Tabagas_Ru

I thought you might be interested in this

Here is the abstract:


ORIGINAL RESEARCH COMMUNICATION
Oral administration of vitamin C decreases muscle mitochondrial biogenesis and hampers training-induced adaptations in endurance performance1,2,3
Mari-Carmen Gomez-Cabrera, Elena Domenech, Marco Romagnoli, Alessandro Arduini, Consuelo Borras, Federico V Pallardo, Juan Sastre and Jose Viña

1 From the Department of Physiology, Faculty of Medicine, University of Valencia, Valencia, Spain (M-CG-C, ED, AA, FVP, JS, and JV); the Catholic University of Valencia, Valencia, Spain (CB); and the Polytechnic University of Valencia, Valencia, Spain (MR)

Background: Exercise practitioners often take vitamin C supplements because intense muscular contractile activity can result in oxidative stress, as indicated by altered muscle and blood glutathione concentrations and increases in protein, DNA, and lipid peroxidation. There is, however, considerable debate regarding the beneficial health effects of vitamin C supplementation.

Objective: This study was designed to study the effect of vitamin C on training efficiency in rats and in humans.

Design: The human study was double-blind and randomized. Fourteen men (27–36 y old) were trained for 8 wk. Five of the men were supplemented daily with an oral dose of 1 g vitamin C. In the animal study, 24 male Wistar rats were exercised under 2 different protocols for 3 and 6 wk. Twelve of the rats were treated with a daily dose of vitamin C (0.24 mg/cm2 body surface area).

Results: The administration of vitamin C significantly (P = 0.014) hampered endurance capacity. The adverse effects of vitamin C may result from its capacity to reduce the exercise-induced expression of key transcription factors involved in mitochondrial biogenesis. These factors are peroxisome proliferator–activated receptor co-activator 1, nuclear respiratory factor 1, and mitochondrial transcription factor A. Vitamin C also prevented the exercise-induced expression of cytochrome C (a marker of mitochondrial content) and of the antioxidant enzymes superoxide dismutase and glutathione peroxidase.

Conclusion: Vitamin C supplementation decreases training efficiency because it prevents some cellular adaptations to exercise.

Key Words: Free radicals • VO2max • antioxidant enzymes • antioxidant supplements • exercise • exhaustion • vitamins • gene expression • hormesis • reactive oxygen species





And here is the news release


Reuters Health

Thursday, January 17, 2008

NEW YORK (Reuters Health) - Taking vitamin C can blunt the body's response to endurance training, a new study in humans and rats shows.

Based on the findings, "the common practice of taking vitamin C supplements during training (for both health-related and performance-related physical fitness) should be seriously questioned," principal investigator Dr. Jose Vina of the University of Valencia in Spain and colleagues conclude.

Exercisers take the antioxidant based on the assumption that it protects their muscles from the oxidative stress that results from physical exertion, Vina's group reports in the American Journal of Clinical Nutrition. However, the researchers point out, oxidative stress during exercise may actually help the body to build endurance by forcing muscles to adapt.

To investigate, Vina and his team had 14 sedentary men undergo 8 weeks of training, during which 5 of them took 1 gram of vitamin C daily. They also put 24 rats through 3- and 6-week exercise training protocols, and gave half of the animals vitamin C daily.

The men who didn't take vitamin C showed a 22-percent increase in their body's ability to take up and use oxygen during exercise, compared with just a 10.8-percent increase for the men given vitamin C. Similar results were seen for the rats.

When the animals were forced to run to the point of exhaustion after 6 weeks of endurance training, those that weren't dosed with vitamin C were able to run nearly twice as far as they had before training, while those given the vitamin only increased their distance by 25 percent. Tests on the muscle tissue of the animals found that rats that weren't given vitamin C had added more mitochondria, the "engines" within cells that convert nutrients into energy.

The findings suggest that the release of free radicals during exercise helps muscles to adapt by changing gene expression, Vina and his team note, while antioxidants such as vitamin C may interfere with this process. In fact, they add, exercise itself could act as an antioxidant by boosting the body's expression of antioxidant enzymes.

"Taking into account that a high fitness level is associated with a lower risk of premature death from any cause, the effect of vitamin C administration on endurance capacity has important implications for nutritionists, physicians, and exercise trainers and practitioners," they conclude.

SOURCE: American Journal of Clinical Nutrition, January 2008.

Reuters Health

ZXiMan

Jeeeez, I better cut back on my orange juice consumption!

Carbonfiberboy 

Yes, but what do you think? I take 1g/day and 2g on a day with a very hard or long ride. My endurance seems, if anything, better than those who don't supplement with C. Not that it couldn't be better!

Tabagas_Ru

Maybe it could be better if you took less. They also used sedentary men and trained them for 8 weeks. By the looks of things around here you have been at this for more than 8 weeks.

I wonder what would happen if they took them and gave them less Vit C, or if they used people who are better trained then the people they used?

If what they are saying is true may be it goes to show that vitamins are not benign in any quantity, but that you can take too much and that they can have ill effects. It is also interesting that they point to free radicals signaling for the muscle to adapt and eventually allowing the muscle to adapt and perform better. This could show that Vit C really does work in reducing the stress during recovery on muscles so they don't have to adapt as much, and that free radicals are beneficial in certain amounts because of forcing the muscle to adjust to a new environment.

