Sports NutritionSports Nutrition

SPORTS NUTRITIONSPORTS NUTRITION

Sports NutritionSports Nutrition

Sports nutrition is the study and practice of nutrition and diet as it relates to athletic performance.

It is concerned with the type and quantity of fluid and food taken by an athlete, and deals with nutrition such as vitamins, minerals, supplements and organic substances such as carbohydrates, proteins and fats.

Although an important part of many sports training regimens, it is most commonly considered in strength sports (such as weight lifting and bodybuilding) and endurance sports (for example cycling, running, swimming).

ENERGY SYSTEMS

The human body must continuously be supplied with energy to perform its many complex functions.

Two metabolic systems energy for the body – one dependent on oxygen and the other able to function without oxygen.

Both of these systems provide energy, however, the use of one system over the other depends on the duration, intensity and type of physical activity.

ANAEROBIC ENERGY SYSTM

There are to energy system in the body phosphagen system and lactic acid system hat can operator in the absence of the oxygen.

These system are capable of producing ATP energy at a high rate.

They are utilized when the rate of energy production demanded of the exercise exceeds that of the aerobic system alone.

The main limitation of this system is the relatively small amount of ATP that can be made before fatigue ensues.

Aerobic Energy System

The aerobic system supplies all of the energy for low to moderate intensity exercise.

It supplies energy for sleeping, resting, sitting, walking and other firms of low intensity physical activity.

As the activity becomes more intense, to the point that it can only be sustained for a matter of a few minutes, the aerobic system can no longer provide energy at a sufficient rate.

At this stage, ATP production is supplemented by the lactic acid and phosphagen system. Exercise that relies heavily on oxygen for the provision of energy is called an aerobic exercise.

Energy

Energy requirement of sportsperson and athletes vary widely depending upon the intensity of the activity involved.

For the purpose of defining energy requirements, sports and athletic events are divided into two broad categories like power and non-power events, with additional categories representing activities 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 skilled category (archery, Yatching) range from 3500-4500 kcal/day.

It is important that the daily energy intake is contributed by carbohydrates, fats and protein. Percentage energy from these three sources should be 50-55%, 30 and 15-20% respectively.

Carbohydrate

on comparing the average work time on consumption of mixed diet, high fat/ protein diet and high carbohydrate diet, the longest work time was observed with a high carbohydrate diet.

Since the RDA for carbohydrate is 50-55% of total calories, and many carbohydrate, and many carbohydrate rich foods are fiber-rich food-which means lots of chewing and higher satiety due to the bulking capacity of dietary fiber.

However, for athletes with very high energy requirements of over 3000-5000 kcal a day, consuming and byproducts are concentrated carbohydrate foods i.e.,

refined starchy foods, nuts and oilseeds. Milk and byproducts are advised. Still, a nutrient rich diet remains central for adequacy sake, while vital, energy alone is nit enough to support performance.

CARBOHYDRATES

COMPLEX

(contain other useful nutrients)

Preferred option for carb intake due to being an efficient energy source, readily used.

Stores depleted quickly so need to be replaced frequently

SIMPLE

Carbohydrates stored as GLYCOGEN in the muscles and liver.

Muscles cannot perform without it. Therefore need to be replenished

Protein

According to the RDA, a normal person is required to consume 0.8 g to 1.0 g protein/kg body weight.

Protein intake equal to 15-20 % of total calorie will meet the protein requirements of most athletes. ICMR, 1985, recommends 12-14 % of total energy requirements and upper limit could be placed at 2 g/kg body weight. Consuming more protein than 2.0 g/kg body weight results in increased protein oxidation, urea formation, diuresis and can increase risk for dehydration.

Vitamins and minerals

Owing to increased energy requirements and exercise-induced production of free radicals, higher amounts of B- vitamins with anti- oxidant properties are required for athletes.

The B-vitamin requirement is 1mg/1000 kcal for thiamin and riboflavin and10-20mg/1000 kcal for niacin. Intake of retinol may be placed at 1000-2000 micrograms per day.

Vitamin E, which is an antioxidant should be taken at the 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 and 19 year of age. Female athletes, who train heavily, have a high incidence of amenorrhea and thus conserve iron stores.

In any case, iron intake should not be less than 50-75 mg for sports men and 60-100 g for sports women.

Vitamin and Minerals

Vitamin (a) Intake to keep enzymes saturated with adequate

tissue store.(b) Different additional supplement of certain antioxidant

vitamins and to guard against any dietary inadequacy.

Minerals (a) Electrolytes are important-supplements given during

sports events. (b) Iron : Additional iron supplements to prevent sports

anemia ; Haem iron supplement would be better. (c) trace minerals : Zn, Cu, Se important. Selenium is

an antioxidant.

Nutrition requirement of sports persons and athletes

Nutrition

Per day Per kg body weight

Energy per cent derived from.

