Document Type : Research Paper
Authors
1 Ph.D. Student of Sport Physiology, Ferdowsi University of Mashhad
2 Professor of Sport Physiology, Guilan University
Abstract
The aim of this study was to compare of different timing effect of carbohydrate intake before exercise on maximal fat oxidation (MFO) and Fatmax in endurance runners. Eight professional endurance runners (age 21.6±2.61 years, VO2max 63.0±8.7 ml.kg.min, body fat percentage 9.1±1.92, Background 7±3 years) participated as the subject in four separate trials. In the first session, the participants performed a graded exercise tests at 8 a.m. in fasted condition on treadmill to exhaustion in order to determine the amount of Fatmax and MFO. In the second, third and fourth session, with an interval of seven to ten days, participants in fasted condition, consumed 1 gr carbohydrate per kg body weight, with 500 ml water five minutes, one and three hours before the beginning of graded exercise tests. The amount of MFO and Fatmax were measured through indirect calorimetry method using the gas analysis system with aim of stoichiometric equation. The analysis of variance tests with repeated measures was used for data analysis. When carbohydrate is consumed five minutes and one hour prior to physical activity, MFO and Fatmax depict the lowest and highest decline respectively. MFO and Fatmax, in fasted condition, was significantly higher than the consumption of carbohydrate five minutes, one hour and three hours before the exercise (P<0.05). But no significant difference was seen in MFO and fatmax between different conditions of carbohydrate consumption. In general, the results indicated that consumption of carbohydrate in different timings before exercise cause the decrease in MFO and transferring of Fatmax to lower intensity of exercise. This means that the start of fat oxidation reduction occurs in lower intensity and participants depend more on carbohydrate sources.
Keywords
Main Subjects
- Venables M C, Achten J, Jeukendrup A E. Determinants of fat oxidation during exercise in healthy men and women: A cross-sectional study. Journal of Applied Physiology. 2005; 98(1): 160-67.
- Achten J, Gleeson M, Jeukendrup A E. Determination of the exercise intensity that elicits maximal fat oxidation. Medicine and Science in Sports and Exercise. 2002; 34(1): 92-97.
- Lima-Silva A E, Bertuzzi R C, Pires F O, Gagliardi J F, Barros R V, Hammond J, et al. Relationship between training status and maximal fat oxidation rate. Journal of Sports Science & Medicine. 2010; 9(1): 31-35.
- Achten J, Jeukendrup A E. The effect of pre-exercise carbohydrate feedings on the intensity that elicits maximal fat oxidation. Journal of Sports Sciences. 2003; 21(12): 1017-24.
- Ashley C D, Kramer M L, Bishop P. Estrogen and substrate metabolism: A review of contradictory research. Sports Medicine. 2000; 29(4): 221-7.
- Bogdanis G C, Vangelakoudi A, Maridaki M. Peak fat oxidation rate during walking in sedentary overweight men and women. Journal of Sports Science & Medicine. 2008; 7(4): 525-31.
- Hawley J A, Schabort E J, Noakes T D, Dennis S C. Carbohydrate-loading and exercise performance. An update. Sports Medicine. 1997; 24(2): 73-81.
- Hargreaves M, Hawley J A, Jeukendrup A. Pre-exercise carbohydrate and fat ingestion: Effects on metabolism and performance. Journal of Sports Sciences. 2004; 22(1): 31-8.
- Brouns F, Rehrer N J, Saris W H, Beckers E, Menheere P, ten Hoor F. Effect of carbohydrate intake during warming-up on the regulation of blood glucose during exercise. International Journal of Sports Medicine. 1989; 10 Sup 1: S68-75.
- Horowitz J F, Mora-Rodriguez R, Byerley L O, Coyle E F. Lipolytic suppression following carbohydrate ingestion limits fat oxidation during exercise. The American Journal of Physiology. 1997; 273(4 Pt 1): E768-75.
- Van Loon L J, Greenhaff P L, Constantin-Teodosiu D, Saris W H, Wagenmakers A J. The effects of increasing exercise intensity on muscle fuel utilisation in humans. The Journal of Physiology. 2001; 536(Pt 1): 295-304.
- Gray S C, Devito G, Nimmo M A. Effect of active warm-up on metabolism prior to and during intense dynamic exercise. Medicine and Science in Sports and Exercise. 2002; 34(12): 2091-6.
- Romijn J A, Coyle E F, Sidossis L S, Rosenblatt J, Wolfe R R. Substrate metabolism during different exercise intensities in endurance-trained women. Journal of Applied Physiology. 2000; 88(5): 1707-14.
- Mohebbi H, Damirchi A, Rohani H, Shadmehri S. Comparison of maximal fat oxidation in untrained male and female students. Olympic. 2010; (2): 43-50. (In Persian).
- Howley E T, Duncan G E, Del Corral P. Optimum intensity for fat oxidation. Medicine & Science in Sports & Exercise. 1997; 29(5): 199.
- Mohebbi H, Azizi M, Tabari E. Effect of time of day on MFO and FATmax during exercise in obese and normal weight women. Physical Education and Sport. 2011; 9(1): 69-79. (In persian).
- Khosravi N, Souri R, Shahgholian S. The effect of time of day on fat oxidation indexes (MFO, Fat max, MFO time) in healthy young women. Sport Biosciences. 2012; 5(11): 75-88. (In persian).
- Aucouturier J, Rance M, Meyer M, Isacco L, Thivel D, Fellmann N, et al. Determination of the maximal fat oxidation point in obese children and adolescents: Validity of methods to assess maximal aerobic power. European Journal of Applied Physiology. 2009; 105(2): 325-31.
- Rohani H, Damirchi A, Hasan Nia S, Rohani M. The effects of dehydration on maximal fat oxidation (MFO) and the exercise intensity proportional to the MFO (Fatmax). Olympic. 2008; 4(44): 89-98. (In persian).
- Safari Musavi S S, Mohebbi H, Damirchi A, Havanlu F. Effect of reduced muscle glycogen on MFO and Fatmax during exercise in untrained men. Exercise Metabolism. 2012; 2(2): 113-23. (In Persian).
- Achten J, Jeukendrup A E. Maximal fat oxidation during exercise in trained men. International Journal of Sports Medicine. 2003; 24(8): 603-8.
- Jeukendrup A E, Wallis G A. Measurement of substrate oxidation during exercise by means of gas exchange measurements. International Journal of Sports Medicine. 2005; 26(1): S28-37.
- Romijn J A, Coyle E F, Hibbert J, Wolfe R R. Comparison of indirect calorimetry and a new breath 13C/12C ratio method during strenuous exercise. The American Journal of Physiology. 1992; 263(1): E64-71.
- Bonen A, Belcastro A N, MacIntyre K, Gardner J. Hormonal responses during intense exercise preceded by glucose ingestion. Canadian Journal of Applied Sport Sciences. 1980; 5(2): 85-90.
- Bonen A, Malcolm S A, Kilgour R D, MacIntyre K P, Belcastro A N. Glucose ingestion before and during intense exercise. Journal of Applied Physiology: Respiratory, Environmental and Exercise Physiology. 1981; 50(4): 766-71.
- Rohani H, Safari Musavi S S, Golamian S, Farzaneh E. Comparison of maximal fat oxidation and Fatmax in trained and untrained women. Exercise Physiology. 2015; 7(28): 31-44. (In Persian).
- Jeukendrup A E. Modulation of carbohydrate and fat utilization by diet, exercise and environment. Biochemical Society Transactions. 2003; 31(6): 1270-3.
)