The effect of carbohydrate ingestion on the experience of fatigue during prolonged exercise
AbstractBackground: Muscle fatigue occurs during prolonged exercise as the body’s energy stocks in the form of muscle glycogen and blood glucose levels within the body become depleted. The sensation of fatigue can become so intense that the person must reduce his or her efforts, or even stop the exercise altogether. Studies have shown that the ingestion of carbohydrate solutions can delay this onset of fatigue. The ingestion of multiple transportable carbohydrates can improve performance and increases exercise capacity more than single transportable carbohydrates. Therefore, the ingestion of multiple transportable carbohydrates may decrease the experience of fatigue during a fixed workload. The purpose of the randomized, double-blind, placebo-controlled study presented in this paper is to explore the effects of the ingestion of multiple transportable carbohydrates such as glucose with fructose, and glucose with sucrose, in decreasing the experience of fatigue as compared to an isoenergetic amount of glucose. Methods: Twelve healthy, trained male athletes cycled 180 minutes at 50% maximum power output while receiving a solution providing either 1.8 g/min of glucose (GLU), 1.2 g/min of glucose + 0.6 g/min of fructose (GLU+FRUC), 0.6 g/min glucose + 1.2 g/min sucrose (GLU+SUC) or water (WAT). The experience of fatigue was assessed with the Borg scale where subjects were asked to rate their perceived exertion every 30 minutes during exercise. Results: The results of this study cannot be published. Conclusion: Although the results cannot be published, some speculations can be made. RPE (ratings of perceived exertion) are expected to differ significantly between the four ingested solutions during the later stages of exercise. The expectation is that the RPE for those subjects ingesting multiple transportable carbohydrates will be lower than those ingesting glucose and water. The same should hold true for the single transportable carbohydrate versus water trials. In summary, when glucose and fructose or glucose and sucrose are ingested simultaneously at high rates during cycling exercise, the experience of fatigue is likely to be reduced in comparison to the ingestion of an isoenergetic amount of glucose.
Edwards RH. Human muscle function and fatigue. Human muscle fatigue: physiological mechanisms. 82: Pitman Medical London; 1981. p. 1-18.
Ament W, Verkerke GJ. Exercise and fatigue. Sports Medicine. 2009;39(5):389-422.
Burgess ML, Robertson RJ, Davis JM, Norris JM. RPE, blood glucose, and carbohydrate oxidation during exercise: effects of glucose feedings. Medicine and science in sports and exercise. 1991;23(3):353-9.
Coyle EF, Coggan AR, Hemmert MK, Ivy JL. Muscle glycogen utilization during prolonged strenuous exercise when fed carbohydrate. Journal of applied physiology (Bethesda, Md : 1985). 1986;61(1):165-72.
Rowlands DS, Thorburn MS, Thorp RM, Broadbent S, Shi X. Effect of graded fructose coingestion with maltodextrin on exogenous 14C-fructose and 13C-glucose oxidation efficiency and high-intensity cycling performance. Journal of applied physiology (Bethesda, Md : 1985). 2008;104(6):1709-19.
Utter AC, Kang J, Nieman DC, Williams F, Robertson RJ, Henson DA, et al. Effect of carbohydrate ingestion and hormonal responses on ratings of perceived exertion during prolonged cycling and running. Eur J Appl Physiol Occup Physiol. 1999;80(2):92-9.
Backhouse SH, Bishop NC, Biddle SJ, Williams C. Effect of carbohydrate and prolonged exercise on affect and perceived exertion. Medicine and science in sports and exercise. 2005;37(10):1768-73.
Jeukendrup AE. Carbohydrate intake during exercise and performance. Nutrition. 2004;20(7–8):669-77.
Jentjens RL, Jeukendrup AE. High rates of exogenous carbohydrate oxidation from a mixture of glucose and fructose ingested during prolonged cycling exercise. The British journal of nutrition. 2005;93(4):485-92.
Jeukendrup A. A step towards personalized sports nutrition: carbohydrate intake during exercise. Sports medicine (Auckland, NZ). 2014;44 Suppl 1:S25-33.
Jeukendrup AE, Jentjens R. Oxidation of carbohydrate feedings during prolonged exercise: current thoughts, guidelines and directions for future research. Sports medicine (Auckland, NZ). 2000;29(6):407-24.
Jentjens RL, Moseley L, Waring RH, Harding LK, Jeukendrup AE. Oxidation of combined ingestion of glucose and fructose during exercise. Journal of applied physiology (Bethesda, Md : 1985). 2004;96(4):1277-84.
Jentjens RL, Achten J, Jeukendrup AE. High oxidation rates from combined carbohydrates ingested during exercise. Medicine and science in sports and exercise. 2004;36(9):1551-8.
Davidson RE, Leese HJ. Sucrose absorption by the rat small intestine in vivo and in vitro. J Physiol. 1977;267(1):237-48.
Jeukendrup AE. Carbohydrate feeding during exercise. European Journal of Sport Science. 2008;8(2):77-86.
Currell K, Jeukendrup AE. Superior endurance performance with ingestion of multiple transportable carbohydrates. Medicine and science in sports and exercise. 2008;40(2):275-81.
Triplett D, Doyle JA, Rupp JC, Benardot D. An isocaloric glucose-fructose beverage’s effect on simulated 100-km cycling performance compared with a glucose-only beverage. Int J Sport Nutr Exerc Metab. 2010;20(2):122-31.
Borg GA. Psychophysical bases of perceived exertion. Medicine and science in sports and exercise. 1982;14(5):377-81.
Frayn KN. Calculation of substrate oxidation rates in vivo from gaseous exchange. J Appl Physiol Respir Environ Exerc Physiol. 1983;55(2):628-34.
Kang J, Robertson RJ, Goss FL, DaSilva SG, Visich P, Suminski RR, et al. Effect of carbohydrate substrate availability on ratings of perceived exertion during prolonged exercise of moderate intensity. Percept Mot Skills. 1996;82(2):495-506.