Fat and carbohydrate for exercise

Current Opinion in Clinical Nutrition and Metabolic Care

Volumn 9, Issue 4, 2006, Pages 476-481

  Burke, Louise M ^a,c   Hawley, John A ^b  

^a AUSTRALIAN INSTITUTE OF SPORT   (Australia)

^b RMIT UNIVERSITY   (Australia)

^c Department of Sports Nutrition ^*  (Australia)

Author keywords

Athletic performance; ATP; Dietary periodization; Muscle glycogen; Triacylglycerol

Indexed keywords

BIOFUEL; CARBOHYDRATE; FAT; GLUCOSE;

ADAPTATION; ATHLETE; BRAIN FUNCTION; CARBOHYDRATE INTAKE; CELL FUNCTION; DIET; ENDURANCE; EXERCISE; HUMAN; MACRONUTRIENT; METABOLISM; MOLECULAR DYNAMICS; MUSCLE; NUTRIENT; NUTRIENT LOADING; OUTCOME ASSESSMENT; OXIDATION; PERFORMANCE; REVIEW; SIGNAL TRANSDUCTION; STEADY STATE; TRAINING;

EID: 33746209088     PISSN: 13631950     EISSN: 15353885     Source Type: Journal    
DOI: 10.1097/01.mco.0000232911.69236.3b     Document Type: Review

References (28)