Energy, kcal

Protein, g

Fat, g

Carbohydrate, g

Vitamins and minerals

Calcium, g

Iron, mg

Vitamin, A, mg

Thiamine, mg

Riboflavin, mg

Niacin, mg

Vitamin C, mg

3000-6000

135-225

120-200

400-600

1.5-3.0

50-85

1080-2500

3-6

3-6

30-60

80-150

50-80

2-3-5

2-3

6-8

-

15

30

55

Requirement

Water and Electrolytes

Water probably has a greater effect on athletic performance than any other nutrient. Most people obtain around two thirds of their water intake from drinking fluids and between 20-40 % from solid foods.

Athletes, on the other hand, must obtain as 90 % of their water intake by drinking water.

The two group of athletes most vulnerable to dehydration are marathon runners and wrestlers.

Dehydration is serious problem for athletes.

It is important to understand nutritionally related factors that cause fatigue & reduced performance.

These being : - depletion of muscle stores & dehydration

Hydration and Performance

• Dehydration leads to:

• Increased body temperature

• Elevated heart rate • Increase in perceived exertion

• Dehydration affects: • Performance – endurance and intensity • Coordination and skill • Concentration and decision making • Negative effects when fluid deficits are as low as

2%

Requirements of fluid, carbohydrate and sodium

Type of event

Water ml

Requirement

Carbohydrate g/ liter

Sodium mEq/l

Event lasting less than one hour Event lasting between 1 to 3 hrs

Event lasting more than 3

hours

300-500

300-500 (before the event)300-500 (before the event) 500-1000 ml

60-100( 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 well to ensure maximum return from heavy training schedules.

The competition diet is established providing athletes with knowledge of special eating practices, before, during and after the event to maximise their performance.

GENERAL PRINCIPLESGENERAL PRINCIPLESOF SPORTS NUTRITIONOF SPORTS NUTRITION

Recommended balanced diet for average sports person is….

55 – 60% Carbohydrates 25 – 30% Fats 10 – 15% Protein

Recommended balanced diet for more strenuous athlete is…

70% carbohydrates 15 – 20% Fats 10 – 15% Protein

STRATEGIES TO REDUCE, DELAY OR OFFSET STRATEGIES TO REDUCE, DELAY OR OFFSET THESE FACTORSTHESE FACTORS

General preparation of energy stores(increase carbohydrate intake to ensure natural

storage 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 of carbohydrates

80 – 85% of kg intake) Pre-competition meal(ensure that glycogen stores are topped up for

strenuous exercise, adequate hydration)

STRATEGIES CONT..STRATEGIES CONT..

Carbohydrate supplementation (marathons) (generally in fluid form in small amounts and frequent

intervals – this maintains blood glucose levels and spares muscle glycogen)

Glycogen replenishment (first 15 min after exercise eat foods high in glycogen

e.g. fresh fruit, lollies….. Following two hours meal high in complex carbs &

protein Fluid replenishment Before, during and after

Sources, function, usesSources, function, uses

Sources Function Sports of primary use

CHO Breads, cereals, rice, pasta, fruit & vegetables

The bodies main source of energy to carry out every-day activities

Team Sports (football, netball etc)

Protein Beef, lamb, fish, chicken, eggs

Builds and repairs all body cells

Marathon (Long in duration)

Fats Animal Products – meat, chicken etc (saturated)

Plants – Avocado (unsaturated)

Supply essential fatty acids that form membrane of cells. Vital in hormone production

Walking, mowing lawns

Secondary energy source when CHO’s are used

Water Straight from a tap/bottle, fruits (oranges, pears)

Transport other nutrients, cells, hormones & wastes around the body

All

Sport Nutrient Requirements

Each sports person will have different dietary requirements 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 & low

fat eating plan recommended • Overall nutritional adequacy is of paramount

importance but particularly iron and calcium Increased fluid requirements also present

• Basic sports nutrition principles do apply to children and adolescents but promoting good nutrition is particularly important.

GUIDELINES FOR A SPORTS GUIDELINES FOR A SPORTS PERSON DIETPERSON DIET

1. Increase complex carbohydrates

2.Decrease dietary fat

3.Ensure adequate protein intake

4. Increase dietary fibre

5.Decrease/eliminate alcohol

6.Decrease salt intake

7. Increase water intake

Dietary Guidelines

An adequate, balanced diet is necessary for an effective performance but does not guarantee it because nutrition is but one aspect of performance.

A poor diet, on the other hand guarantees substance performance.

Ingestion of one or more nutrient in amounts much greater than body needs will not enhance performance.

Loss of water in sweat is accompanied by a very small loss 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 low in protein and high in complex carbohydrate should be eaten 3 to 5 hours before the competition.

● Coffee, tea, beer and caffeine containing soft drinks should be avoided. The increased carbodioxide levels in the digestive tract after taking carbonated beverages reduce the body’s urge to take additional fluids. Soft drinks provide only empty calories.

● Proper fluid balance maintains blood volume, which in turn, supplies blood to the skin for body temperature regulation.