Based on the limited evidence available, carbohydrate (CHO) oxidation was greater in CHO conditions (glucose and glucose+fructose) compared to water placebo, but no differences between the two CHO blends tested were observed in male cyclists. Exogenous CHO oxidation was greater in the glucose+fructose condition vs. glucose-only in a single study.      
 

• Grade I means there is Good/Strong evidence supporting the statement;
• Grade II is Fair;
• Grade III is Limited/Weak;
• Grade IV is Expert Opinion Only;
• Grade V is Not Assignable.
• High (A) means we are very confident that the true effect lies close to that of the estimate of the effect;
• Moderate (B) means we are moderately confident in the effect estimate;
• Low (C) means our confidence in the effect estimate is limited;
• Very Low (D) means we have very little confidence in the effect estimate.
• Ungraded means a grade is not assignable.

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  • Currell K and Jeukendrup A. Superior endurance performance with ingestion of multiple transportable carbohydrates. Med Sci Sports Exerc. 2008 (40) 2,275-2,281.
  •  Jeukendrup AE, Moseley L, Mainwaring GI, Samuels S, Perry S, Mann CH. Exogenous carbohydrate oxidation during ultraendurance exercise. J Appl Physiol. 2006; 100: 1,134-1,141.

Training with limited carbohydrate (CHO) availability may lead to some metabolic adaptations during training, but did not lead to performance improvements. Based on the evidence examined, while there is insufficient evidence supporting a clear performance effect, training with limited CHO availability impaired training intensity and duration.

 

• Grade I means there is Good/Strong evidence supporting the statement;
• Grade II is Fair;
• Grade III is Limited/Weak;
• Grade IV is Expert Opinion Only;
• Grade V is Not Assignable.
• High (A) means we are very confident that the true effect lies close to that of the estimate of the effect;
• Moderate (B) means we are moderately confident in the effect estimate;
• Low (C) means our confidence in the effect estimate is limited;
• Very Low (D) means we have very little confidence in the effect estimate.
• Ungraded means a grade is not assignable.

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• Worksheets
  • Bartlett JK, Lourhelainen J, Iqbal Z, Cochran AJ, Gibala MJ, Gregson W, Close GL, Drust B, Morton JP. Reduced carbohydrate availability enhances exercise-induced p53 signaling in human skeletal muscle: Implications for mitochondrial biogenesis. Am J Physiol Regul Integ Comp Physiol. 2013; 304: R450-R458.
  • Camera DM, West DWD, Burd NA, Phillips SM, Garnham AP, Hawley JA, Coffey VG. Low muscle glycogen concentration does not suppress the anabolic response to resistance exercise. J Appl Physiol. 2012; 113: 206-214. 
  • Havemann L, West SJ, Goedecke JH, Macdonald IA, St Clair Gibson A, Noakes TD, Lambert EV. Fat adaptation followed by carbohydrate loading compromises high-intensity sprint performance. J Appl Physiol. 2006; 100: 194-202.
  • Howarth KR, Philips SM, MacDonald MJ, Richards D, Moreau NA, Gibala MJ. Effect of glycogen availability on human skeletal muscle protein turnover during exercise and recovery, J Appl Physiol. 2010; 109: 431-438.  
  • Hulston CJ, Venables MC, Mann CH, Martin C, Philp A, Baar K, Jeukendrup AE. Training with low muscle glycogen enhances fat metabolism in well-trained cyclists. Med Sci Sports Exerc. 2010; 42(11): 2,046-2,055.
  • Lima-Silva AE, Pires FO, Bertuzzi R, Silva-Cavalcante MD, Oliveira RSF, Kiss MA, Bishop D. Effects of a low or high carbohydrate diet on performance, energy system contribution and metabolic responses during supramaximal exercise. Applied Physiology, Nutrition, and Metabolism, 2013; 38 (9): 928-934.
  • Morton JP, Croft L, Bartlett JD, MacLaren DPM, Reilly T, Evans L, McArdle A, Drust B. Reduced carbohydrate availability does not modulate training-induced heat shock protein adaptations but does upregulate oxidative enzyme activity in human skeletal muscle. J Appl Physiol. 2009; 106: 1,513-1,521. 
  • Psilander N, Frank P, Flockhart M, Sahlin K. Exercise with low glycogen increases PGC-1a gene expression in human skeletal muscle. Eur J Appl Physiol. 2013; 113: 951-963.
  • Stellingwerff T, Spriet LL, Watt MJ, Kimber NE, Hargreaves M, Hawley JA, Burke LM. Decreased PDH activation and glycogenolysis during exercise following fat adaptation with carbohydrate restoration. Am J Physiol Endocrinol Metab. 2006; 290: E380-E388. 

In the majority of studies examined, neither glycemic index (GI) nor glycemic load (GL) affected endurance performance or metabolic responses when conditions were matched for carbohydrate (CHO) and energy.  

