"The importance of nutrition following training-induced homeostatic disruption can be traced to our most ancient of writings. Esau, the first born of Isaac, in what is estimated to be 1800 B.C. appears to have had incredible genetics. His training sessions, however, were not found in the gym, but rather in the field as he hunted the most ferocious of beasts. So vital was the post-workout meal to the father of the Edomites that he sold his birthright to his brother Jacob for it!" -- Jacob Wilson, HYPERplasia the Magazine Glycemic Index and Sports Nutrition The glycemic index is a ranking of carbs according to the extent to which they raise blood sugar levels after eating. Foods with a high-glycemic index are those which are rapidly digested and absorbed and result in marked fluctuations in blood sugar levels. In general, sports nutritionists recommend that one ingest low-glycemic carbs before exercise and high-glycemic carbs immediately after exercise. Less post-prandial hyperglycemia and hyperinsulinemia have been observed after the consumption of the low-glycemic foods when compared with high-glycemic foods.(1) Such metabolic and hormonal responses promote more stable blood sugar levels and maintain free fatty acids at higher levels during exercise, which in turn promotes fatty acid burning. On the other hand, a high-glycemic CHO-rich meal may be beneficial for the glycogen storage and muscle protein anabolism after exercises by promoting greater glucose and insulin responses.(1) While rapid glycogen re-synthesis is seldom a concern for the physique athletes, high-glycemic carb ingestion immediately after resistance exercise can decrease muscle protein breakdown and urinary urea excretion, resulting in a more positive body protein balance.(2) Post-Exercise High-Glycemic Carb Ingestion Promotes Fat Gain? Hardly Some have speculated that post-exercise ingestion of high-glycemic carbs may inhibit fat loss. However, I feel this is hardly a concern for the serious athletes when carbs are ingested immediately after rigorous exercise when the muscle cells are highly receptive to insulin and "screaming" for new fuel. It must be realized that the physiological state of that of a sedentary individual and that of a well-trained athlete following exercise are polar opposites. The so-called AMP-activated protein kinase acts as a "metabolic switch" in multiple tissues after exercise; the net effect of its activation is to increase fatty acid burning and diminish storage fat synthesis. To investigate the hormonal and metabolic adaptations occurring when high-glycemic carbs are ingested after exercise, Dr. Krezentowski and co-workers compared the fate of a 100-g oral glucose load in healthy volunteers after an overnight fast at rest either without previous exercise or after a 3-h exercise performed on a treadmill at about 50% of the individual VO2max.(3) Indirect calorimetry indicated that glucose ingestion in post-exercise recovery was associated with decreased carbohydrate burning and increased fat burning when compared to control conditions. More recently, Dr. Folch and colleagues reported that de novo lipogenesis (the metabolic route by which mammals convert excessive dietary carbs into fat) is totally suppressed following exercise, even when a very large carb load is ingested, and that fat burning remained high in subjects who had exercised following both the small and large carb meal.(4) Finally, Dr. Bird and co-workers observed that post-exercise ingestion of high-glycemic carbohydrates do not inhibit resistance training-induced fat loss.(5) In summary, it seems to me that the guys who are afraid about fat gain as a result of post-exercise high-glycemic carb ingestion are worrying about a non-issue. Don't Forget Aminos, Dude! Obviously, you also have to take in some amino acids immediately after exercise, as protein balance over the muscle remains negative after resistance exercise when only carbs are ingested.(6) While amino acid ingestion alone significantly increases muscle protein anabolism after resistance exercise(7), consumption of both amino acids and carbs results in much greater effects on muscle protein anabolism(8), suggesting an interactive effect between insulin, amino acids and resistance exercise. Interestingly, a recent placebo-controlled study reported that post-exercise protein-carb supplementation
    1) reduces bacterial/viral infections
    2) decreases medical visits due to muscle or joint problems
    3) diminishes episodes of heat exhaustion
    4) reduces muscle soreness
    5) improves rifle scores in US Marine recruits during basic training.(9)
About Anssi Manninen Anssi Manninen holds an M.H.S. in sports medicine from the University of Kuopio Medical School. His numerous cutting-edge articles in Muscular Development firmly established his reputation as a leading authority on hard-core sports nutrition. Anssi's articles have also been published in scientific journals, including The Journal of International Society of Sports Nutrition, Nutrition & Metabolism, and Journal of Sports Science and Medicine. Anssi is also an Associate Editor for Nutrition & Metabolism, a leading scientific journal in the area of nutritional biochemistry.
References 1. Siu PM, Wong SH. Use of the glycemic index: effects on feeding patterns and exercise performance. J Physiol Anthropol Appl Human Sci. 2004;23(1):1-6. 2. Roy BD, Tarnopolsky MA, Macdougall JD, Fowles J, Yarasheski KE. Effect of glucose supplement timing on protein metabolism after resistance training. J Appl Physiol. 1997;82:1882-8. 3. Krzentowski G, Pirnay F, Luyckx AS, Pallikarakis N, Lacroix M, Mosora F, Lefebvre PJ. Metabolic adaptations in post-exercise recovery. Clin Physiol. 1982;2(4):277-88. 4. Folch N, Peronnet F, Massicotte D, Duclos M, Lavoie C, Hillaire-Marcel C. Metabolic response to small and large 13C-labelled pasta meals following rest or exercise in man. Br J Nutr. 2001;85:671-80. 5. Bird SP, Tarenning KM, Marino FE. Independent and combined effects of liquid carbohydrate/essential amino acid ingestion on hormonal and muscular adaptations following resistance training in untrained men. Eur J Appl Physiol. 2006;97:225-38. 6. Borsheim E, Cree MG, Tipton KD, Elliott TA, Aarsland A, Wolfe RR. Effect of carbohydrate intake on net muscle protein synthesis during recovery from resistance exercise. J Appl Physiol. 2004;96:674-8. 7. Tipton KD, Ferrando AA, Phillips SM, Doyle D Jr, Wolfe RR. Postexercise net protein synthesis in human muscle from orally administered amino acids. Am J Physiol. 1999;276:E628-34. 8. Rasmussen BB, Tipton KD, Miller SL, Wolfe SE, Wolfe RR. An oral essential amino acid-carbohydrate supplement enhances muscle protein anabolism after resistance exercise. J Appl Physiol. 2000;88:386-92. 9. Flakoll PJ, Judy T, Flinn K, Carr C, Flinn S. Postexercise protein supplementation improves health and muscle soreness during basic military training in Marine recruits. J Appl Physiol. 2004;96:951-6.