Someone like you who spends more then 8 weeks riding probably has about as good endurance as they can get, so the law of diminishing returns comes in. In your case the Vit C works because it prevents muscle damage from free radicals. In the case of someone who is sedentary their fitness will improve much quicker than an athletes, so supplementing with C will decrease the re-modeling that goes on that is needed for the muscle to change its structure to accommodate new activity. Whereas someone who has been doing endurance exercises for a while has already had their muscles adapt to the activity.

There is also no mention of long term effects. Maybe the slower rise in endurance would mean a higher endurance in the long run with the supplementation, and a quicker plateau without the supplementation

Too bad I can't get the whole article.

Carbonfiberboy 

I get what you're saying, but it's not just about endurance. It's also about cellular mitochondrial density. My endurance is good, but my climbing is not so great, meaning my watts at LT could definitely be better. On a good day, I climb about 2250'/hr. on a 1 to 2 hour climb. This is the sentence that got me:

"The adverse effects of vitamin C may result from its capacity to reduce the exercise-induced expression of key transcription factors involved in mitochondrial biogenesis. "

So I'm going to try cutting back to just the C that comes with my multiple. Probably won't make a noticeable difference, or at least a difference that can be sorted out from background noise, but it's worth a try. Thanks. If I catch a cold, I'm going back to it, though.

catherine96821

thanks

we drink Emergen-C in our water bottles every ride. maybe THAT is why I suck!?

babydee

Thanks for the research-based post. I would have never considered Vitamin C as a bad guy in endurance exercise.

I have never taken large doses of any vitamin, but I have been taking 250-500mg daily of C lately, plus whatever is in my food. I might shop around for more research and consider just relying on my multivitamin and food.

BTW, nice having access to research via a nursing program or working in a teaching hospital! Not sure what your situation is, but I have a nice online journal library where I work.

Carbonfiberboy 

Bump.

Carbonfiberboy 

I posted that I would try reducing my C supplement on Jan. 20, so it's been about 6 weeks now. I've completely stopped the 1g C and only take 100 mg in my multiple plus OJ with breakfast. I have changed three things this season: the C, my weight training https://www.bikeforums.net/training-nutrition/379650-strength-training-cyclists.html, and I've also started taking 2g GABA before bed. Sorry, but if I won't live long enough to only change one thing a season!

Last night I did my first Tempo interval of the season on my rollers-with-resistance. I do these in my biggest gear near the upper end zone 3, or a HR of 82% of MHR or 89% of LTHR. Cadence 75-80. Meant to be a serious leg stressor. Went for 45 minutes continuous with almost no leg pain. That's longer than I've ever been able to go and with much less pain. I was 2 rpm faster than last year at this time and only had 3 beats of HR drift.

I interpret pain from this exercise as being from lactate, since it really doesn't take much muscular power as I pedal a very nice (pat, pat) circular stroke. I then interpret less lactate as meaning the mitochondria were working better in the Krebs cycle and making less of it.

So if that's true, then why? I don't really think the GABA does anything, or if anything, not much. I haven't become a muscular giant or lost a bunch of weight or anything like that. While the weight training does seem to have made me stronger on the bike, from what I've read it doesn't seem like it should have had much effect on this particular exercise, especially since muscles are involved in pedaling that are not involved in weight lifting.

So maybe less C is a good thing? I also haven't been sick, even though about everyone else I know has been. Anybody else?

BryanW

I read an article recently that says taking extra VitC has never been shown to reduce the risk of catching a cold, though it does reduce the length and severity of symptoms once you have one (by about 20% IIRC).

gkb

overthinking

Creakyknees

Geez you can turn your biggest gear at 89% LTHR and 80 rpm? Time for a bigger ring....

JohnKScott

Is anyone else seeing a sci-fi movie in here anywhere? Anti-Vitamin C ray anyone? Anyone?

Tabagas_Ru

Congrats on the improvement.

It is good that you are getting into the weight training, it is very important to do weights. Weight training stimulates testosterone release whereas endurance exercises can inhibit it. So you are probably seeing benefits from an improved weight training programme. But it could be quite possible that all the steps you have taken have contributed.

Keep a log and see if the improvements actually benefit you through the whole year. If you already do, it would be interesting to compare it against other years where you did something different.

I am curious, what do you take GABA for?

Carbonfiberboy 

I've kept a log for many years. So far, I've been faster every year, partly from learning how to train smarter, and partly from accumulated ability. So the fact that I'm stronger this year is not an outlier, further muddying the waters. I've weight-trained for a long time, as a kid and then starting up again in '79. The new thing this year is that I seem to have found a way to get more biking strength out of it. I'm a hard gainer.

GABA is supposed to stimulate the nighttime release of HGH. There are studies that supposedly document this, but who knows what the conditions, participants, etc., were. I don't think it does much, other than make me breathe hard about 20 minutes after ingestion. But maybe my program already stimulates as much HGH release as there is going to be.

Carbonfiberboy 

Well, that's a 52X12. I can't get the other gears I want with an 11. What I need is more than a 500w resistance unit on my rollers. Or add another one, except they don't make 'em like mine any more. As it is, I can't do muscle tension intervals on the rollers, though I'd like to be able to. Luckily, I've got a 15 minute hill just a few miles away . . .

Tabagas_Ru

It sounds like you know your stuff you get older but you get better, sounds like you are doing something right

Thanks for the info on GABA.