Electrolyte needs and real food

"If the right study exists, though, I'd love to see it."

A long time ago I was part of a "nutrition study" run by a major university. There was no interest, let alone control, concerning what I ate, drank, or did in the in the days or hours leading up to the endurance tests (12 if I recall). The results were "positive" though, for the product.

Imagine that.

The paper was focused on whether or not CHO in the recovery drink helps muscle synthesis. That is interesting, but do not lose sight of the real reason for CHO in the recovery drink, mentioned almost in passing:

There remain valid reasons for the inclusion of carbohydrates into protein supplements that are to be consumed following resistance exercise. These included the maximization of glycogen restoration, especially when the time period between exercise sessions is short.

CHO may also help with muscle synthesis, but afaik its biggest role is glycogen replacement.

–MV

"These included the maximization of glycogen restoration, especially when the time period between exercise sessions is short."

Any period longer than 8 hours which includes a balanced dinner (or two) is not "short".

There may be a period of "optimized uptake", but if you've got an evening to recover, those muscles will be well fueled by morning.

In this context 24 hours is short.

It is true that a lot of glycogen replenishment will take place overnight, but full replenishment takes longer than that.

–MV

"Given that it's not been all that easy to show a reproducible ergogenic or muscle synthesis effect of protein addition to exercise drinks at all"

Wasn't the positive effect on muscle synthesis the main point made by the article Bob linked us to a page or two ago? The article you cite is concerned with the addition of a carb source to protein during the recovery phase to enhance muscle rebuilding/accretion. It does not address intake during exercise, which was the primary focus of Bob's article. In the latter case, I should think the ratio would be of considerable concern, due to the potential for kidney damage and the extra energy required to metabolize protein, as much as 25% of the ingested protein according to McArdle(Diet Induced Thermogenisis).

"that there is likely to be enormous variability based on individual variation (both intrinsic and conditioning-related), exercise intensity, availability of stores from body fat and meals, etc., it strains the imagination to think it would even be possible to detect meaningful differences between various ratios."

All of these variables factor into the problem, no doubt. That would likely account for the 1.2-1.8 grams of protein/kg/day general recommendation. Shawn Bearden, our resident professor of Exercise Physiology gave me a recommendation of 1-1.2 grams/kg/day when I sent him an inquiry. It seems to me that if the majority of dietary protein is to be taken in at dinner, and secondarily breakfast, it would be well to error on the low side in a drink taken while exercising, for the reasons I give above, with the goal of mitigating muscle catabolism while on the move yet avoiding the downside of over supplementing.

"Wasn't the positive effect on muscle synthesis the main point made by the article Bob linked us to a page or two ago?"

If you mean the van Loon article on the Gatorade Sports Science site, and a clear effect of protein addition, not really. The key sentence is "However, no significant differences were observed in muscle protein synthesis rates between the carbohydrate and carbohydrate plus protein trial, despite clear differences in whole-body protein balance." If you look at the original paper, they can't see a statistically significant effect when they looked directly at muscle, and the last sentence of the abstract for that paper is "Protein coingestion does not further increase muscle protein synthesis rates during continuous endurance type exercise." (That refers to carbohydrate plus protein vs carbohydrate alone.)

FWIW, I think they probably *would* see an effect with more subjects and optimized conditions (perhaps longer exercise), but I was trying to illustrate that it's hard enough to see the effect of adding protein at all that determining what ratio is optimal could be virtually impossible, even if there might potentially be an optimum in a meaningful sense for a given person.

I see now that I should have been more explicit about my point in citing the recovery article. What I like about it is that the authors look carefully at the evidence for various contentions before drawing any conclusions. For example, "It has been further stated by Stark et al. [1] that '(…) studies using protein sources with a carbohydrate source tended to increase LBM more than did a protein source alone' (herein cited as references 11, 12, 13, 14, 15, 16). This fails to adequately reflect the data within these cited studies. The majority of those studies compared the co-ingestion of protein and carbohydrate versus carbohydrate alone [11,12] or versus a different source of protein whilst maintaining similar amounts of carbohydrates [13-15]. Moreover, the last cited study [16] analysed the impact of supplementation timing, not supplement composition. To date there are no clinical studies comparing the impact of the co-ingestion of carbohydrate-protein with just protein supplement on LBM." Their conclusion in the abstract is "our conclusions are that further studies are necessary prior to any conclusions that enable evidence-based recommendations to be made."

Cheers,

Bill S.

"Given that it's not been all that easy to show a reproducible ergogenic or muscle synthesis effect of protein addition to exercise drinks at all, and that there is likely to be enormous variability based on individual variation (both intrinsic and conditioning-related), exercise intensity, availability of stores from body fat and meals, etc., it strains the imagination to think it would even be possible to detect meaningful differences between various ratios."