• Grade I means there is Good/Strong evidence supporting the statement;
• Grade II is Fair;
• Grade III is Limited/Weak;
• Grade IV is Expert Opinion Only;
• Grade V is Not Assignable.
• High (A) means we are very confident that the true effect lies close to that of the estimate of the effect;
• Moderate (B) means we are moderately confident in the effect estimate;
• Low (C) means our confidence in the effect estimate is limited;
• Very Low (D) means we have very little confidence in the effect estimate.
• Ungraded means a grade is not assignable.

• Detail
• Quality Rating Summary
  For a summary of the Quality Rating results, click here.
• Worksheets
  • Bennett CB, Chilibeck PD, Barss T, Vatanparast H, Vandenberg A, Zello GA. Metabolism and performance during extended high-intensity intermittent exercise after consumption of low- and high-glycaemic index pre-exercise meals. Brit J Nutr. 2012; 108: S81-S90. 
  • Brown LJS, Midgley AW, Vince RV, Madden LA. McNaughton LR. High vs. low glycemic index three-hour recovery diets following glycogen-depleting exercise has no effect on subsequent 5km cycling time trial performance. J Sci Med Sport. 2013; 16(5): 450-454.
  • Chen Y, Wong S, Wong C, Lam C, Huang Y, Siu P. The effect of a pre-exercise carbohydrate meal on immune response to an endurance performance run. Br J Nutr. 2008;100: 1,260-1,268.
  • Chen Y, Wong SHS, et al. Effect of CHO loading patterns on running performance. IJSM 2008; 29: 598-606.
  • Chen YJ, Wong SHS, Chan COW, Wong CK, Lam CW, Siu PMF. Effects of glycemic index meal and CHO-electrolyte drink on cytokine response and run performance in endurance athletes. J Sci Med Sport. 2009; 12: 697-703. 
  • Cocate P, Pereira L, Marins J, Cecon P, Bressan J, AlfenasR. Metabolic responses to high glycemic index and low glycemic index meals: A controlled crossover trial. Nutr J. 2011; 10: 1-10.
  • Erith S, Williams C, Stevenson E, Chamberlain S, Crews P, Rushbury I. The Effect of High Carbohydrate Meals with Different Glyecemic Indices on Recovery of Performance During Prolonged Intermittent High-Intensity Shuttle Running. Int J Sports Nutr Exerc Metab. 2006; 16 (4): 393-404.
  •  Hamzah S, Higgins S, Abraham T, Taylor P, Vizbaraite D, Malkova D. The effect of glycaemic index of high carbohydrate diets consumed over five days on exercise energy metabolism and running capacity in males. J Sports Sci. 2009; 27(14): 1,545–1,554.
  •  Hulton AT, Gregson W, Maclaren D, and Doran DA. (2012). Effects of GI meals on intermittent exercise. Int J Sports Med. 33:756-62.
  • Kern M, Heslin CJ, Rezende RS. Metabolic and Performance Effects of Raisins Versus Sports Gel as Pre-Exercise Feedings in Cyclists. Journal of Strength and Conditioning Research, 2007, 21 (4): 1,204-1,207.
  • Little JP, Chilibeck PD, Ciona D, Forbes S, Rees H, Vandenberg A, Zello GA. Effect of low- and high-glycemic-index meals on metabolism and performance during high-intensity, intermittent exercise. Int J Sport Nutr Exerc Metab. 2010 Dec; 20(6): 447-456.  
  • Moore LJS, Midgley AW, Thomas G, Thurlow S. McNaughton LR. The effects of low- and high-glycemic index meals on time trial performance. Int J Sports Physiol Perform. 2009; 4: 331-344.
  • Moore LJS, Midgley AW, Thurlow S, Thomas G, and McNaughton LR. Effect of the glycaemic index of a pre-exercise meal on metabolism and cycling time trial performance. J Sci Med Sport. 2010; 13: 182–188.
  •  Moore LJS, Midgley AW, Vince R, McNaughton LR. The effects of low and high glycemic index 24-h recovery diets on cycling time trial performance. J Sports Med Phys Fitness. 2011; 51: 233-240.
  • Wong SH, Chan OS, Chen YJ, Hu HL, Lam CW, Chung PK. Effect of pre-exercise glycemic index meal on running when CHO-Electrolyte solution is consumed during exercise. Int J Sport Nutr Exerc Metab. 2009; 19(3): 222-242.
  • Wong SH, Chen YJ, Fung WM, Morris JG. Effect of glycemic index meals on recovery and subsequent endurance capacity. Int J Sports Med. 2009, 30 (12): 898-905.
  • Wu CL, Williams C. A low glycemic index meal before exercise improves endurance running capacity in men. Int J Sport Nutr Exerc Metab. 2006; 16(5): 510-527.