1	Nutrition and Athlete Performance Lynn V. Amores, MD Resident Physician UCI Department of Family Medicine
2	Position Statement “ It is the position of the ADA, Dieticians of Canada, and the American College of Sports Medicine that physical activity, athlete performance, and recovery from exercise are enhanced by optimal nutrition. These organizations recommend appropriate selection of food and fluids, timing of intake, and supplement choices for optimal health and exercise performance.”
3	Key Points Summary of energy, nutrient, and fluid recommendations for active adults and competitive athletes: #1 High intensity training: adequate energy to maintain body wt, maximize training effects #2 Body Weight/Composition can affect performance but should not be used as sole criterion for participation; discourage daily weigh-in
4	Key Points #3 Carbohydrates: important to maintain blood glucose levels and replace muscle glycogen 6-10 g/kg of body wt per day Example: 70kg (154 lb) Male would need 420 to 700g of carbs per day
5	Key Points #4 Protein requirements: Slightly increased in highly active people *Endurance athletes: 1.2 to 1.4g of protein/kg of body wt per day For example a 70kg male needs 84 to 98g of protein
6	"Resistance and Strength athletes" Resistance and Strength athletes: 1.6 to 1.7 g of protein/kg of body wt per day For example a 70 kg male needs 112 to 119 g of protein per day
7	Key Points #5 Do not restrict fat intake Fat provides energy, vitamins, and essential fatty acids No benefit to reducing fat to 15% calories from fat or less vs. 20-25% calories from fat
8	Key Points #6 Athletes at greatest risk for nutrient deficiencies Restrict energy intake Severe wt loss practices Eliminate food groups High-Carbs with low nutrient density
9	Key Points #7 Dehydration decreases exercise performance Ensure adequate intake before, during, after exercise Drink enough to balance fluid losses
10	How much H2O to drink?? 2 hours BEFORE exercise 400 to 600ml (14 to 22 oz) DURING exercise 150 to 350 ml (6 to 12 oz) every 15 to 20 min *AFTER exercise at least 450 to 675 ml (16 to 24 oz) for every pound (0.5 kg) lost during exercise
11	Key Points #10 Dietary goal AFTER exercise: Provide adequate energy and carbs to replace muscle glycogen and ensure rapid recovery * Carb intake: 1.5 g/kg body wt within first 30 min and then every 2h over next 4-6 hr * Protein intake important to repair muscle * Eat a mixed meal
12	Key Points #11 No vitamins or minerals are required if the athlete is consuming adequate energy from variety of foods * May be required if athlete is dieting, limits food groups (vegetarian), sick or injury recovery
13	Key Points #12 Athletes should be counseled regarding use of ergogenic aids (Products that claim to increase work output or performance) Use with caution!! Is it safe? Effective? Potent? Legal???
14	Key Points #13 Vegetarian athletes may be at risk for low energy, protein, and other nutrient intakes due to replacing meat and dairy with low-energy-dense foods
15	Meeting ENERGY NEEDS FIRST nutrition priority for athletes Energy Balance: essential for maintaining lean tissue mass, immune system, reproductive function, optimum performance What is energy balance??
16	"Energy balance =" Energy balance = State when ENERGY INTAKE (sum of energy from food, fluids, supplements) EQUALS ENERGY EXPENDITURE (the sum of energy expended as basal metabolism, thermic effect of food, and physical activity)
17	What if intake is limited? Compromised performance Compromised benefits of training Fat and lean tissue mass (muscle) will be used by the body for fuel Loss of muscle results in loss of strength and endurance
18	Mean Energy Requirements Women and men slightly to moderately active, between 19 to 50 yr age: 2,200 to 2,900 kcal per day! Normally active people: Energy intake of 1.5 to 1.7 times resting energy expenditure (37 to 41 kcal/kg per day)
19	Athlete Requirements Evaluate the kind of exercise: frequency, intensity, duration Add that to amount needed for normal daily activity Example: Male runner 70kg, runs 10mi per day at 6 min pace à 1,063 kcal per day to cover energy expended on top of energy cost of daily activities Total of 3,653 to 3,933 kcal per day
20	Requirements for resistace training Usually requires less energy vs. endurance May be as high due to increased body size and high levels of fat-free mass
21	Weight Change Often athletes want to increase or decrease to meet demands of their sport Best done slowly during off season Gain weight: additional calories (500 to 1000 kcal/day) + weight training Weight loss: more problems, decreased intake can compromise performance
22	Weight Loss Registered dietitian trained in sport nutrition Gradual (1 to 2lb per wk) Realistic weight based on : genetic, physiology, social, sport and psychological factors
23	Healthful Weight? Realistically maintained Allows for positive advances in exercise performance Minimizes risk of injury or illness Reduces risk factors of chronic disease
24	Body Composition One of many factors contributing to optimal exercise performance Along with body wt, may affect success Composition affects strength, agility and appearance Weight affects speed, endurance, and power Strength to weight ratio
25	Body Composition Determine on an individual basis Age, gender, genetics, requirements of sport Wrestling weight classes Aesthetics: dance, gymnastics, figure-skating Lose BOTH muscle and fat with extreme wt losses à Compromised performance!
