Sports nutrition covers many different areas of health and fitness. Strategies mentioned in this article not only benefit intense training (multiple days per week, especially if training more than once a day) or prolonged training (>60-90 minutes of moderate to high intensity training), but also those who are initiating training, those who are attempting to lose weight without losing lean muscle mass, and for the elderly to prevent muscle loss associated with aging.
The amount of protein that is required varies according to the stage at which you are training / competing, and the type of sport in which they are competing in. Individuals who are initiating training have a higher protein requirement than those that are in later stages of training. As the muscles adapt to the stress of resistance exercising, requirements decrease.
The Recommended Daily Allowance (RDA) for total protein intake per day is 0.8g / kg / day (or 15 to 20% of your total energy intake) – this is appropriate for the average individual who does not train intensely or often. While there is a lack of concrete evidence regarding the exact role of higher protein diets or how much protein these diets should contain, it is suggested that 1.4 – 2.0g protein / kg /day is consumed by people participating in training programs.
Side Effect of High Protein Diets
Protein intakes of <2g/kg/day are unlikely to cause side effects. There is little information of side effects of high protein intakes of >2g/kg/day.
High protein intakes may, however:
- Weaken your bones
This occurs by increasing the amount of protein excreted in the urine, causing weakened bones. This is especially so if the source of the protein is from protein shakes/supplements and not whole food.
- Contribute to the development of kidney disease.
Especially if there are pre-existing conditions including high blood pressure and diabetes.
- May result in a deficiency in other nutrients
High protein intakes may result in other important nutrients being omitted in order to eat more protein. This is mainly a problem when carbohydrate in the diet is restricted. Deficient glycogen stores (from inadequate carbohydrate intake) in strength training result in impaired muscle protein synthesis and decreased levels of performance. Carbohydrates also contain many vitamins and minerals needed by the body to maintain it’s normal functions. It is therefore important to not forget how beneficial carbohydrates are in all forms of exercise and sports, especially for endurance sports.
High protein diets may affect hydration levels by increasing solute excretion through passing increased amounts of urine. This combined with sweating from exercising causes concern for chronic dehydration. Chronic dehydration can, in the long term, contribute to the development of kidney disease.
Amount and Type of Protein
It is important for athletes and sports people to get the timing of protein and carbohydrate intake (before, during and after exercise / training) correct in order to:
- Prevent lean muscle mass loss / preserve the lean muscle
- Build new muscle
- Help with recovery
By taking the correct amount and type of protein, at the correct time, training adaptation and recovery will be optimized. We must not forget that restoring muscle glycogen is just as, if not more important that protein intake. The combination of carbohydrate and protein intake post exercise is most beneficial to improve lean muscle mass and fat percentage. If protein is taken on its own it will then be converted to glucose and used to replenish glycogen stores, instead of muscle restoration. It is therefore important to aim for an optimal ratio of carbohydrate and protein.
Carbohydrates provide fuel for your body like petrol provides fuel to a car. Without carbohydrates, your performance will not be optimized and you will soon crave sweet, sugary foods. Energy is stored in the body in the form of glycogen in the muscles and the liver. During high intensity exercise, this stored energy will last 30 minutes, therefore strenuous exercise that takes longer than this will require carbohydrate intake during the event. About 2 hours of low intensity exercise will be achievable when start your session with full energy stores.
Some proteins are better sources than others due to the kinds of amino acids they contain. Animal sources such as eggs, dairy products, chicken, fish, pork and beef are the best. Milk proteins have been found to be superior to soy in promoting protein synthesis post exercise.
A recent study showed that ingestion of 20-25g protein post resistance training results in most efficient protein synthesis (as long as it is taken in combination with intermediate – high GI carbohydrate).
Table to show how much of each food source will give 20g protein (highest amount recommended for post exercise recovery).
|PROTEIN SOURCE||AMOUNT containing 20g protein|
|Low fat milk (2% fat)||2 ½ cups|
|Low fat evaporated milk (3.5% fat)||270g|
|Fat free flavoured yoghurt||480g|
|Fat free cottage cheese||165g|
|Almonds, Dried blanched||100g|
|Tuna, solid in brine||80g|
|Chicken, white, roasted, no skin||65g|
|Beef fillet, lean||70g|
|Pork loin chop (trimmed of fat)||70g|
For convenience and preference, there are protein supplements available that are low in fat, easy to prepare and can be more palatable straight after training compared to whole food sources of protein.
Different individuals respond differently to high protein diets – such as the obese, athletes or weight lifters that are well into their training regime, and athletes or weight lifters that are initiating exercise. It is therefore difficult to give general guidelines on amounts, types and timing of protein intake.
If you would like to learn more about how to incorporate proteins and carbohydrates in your diet effectively to suit your requirements, please contact NuChoice or register to receive a tailor-made diet plan.