It is great to see the much needed new and revised position statement by the Academy of Nutrition and Dietetics, Dietitians of Canada, and the American College of Sports Medicine! Just published in the journal Medicine and Science in Sports and Exercise, you can now download the new statement here: it is free.
The new position statement
The statement discusses the evidence that the performance of, and recovery from, sporting activities are enhanced by well-chosen nutrition strategies. The guidelines go into a fair amount of detail, specifying amounts, timing and in many cases the type of nutrients that have to be ingested in order to get these benefits. The guidelines span across a range of sports and are suitable for both training and competition. Recommendations in the paper are generally in grams or milligrams of a specific nutrient and does not detail the foods that should or could be eaten to achieve these guidelines. These general recommendations can be adjusted by sports dietitians to accommodate the unique issues of individual athletes regarding health, nutrient needs, performance goals, physique characteristics (ie, body size, shape, growth, and composition), practical challenges and food preferences.
Below is an example of one of the recommendation. It is also clearly outlined in the paper who these guidelines are for and when they should be applied. There is no one size fits all and what and how much needs to be ingested depends on goals, the event, practicalities, personal preferences and so on.
It is also great to see that the new statement included the new carbohydrate intake guidelines during exercise discussed in a previous blog.
Evidence
After a careful analysis of evidence, the expert group divided evidence into different categories: good evidence, fair evidence, limited evidence, expert opinion only or not sufficient information to categorize the evidence. A number of questions are addressed and answered in a statement which is labeled with a ranking the experts came up with for the level of evidence. For example one question is:
"In adult athletes, what effect does consuming high or low glycemic meals or foods have on training related metabolic responses and exercise performance?"
The answer received a grade “good” evidence: "In the majority of studies examined, neither glycemic index nor glycemic load affected endurance performance nor metabolic responses when conditions were matched for carbohydrate and energy."
Another question that received an answer with a good evidence rating:
"In adult athletes, what is the effect of consuming carbohydrate and protein together on carbohydrate and protein-specific metabolic responses
during recovery?"
Answers:
"Compared to ingestion of carbohydrate alone, coingestion of carbohydrate plus protein together during the recovery period resulted in no difference in the rate of muscle glycogen synthesis."
"Co-ingestion of protein with carbohydrate during the recovery period resulted in improved net protein balance post-exercise."
"The effect of co-ingestion of protein with carbohydrate on creatine kinase levels is inconclusive and shows no impact on muscle soreness post-exercise."
Remaining questions
In my opinion the paper does address training versus competition and mentioned that some training might be treated as competition because quality of training is so important. Where future position statements can make some further improvement is specifying advice for very specific goals of training. Also many recommendations are based on endurance sports because this is where most of the research has been done but the applications in teams sports are less clear. For example, carbohydrate intake recommendations during exercise are listed in grams per hour depending on the duration of exercise. However, is 90 min of endurance exercise the same as 2 x 45 min of soccer? Or even within endurance sports, are recommendations for the marathon runner identical to that of a cyclist or triathlete?
Nuances
In some areas the paper misses some of the nuances of observations. For example with carbohydrate feeding during exercise from glucose:fructose versus glucose it is concluded that there is little effect on the metabolic response and I would disagree with this statement as the measurement that was looked at (total carbohydrate oxidation) may stay roughly the same there are large shifts in the substrates being oxidized during exercise. I am not even sure I would have come to the same conclusion about little or no changes in total carbohydrate oxidation with carbohydrate blends versus glucose as this depends on the amount of carbohydrate ingested. And even if there was no difference there are 3 studies to date that show performance benefits of the blends in specific situations. Those are not specifically mentioned. Looking at metabolic effects is important, but surely performance effects are more important to report.
Conclusion
I think that these guidelines are a huge step in the right direction and they provide more detail than any other guidelines or position statements have done before. Chapeau to all the authors of the statement! At the same time there are still plenty of areas where we don’t have enough data to come to clear recommendations and thus there is still plenty of work to do!
References
Carbohydrate intake recommendations - Asker Jeukendrup