|
|
|
|
home supplements vital stats physiology articles books software links |
POST-EXERCISE PROTEIN-CARBOHYDRATE SUPPLEMENTATION
Physical training promotes better health, which often adds to intrinsic, health values such as increased energy and stamina, youthful appearance, and prolonged life. As people dedicate time to engage in physical training, they need to ensure that the body has the energy and nutrients to recover and build muscle. After a bout of aerobic or anaerobic training, it has been proven that the body undergoes a significant decrease in muscle glycogen and assumes a catabolic state. Immediately, the body attempts to recover and return the body to a pre-exercise state, which are full glycogen stores and a positive nitrogen balance. Therefore, it is important to provide the body with quality foods/supplements in order to replenish glycogen stores and to promote protein resynthesis. Because of this knowledge, many studies aim to illustrate the benefits of digesting a protein-carbohydrate supplement following exercise. In fact, studies prove that carbohydrate supplements taken immediately after exercise results in faster repletion of muscle glycogen compared to the same supplement just two hours later (Tarnopolsky, Bosman, MacDonald, Vandeputte, Martin, and Roy, 1877). The purpose of this paper is to demonstrate the benefits of consuming protein-carbohydrate foods/supplements post physical training in order to replenish muscle glycogen and increase protein resynthesis. Recovery involves a process of repairing muscle damage and replenishing glycogen stores. According to William J. Kraemer et al., “recovery involves the coordinated functioning of several physiological processes that are heavily influenced by the availability and actions of specific hormones and nutrients” (1544). Furthermore, “heavy-resistance exercise disrupts or damages certain muscle fibers that later must undergo a remodeling repair process” (Kraemer, Volek, Bush, Putukian, and Sebastianelli, 1544). The optimal environment for such a remodeling repair process is an abundance of protein and carbohydrates in the muscles. In current times, fitness professionals suggest that athletes consume a protein-carbohydrate drink upon completion of aerobic or anaerobic training in order to optimize recovery as well to achieve greater training adaptations. As a bonus, studies show that resistance training increases the uptake of amino acids and glycogen into the muscles, therefore, providing a window of opportunity for protein-carbohydrate nutrients to enter the damaged tissues (Roy and Tarnopolsky, 890). After a bout of aerobic or anaerobic training, the muscle system is in a catabolic state due to muscle fiber damage. Protein is essential for the repair and growth of muscle tissue. The amino acids that make of protein form all of the building blocks for the human body (Picard, 3). Tiny tears form in the muscle fibers, and an abundance of protein ensures resynthesis and a greater chance of achieving a positive nitrogen balance. The consumption of protein also helps to return the body to an anabolic state, which is a state of muscle growth. Furthermore, BCAAs have been shown to attenuate protein degradation, enhance lean body mass, and prevent fatigue (Kraemer, Volek, Bush, Putukian, and Sebastianelli, 1544). After a bout of aerobic or anaerobic training, muscle glycogen stores are depleted and must be replenished for the body’s ability to perform subsequent training sessions. With this in mind, carbohydrates are the bodies preferred energy source. Without sufficient consumption of carbohydrates, physiological processes begin to suffer. For example, inadequate carbohydrate intake during recovery may compromise glycogen resynthesis and impair athletic performance (Kraemer, Volek, Bush, Putukian, and Sebastianelli, 1545). The body breaks down carbohydrates into a blood sugar called glucose. Glycogen is the storage form of glucose, and two-thirds of glycogen storage is found in the muscles, while one-third is found in the liver. Strength and power output are greatly dependent upon glycogen levels in the muscles. A secondary physiological benefit of glycogen is the H20 that enters the muscle tissues when glycogen repletion occurs. H20 synergistically contributes to protein resynthesis and muscle hydration. Moreover, the influx of water ensures that metabolic wastes are carried out of the muscle tissues. In addition to replacing energy stores, digesting carbohydrates raises insulin levels, which is a main transporter of nutrients to damaged muscle tissues. The mechanism thought to be responsible for this effect of insulin is known as the GLUT-4 transporters, and the migration of these transporters from intracellular stores to the sarcolemma and t tubules of muscle is partially meditated by phosphatidylinositol 3-kinase (Tarnopolsky, Bosman, MacDonald, Vandeputte, Martin and Roy, 1877). The beneficial implications of these findings lend to the idea that it is possible to boost glycogen repletion by merely altering the timing of nutrient intake. Below are selected scientific studies demonstrating the recovery and growth benefits of post-exercise protein-carbohydrate supplementation. In a study performed by Kraemer, Volek, Bush, Putukian, and Sebastianelli, the hormonal responses from consuming supplementation following heavy-resistance exercise were shown to be positive. The sample group consisted of nine resistance-trained men who consumed either a protein-carbohydrate supplement or placebo. The supplement was consumed two hours prior and two hours after resistance training. Blood sample were taken prior and after exercise as well. The results revealed the following: lactate response was significantly lower after supplementation, growth hormone and prolactin responses were significantly higher after