1. Bussau VA, Fairchild TJ, Rao A, et al. Carbohydrate loading in human muscle: an improved 1 day protocol. Eur J Appl Physiol 2002; 87:290-295.
2. McInerney P, Lessard SJ, Burke LM, et al. Failure to repeatedly supercompensate muscle glycogen stores in highly trained men. Med Sci Sports Exerc 2005; 37:404-411. This study of repeated carbohydrate loading techniques has relevance to athletic practice as well as the science underpinning exercise performance. Well trained athletes were able to perform intermittent high-intensity cycling sprints for longer after repeated bouts of carbohydrate loading, despite a reduction in the efficiency of glycogen storage in the second carbohydrate loading protocol.
3. Rauch HG, St Clair Gibson A, Lambert EV, et al. A signalling role for muscle glycogen in the regulation of pace during prolonged exercise. Br J Sports Med 2005; 39:34-38. This study found a relationship between pacing and glycogen utilization. Cyclists undertook a 3-h cycling bout, completing the last hour as a time trial, with normal dietary preparation or following carbohydrate loading. Carbohydrate loading enhanced the mean power output in the 1-h time trial and increased glycogen utilization so that finishing muscle glycogen content was very similar after each trial.
4. van Loon LJ, Murphy R, Oosterlaar AM, et al. Creatine supplementation increases glycogen storage but not GLUT-4 expression in human skeletal muscle. Clin Sci 2004; 106:99-106.
5. Burke LM, Kiens B. 'Fat adaptation' for athletic performance: the nail in the coffin? J Appl Physiol 2006; 100:7-8. This editorial provides a succinct summary of the literature on fat-loading techniques for endurance and ultra-endurance athletes. The authors conclude on the basis of evidence from recent studies of performance changes and underlying mechanisms that these techniques do not benefit and may impair performance.
6. Havemann L, West S, Goedecke JH, et al. Fat adaptation followed by carbohydrate-loading compromises high-intensity sprint performance. J Appl Physiol 2006; 100:194-202. This paper was highlighted for an editorial because it appears to provide the final proof that fat adaptation strategies are not useful for performance enhancement of the usual range of endurance and ultra-endurance events. The study applied the fat adaptation-glycogen restoration protocol to a 100-km cycling protocol involving regular 1- and 4-km sprints - a protocol described by the authors as being representative of a real-life cycling race. The differences in overall performance were not statistically significant; however there was a trend to lower power production in the 4-km sprints, and a significant reduction in power output in the 1-km sprints.
7. Goedecke JH, Christie C, Wilson G, et al. Metabolic adaptations to a high-fat diet in endurance cyclists. Metabolism 1999; 48:1509-1517.
8. ••] because it provides a mechanism to explain the lack of improvements in endurance and ultra-endurance performance with protocols of fat adaptation followed by glycogen loading. This dietary strategy was shown to reduce the activity of pyruvate dehydrogenase, a key enzyme in carbohydrate oxidation. Such a change would be expected to impair glycogen utilization and, therefore, reduce the capacity for exercise undertaken at high submaximal intensities.
9. Claassen A, Lambert EV, Bosch AN, et al. Variability in exercise capacity and metabolic response during endurance exercise after a low carbohydrate diet. Int J Sport Nutr Exerc Metab 2005; 15:97-116. This study provides information about one of the mechanisms by which carbohydrate intake during exercise enhances performance. Individuals who undertook prolonged bouts of cycling with depleted muscle glycogen stores differed in their response to infusion of carbohydrate during the session to maintain euglycemia. The variability in performance benefits arising from maintenance of blood glucose levels was large and was independent of changes in carbohydrate oxidation.
10. Jentjens RL, Shaw C, Birtles T, et al. Oxidation of combined ingestion of glucose and sucrose during exercise. Metabolism 2005; 54:610-618. Part of a series of studies in which different amounts and types of carbohydrates are ingested during prolonged cycling to see the peak rate of oxidation of exogenously derived carbohydrates. This study compared moderate (1.2 g/min) and high (2.4 g/min) amounts of glucose or glucose plus sucrose, and found oxidation rates of 1.2 g/min with the intake of large amounts of the mixture of sugars.
11. Jentjens RL, Jeukendrup AE. High rates of exogenous carbohydrate oxidation from a mixture of glucose and fructose ingested during prolonged cycling exercise. Br J Nutr 2005; 93:485-492. Another study in the series. High rates of intake of glucose and fructose mixtures (2.4 g/min) result in peak oxidation rates of exogenous carbohydrate of 1.75 g/min.
12. Jentjens RL, Underwood K, Achten J. Exogenous carbohydrate oxidation rates are elevated following combined ingestion of glucose and fructose during exercise in the heat. J Appl Physiol 2006; 100:807-816. The findings of this paper provide a practical alternative to the advice that intakes of large amounts of carbohydrate during exercise in the heat compromise the gastric emptying of fluid, and interfere with hydration status. In this study, the combined intake of fructose and glucose at 1.5 g/min provided higher rates of carbohydrate oxidation and fluid availability than the same amount of carbohydrate in the form of glucose alone.
13. Jeukendrup AE, Moseley L, Mainwaring GI, et al. Exogenous carbohydrate oxidation during ultra-endurance exercise. J Appl Physiol 2006; 100:1134-1141. This study investigated ultra-endurance cycling (5 h) at lower exercise intensities than in the previous series of studies. The combined intake of glucose and fructose in substantial amounts (1.5 g/min) allowed higher rates of oxidation of exogenous carbohydrates during exercise with less gastric fullness than a solution containing 1.5 g/min of glucose alone. There was evidence of a substantial contribution of gluconeogenesis to carbohydrate oxidation late in exercise.
