NUTRITION
Gillian Woodward
Protein in Sport How much protein do athletes really need? How often have you seen high protein supplements being recommended in sporting magazines? How many sports bars and drinks promote their high protein content? In this edition we look at the truth about our protein requirements for sport.
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HE RDI (Recommended Daily Intake) for protein is approximately 1 gram per kilogram body weight. Hence, if you weigh 75 kg, you need about 75 grams per day. Most Australians have an intake much higher than this – in fact, more like 120-150 grams is easily attainable. Why? Because many of our food groups contribute protein – even breads and cereals may have 2-3 grams per serving. Meat and dairy foods are of course the main sources of protein, but considerable amounts are found in legumes, nuts and seeds, with smaller quantities in our vegetables and fruits. In early sports nutrition advice there was great emphasis on the higher need for protein in those who exercised compared with those who were more sedentary in lifestyle. This was considered necessary due to the need for more muscle in exercise and extra need for repair of damaged tissue. Some protein may also be broken down to provide energy, but when a good supply of carbohydrate and fatty acids is available, the body avoids this energy pathway. Despite these extra needs in exercise, it is now recommended that only an increase to 1.2-1.4 grams per kg body weight is needed by endurance athletes, including orienteers. This means our 75 kg athlete would need 90-105 grams of protein daily, still highly attainable from a normal diet. A 10 gram serve of protein would be found in 30 grams of meat (the eye of a loin lamb chop), 40 grams (2 slices) of cheese, 3 slices of bread, 2 eggs, 2/3 cup of baked beans, 300 ml milk, 200 grams of yoghurt or 2 protein sports bars. From these few examples, you can see how easily we obtain our protein requirement each day. Our body does not distinguish between animal or vegetable protein, so either are useful sources. For vegetarians, it is important to include a variety of protein foods like legumes, nuts, seeds, grains as well as eggs and dairy foods (these latter two if you are lacto-ovo-vegetarian). Some athletes (particularly those involved in strength sports) take high protein supplementary drinks or powders to achieve higher protein intakes of 2-4 grams per kilogram body weight. They are lead to believe by advertising or product promotion, that such a process will enhance muscle growth. In fact what is actually required for muscle growth is the right genetics, a well designed resistance training program and of course a high energy, high carbohydrate, adequate protein intake to fuel the developing muscle.
42 THE AUSTRALIAN ORIENTEER JUNE 2005
The problems with extreme protein intakes above 2 grams per kilogram include the fact that they can cause dehydration, as well as loss of calcium from bone (more being excreted on higher protein diets). The protein may also replace other important nutrients in the diet such as carbohydrate and vitamins. Another disadvantage is that high protein foods are usually much more expensive to purchase and they often contain a lot of saturated fat, which can lead to higher blood cholesterol levels and contribute to blocked arteries. Timing of protein intake, however, may be of more importance to sporting performance than previously considered. In a typical Australian diet, a large proportion of our protein intake tends to occur at the main (evening) meal of the day, via a substantial serve of meat. It is now thought that spreading our protein foods throughout the day more evenly in smaller doses, may be more beneficial for muscle growth and maintenance. This is also considered a good strategy for those who are trying to maintain muscle mass while losing body weight. A constant supply of amino acids (the building blocks of protein) is needed throughout the day for muscle growth. This is easily done if you add milk and /or yoghurt to cereal at breakfast, use lean meat, fish, egg or cheese in a sandwich at lunch and then eat a slightly smaller portion of meat/fish/ egg/legumes at the evening meal. Nuts and seeds or dairy foods can also be eaten or drunk as proteinrich snacks throughout the day. Is there a case for using high protein energy drinks or meal replacements in sport? Yes there may be, particularly in those who are undertaking heavy (endurance) training schedules and find it difficult to achieve a high enough energy intake to prevent weight loss. Some athletes also find it difficult to consume solid foods prior to or even after training or competition. The meal replacement drinks can be useful in these cases and also as between-meal snacks for those wanting to ‘bulk up’ or gain muscle mass. In Orienteering however, most are aiming to maintain a lean body mass to enhance their speed, so unless weight loss has occurred through illness or other cause, such supplements should not be necessary.
