Food for Sport

Nutrition is one component to reaching your personal best. Genetic factors and training also contribute to optimal sport performance for each person.

Genes + Training + Nutrition = Optimum Performance

When you consider how much time and effort you put into your training, it makes sense to put the same into your nutrition plan.

Energy

Three types of food provide energy: carbohydrate, protein, and fat, each of which supplies different amounts of energy per gram. Iron, the mineral, is involved with both energy production and transporting oxygen around the body. These nutrients impact on energy levels and are important for good sports performance.

Athletes tend to think of energy as 'get up and go', and measure their own energy levels by the way they feel. Nutritionists and dietitians refer to energy as fuel for body processes, measured in kilojoules (kJ) or kilocalories (kcal).

You will see kJ and/or kcal if you look on a nutritional panel on food packaging.

• To convert kJ to kcal, divide by 4.2, eg 1200kJ/4.2 = 286kcal
• To convert kcal to kJ, multiply by 4.2, eg 200kcal x 4.2 = 840kJ

Carbohydrates

Carbohydrates are the major source of fuel for everyone, especially athletes. Sports dietitians and nutritionists recommend carbohydrate foods such as breads, cereals, fruits, vegetables and pulses make up more than half of our total energy intake. Aim for 5-10 grams per kilogram body weight per day.

Carbohydrates are stored in the body as glycogen in the muscles and liver. Glycogen is the main source of energy for the muscles to perform during exercise. The body can only store a limited amount of glycogen, so it is essential to eat carbohydrates every day. When muscle glycogen stores are used up, exhaustion occurs.

Glycaemic Index

The Glycaemic Index (GI) is an indicator of the effect a carbohydrate food has on the body. It describes the rate carbohydrate is digested, and its influence on blood sugar.

Foods which have a high GI are those which are repidly digested and absorbed and result in marked fluctuations in blood sugar levels. Low GI foods are absorbed and digested more slowly and produce gradual rises in blood sugar and insulin levels.

The table below shows examples of carbohydrate foods and when to eat them depending on the GI value.

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Low GI (Eat prior to sports event)	Moderate GI (Eat after to sports event)	High GI (Eat after to sports event)
baked beans brown bread muesli porridge pasta long grain white rice most fruits apple or orange juice milk yoghurt	muesli bar rice bubbles cornflakes brown rice ripe banana kiwifruit pineapple melon pita bread crumpet	sports drinks sports gels white bread cereal wheat biscuits jellybeans/sweets honey glucose baked potato pumpkin, swede water crackers

Protein

Protein is essential for the growth and repair of all body tissues including muscle and bone. It is involved with carrying oxygen around the body, hormone and enzyme production, and the immune system.

Athletes have slightly higher protein needs than the average person due to extra wear and tear on their bodies. The table below shows our daily protein needs for different types of training.

Activity	Grams of Protein/kg body weight (g/kg/day)
General public and athletes taking part in low intensity training, eg golf.	0.8 - 1.0 g/kg per day
Endurance training, eg distance running.	1.2 - 1.4 g/kg per day
Strength or power training, eg weight training for field sports or body building.	1.6 - 1.7 g/kg per day
Adolescent athletes.	2.0 g/kg per day

Animal sources of protein such as lean red meat provide a good source iron, zinc and vitamin B12 as well as high quality protein. They contain all the essential amino acids the body needs. Click here for recipes providing high quality protein.

Plant sources of protein are generally lower in at least one amino acid, so strict vegetarians have to combine foods carefully to get enough high quality protein from food.

Excess protein in the diet can put an extra strain on the kidneys and increases your risk of dehydration. A diet very high in protein may increase calcium loss and cause weakened bones. Be particularly aware of your protein intake if taking protein supplements in addition to a balanced diet.

Fat

Fat has over twice the energy value of carbohydrates or protein. It is a concentrated form of energy and easy to eat more than you need, leading to weight gain. Excess fat in the diet also contributes to heart disease and other health problems. Even for athletes who burn off the extra energy fat supplies, there is an increased risk of adverse effects later in life. Dietary fat has important roles in the body including insulation from the cold and aiding in the absorption and transportation of the fat-soluble vitamins (A, D, E and K). So it is neither necessary nor healthy to exclude all fat from the diet – low fat is the key.

