Proteins.pdf
Transcript
PROTEINS Proteins consists of series of amino acids. These serves as the basic building blocks for proteins. They are composed of atoms of carbon(C), oxygen (o), hydrogen (H), and nitrogen (N). Athletes engaged in endurance, strength/power, or team sports have higher protein require...
PROTEINS Proteins consists of series of amino acids. These serves as the basic building blocks for proteins. They are composed of atoms of carbon(C), oxygen (o), hydrogen (H), and nitrogen (N). Athletes engaged in endurance, strength/power, or team sports have higher protein requirements. Protein Synthesis For athletes in training their goal is to maintain or increase lean body mass (FFM) ◦ An increase in muscle size and thus mass is caused by an increase in protein synthesis. Increased protein synthesis is reflected by an positive nitrogen balance... Anabolic environment. ◦ Muscle mass maintenance (endurance athletes) is sustained by discouraging protein degradation. Protein degradation is reflected in a negative nitrogen balance... Catabolic environment Protein Needs in Athletes Endurance Athletes: ◦ Protein oxidation occurs as an energy source ◦ After prolonged or high intensity exercise a negative net protein balance is seen ◦ Training seems to have a protein sparing effect, protein oxidation during exercise decreases with training. ◦ Athletes have difficulty maintaining energy balance but are in nitrogen balance. Research has shown a linear relationship between energy intake and protein intake. When they consumed 12% protein of 6500kcal, easily met requirements. When energy intake matches output in endurance exercise athletes don’t need to supplement with extra protein. Resistance Training/Strength Athletes: numerous research studies but no clarity about how much “extra” protein a strength athlete needs. The goal of the resistance trained athlete is to increase FFM (must be in positive protein balance after exercise, promote muscle synthesis) ◦ The general consensus is that a general increase in dietary protein intake will promote muscle growth If athletes consume 15% of their calories as protein are they getting enough to promote an increase in FFM? ◦ Let’s do the math for a male involved in a moderate intensity resistance training program (160lbs=72.7kg): PROTEIN CONSUMED: TEE = 3000kcal 15% of 3000kcal= 450kcal/4kcal/gPRO = 112g PRO = 112/72.7 = 1.45 g/kg BW/day What about 20%? 3000kcal *20%= 569kcal/4kcal/gPRO=140g PRO = 1.9 g/kg/day How much protein an Athletes consume daily? Protein is critical for optimal athletic performance. Even among athletes protein recommendations are not one-size-fits-all. Individual protein requirements based on variety of factors: Current body weight Total energy intake Desire to lose or gain weight CHO availability Exercise intensity and duration Training status Quality of dietary protein Age Based on Body weight: The RDA for general public is 1g/kg body weight. 12- 14% normal requirements but for athletes 12-20% of total calories. Daily Protein Recommendation for Athletes Type of Athletes Daily grams of % of Total Calories Protein/kg Body weight Contributed by Protein Sedentary Individual 0.8-1g / kg 12-15% Strength Athletes 1.4 -2.0g/kg 15-20% Endurance Athletes 1.2-1.8g/kg 12-18% Team sports athletes 1.2-1.6g/kg 12-16% Total Energy Intake: If an athlete is consuming as adequate number of calories, protein requirements can be calculated in the middle of the recommended range. Adequate energy intake, mainly in the form of CHO, spares muscle protein and promotes protein synthesis. Athletes should consume calories dense, foods and fluids, along with additional snacks, during intense training sessions and long duration exercise to spare protein. Desire to Lose or Gain Weight: Many athletes have the goal of either gaining or losing weight. In both the situation, protein needs are increased and should be calculated at the high end of the recommended range. Protein is not only to recover from the workouts, but also to ensure that the athletes stays in positive nitrogen balance when calorie intake is lower than normal. Adequate daily calorie should be provided to maximize the use of ingested protein. CHO Availability: CHO are only fuel that can be metabolized anaerobically and thus become the primary source during intense aerobic activity. CHO availability , protein metabolized for energy , thus moderating protein requirements. Exercise Intensity and Duration: Amino acid uptake after the resistance training session does increases, indicating that the amino acids are being used for muscle repair and construction rather than for energy. Use of protein for energy in endurance athletes, and for muscle repair and synthesis with intense resistance training, explain the recommendations for increased daily protein intake. Training State / Fitness Level: Protein utilization appears to be higher for athletes who are less fit. When endurance training is initiated, nitrogen balance may be negative for the first 2 weeks. When strength training is first initiated, protein requirements may be higher in the first weeks to support new muscle growth. Dietary Protein Quality: Athletes need to consume adequate amounts of all essential amino acids to sustain protein functions. As compared non vegetarian, vegetarian athletes have slightly higher protein needs because of the intake of incomplete proteins, and therefore protein intake levels should be calculated at the high end of the recommended range. Age:Youth and teenage athletes have increased protein requirements to support growth and development, as well as sport performance. Educating older adult athletes on the importance of consuming adequate total calories and nutrient dense protein source is essential. Why is protein essential for daily training? Protein has many roles in the body; however, it is particularly important for handling the stress of daily training and competition. Adequate protein consumption not only will lead to optimal performance, but also will prevent adverse health condition such as sports anemia. What type , how much and when should Protein be consumed before exercise? Consuming protein prior to training or competition relates to the speed of digestion as it takes slightly longer to empty from stomach than do CHO. Pre-activity protein consumption can increase satiety. 