The Van Loon article seems to contradict your statement that there is no reproducible muscle synthesis effect of ingesting protein before or during exercise. They seem to be on fairly solid ground here, as far as I can tell. However, they make no claims about the coingestion of protein and carbohydrate over carbohydrate alone improving exercise performance.

Copied from the Van Loon article.

'•The ingestion of dietary protein prior to and/or during exercise stimulates skeletal muscle protein synthesis rates during resistance or endurance type exercise.
•Allowing muscle protein synthesis rates to increase during exercise training may facilitate the skeletal muscle adaptive response to exercise training and improve training efficiency.
•The ingestion of protein with carbohydrate during exercise does not acutely improve exercise performance above carbohydrate ingestion alone, when ample carbohydrate is ingested.'

'In the first study, recreational athletes ingested carbohydrate-containing drinks (0.15 g/kg body mass/h) with or without additional protein (0.15 g/kg body mass/h) prior to and during 2 h of resistance type exercise. Using contemporary stable isotope methodology, it was shown that protein co-ingestion prior to and during resistance type exercise substantially increases muscle protein synthesis rates during exercise (Beelen et al., 2008a). The capacity to increase muscle protein synthesis rates during exercise extends the time frame during which the skeletal muscle adaptive response can be facilitated.'

"If the right study exists, though, I'd love to see it."

I think the Van Loon article might be a good place to start. It could at least provide a baseline for evaluating other articles. He also makes a good case for coingesting protein and carbs before and during exercise as opposed to immediately after, due to damage to the lining of the small intestine sustained during prolonged endurance exercise by shunting blood away from it to the working muscles. This is a known problem for endurance athletes, and has been linked to seepage of bacteria into the bloodstream, as well as the malabsorption of nutrients. I doubt that this is a concern for most backpackers, so distributing your protein across the time spectrum will probably work just fine. How much to ingest when is the main question to be answered, IMO.

" The key sentence is "However, no significant differences were observed in muscle protein synthesis rates between the carbohydrate and carbohydrate plus protein trial, despite clear differences in whole-body protein balance." If you look at the original paper, they can't see a statistically significant effect when they looked directly at muscle, and the last sentence of the abstract for that paper is "Protein coingestion does not further increase muscle protein synthesis rates during continuous endurance type exercise." (That refers to carbohydrate plus protein vs carbohydrate alone.)"

Yes, but then they go on to say a bit further into the article that it is probably a good idea to add protein to your carb drink on the basis of its demonstrated impact on whole body protein balance. Granted, they also admit the need for further studies
to determine the effect on skeletal muscle. The other point that has me convinced is the apparent positive effect on post recovery muscle synthesis, assuming I haven't damaged the lining of my small intestine.

"FWIW, I think they probably *would* see an effect with more subjects and optimized conditions (perhaps longer exercise), but I was trying to illustrate that it's hard enough to see the effect of adding protein at all that determining what ratio is optimal could be virtually impossible, even if there might potentially be an optimum in a meaningful sense for a given person."

Probably. They sure seemed to be leaning in that direction. Still, the likelihood that it "primes the pump" for post exercise recovery seems to me reason enough to include a small amount in my drink. It is only 12 grams out of 70, and if it helps
to maintain my nitrogen balance, critical not just for muscle synthesis, but also for a number of other critical functions, for example hormone synthesis, that alone would be reason enough to add at least a small amount. I certainly do not depend on it for the majority of the muscle synthesis required to repair skeletal muscle damage sustained in traversing some fairly rough terrain in the Sierra.

I see now that I should have been more explicit about my point in citing the recovery article. What I like about it is that the authors look carefully at the evidence for various contentions before drawing any conclusions. For example, "It has been further stated by Stark et al. [1] that '(…) studies using protein sources with a carbohydrate source tended to increase LBM more than did a protein source alone' (herein cited as references 11, 12, 13, 14, 15, 16). This fails to adequately reflect the data within these cited studies. The majority of those studies compared the co-ingestion of protein and carbohydrate versus carbohydrate alone [11,12] or versus a different source of protein whilst maintaining similar amounts of carbohydrates [13-15]. Moreover, the last cited study [16] analysed the impact of supplementation timing, not supplement composition. To date there are no clinical studies comparing the impact of the co-ingestion of carbohydrate-protein with just protein supplement on LBM." Their conclusion in the abstract is "our conclusions are that further studies are necessary prior to any conclusions that enable evidence-based recommendations to be made."

Lots more to be learned, no question about that. The practical challenge, to coingest or not to coingest, remains, however, even in the absence of definitive evidence pointing to the benefits or lack thereof, of protein/carb coingestion while exercising. In the absence of proof positive, but with the undeniable benefits on whole body protein balance and likely benefits for skeletal muscle synthesis, I have chosen to add a moderate amount of protein to my carb drink. I think it has a uniquely personal decision at this point.