BPK 110 Human Nutrition: Current Concepts

Transcription

1 Lecture 11b BPK 110 Human Nutrition: Current Concepts Lecture 12a Nutrition, Fluids & Athletic Performance 1. Vitamins & Performance 2. Physical Activity & Bone Loss 3. Iron & Performance 4. Minerals & Performance 5. Fluids & Temperature Regulation 6. Sports Drinks 7. Supplements & Performance 8. Caffeine & Energy Drinks

2 Learning Objectives To understand and explain how vitamins and minerals are may influence sports performance To understand and explain how exercise is thought to influence both bone remodeling and mineral content, To understand and describe who is at risk for anemia and sports anemia as well as what dietary approaches can help to prevent and help treat iron deficiency anemia To understand and explain how fluids including sports drinks can be used to prevent dehydration and hyponatremia To explain the cases for and against the use by athletes of sports supplements and caffeine to influence their performance 2

3 1. Vitamins and Performance B vitamins are involved in energy metabolism claimed to benefit performance... a) Thiamin, Riboflavin, Niacin and Performance? Webster et al, 1998 studied these B vitamins & performance: used randomized, double-blind, counter-balanced design supplemented cyclists with B vitamins for 7 d. measured lactate, glucose & free fatty acids & time for 2000 m time-trial after a 50 km ride also measured perceived exertion & EE Results? No differences found btwn groups Ø Possible Side Effects? niacin slows fatty acid release; (-) effect on glycogen stores

4 1b) Vitamin B 6 Supplements and Performance? involved in energy release from nutrients, breakdown of glycogen to glucose, production of hemoglobin Vit B 6 supplements claimed to performance.. Virk et al 1992 studied effects of Vit B 6 supplements: subjects with or without Vit B 6 supplement for 9 days (n=5) plasma was analyzed for glucose, lactate, glycerol, free fatty acids (FFA), catecholamines & amino acids examined plasma energy substrates, catecholamines, & 13 amino acid concentrations during exercise. Main Results were FFA concentrations & no change in time to exhaustion with exercise@ 71.0%of VO 2 max Ø Possible Side Effects? Vit B 6 can be toxic in high doses

5 1c)Vitamin B 12 Supplements and Performance? Vit B 12 is used in DNA/RNA synthesis & Vit B 12 = immature red blood cells & possible anemia recall anemia = hematocrit or red blood cell count supplements/injections of Vit B 12 said to performance no performance changes with Vit B 12 supplements/ injections have been published in a controlled study

6 Vit B 12 deficiency is just one of many causes of anemia normal diet gives adequate Vit B 12 Swiss Cheese nutrient-dense foods best way to meet Vit B 12 needs a note for vegans Vit B 12 only in foods of animal origin or plants contaminated with micro-organisms Vit B 12 supplements vegans may need to eat Vit B 12 fortified bread and cereals or take supplements A vegan is.

7 Citrus Fruits 1 d) Vitamin C & E: The Antioxidants Corn Oil oxidative cell lipid damage is possible with intensity exercise antioxidant vitamins in diet thought to prevent this Goldfarb, A. H from studies on antioxidants:..viability of antioxidants alone & in conjunction with each other in preventing exercise-induced lipid peroxidation requires further investigation. Ji, LL 1995 studies of antioxidants state: Because acute strenuous exercise & chronic exercise training increase consumption of various antioxidants, it is conceivable that dietary supplementation of specific antioxidants would be beneficial.

8 2. Physical Activity & Bone Loss a) Stress Fractures & Excessive Exercise - bone remodeling: osteoblasts & osteoclasts - What is bone remodeling? b) Women Athletes & Dancers: - calcium intakes may be low in these groups - Terrible Triad: amenorrhea, osteoporosis & eating disorders Describe the Terrible Triad:

9 3. Iron & Performance a) Iron Deficiency: Who is at Risk? endurance athletes, women are especially prone iron lost in sweat, GI blood loss, menstruation Female vegetarian athletes risk; often eat iron food (heme vs non-heme iron) red blood cell destruction (e.g. foot strike)= exertional hemolysis - no longer considered to influence iron status note growing teens have iron needs sports anemia (small hemoglobin) vs. iron deficiency anemia iron deficiency: anemia & s muscle myoglobin gives O 2 delivery & aerobic capacity athletic women & teens may need supplements after blood check & visit to MD

10 4. Minerals & Performance chromium, zinc & copper have release in training; significance not clear electrolyte loss (sodium, potassium, chloride & magnesium) in sweat during activity sodium, potassium, chloride lost for untrained athletes vs. trained what are dietary sources of these minerals to replace those lost in sweat?

11 5. Fluids & Temperature Regulation a) Warm Climates can give: H 2 O hyperthermia ( body temp), &/or heat stroke heat stroke: body core temp. >40 C, nausea, pallor, sweat, dizzy, headache, nausea etc can be fatal!! On hot humid days: drink lots, activity Why? humidity = heat loss & body core temp evaporation of sweat is key!! b) How much & when to drink? prior to exercise..thirst is not enough often, more if hot & humid always: never restrict fluids as coach or otherwise up to 2 liters/hour is common

12 5. Fluids & Temperature Regulation Sodium Depletion/Hyponatremia Endurance sports > 3 hours: With profuse sweating Sodium (Na + ) loss or overhydration (H 2 0 intoxication) Na + not replaced can give a dangerous condition of Na + depletion, known as hyponatremia = low Na + concentration in body fluids Symptoms: bloating, puffiness from H 2 0 retention, confusion, seizure, severe headache, vomiting Prevention: increased Na intake in latter stages of long endurance events, especially during events in hot environments 12

13 6. Sports Drinks a) Advantages: includes H 2 0 to fluid losses supplies glucose = glycogen sparing effect supplies sodium & other electrolytes lost in sweat need <8 % CHO or drinks may dehydrate you most are about 7% glucose b) Disadvantages: cost & hype can make it at home use 1/3 tsp salt/liter H 2 0 (for sodium) + 1 cup of sweetened fruit juice (for potassium & glucose) BPK_110_ERAIDE???

14 7. Supplements & Performance athletes are a huge & favorable market for the supplement industry they are most often victimized by frauds 84% of world class athletes take supplements. From our review of supplements does this appear justified?

15 7. Supplements & Performance Controversy 7 Who may need vitamin/mineral supplements: pages 291 to 299 for choosing a supplement. make an informed choice!! 15

16 7. Vitamin and/or Mineral Supplements?? Those who probably don t need supplements: pages 291 to 299 for choosing a supplement. make an informed choice!! Do you fall into the first category? Two main questions: 1. What form: chewable, liquid or pills? 2. Who are you & what vitamins & minerals might you need? FOLLOW DRI standards 16

17 7. Caffeine in Beverages: can dehydrate you since it enhances fluid loss caffeine is a diuretic that stimulates urine production stimulates fatty acid release- some evidence suggests it has a glycogen sparing banned by sports governing bodies

18

19 Energy Drinks? Guarana Berries: from Brazil s Amazon Rainforest 7x as much caffeine (guaranine) as coffee beans Caffeine/guaranine in energy drinks is unregulated since they are made with this natural food difficult to find guaranine amounts in energy drinks

20 Lecture 11b BPK 110 Summary Lecture 12a 1. Vitamins & Performance 2. Physical Activity & Bone Loss 3. Iron & Performance 4. Minerals & Performance 5. Fluids & Temperature Regulation 6. Sports Drinks 7. Supplement Industry 8. Caffeine & Energy Drinks