Sports NutritionSports Nutrition Sports nutrition is the study and practice of nutritionand diet as it relates to athletic performance. It is concerned with the type and quantity of fluidand food taken by an athlete, and deals withnutrition such as vitamins, minerals, supplementsand organic substances such as carbohydrates,proteins and fats.Although an important part of many sports trainingregimens, it is most commonly considered instrength sports (such as weight lifting andbodybuilding) and endurance sports (for examplecycling, running, swimming).
ENERGY SYSTEMS The human body must continuously be suppliedwith energy to perform its many complexfunctions. Two metabolic systems energy for the body –one dependent on oxygen and the other able tofunction without oxygen. Both of these systems provide energy, however,the use of one system over the other depends onthe duration, intensity and type of physicalactivity.
ANAEROBIC ENERGY SYSTM There are to energy system in the bodyphosphagen system and lactic acid system hatcan operator in the absence of the oxygen. These system are capable of producing ATPenergy at a high rate. They are utilized when the rate of energyproduction demanded of the exercise exceedsthat of the aerobic system alone. The main limitation of this system is the relativelysmall amount of ATP that can be made beforefatigue ensues.
Aerobic Energy System The aerobic system supplies all of the energy for lowto moderate intensity exercise. It supplies energy for sleeping, resting, sitting, walkingand other firms of low intensity physical activity. As the activity becomes more intense, to the point thatit can only be sustained for a matter of a few minutes,the aerobic system can no longer provide energy at asufficient rate. At this stage, ATP production is supplemented by thelactic acid and phosphagen system. Exercise thatrelies heavily on oxygen for the provision of energy iscalled an aerobic exercise.
Energy Energy requirement of sportsperson and athletesvary widely depending upon the intensity of theactivity involved. For the purpose of defining energy requirements,sports and athletic events are divided into twobroad categories like power and non-powerevents, with additional categories representingactivities of different intensities.
The energy requirements under power categories(throwers, sprinters, jumpers, boxing, wrestling,weight lifting) range from 3500-6000 kcal/day,while those under nonpower (other athletics,hockey, volleyball, swimmers) and other skilledcategory (archery, Yatching) range from 3500-4500 kcal/day. It is important that the daily energy intake iscontributed by carbohydrates, fats and protein.Percentage energy from these three sourcesshould be 50-55%, 30 and 15-20% respectively.
Carbohydrate on comparing the average work time onconsumption of mixed diet, high fat/ protein dietand high carbohydrate diet, the longest work timewas observed with a high carbohydrate diet. Since the RDA for carbohydrate is 50-55% oftotal calories, and many carbohydrate, and manycarbohydrate rich foods are fiber-rich food-whichmeans lots of chewing and higher satiety due tothe bulking capacity of dietary fiber.
However, for athletes with very high energyrequirements of over 3000-5000 kcal a day,consuming and byproducts are concentratedcarbohydrate foods i.e.,refined starchy foods, nuts and oilseeds. Milk andbyproducts are advised. Still, a nutrient rich dietremains central for adequacy sake, while vital,energy alone is nit enough to supportperformance.
CARBOHYDRATESCOMPLEX(contain otheruseful nutrients)Preferred option for carbintake due to being anefficient energy source,readily used.Stores depleted quickly soneed to be replacedfrequentlySIMPLECarbohydratesstored asGLYCOGEN inthe muscles andliver.Muscles cannotperform without it.Therefore need tobe replenished
Protein According to the RDA, a normal person is requiredto consume 0.8 g to 1.0 g protein/kg body weight.Protein intake equal to 15-20 % of total calorie willmeet the protein requirements of most athletes.ICMR, 1985, recommends 12-14 % of total energyrequirements and upper limit could be placed at 2g/kg body weight. Consuming more protein than 2.0g/kg body weight results in increased proteinoxidation, urea formation, diuresis and can increaserisk for dehydration.
Vitamins and minerals Owing to increased energy requirements andexercise-induced production of free radicals, higheramounts of B- vitamins with anti- oxidant propertiesare required for athletes. The B-vitamin requirement is 1mg/1000 kcal forthiamin and riboflavin and10-20mg/1000 kcal forniacin. Intake of retinol may be placed at 1000-2000micrograms per day. Vitamin E, which is an antioxidant should be taken atthe level of 10-20 IU. Vitamin C, which is also essential for iron absorption,its intake should be 100-200mg/day.
Specially for the female athletes between 13 and19 year of age. Female athletes, who trainheavily, have a high incidence of amenorrheaand thus conserve iron stores. In any case, iron intake should not be less than50-75 mg for sports men and 60-100 g for sportswomen.
Vitamin and MineralsVitamin(a) Intake to keep enzymes saturated with adequatetissue store.(b) Different additional supplement of certain antioxidantvitamins and to guard against any dietaryinadequacy.Minerals(a) Electrolytes are important-supplements given duringsports events.(b) Iron : Additional iron supplements to prevent sportsanemia ; Haem iron supplement would be better.(c) trace minerals : Zn, Cu, Se important. Selenium isan antioxidant.
