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Nutritional Considerations for Intense Training and Sports Competition

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Nutritional Considerations for Intense Training and Sports Competition. Chapter 8 Part 2. Carbohydrates During Exercise. Competition less than 30 min 5,000 meter ( ~ 12 min) 10,000 meter ( ~ 26 min ) Not necessary. Carbohydrates During Exercise. Prevention of hypoglycemia - PowerPoint PPT Presentation

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Nutritional Considerations for Intense Training and Sports Competition

Nutritional Considerations for Intense Training and Sports CompetitionChapter 8 Part 2Competition less than 30 min5,000 meter (~ 12 min)10,000 meter (~ 26 min)Not necessaryCarbohydrates During Exercise2B-D 385+30 min, may be an intake of food and fluid during the event, potentially to influence the outcome-possibly psychological rather than physiologicalAll of which can impair performancePrevention of hypoglycemiaCentral nervous system effectsDizzinessNauseaDisorientation Carbohydrates During ExerciseB-D 387 CNS-brain needs glucose. Earliest medical problems identified-Boston marathon. Adding CHO prevented hypoglycemic symptoms3High intensity aerobic exercise1 hourDecreases liver glycogen55%2 hoursDepletes liver and muscle glycogenIntermittent sportsUp to 5 hours

Carbohydrates During Exercise4Book 238-9 75% aerobic capacity level generally maintained during final stages, CHO feedings 43g in 400 ml water.Allows for a greater intensity during prolonged activitiesAbout 60 g of carbohydrates each hour benefits:High-intensity, long-duration aerobic exerciseNot needed for repetitive short bouts of near-maximal effortHowever, it wont hurt if you like to drink CHO drinks during such exercise

Carbohydrates During Exercise 5Carbohydrate feeding during exercise at 60 to 80% of aerobic capacity postpones fatigue by 15 to 30 minutes, with performance improvement generally ranging between 15 and 35%. 50% VO2max, mostly fat oxidation, little gly breakdown.A person can ward off fatigue and extend endurance with a single concentrated carbohydrate feeding approximately 30 minutes before anticipated fatigue.

Why?Spares muscle glycogenHelps maintain blood glucose levelsImproves mental and physical performanceShould only be glucoseFructose causes significant GI distress

Carbohydrates During Exercise4:1 helps minimize muscle damage6CHO ingestion - Williams (1989)Run a fixed distance in 2 hours1 liter glucose polymerNo difference in total distance coveredRunning speed greater over last 30 min

Carbohydrates During Exercise7B-D 388-9. trained marathon runners use CHO at oxidation rate at 3-4 g/min but this would be depleted before finish line. Definitely benefit from CHO ingestion-best in later stages of exercise

Ergogenic Advantage8238-CHO postpones fatigue 15 to 30 min, feeding 30 min before fatigue, restores blood glucose levelsIngested CHO available for oxidationHow much CHO should be consumed?Rate of oxidation of exogenous CHO = 1 g/min30-60 g/h (Coyle, 1991)When should CHO be consumed?Early and oftenEvery 15 minutes from the beginning of exerciseYou may not need it early on, but you do need the fluid and its not gonna hurt youCarbohydrates During Exercise9390 max rate of CHO oxidation-1 g/min, however, consumption in excess of this for maximum oxidation rate. Recommendation of 30-60 g/h general guideline. amount and time of cho intake, cho oxidation preserves muscle glyCoyle general guideline, first 60 min-little CHO is oxidized. But if ingested late in 2 h trial, performance during 15 min time trial was worse.Fluid replacement Electrolyte concentrationsSodiumPotassiumCalciumMagnesiumChloride Carbohydrates During Exercise10Fluid-way to replace CHOThe ideal hydration solution contains between 5% and 8% carbohydrates. Too high, slow gastric emptying, causes diarrheaMaintains blood glucose during prolonged exerciseAllows CHO metabolism to continue at a time when hypoglycemia would normally occur

Carbohydrate-Electrolyte BeveragesThis permits carbohydrate replenishment without adversely affecting fluid balance and thermoregulation11Fluid choices for endurance eventsWater No CHOSports drinks (5-8% CHO + electrolytes)600-1000 mLIdealSoft drink (11% CHO)500 mLToo much sugar, not enough fluid and too much carbonationFruit juices (8-12% CHO)500 mLToo much sugar, not enough fluidSports gel (60-70% CHO)(1-2 gels)

Carbohydrates During Exercise12Soda, slower absorptionNon-endurance sports (< 30 min)Start well hydratedReplace fluid as soon as possible after competitionFluids ingested during event wont help performance

Carbohydrates During Exercise

B-D 40413Events of 30-60 minBegin well hydratedUse fluid replacement plan from trainingCool beverage (15-20oC) with or without CHOFluids likely wont help, but they may be of psychological benefit

Carbohydrates During Exercise

Events of 1-3 hBegin well hydratedUse fluid replacement use in trainingDrink as much as is practicalCool beverage (15-20oC) with CHOBegin ingesting fluid earlyPlan to consume 30-60 g CHO/h of exerciseAgain, every 15 min, 250 ml of fluid

Carbohydrates During Exercise

Events greater than 3 hBegin exercise well hydratedUse fluid replacement plan from trainingCool beverage (15-20oC) with CHOChange flavorsStart ingesting early during exercisePlan to consume 30-60 g/h Plan for sodium replacement (most drinks have sodium in themPlan for solid food as time goes on

Carbohydrates During Exercise

Foods (50 g CHO)Bananas (2-3)Jelly beans (50 g)Jam sandwich (2 slices bread, 4 t jam)Chocolate bar (1-2)Breakfast bar (1-2)Sports bars (1-2) Carbohydrates During ExerciseMultiple daily eventsTeam sport tournamentsGoalsRestore muscle and liver glycogenReplacement of fluid/electrolytes lost in sweatRegeneration and repair damage caused by exerciseRecovery B-D 415 multiple events-swimming, track and field, team sports more than one event/day. Competition lasts 1-3 weeks.18Should include simple and complex carbohydratesSimple: Fruits, juices, lemonade, etc.Complex: Rice, potatoes, pasta, etc.Single large meal or small frequent meals will replenish glycogen stores.Should be consumed as soon as possible after the activity50-75 g CHO Every 15 minEvery 2 h (500-700 g)

Carbohydrates after Exercise241-legumes etc, slow absorption rate.19

Factors affecting Absorption/EmptyingGastric volume affects stomach emptying rate20

P 245, Table 8.2-beverages for fluid replacement. Maximum fluid stomach empties-1700 ml/h. recommended to consume 1000 ml or 1 quart/hr21

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