Practical tips to reduce saturated fat:

• Limit high fat snacks (eg chips, chocolate) and fried foods.
• Choose low fat dairy products (eg milk, yoghurt, cheese).
• Use low fat cooking methods (eg bake, grill, steam, microwave).
• Buy lean red meat and trim off all visible fat.
• Remove skin and fat from chicken before cooking.
• Use vegetable oils eg olive or canola, which provide mono and polyunsaturated fat instead of butter, a source of saturated fat.

The table below compares the fat content of some foods:

Fat content of a sample of foods
80g lean beef mince	5g
1 lean grilled lamb chop	5g
1 scone	5g
2 chocolate biscuits	6g
1 regular muesli bar	6g
1 slice pizza	10g
1 50g packet potato chips	18g
1 croissant 5g	23g

Iron

Iron is an essential component of two blood proteins: haemoglobin, which carries oxygen around the body and myoglobin, which holds oxygen in the muscles. Iron deficiency reduces oxygen supply to muscles and slows down metabolic reactions required for energy. This can decrease performance, as you can suffer fatigue, cramps headaches and shortness of breath. Therefore an adequate iron intake is vital for people involved in sports and exercise.

Iron deficiency occurs when:

• You do not eat enough foods containing iron, eg fad diets, low energy diets, poorly balanced vegetarian diets.
• You have increased iron needs, eg to replace monthly blood loss for females, in times of growth (childhood and adolescents) and increased physical activity.

Females are at higher risk of iron deficiency due to regular loss in menstruation. It is important they choose foods rich in iron, eg lean red meat. Dietary iron is found in two forms:

• Haem iron is only found in animal products. It is easily absorbed and used by the body. The body will absorb more haem iron if iron stores are low. Generally the redder the meat, the higher the iron content. Beef and lamb are two of the richest sources of haem iron.
• Non-haem iron is found in both animal and plant products. It is poorly absorbed by the body (about 5%). Consumption of animal proteins (meat, fish or poultry) and vitamin C can boost absorption of non-haem iron. For example, iron absorption from plant foods can be increased by up to four times by combining with red meat in a meal, ie eating meat and vegetables together. However, Tannins in tea and coffee, phytates in wholegrain cereals, oxalates in some vegetables (eg spinach) and some types of fibre inhibit absorption of non-haem iron.

Iron supplements should only be taken under medical supervision. In the long term, food is the safest and healthiest way to maintain iron status. Frequent use of iron supplements may reduce the absorption of zinc, copper and calcium, increasing the risk of deficiencies.

Practical tips to improve iron absorption:

• Include lean red meat in your meals three to five days a week (the red meat provides iron and increases the absorption of non-haem iron in the meal)
• If you are not having a haem iron-containing food such as red meat in your meal, include a good source of non-haem iron, eg beans or silverbeet.
• Include foods containing vitamin C with your meal, eg fruit and vegetables or orange juice.
• Avoid tea and coffee for 1-2 hours around meal times.

Click here for Iron rich recipes.

Calcium

Calcium is needed for building and maintaining strong bones and teeth, muscle function, blood clotting and nerve transmission. Insufficient calcium intake can contribute to stress fractures (broken bones) in the short term or osteoporosis (thinning of the bones) later in life, especially in females.

Women in endurance sports, gymnasts and ballet dancers who lower body fat to a minimum level, are at particular risk. They may develop athletic amenorrhoea, where menstruation ceases altogether. This can lead to a loss of calcium from the bones causing fragile bones. If you are a female and experience altered or cessation of monthly periods, see a doctor.

A high calcium intake can help. Low fat dairy products are the best sources of calcium in the New Zealand diet, eg calcium-enriched or trim milk, yoghurt or lower fat cheeses (edam or cottage).

