Optimisation of Carbohydrates for Endurance Athletes
by Doug Stewart
Carbohydrates are seen by many as perhaps the most valuable energy substrate for endurance athletes operating at an elite level. A recently published paper explored the current research on carbohydrates for endurance athletes and future research requirements.
The paper provides a very detailed summary, looking at carbohydrates pre, during, and post competition, as well as during training and in other scenarios. There is too much information to go into in a single newsletter, but I think there are a few very actionable elements in it for endurance athletes.
For example, the periodisation of carbohydrates is highlighted, as are the potential performance benefits of various types of carbohydrates for recovery post exercise.
Focussing on the periodisation approach, the authors suggest that varying carbohydrate intake based on the demands of the upcoming training session looks to be the optimal tactic. This should allow for the workout to be completed, whilst minimising the likelihood of too little or too much impact on training adaptations. They propose the following framework:
Framework for carbohydrate periodization based on the demands of the upcoming exercise session. Exercise intensity domain selection refers to the highest intensity attained during the exercise session. The exact carbohydrate requirements are to be personalized based on the expected energy demands of each exercise session. CHO carbohydrates, CP critical power, LT1 lactate threshold 1, LT2 lactate threshold 2, MLSS maximal lactate steady state
Source: Podlogar and Wallis, 2022
With respect to types of carbohydrates, the authors highlight the importance of varying these (glucose and fructose) when exercising. This has been fairly well publicised, and they recommend a mix of 1 part glucose to 0.8 fructose (as opposed to the earlier research that suggested a 2:1 ratio). Interestingly, one of the authors of this piece published a paper earlier this September showing that the addition of fructose to a carbohydrate rich breakfast improved endurance cycling performance, versus a control breakfast without fructose.
However, whilst the authors acknowledge that varying carbohydrate types for recovery does not appear to improve muscle glycogen storage, there does appear to be a benefit for liver glycogen stores. By combining fructose and glucose post training/racing, then it seems likely that liver glycogen storage will recover faster than it would without fructose.
The authors do acknowledge that more research is needed in this area to determine the performance benefits, if any, of this approach.
Additionally, they highlight that the vast majority of the research they reviewed was conducted on healthy male athletes, and that more research is required on female athletes, and on those that suffer from diabetes type 1.
However, I think this summary paper is a fantastic insight into the current understandings around carbohydrates and the role they play for optimising endurance performance. Moreover, the paper has highlighted gaps in knowledge, identifying where further research is required and therefore where we cannot be sure of the best approach.
References:
Podlogar, T., Cirnski, S., Bokal, Š., Verdel, N. and Gonzalez, J.T., 2022. Addition of Fructose to a Carbohydrate-Rich Breakfast Improves Cycling Endurance Capacity in Trained Cyclists. International journal of sport nutrition and exercise metabolism, 1(aop), pp.1-7.
Podlogar, T., Wallis, G.A. New Horizons in Carbohydrate Research and Application for Endurance Athletes. Sports Med (2022). https://doi.org/10.1007/s40279-022-01757-1