don't forget the old rule to never do anything new during the marathon. At least on some of your long runs, take whatever you're going to take during the race to make sure there won't be any unpleasant surprises.

Reading your post again, I might add that the idea is not to deplete your muscles so that the body learns to burn fat efficiently instead of carbs. This may be critical in 100 mile races, but when you run out of carbs, this is that sudden "bonking" or "hitting the wall". We do metabolize fat at just about any speed and length, but concentrating on burning fat more efficiently would just let us run 12 min miles instead of 13 min miles at the end of a tanked marathon. Train to not hit the wall in the first place and keep all 8 cylinders going.

interesting. I'd say no during training, yes during race

I slightly disagree with the previous posts. For one reason; hot weather. If it's hotter than usual, I would say take some water and/or replacement fluids. Even a small bite or two of an energy bar. My thoughts are more about recovery. The faster and staronger you recover, the better your training will be. Thats' what we ultimatley want right? What I do agree with is conditioning your body to do without for a while. Hoever, do not do damage if extreme conditions.

runner1234 wrote:

My thoughts are more about recovery. The faster and staronger you recover, the better your training will be. Thats' what we ultimatley want right? What I do agree with is conditioning your body to do without for a while. Hoever, do not do damage if extreme conditions.

this is exactly right. If you're doing long runs that just hammer your body, you won't be ready for your next workout.

this avoidance of fuel seems to be pretty unique to runners. i think it has a lot to do with the fact that it's just difficult to carry anything with you.

however, learn to clip a couple GUs to your waist band, and know where the drinking fountains are, and you'll do much better.

turkey leg wrote:

Reading your post again, I might add that the idea is not to deplete your muscles so that the body learns to burn fat efficiently instead of carbs. This may be critical in 100 mile races, but when you run out of carbs, this is that sudden "bonking" or "hitting the wall". We do metabolize fat at just about any speed and length, but concentrating on burning fat more efficiently would just let us run 12 min miles instead of 13 min miles at the end of a tanked marathon. Train to not hit the wall in the first place and keep all 8 cylinders going.

The body responds by burning a higher percentage of fat earlier in the race which conserves the glycogen stores for later on. That's the adaptation you're looking for. The argument is that by introducing carbs during the run your body will not make this adjustment.

Easy long run = No gels, drinks, water

Marathon-paced long run = Practice gels, drinks, whatever you plan to do during the marathon

jaguar1 wrote:

Easy long run = No gels, drinks, water

Marathon-paced long run = Practice gels, drinks, whatever you plan to do during the marathon

Just to clarify; During easy long runs you recommend no gels but do drink water?

calarifier wrote:

Just to clarify; During easy long runs you recommend no gels but do drink water?

Only if you absolutely need it (~middle of the summer).

Should add... I know I need water if I start cramping at all. Then it really helps to get some (~golf course), which shouldn't compromise the gycogen sparing effect. Cramping could be due to an electrolyte imbalance, so those electrolyte strips might be helpful. I alternate Sunday's of doing the long run easy and sometimes with short pickups (~usually a little longer too) vs. a long run with marathon-pacing and drinks/etc..

Take the gels. There is NO evidence that depriving yourself improves fat utilization long term. Some research by Louise Burke at AIS shows that such a tactic might *might* impair glycogen synthesis.

Also, glycogen storage is not the limiting factor in marathon running. Even at the end of a marathon the leg muscles will have some (not much) glycogen remaining.

Here is my argument for taking the gels and such during training runs: you are able to maintain the desired intensity far better and that creates a better training stimulus.

As for those who think gels impair fat or glycogen storage, how about showing those studies that support this idea. I will admit that the idea has an intuitive feel to it; however, intuition is often wrong.

luv2run wrote:

As for those who think gels impair fat or glycogen storage, how about showing those studies that support this idea. I will admit that the idea has an intuitive feel to it; however, intuition is often wrong.

I sure can't cite any studies -- one way or the other. That's why I asked the question. Fundamentally, you raise a good point. Aren't there studies that address these questions head on?

The real question here is, are most runners cavemen?!

The primary determinant of marathon success is not % of glycogen usage to % of fat usage, it's aerobic capacity in relation to weight.

With proper training, most guys can store about 30 calories of glycogen per kg of bodyweight. So, for a 70kg person, that's about 2100 calories. Now, a typical road marathon is going to require one to burn roughly 40 calories per kg of bodyweight. So, if it takes 2800 calories to get through the marathon, and you only have 2100 worth of glycogen on hand, you want your body to get used to taking in glycogen while running at high speed.

You don't get used to something by doing it in your big race. You do it in your day-to-day training. Reckon you ought to be taking in about 3-4 calories per kg of bodyweight in a 2:1 glucose:fructose combo whenever you are doing 60+ minute runs at a pace meant to stimulate aerobic capacity. Get used to drinking about 2-3 oz of sport drink mix mentioned previously every 5th minute of your run. Yes, about every 5th minute; you want a steady trickle going in to match the steady trickle being sweated out.

The idea is not to see how fast you can run on low octane fuel (fat), the idea is to see how fast you can run, period, right? I mean, you are racing, yeah?

Word!

I do think that this advice in Running Times is correct. You do have to adapt your body to glycogen sparing, and I don't drink anything but water on the long runs.

Your body is "glycogen sparing" the other 22-23hrs of the day that you aren't running.

jwiley wrote:

The primary determinant of marathon success . . . is aerobic capacity in relation to weight.

Bullsh*t. If that was true we'd go at near max heart rate the entire way. And all of the sub 2:10 marathoners with VO2 maxes all over the board proves otherwise. Moreover, after 2-3 years of proper training VO2max is topped out - that must be why so many marathon records are set by teenagers.

Your example of the 70 kg person is only valid assuming zero calories are supplied by fat. Fats are metabolized alongside glycogen in just about every activity (and non-activity). And it's not a far stretch to expect the missing 700 calories (25%) to be met with this fat metabolism.

There is no better fuel source than the body's own glycogen, which is compeletly different than glucose/fructose. Sipping every 5th minute in every run over 60 minutes? Ok, you either write for Runner's World and are getting paid to spew this garbage or you're chickensh*t. Pop that titty out of your mouth and train your body like it's capable of doing.

VO2 max and aerobic capacity are not the same thing. You are deep into anaerobic territory when at VO2 max. Deep. So yes, marathon racing is far and away a contest of who has the greatest aerobic capacity in relation to their body weight. Aerobic capacity is generally found at a pace one can hold for 2-3 hours.

At that type of pace, sure your body is burning fats alongside glycogen, but the ratio is heavily weighted towards the glycogen. As you become more and more depleted your perceived effort climbs and eventually your body can no longer sustain without more glycogen coming in. Go ahead and being a tough guy and run all day with no fluid or glycogen replenishment, I'm sure you'll get great at it, but there will be others who run faster, even if they are total pussies in your view.