General sports nutrition

Not all calories are equal – the quality of the calorie intake is vital to any athlete interested in long-term energy and endurance. Athletic ability and aerobic fitness do not guarantee optimum performance ( or good health) the need for quality fuel and sound nutrition is just as important to success as the training at a track or gym.

PROTEIN

Protein is needed for most substances in the body from bones to muscles, hair, cell membranes, arteries, hormones and enzymes.  It is the bodies primary source of fuel after the carbohydrate stores have been depleted.  However excess protein is not good for you, its very dehydrating, you need 8 times as much water to burn off a calorie of protein compared to a calorie of fat or carb. The kidneys and liver can also suffer stress from too much protein.

When ever people think about sports nutrition their main thought is must eat more protein, this is amplified with Gym’s selling protein supplements, sports magazines advertising protein bars.  The steak and egg approach to building muscles has now been proven false.  The human body can only use a limited amount of protein per day. The general guidelines for protein requirements are :-

Estimate of protein needed (g/kg/per day) – MALES – Females 15% less

Sedentary  – 0.8 -1.0

Recreational Exerciser’s- 0.8 -1.0

Serious Resistance Training – Early Phase – 1.5 – 1.7

Serious Resistance Training – Maintenance – 1.00 – 1.2

Serious Endurance Training – 1.2- 1.6

Adolescent Athletes – 1.5-2.0

But most people find it very easy to eat a lot more. Men and women in the UK eat about 45-55% more protein than they need each day, according to the National Diet and Nutrition Survey.

For the majority of athletes their current diet will be sufficient in protein.  Those that are eating too much concentrated protein especially red meat may find that their digestion  improves and decrease toxic by products such as uric acid. Long distance runners may need up to 1.6g/kg especially if they are very lean.

The need for amino acid or protein supplements is questionable, these supplements are not only expensive but more often than not unnecessary. The body’s not very skilled in the practice of riding itself of the extra protein and this puts stress on the kidneys.  Too much protein in the diet can also stop the body’s absorption on calcium. It is often said that Vegan diets may find it difficult to consume sufficient protein, however with meal planning  and eating a range of foods its quite easy to consume your daily requirements.

It’s easy to get your protein requirements because protein is found in most foods:

  • Meat, poultry and fish 7 grams per ounce
  • Beans, dried peas, lentils 7 grams per 1/2 cup cooked
  • One large egg 7 grams
  • Milk 8 grams per cup
  • Bread 4 grams per slice
  • Cereal 4 grams per 1/2 cup
  • Vegetables 2 grams per 1/2 cup

Protein is made up from 20 different amino acids , if these are consumed via an animal source they are classed as complete, if via a plant based diet theses are           incomplete and you then need to ensure that your diet has a sufficient variety to make a complete protein.  For example brown bread and peanut butter on their own are incomplete proteins but combined they make a complete protein.

It is essential to eat your required calories when exercising. If there are too few calories in the diet and therefore insufficient glycogen stored in the muscles or liver for fuel then the body will use protein as a source of energy, reducing muscle mass.

If you find you are losing muscle mass increase your protein intake by 4 to 8g per day but at the same time increase your carbohydrate to ensure that your body uses glycogen as its fuel and not protein which is needed for growth and repair.

CARBOHYDRATES

For regular athletes especially those exercising strenuously for 2 hours of more a day  the diet should be around 70% carbohydrates.  The majority of theses should be complex carbohydrates and not simple carbohydrates , found in cakes, white bread etc. They are more nutrient-dense and, compared to sugary foods, provide more B vitamins necessary for energy metabolism as well as more fibre and iron.

Studies have shown that diets of 50/60% carbs are not enough to replenish glycogen stores after a strenuous activity of more than 2 hours.  When you eat whole fruits, vegetables, beans and grains you are gaining valuable fibre at the same time.  This fibre slows the immediate release of sugar into the blood stream which helps control the release of insulin from the pancreas.

Adequate carbohydrate stores (muscle and liver glycogen and blood glucose) are critical for optimum athletic performance. Consuming adequate carbohydrate on a daily basis is necessary to replenish muscle and liver glycogen between daily training sessions or competitive events. Consuming carbohydrate prior to exercise can help performance by “topping off” muscle and liver glycogen stores. Furthermore, consuming carbohydrate during exercise can improve performance by maintaining blood glucose levels and carbohydrate oxidation.

Try not to have your quick energy boost as a chocolate bar or sugary drink, the energy boost will only last 7 to 10 mins followed by a sudden drop in energy as insulin is released to remove the glucose from the blood stream.

Muscle glycogen represents the major source of carbohydrate in the body (1,200 to 1,600 kilocalories), followed by liver glycogen ( 300 to 400 kilocalories) and, lastly, blood glucose ( 100 kilocalories). Carbohydrate is the preferred fuel for exercise intensities at and above 65% of V02max – the levels at which most athletes train and compete.  According  to Bergstrom and associates(1), The greater the pre-exercise glycogen content, the greater the endurance potential. They compared the exercise time to exhaustion at 75% of VO2max after three days of three diets varying in carbohydrate content. A mixed diet (50% calories from carbohydrate) produced a muscle glycogen content of 106 mmol/kg and enabled the subjects to exercise 115 minutes. A low carbohydrate diet (less than 5% of calories from carbohydrate) produced a muscle glycogen content of 38 mmol/kg and supported only an hour of exercise. However, a high-carbohydrate diet (>82% of calories from carbohydrate) provided 204 mmol/kg of muscle glycogen and enabled the subjects to exercise for 170 minutes.

Best carbohydrates are:-

Wholegrain breads and cereal

All grains

Pasta

Potato’s

Beans

Fruit

FATS

Fats are important in all diets and are needed for effective absorption of A,D,E and K

Your body can produce all the cholesterol it needs and it’s essential to health, it aids hormone production and surrounds nerve fibres like a protective sheath and helps assimilate .  As long as you do not have a history of heart disease up to 30% fat is acceptable.

Aerobic exercise increases the amount of HDL in the blood stream, then by allowing cholesterol to break away from the artery wall and transport to the liver where it is broken down.  However for those that stop exercise  and continue to eat a high fat diet research has shown that they are more likely to have a heart attack than those that were sedentary all along.  The body becomes dependent upon the aerobic exercise to properly dissipate the cholesterol .

The guidelines for carbohydrate consumption during competition call for 30-60 g/hour. However it is possible that these recommendations fall short when it comes to endurance and ultra-endurance events.

Never eat excessive fats before a race, fats are digested slowly and cumulative effects can be felt for up to 60 hours.

  1. Bergstrom J, Hermansen E, Hultman E, Saltin B. Diet, muscle glycogen and physical performance. Acta Physiol. Scand. 1967 71:140-150.

 

 

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