14. Wallis GA, Dawson R, Achten J, et al. Metabolic response to carbohydrate ingestion during exercise in males and females. Am J Physiol Endocrinol Metab 2006; 290:E708-E715. The Jeukendrup research group has been systematic in examining the metabolism of carbohydrates consumed during exercise. In this study, males and females showed similar rates of oxidation of consumed carbohydrates, when glucose and fructose were ingested (1.5 g/min) during 2 h of submaximal cycling. It is good to see studies of the effect of gender on metabolism during exercise as most studies are undertaken on men and assumed to apply to women without direct support.
15. Yeo SE, Jentjens RLPG, Wallis GA, et al. Caffeine increases exogenous carbohydrate oxidation during exercise. J Appl Physiol 2005; 99:844-850. Caffeine has been suggested to alter carbohydrate metabolism in different ways, including decreasing muscle glucose uptake. The unique finding of this study is that caffeine added to a glucose solution increased the oxidation of glucose during the second hour of cycling by around 25%. This finding needs to be confirmed.
16. Carter JM, Jeukendrup AE, Mann CH, et al. The effect of glucose infusion on glucose kinetics during a 1-h time trial. Med Sci Sports Exerc 2004; 36:1543-1550.
17. Carter JM, Jeukendrup AE, Jones DA. The effect of carbohydrate mouth rinse on 1-h cycle time trial performance. Med Sci Sports Exerc 2004; 36:2107-2111.
18. Carter J, Jeukendrup AE, Jones DA. The effect of sweetness on the efficacy of carbohydrate supplementation during exercise in the heat. Can J Appl Physiol 2005; 30:379-391. This study addresses the hypothesis that a sweet taste provides part of the mechanism to explain the ergogenic effect of carbohydrate consumed during exercise. Sweet and nonsweet forms of carbohydrate were both associated with an increased cycling time to exhaustion in the heat, compared with the intake of water.
19. Goedecke JH, Clark VR, Noakes TD, et al. The effects of medium-chain triacylglycerol and carbohydrate ingestion on ultra-endurance exercise performance. Int J Sport Nutr Exerc Metab 2005; 15:15-28. This study provides the 'nail in the coffin' for the use of MCT oils as a supplementary fuel source during ultra-endurance cycling. Other studies have failed to find a performance benefit, while this study reported a decrement in performance.
20. Hooper SM, Hughes JA, Newcombe RG, et al. A methodology for testing the erosive potential of sports drinks. J Dent 2005; 33:343-348. This study developed and tested a methodology in situ that simulated the consumption of sports drinks.
21. von Fraunhofer JA, Rogers MM. Effects of sports drinks and other beverages on dental enamel. Gen Dent 2005; 53:28-31. This study used an in-vitro method to test the effect of a variety of drinks on dental enamel.
22. Coombes J. Sports drinks and dental erosion. Am J Dent 2005; 18:101-104. This paper provides a review of the issues of sports drink and dental erosion, noting that although there is much in-vitro evidence that acidic drinks such as wine, fruit juices, and carbonated soft drinks have erosive potential and there are relationships between consumption of these drinks and erosion, only one study has reported an association between sports drinks and dental erosion. Other factors such as drinking habit and salivary production may be more important determinants of dental erosion.
23. Venables MC, Shaw L, Jeukendrup AE, et al. Erosive effect of a new sports drink on dental enamel during exercise. Med Sci Sports Exerc 2005; 37:39-44. This study investigated the effect of a new formulation of a sports drink on dental erosion and found a significant reduction compared with the standard commercial formulation.
24. Ramalingam L, Messer LB, Reynolds EC. Adding casein phosphopeptide- amorphous calcium phosphate to sports drinks to eliminate in vitro erosion. Pediatr Dent 2005; 27:61-67. Another modification to the formulation of sports drinks was able to reduce the effect on dental enamel.
25. Febbraio MA, Steensberg A, Walsh R, et al. Reduced glycogen availability is associated with an elevation in HSP72 in contracting human skeletal muscle. J Physiol 2003; 538:911-917.
26. Pilegaard H, Ordway GA, Saltin B, et al. Transcriptional regulation of gene expression in human skeletal muscle during recovery from exercise. Am J Physiol Endocrinol Metab 2000; 279:E806-E814.
27. Hansen AK, Fischer CP, Plomgaard P, et al. Skeletal muscle adaptation: training twice every second day vs. training once daily. J Appl Physiol 2005; 98:93-99. This study received much publicity in the lay and scientific press with its findings that training twice every second day may be superior to daily training. Of course, the training model and use of untrained individuals make it difficult to extrapolate the results to elite athletes. Nevertheless, it invites discussion and further study.
28. Creer A, Gallagher P, Slivka D, et al. Influence of muscle glycogen availability on ERK1/2 and Akt signaling after resistance exercise in human skeletal muscle. J Appl Physiol 2005; 99:950-956. ERK1/2 and Akt are two of the signaling pathways that have been implicated for cellular growth and development in response to resistance training. In this study, a bout of resistance exercise was undertaken with high- or low-glycogen levels by trained cyclists. There was no change in the activation of the ERK 1/2 pathway, however stimulation of the Akt pathway was greater in the high-carbohydrate trial than the low-glycogen trial, suggesting a more favorable response.