26	Body Composition Estimated minimal level of body fat compatible with health 5% males 12% females
27	Body Composition Examples - MALE <6% Male middle to long distance runners, body builders 6% to 15% Male basketball, cyclists, gymnasts, sprinters, jumpers, triathletes, wrestlers Variable (6% to 19%) Power sports: football, rugby, ice and field hockey
28	Body Composition Examples – FEMALE 6% to 10% Bodybuilding, triathlon, cycling, running 10% to 20% Racquetball, skiing, soccer, tennis, volleyball
29	Body Composition MINIMAL compatible with health: 5% male 20% female
30	Macronutrient Requirements Carbohydrates Protein Fats
31	Nutrient requirements Carbohydrates Blood has glucose Muscle has glycogen As intensity of exercise increases, amount of carbs used for energy increases Shifts from muscle glycogen to glucose in blood Intensity DECREASES if glucose not maintained
32	Nutrient Requirements Fat contributes over wide range of intensities, is metabolized at same rate over wide range Proportion DECREASES as intensity INCREASES because carbs are used more
33	Nutrient Requirements Protein contributes to energy at rest and during exercise In fed person, it provides less than 5% of energy expended However, as duration increases it is used by the body to maintain glucose in the blood (gluconeogenesis in liver)
34	Nutrient Requirements Protein: Resistance exercise thought to increase protein requirements more than endurance exercise Increasing intake beyond recommended level is UNLIKELY to result in increase of lean tissue Rate at which protein tissue is built is limited
35	Vitamins and Minerals “Micronutrients” Important in energy production, Hb synthesis, bone health, immune system, protection from oxidation damage Help build and repair muscle tissue following exercise
36	Vitamins and Minerals Basically, the current RDA’s are appropriate for athletes May need to supplement those who restrict energy intake, have severe wt loss practices, eliminate food groups
37	B Vitamins Exercise MAY increase the need perhaps up to twice the recommended amount Thiamin, riboflavin, Vit B-6, niacin, pantothenic acid, biotin: Energy production DURING exercise Folate and B-12: Red blood cell production, protein synthesis, tissue repair and maintainance
38	Calcium, Iron, Zinc Primary minerals low in the athlete diet, especially females Usually due to restricting diet (meat and dairy) Low Calcium: low bone density, stress fractures Iron: Anemia check it early, can take 3 to 6 mos to correct Zinc: not clear what deficiency causes, is necessary for growth, build/repair of muscle tissue, energy production
39	Hydration Performance is optimal when fluid balance is maintained during exercise, impaired with progressive dehydration Dehydration increases risk of heat stroke
40	Hydration Water and electrolyte balance: Losses during exercise: Evaporation of water accounts for over 80% of metabolic heat loss (Vs. convection, radiation, conduction, vaporization) Sweat rate varies (body size, exercise intensity, ambient temp, humidity, acclimation) Can exceed 1.8 mL per hr Sweat contains sodium (and K+, iron, Ca++)
41	Hydration Dehydration: Fluid losses exceed fluid intake **Hypohydration: Athlete dehydrates self prior to comp Fluid restrict, diuretics, sauna Sports with weight classes
42	Hydration Hyponatremia Low sodium concentration in the blood Prolonged heavy sweating Retaining excess H2O Overhydration not uncommon Study of triathletes in New Zealand Ironman: 11 of 605 developed severe Hyponatremia Most of the 11 were overhydrated (wt)
43	Hydration Before, during, and after exercise BEFORE Generous amt of fluid 24 hr before 400 to 600mL 2hr before
44	Hydration DURING exercise: Partial dehydration can compromise performance 150 to 350mL (6 to 12 oz) at 15 to 20 min intervals beginning at start of exercise Beverages with 4-8% carbs recommended for events lasting > 1 hr
45	Hydration No physiologic need to replace electrolytes (eg, Na) during exercise less than 3-4 hr However, including Na recommended in events longer than 1 hr May increase drive to drink, therefore amt of fluid comsumed May prevent hyponatremia
46	Hydration AFTER exercise: Most complete exercise dehydrated Usually do not consume enough fluid during exercise Up to 150% of weight loss in H20 may need to be consumed to cover losses Na may help to retain H20 better
47	The Training Diet Food Guide Pyramid Appropriate to use carbs as much of the additional energy Variety is key, keep proportions consistent
48	The Training Diet: Pre-Exercise Meal Eating before exercise vs. fasting shown to improve performance Right amount: not hungry nor with undigested food in stomach before activity General guidelines: -Sufficient fluid to maintain hydration -Low in fat and fiber (gastric emptying) -High in carbs to maintain blood glucose -Moderate protein -Familiar foods
49	The Training Diet: Pre-Exercise Carbs: Some studies show it enhances performance 200 to 300g in meal 3-4 hr prior to exercise Within 1hr of start is controversial
50	The Training Diet: During Exercise Current research supports the benefit of carbs during exercise (eg, sports drinks) Especially athletes exercising in am after overnight fasting Helps maintain glucose and improve performance
51	The Training Diet: During Exercise Longer events: Consuming 0.7g carb/kg of body wt per h is shown to extend endurance performance 70kg male runner, 49g carbs per hour of endurance exercise
52	The Training Diet: During Exercise Carbs even more important if: Athlete not carb loaded Has not consumed pre-exercise meal Restricting energy intake for wt loss
53	The Training Diet: During Exercise Carb intake should begin shortly after activity 15 to 20 min intervals during first 2 hrs More effective than taking the same amount as a bolus 2hr after start of activity Glucose
54	The Training Diet: Post-Exercise Meal Depends on length and intensity of exercise session, and when the next intense workout will be Immediately after exercise vs. wait 2 hr à higher glycogen levels Recommended: 1.5g carb/kg at 2h intervals Other study: 0.4g carb/kg every 15 min for 4 h after exercise Not necessary for athletes taking one or more days between training sessions/events
55	In Summary Athletes should work with their coaches, trainers, health professionals, and family to meet sports-related nutrition goals Base nutrition recommendations for athletes on current scientific data and the needs of the individual athlete Reference: “Nutrition and Athletic Performance”, Medicine and Science in Sports and Exercise. 2000; 32: 2130-2145 Official journal of the American College of Sports Medicine