supplementation, and insulin like growth factor-I was higher after supplementation. This data illustrates that post-training supplementation can induce metabolic and hormonal responses that could enhance anabolic processes, such as glycogen resynthesis and protein synthesis (1544). In a study conducted by Loon, Kruijshoop, Verhagen, Saris, and Wagenmakers, the focus was on post-exercise levels after the ingestion of carbohydrate and wheat hydrolysate (2508). This knowledge would be of interest to the health & fitness community in designing nutritional programs aimed at maximizing post-exercise insulin levels and to increase plasma amino acid availability (2508). Their results showed that the addition of wheat hydrolysate led to an additional rise in insulin response compared to carbohydrate intake alone (2508). In a study conducted by Rasmussen, Tipton, Miller, Wolf, and Wolfe, the focus was designed to determine the response of muscle protein to the bolus ingestion of drink containing essential amino acids and carbohydrate after resistance exercise. Compared to the placebo, the protein-carbohydrate mixture produced anabolic responses by increasing protein synthesis (386). In a study conducted by Tarnopolsky, Bosman, MacDonald, Martin, and Roy, men were given supplements consisting of carbohydrates (CHO) and protein-carbohydrate (PRO-CHO) and a placebo (P1) in the first four hours following endurance exercise. Both the CHO & PRO-CHO supplement trials showed higher levels of insulin and glucose levels than the P1. However, the CHO & PRO-CHO trials were nearly identical in respect to muscle glycogen resynthesis Tarnopolsky, 1881). It should be noted that the purpose of this study did not included the effects of protein intake on protein resynthesis. A 1998 study conducted by B. D. Roy and M. A. Tarnopolsky focused on macronutrient intakes protein (Pro) and carbohydrate (CHO) and how the intakes affect insulin response and rate of muscle glycogen resynthesis in test subjects who perform resistance training. The test subjects, 10 young males between the ages of 19 and 21 years of age, participated in a placebo-controlled, double-blind trial. Each of the trials included controlled, resistance training and intake of a combination of carbohydrate and protein, carbohydrate only, and a placebo, which breaks down as follows: CHO/Pro/fat (~66% CHO-~23% Pro-~11% fat; commercially available sports drink, Mead-Johnson, Canada; CHO source: 56% sucrose-44% glucose polymer from corn syrup solids), CHO only (identical CHO as CHO/Pro), and placebo (Pl; Sucralose, sucrose derivative not recognized as CHO by the body). The study demonstrated that there is significant decrease in muscle glycogen after resistance training in all three trials. However, it was concluded that in trials where the test subjects had an intake of CHO/Pro and CHO only immediately and one hour after their resistance training, there were higher rates of muscle glycogen resynthesis over the first four-hour period following the training than in the placebo trial (890). In conclusion, the supplementation of protein-carbohydrate drinks achieves two goals. First, the recovery process is speedier and more complete. Secondly, it leads to greater training adaptations. After all, optimizing nutrition during the recovery period between training sessions may lead to more favorable nitrogen balance and glycogen levels between training bouts (Kraemer, Volek, Bush, Putukian, and Sebastianelli, 1545). In an age when health and fitness scientific knowledge is growing rapidly, it becomes obvious that whether one is a well-trained athlete or just concerned with over-all wellness, the advantages of protein-carbohydrate supplementation are certainly evident. The studies described above supports the necessity to consume protein-carbohydrate supplements after physical training in order to replenish muscle glycogen and provide protein for muscle repair and growth. REFERENCES Balon, T.W., Zorzano, A, Treadway, J. T., Goodman, M. N., & Ruderman, N. B. (1990). Effect of insulin on protein synthesis and degradation in skeletal muscle after exercise. Am. J. Physiol., 258 E92-E97. Davis, J. M. (1995). Carbohydrates, branched-chain amino acids, and endurance: the central fatigue hypothesis. Int. J. Sport Nutr. 5, S29-S38. Kraemer, William J., Volek, Jeff S., Bush, Jill A., Putukian, Margot, & Sebastianelli, Wayne J. (1998). Hormonal responses to consecutive days of heavy-resistance exercise with or without nutritional supplementation. J. Appl. Physiology, 85(4), 1544-1555. Loon, Luc JC van, Saris, Wim HM, Kruijshoop, Margriet, & Wagenmakers, Anton JM. (2000). Maximizing postexercise muscle glycogen synthesis: carbohydrate supplementation and the application of amino acid or protein hydrolysate mixtures. Am J Clin Nutr, 72, 106-111. Loon, Luc J. C. van, Kruijshoop, Margriet, Verhagen, Hans, Saris, Wim H. M., and Wagenmakers, Anton J. M. (2000). Ingestion of protein hydrolysate and amino acid-carbohydrate mixtures increases postexercise plasma insulin responses in men. J. Nur, 130, 2508-2513. Picard, Dave. (2001). Bodybuilding for real people and real life results. http://www.getbig.com/articles, 1-3. Rasmussen, Blake B., Tipton, Kevin D., Miller, Sharon L., Wolf, Steven E., Wolfe, Robert R. (2000). An oral essential amino acid-carbohydrate supplement enhances muscle protein anabolism after resistance exercise. J. Appl. Physiology, 88, 386-392. Roy, B. D. & Tarnopolsky, M. A. (1998). Influence of differing macronutrient intakes on muscle glycogen resynthesis after resistance exercise. J. Appl. Physiology, 84(3), 890-896. Tarnopolsky, M.A., Bosman, M., MacDonald, J.R., Vandeputte, D., Martin, J., & Roy, B.D. (1997). Postexercise protein-carbohydrate and carbohydrate supplements increase muscle glycogen in men and women. J. Appl. Physiology, 83(6), 1877-1883. |