Presentation on theme: "Dietary Recommendation for Athletes Dr. David L. Gee FCSN/PE 446."— Presentation transcript:
Dietary Recommendation for Athletes Dr. David L. Gee FCSN/PE 446
Training Diet Recommendations: High Carbohydrate Diet l For Power Athletes l Traditional recommendation –> 55% of calories l Why? –primary source of energy –effect of repeated high intensity workouts on glycogen
Training Diet Recommendations: High Carbohydrate Diet l For Endurance Athletes l Traditional recommendation –> 60% of calories l Why? –endurance training reduces glycogen –repeated training effects
ADA/ACSM Position Paper Dietary Carbohydrates l 6-10 gCHO/kg BW –Upper end with high intensity –Upper end with long duration l Recommends against % CHO guidelines l 4000 Cal/day @ 50%CHO for 70kg athlete –= 7.1 gCHO/kg l 2000 Cal/day @ 60%CHO for 60kg athlete –= 5 gCHO/kg
Training Diet Recommendations: High Carbohydrate Diet l Recovery Meal l CHO ingested within 2hrs of workout is converted to glycogen 50% more rapidly. –Rec: up to 1.5 g CHO/kgBW of mixed CHO within 2 hours (hi glycemic index?) –Particularly important for multiple workouts/events per day l Role for protein in recovery meal?
Training Diet Recommendations: High Carbohydrate Diet: Recovery Meal l Example: – 50 kg x 1.5 gCHO/kg = 75gCHO – = 5 servings of bread or fruit l Whole/real foods preferred – Cheapest, has other nutrients l Sport Supplements – Convenient – Concentrated – Expensive
Training Diet Recommendations: Moderate Protein Diet l RDA = 0.8 gP/kgBW l For Power Athletes l ACSM/ADA: –1.6-1.7gP/kgBW l maintenance of large muscle mass l optimizes rate of protein synthesis (?) l Is more protein a problem?
Training Diet Recommendations: Moderate Protein Diet l For Endurance Athletes l ACSM/ADA: –1.2-1.4gP/kgBW l replaces proteins used as fuel during endurance training (10-15% of energy)
Training Diet Recommendations: Moderate Protein Diet l Most athletes do NOT need to consume supplementary amounts of protein l typical US diet: 15% of calories l 4000 Cal diet = 150g Pro in the diet l 90 kg Power athlete needing 1.6gP/kg = needs 144g Pro
Which athletes are at risk for inadequate protein intake? l Limited caloric intake –low meat/dairy intake –very low fat intake –weight conscious athlete l 2000 Calorie, 10% protein l = 200 PRO Cal = 50g PRO provided l 1.6 gPRO x 55 kg = 88g PRO needed
MetRx Protein Plus Powder l INGREDIENTS: METAMYOSYN® (Unique Blend of Milk Protein Concentrate, Calcium Caseinate, Sodium Caseinate, Whey Protein Isolate, L- Glutamine, Dried Egg Whites), Natural and Artificial Flavors, Partially Hydrogenated Oil (soybean and cottonseed oils), Aspartame, Sodium Carboxymethylcellulose, Guar Gum, Xanthan Gum. l $40/container, 16 servings/container, 46gP/serving = $2.50/serving, $75/month, $900/year l 8 oz sirloin steak, $5/lb, 56gP, $2.50 l 5 c NF milk, $2/gal, 40gP, $0.63
Training Diet Recommendations:Low Fat Diet l >55-60% CHO, 10-15% PRO l < 25% FAT l Advantages of moderately low fat (compared to very low fat) –High caloric density –Wider variety of foods available –May be more palatable
Training Diet Recommendations: Summary l Carbohydrates –Moderate to high in carbohydrates »6-10g CHO/kg BW l Protein –Higher than RDA, moderately high –Power athletes: 1.6-1.7gP/kgBW –Endurance athletes: 1.2-1.4gP/kgBW l Fat –Balance of calories, relatively low fat –<25% of calories
Case Study: Brian Competitive Stair Runner l Works 7AM to 3:30PM –Construction contractor in Boston suburbs l Training Schedule –5X/week for 2 hours on stairs »3 hour RT commute to city –Trains weekends by cycling/trail runs l Diet –Realizes he needs hi CHO diet –Eats convenience foods
Brians Diet and Training Schedule l 6:30AM: lg bowl cereal, banana, whole milk l 7AM: coffee w/cream&sugar, doughnut l 12noon: spaghetti with butter, 1-2 slices bread w/butter, 4 Oreo cookies, 2c whole milk l 4-5:30PM: drives to Boston l 5:30-7:30PM: trains l 7:30-9PM: 16 oz sport drink while driving home l 10PM: mac & cheese (frozen dinner), handful of crackers, 2 c milk, 4 Oreos, or a fast-food burger, fries, 2c milk
Brians Diet Analysis l 4000 Cal, 50% CHO, 15% PRO, 35% Fat l Assume 160 lbs = 73kg l PRO needs = 1.4gPRO/kg x 73 = 102gPRO –PRO intake = 4000 x 15% = 600 Cal PRO »= 150 g PRO, protein intake is OK »Or 150g/73kg = 2.1 gP/kgBW l CHO intake = 4000 x 50% = 2000 Cal CHO »= 500 g CHO »= 6.8 g CHO/kg »CHO intake OK, but perhaps marginal l Goal: –Increase CHO, decrease FAT intake –Recognize need for convenience
Case Study: Weight Gain for a Professional Basketball Player l 25 yo CBA rookie l 71 (2.2m) l 215 lbs (98kg) –BMI = 20 –Goal weight 235 lbs
Pre-Event Meal l Goals l Top off glycogen stores l Optimize hydration l Empty upper GI tract
Pre-Event Meal l Meal Composition l High in carbohydrates – mixed complex and simple l Reasonably low in fats and protein l Low in dietary fiber
Pre-Event Meal l Composition (cont.) l High in fluids l Individualize –Use familiar foods