4- 24 hours Prior to training or competition: Prefer lean meats. Low fat dairy Soy products The meal should be combination of CHO, protein and low fat food source. 1-4 hours prior to training or competition: Intake of protein rich foods and beverages should remain moderate, focusing on low fat, nutrient – dense protein sources. What type , how much and when should Protein be consumed during exercise? Amino acid can be used as a source of energy during exercise. They can be transported via the blood to the liver, converted to glucose and released to the blood stream. But ingestion during exercise according to the guild lines have not been established and not appear warranted at this time. What type , how much and when should Protein be consumed after exercise? Protein is a critical nutrient for the post exercise recovery process in muscle. After exercise, protein breakdown diminishes while protein synthesis increases, resulting in a positive muscle protein balance this depends on the amino acid consumption of the food ingested with amino acid concentration and timing of the protein feeding. Which type of protein source is most beneficial to consume after exercise? Food sources that cause hyper-aminoacidemia have been shown to increase the amino acid delivery to the muscle and transport into the muscle, there by increasing the intracellular availability for muscle protein synthesis. Consuming complete proteins, such as whey and casein. Even hydrolyzed protein sources are usually in supplements form taken. Post exercise protein sources should consist of high quality proteins that provide all of the essential amino acids. Research suggest that ingesting CHO and proteins immediately after or within 3 hours after exercise is a important dietary practice for athletes. Ingest a minimum of 6-20gm of protein containing essential amino acids. Consuming CHO in addition to this amounts of protein appears to further enhance exercise recovery. Potential Downside to “High-Protein” Diets Hydration status – Nitrogen that is obtained from consuming protein must be excreted in the urine as urea – Increased urinary output due to high protein load may increase chances of dehydration Diets very high in protein may lack appropriate amounts of carbohydrate, fiber, and some vitamins/minerals – Could impair exercise performance – Could increase long-term risk of diseases such as colon cancer Possibly due to lack of fiber or increased intake of red meat Excessively fatty protein sources could increase risk of cardiovascular disease – Choose mostly lean protein sources For example, salmon is more desirable than a ribeye steak Cont…. Kidney disease – No good evidence of damage in individuals with healthy kidneys – Protein-rich diets are high in phosphorus, which can be harmful to individuals with kidney disease Primarily a concern with elderly or sick individuals, as opposed to healthy athletes Bone health – Higher protein diets may increase calcium loss in urine However, gut absorption of calcium is likely improved, so there may be no net difference – Elevated protein diets appear to have either no or a slightly beneficial effect on skeletal health What About Amino Acid Supplements? As long as the complete protein requirements are met, the individual AA requirements will be met as well – No need for additional AA supplements to prevent deficiency Because vegetarians eat few complete sources of protein, they should be cognizant of complementary protein sources throughout the day to prevent deficiency of particular AAs Branched chain amino acids are popular as a supplement among athletes – Claims mainly center on decreasing muscle soreness and improving either performance or recovery from exercise – Doses can range from 2 to 7 g/day to more than 20 g/day There are potential risks associated with AA supplements – Large doses of single AAs can prevent the absorption of other AAs, which may lead to diarrhea – Can indirectly cause deficiency of other AAs as a result Example: Quantity of Amino Acids in Food 1 cup of low-fat cottage cheese (2%) has 31 g of protein – Translates to 31,000 mg of AAs – The branched chain amino acid content of the cottage cheese (leucine + isoleucine + valine) is 6,942 mg (6.9 g) Whole protein sources are best (may be less expensive) Putting a Meal Plan Together Example: 70-kg athlete requiring 4,000 kcal/day who is exercising 120 min/day, 4 to 6 times/week Macronutrient target recommendations – Grams/kg body weight/day Carbohydrate 7-10 g/kg (490-700 g/day) Protein 1.5-2.0 g/kg (105-140 g/day) Fat Typically use percentage of energy – Percentage of energy Carbohydrate 55-65% of energy (550-650 g/day) Protein 10-15% of energy (100-150 g/day) Fat 20-30% of energy (88-133 g/day) Target recommendations for this athlete − Carbohydrate 600 g/day (60% of energy) − Protein 130 g/day (13% of energy) − Fat 120 g/day (27% of energy) A Potential Distribution of Macronutrients Over the Course of 6 Meals/Day Summary Adequate protein intake is critical for athletic performance and good health For most athletes, protein intakes of 1.5 to 1.8 g/kg/day (0.68-0.81 g/lb/day) will meet protein requirements High-quality protein sources (eg, dairy products, meats, fish, chicken, soy, eggs) should be included in the diet Eating a combination of carbohydrate and protein soon after exercise can help with muscle recovery and muscle building There are potential disadvantages to excessive protein intake above 2 g/kg/day – In general, no additional benefit for strength or muscle building – Increased water loss from the body that may lead to dehydration – High-protein intake may replace carbohydrates and other vital nutrients for athletic performance and good health Decreased overall diet quality