Nutrition requirement of sportspersons and athletesNutritionPer day Per kg body weightEnergy percent derivedfrom.Energy, kcalProtein, gFat, gCarbohydrate, gVitamins and mineralsCalcium, gIron, mgVitamin, A, mgThiamine, mgRiboflavin, mgNiacin, mgVitamin C, mg3000-6000135-225120-200400-6001.5-3.050-851080-25003-63-630-6080-15050-802-3-52-36-8-153055Requirement
Water and Electrolytes Water probably has a greater effect on athleticperformance than any other nutrient. Most peopleobtain around two thirds of their water intake fromdrinking fluids and between 20-40 % from solid foods. Athletes, on the other hand, must obtain as 90 % oftheir water intake by drinking water. The two group of athletes most vulnerable todehydration are marathon runners and wrestlers. Dehydration is serious problem for athletes.
It is important to understand nutritionally relatedfactors that cause fatigue & reducedperformance. These being : - depletion of muscle stores& dehydration
Hydration and Performance • Dehydration leadsto: • Increased bodytemperature • Elevated heart rate • Increase in perceivedexertion • Dehydration affects: • Performance –endurance and intensity • Coordination and skill • Concentration anddecision making • Negative effects whenfluid deficits are as low as2%
Requirements of fluid,carbohydrate and sodiumType of eventWater mlRequirementCarbohydrate g/ literSodium mEq/lEvent lastingless than onehourEvent lastingbetween 1 to 3hrsEvent lastingmore than 3hours300-500300-500(before theevent)300-500(before theevent) 500-1000 ml60-100( with 500-1000 ml water)60-80 (with 800-1600 ml water)60-80 (500-1000 ml)--20-30
THE TRAINING DIET..THE TRAINING DIET.. Athletes now understand that they must eat wellto ensure maximum return from heavy trainingschedules. The competition diet is established providingathletes with knowledge of special eatingpractices, before, during and after the event tomaximise their performance.
GENERAL PRINCIPLESGENERAL PRINCIPLESOF SPORTS NUTRITIONOF SPORTS NUTRITIONRecommended balanced diet for average sportsperson is…. 55 – 60% Carbohydrates 25 – 30% Fats 10 – 15% ProteinRecommended balanced diet for more strenuousathlete is… 70% carbohydrates 15 – 20% Fats 10 – 15% Protein
STRATEGIES TO REDUCE, DELAY OR OFFSETSTRATEGIES TO REDUCE, DELAY OR OFFSETTHESE FACTORSTHESE FACTORS General preparation of energy stores(increase carbohydrate intake to ensure naturalstorage capacity) Carbohydrate loading for endurance events(gradually reduce training early in the week,maintain normal diet to maintain carb levels –reduce training further and consume high level ofcarbohydrates80 – 85% of kg intake) Pre-competition meal(ensure that glycogen stores are topped up forstrenuous exercise, adequate hydration)
STRATEGIES CONT..STRATEGIES CONT.. Carbohydrate supplementation (marathons)(generally in fluid form in small amounts and frequentintervals – this maintains blood glucose levels andspares muscle glycogen) Glycogen replenishment(first 15 min after exercise eat foods high in glycogene.g. fresh fruit, lollies…..Following two hours meal high in complex carbs &protein Fluid replenishmentBefore, during and after
Sources, function, usesSources, function, usesSources Function Sports of primary useCHO Breads, cereals,rice, pasta, fruit &vegetablesThe bodies main source ofenergy to carry out every-day activitiesTeam Sports(football, netballetc)Protein Beef, lamb, fish,chicken, eggsBuilds and repairs all bodycellsMarathon (Long induration)Fats Animal Products –meat, chicken etc(saturated)Plants – Avocado(unsaturated)Supply essential fatty acidsthat form membrane ofcells. Vital in hormoneproductionWalking, mowinglawnsSecondary energysource when CHO’sare usedWater Straight from atap/bottle, fruits(oranges, pears)Transport other nutrients,cells, hormones & wastesaround the bodyAll
Sport Nutrient Requirements Each sports person will have different dietaryrequirements depending on… Training Age Sex Body size Sport played Environment for training and competition
Sport Nutrient Requirements • Increased energy requirements for growth • High carbohydrate, moderate protein & lowfat eating plan recommended • Overall nutritional adequacy is of paramountimportance but particularly iron and calciumIncreased fluid requirements also present • Basic sports nutritionprinciples do apply to children and adolescentsbut promoting good nutrition is particularlyimportant.
GUIDELINES FOR A SPORTSGUIDELINES FOR A SPORTSPERSON DIETPERSON DIET1.Increase complexcarbohydrates2.Decrease dietary fat3.Ensure adequate proteinintake4.Increase dietary fibre5.Decrease/eliminate alcohol6.Decrease salt intake7.Increase water intake
Dietary GuidelinesAn adequate, balanced diet is necessary for aneffective performance but does not guarantee itbecause nutrition is but one aspect of performance. A poor diet, on the other hand guarantees substanceperformance. Ingestion of one or more nutrient in amounts muchgreater than body needs will not enhanceperformance. Loss of water in sweat is accompanied by a very smallloss of salt relative to the amount in the blood. Hence additional salt tablets need not be taken.
● A rapidly digested meal low in fat, moderately lowin protein and high in complex carbohydrateshould be eaten 3 to 5 hours before thecompetition.● Coffee, tea, beer and caffeine containing softdrinks should be avoided. The increasedcarbodioxide levels in the digestive tract aftertaking carbonated beverages reduce the body’surge to take additional fluids. Soft drinks provideonly empty calories.● Proper fluid balance maintains blood volume,which in turn, supplies blood to the skin for bodytemperature regulation.