Pre-Event Meal l Timing of meal –Complete > 2 hours before event l Individualize
Carbohydrates Just Prior to Event l Purpose: provide exogeneous CHO to avoid hypoglycemia and delay glycogen depletion. l For endurance athletes only –Absorption delayed l Response highly individualized l Caution: –May promote reactive hypoglycemia in sensitive individuals
Meals/CHO before/during/after events l Pre-event/Pre-game meal –2-3 hours before event l CHO immediately prior to event –5-15 minutes before event l CHO during event l Post-workout meal –Within 2 hours of workout
Carbohydrates During Event l Sport drinks, energy bars, fruits, breads l Metabolically useful for – endurance athletes »May spare muscle/liver glycogen »May provide extra CHO for more power – those prone to hypoglycemia »Exogenous source of glucose for blood l Dilute concentration (<10%) may be advantageous because it also promotes fluid absorption
Types of Carbohydrate l Fructose –Absorbed more slowly than glucose »Reduced insulin response »Reduced chance of reactive hypoglycemia l May produce more stable blood sugar if consumed 45 minutes prior to exercise »May cause osmotic diarrhea in susceptible individuals in high dosages –Free fructose, high fructose corn syrup (~50%), sucrose
Types of Carbohydrate l Glucose Polymers –Short polymers of glucose »Partial hydrolysis of starch –Soluble, low osmolarity, rapid gastric emptying, digestion, and absorption –Most, but not all studies, suggest that glucose polymers may be superior to glucose, fructose, and sucrose
Types of Carbohydrate l Solid vs Liquid Carbohydrates –Most studies suggests little difference between solid vs liquid carbohydrates »Those that show difference tend to suggest that liquids are more rapidly absorbed –Ultra-endurance athletes may develop aversion to liquid sweet carbohydrates
Types of Carbohydrate l Low Glycemic Index Food –Slowly absorbed resulting in lower, but prolonged elevation of blood glucose –Research findings vary when comparing hi-, mod-, and low- GI foods and performance
Types of Carbohydrate l Individualize type of carbohydrate used –Individual differences –Sport differences –Use before/during workouts »Note outcomes
Carbohydrate Loading l Theory: l Glycogen depletion is a cause of fatigue in endurance athletes. l Increasing glycogen stores above normal levels will enhance performance in endurance athletes.
Diet, muscle glycogen, and endurance performance. Karlson & Saltin. J. Appl. Physiol. 1971-31:203-206. l Subjects: Trained distance runners l Protocol: normal vs high carb diet l Performance test: 30km run l Outcomes: –Muscle glycogen after hi-carb diet was double that than after normal diet –All runners finished 30km faster after hi-carb diet by an average of 8 minutes –No benefit seen in first hour of run, but able to maintain pace toward end of run.
Carbohydrate Loading Protocol: Classic Method l Depletion Phase (3-4 days) –Strenuous endurance training –Very low carbohydrate diet l Repletion Phase (3-4 days) –Tapered training --> rest –Very high carbohydrate diet »8-10g CHO/kg
Carbohydrate Loading Protocol: Classic Method: Drawbacks l High level of fatigue during depletion phase l May result in hypoglycemia and ketoacidosis during depletion phase (nausea, fatigue, dizziness, irritability) l Very unusual diet during depletion phase –Unappetizing –May cause GI distress
Carbohydrate Loading Protocol: Classic Method: Drawbacks l May not result in substantially higher glycogen levels than Modified Method –Effect of different dietary CHO plans and muscle glycogen content (Sharman, 1981) »Protocol: trained runners, 73% VO2max for 90, 40, 40, 20, 20, 0 minutes –Muscle glycogen content »50% CHO diet for 6 days: 160 mmol/kg »50% CHO for 3 days, 70% CHO for 3 days: 203 mmol/kg »15% CHO for 3 days, 70% CHO for 3 days: 207 mmol/kg
Carbohydrate Loading Protocol: Modified Method l Mild Depletion Phase –Normal training with tapering –Moderate carbohydrate diet (~4gCHO/kg BW) l Repletion Phase –Light training --> rest –Very high CHO diet »8-10gCHO/kg BW »400-700gCHO/day »70-80% of total Calories
Carbohydrate Loading l Diet a mixture of complex and simple carbohydrates to maximize liver and muscle glycogen l Effect of Dietary CHO-type on Rate of Glycogen Synthesis (Costill, 1981) –Protocol: trained endurance athletes, 10 mile run @ 80% VO2max + five 1-minute sprints with 3 minute rests –Muscle glycogen content »24 hours l High simple CHO diet: 133 mmol/kg l High complex CHO diet: 138 mmol/kg »48 hours l High simple CHO diet: 145 mmol/kg l High complex CHO diet: 165 mmol/kg
Carbohydrate Loading l Concerns: –2-3 lbs of weight gain (water) »3 grams of water for every extra gram of glycogen stored l 300-400 grams of glycogen = 900-1200 grams of water l 1.2-1.6kg weight gain (2.5-3.5 pounds) » stiffness » hyper-hydration –nausea and diarrhea with diet changes –Useful ONLY FOR ENDURANCE ATHLETES! (events over 60 minutes)
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