Wednesday, March 30, 2011

Putting Carbs to Good Use: Meta-Review Reports Ergogenic Effect of Carbohydrates in Endurance Athletes

One of the leitmotifs, many of my posts here at the SuppVersity share, is the idea that (almost) everything works for someone. From the feedback I am receiving, from the crowd this blog is attracting, I gather that my general advice against high carbohydrate intake is (as human as that may be) often misinterpreted as "carbs are evil, beware of all carbs"! For the average pizza eating fast-food junkie, this certainly is an adequate message, because even if he believes that carbs are the root of all disease, without a MAJOR change in his dietary habits (I am not talking of ordering the normal, instead of the super size menu at McDonalds, here) he will probably still get way more carbs out of his diet than it would fit his sedentary lifestyle.
If, however you are an athlete or avid gym-goer you may probably already start to notice that following what you took to be a one-solution-fits-it-all recommendation lead to performance decreases, laziness, brainfog, lack of sexual desire, bad sleep and many of the other symptoms you would find, when you googled one of the ambiguous terms "adrenal fatigue" or "general fatigue syndrome"... Carbs are more than just insulin triggers, and fatteners. Glucose is the gasoline in your fuel tank and - most importantly - its the substrate your nervous system thrives on. And while it might not be necessary to eat them, very active (and lean) individuals may derive similar benefits from a moderate carb consumption as the athletes from the 50 studies included in a meta-review by Themesi et al. (Themesi. 2011).

The scientists' results suggest that intake of a <8% carbohydrate beverage (~50-80g) [TT] in the course of an endurance event (≥1 h) significantly "enhances endurance exercise performance in adults" as measured by submaximal exercise performance and time to exhaustion [TTE]:
The ES [effect size] for submaximal exercise followed by TT was significant (ES = 0.53; 95% CI = 0.37–0.69; P < 0.001) as was the ES for TT (ES = 0.30; 95% CI = 0.07–0.53; P = 0.011). The weighted mean improvement in exercise performance favored CHO ingestion (7.5 and 2.0%, respectively). TTE (ES = 0.47; 95% CI = 0.32–0.62; P < 0.001) and submaximal exercise followed by TTE (ES = 0.44; 95% CI = 0.08–0.80; P = 0.017) also showed significant effects, with weighted mean improvements of 15.1 and 54.2%, respectively, with CHO ingestion. Similar trends were evident for subanalyses of studies using only male or trained participants, for exercise of 1–3 h duration, and where CHO and PLA beverages were matched for electrolyte content.
Against this background, can the relevant question really be: "To carb or not to carb?" Probably not. You better follow Vince Andrich's recent advice and ask yourself "Are you working your sugar-bags (muscles) hard enough to earn your fair share of carb intake?" in order to make sure that you use just as much carbs as it takes to optimize performance without compromising health and body composition.