Fibre

Fibre is an important dietary factor that aids bowel function and helps to reduce cholesterol levels.

Sources of fibre include fruit, vegetables, wholegrain cereals and pulses such as beans. These foods can help you feel full for longer, which can make weight control easier.

Excessive intake of fibre may cause gut discomfort in some athletes, especially runners. In this case, choose foods lower in fibre before exercise, eg white bread and peeled fruit and vegetables.

Fluids

Maintaining an adequate fluid intake is essential in any healthy diet and is particularly important for athletes. (In fact, water is a critical component in any diet).

Water prevents dehydration, which can impair performance, and helps keep the body cool while exercising.

Thirst is not a good indicator you need fluid - by the time you are thirsty, you have started to become dehydrated. A fluid loss of 2% body weight can impair performance by up to 20%. Therefore it is important to drink before you feel thirsty.

Sodium (Salt)

Many foods contain salt. Adding excess salt to your meals or consuming a lot of high salt foods can disturb your balance of calcium (for bones) and may contribute to high blood pressure.

If you are competing in endurance sports such as triathlons or long distance running, salt is important to replace losses during sweating. You should not cut salt out of your diet completely, but try to reduce intake. In sports drinks, sodium has several important roles:

• Maintains fluid balance.
• Enhances fluid retention (so you don't urinate so much).
• Makes you want to drink more, which is good!

Alcohol

Alcohol can be a pleasant part of your lifestyle but can impair sporting performance, such as:

• Decrease in reaction time.
• Problems with movement, balance, coordination, concentration and effective decision-making.
• Changes in attitude for example, decreased motivation.
• Dehydration and fatigue.
• Delayed healing of soft tissue injuries, eg sprained ankle.
• Weight gain.

Practical tips about alcohol

• When you have finished exercising, rehydrate with water, sports drinks or juice before drinking alcohol.
• Avoid alcohol for 2 days before a competition or important event.
• Avoid alcohol if injured, as healing can be prolonged.

Sample Eating Plan

Here is a sample eating plan with enough carbohydrate and protein portions suitable for either a 55kg long distance runner training for 1-2 hours per day, or a 68kg soccer player training at least an hour per day, or a 85kg person who walks an hour a day.

Note:

• 1 carbohydrate portion = 20 grams
• 1 protein portion = 15 grams

Breakfast 7am
6 carbohydrate portions 1 protein portion	2 slices toast/bread with 2 Tbsp of jam, honey or peanut butter 1 cup cereal with ½ cup of milk, small pot of yoghurt and a banana 1 glass fruit juice 1 glass water
Mid-Morning 10:30am
3 carbohydrate portions	1 scone with thin spread of margarine and jam 1 apple 1 glass water
Lunch 12 noon
5 carbohydrate portions 2 protein portions	2 pita breads with lettuce, tomato, cold meat 1 apple 1 large cereal bar 200ml flavoured milk 1 glass fluid, eg water
Mid-Afternoon
(pre training meal) 3 carbohydrate portions	1 sandwich with jam 1 glass fluid, eg water
Before Training
N/A	1 glass water
Training 5:00pm
N/A	1 glass water
After Training
(Post-training snack)	3 carbohydrate portions 1 banana 1 cereal bar 300ml sports drink
Dinner 7:30pm
(Post-training meal) 5 carbohydrate portions 3 protein portions	125g lean beef or lamb 11/2 cups cooked rice Stir-fried vegetables, eg broccoli, capsicum, beans, carrots 2 Tbsp raisins 1/4 cup cashew nuts 1 glass water
Supper 10:00pm
1 carbohydrate portion	1 cup of hot chocolate

Try incorporating variety into your diet to ensure you are receiving a wide range of vitamins and minerals. See recipes for other lunch and dinner ideas.

For further advice on your specfic dietary requirements for sports performance see a Sports Nutritionist or Dietitan.

For further information, either download a copy of 'food for sport' (370kb .pdf) or order the Food for Sport booklet by calling Beef + Lamb New Zealand, Freephone 0800 733 466 or email enquires@beeflambnz.co.nz.

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