There are thought to be two circumstances related to strength training and competition which increase protein requirements. Firstly, during the initial 10-12 days of training, there is a small increase in protein breakdown. Less body protein is broken down if the amount of protein in the diet is increased at this time. After about 12 days of training, protein balance is restored, and the body is likely to start building extra protein into the muscles if strength training continues

The second circumstance is prolonged heavy resistance training. The specific protein demands depend on the amount of work done and the rate at which muscle mass is developing. Brotherhood estimates that young men on a well-designed muscle building programme might increase their lean body mass by as much as 0.5-1kg per week, requiring extra protein retention of up to 30g of muscle per day during the active phase of muscle building. He acknowledges that this is an extreme value - most of the time, rates of gain of lean body mass with a general strength training programme would be considerably less

Peter Lemon, a researcher based at Kent State University, Ohio, has been investigating athletes' protein needs for a number of years. He concludes that strength training athletes need to consume more protein than the RDA, recommending levels of 1.5-2.0g/kg. He emphasises that although increasing protein intakes above the RDA (in tandem with resistance exercise) may enhance muscle gain, this increase is not a continuing linear relationship - the effect appears to plateau out at relatively modest increases

This was borne out by a recent study which compared a group of experienced strength-trained athletes with a group of sedentary controls. Both groups were tested at three protein intake levels - low, moderate and high (0.86, 1.4 and 2.4 g/kg body weight respectively). The protein intake required to maintain body protein levels was 1.4g/kg for strength athletes and 0.69 for sedentary subjects. An increase in protein intake from low to moderate increased the rate of protein synthesis in strength athletes, but increasing to the high level did not have any further effect. ('Evaluation of protein requirements for strength trained athletes', Tarnopolsky et al, J App Physiol, Vol 73, pp1986-95)

However, other studies have come up with conflicting results - for example, seven experienced male weight lifters were found to maintain their body protein levels at an intake of merely 0.52g/kg body weight. Another study found no difference in strength gain from a diet containing three times the RDA for protein, compared to a diet containing the RDA, in a group of men involved in a resistance weight programme over 28 days

There isn't enough information currently to be able to draw out hard and fast rules on protein requirements. In a review published earlier this year, Janet Walberg-Rankin concludes, 'it is prudent for the resistance trainer to consume at least 1.2g protein per kg body weight per day, but not more than 2g/kg' ('A review of Nutritional Practices and Needs of Bodybuilders', Journal of Strength and Conditioning Research, Vol 9 pp116-124)

A protein requirement which is higher than the RDA does not mean that exercisers need to consume protein supplements (see end of this article). Although the protein requirements may be higher in absolute terms, athletes in training need to be eating more food overall than their sedentary colleagues - this will automatically increase protein intake. The extra protein can easily be obtained when a variety of foods are eaten and the total energy intake is high enough

Protein foods should be chosen with other nutritional goals in mind, too. A mistake some strength athletes make when focusing exclusively on protein is to end up eating lots of high-fat foods. For the sake of general health as well as stamina, it's best to go for lower-fat protein foods which also provide a range of other nutrients. The following table gives a list of some recommended protein foods and their protein content

TABLE: Protein content of selected foods
All foods have low to moderate fat content, and provide 10g of protein:
grilled fish 50g
tuna/salmon 50g
lean beef or lamb 35g
veal 35g
turkey or chicken 40g
game meat 35g
eggs 2 small
cottage cheese 70g
non-fat fruit yoghurt 200g carton
skimmed milk 300ml
wholemeal bread 4 slices
muesli 1 cup (100g)
cooked pasta 2 cups
cooked brown rice 3 cups
cooked lentils .75 cup
red kidney beans .75 cup
A cautionary note about overdoing your protein intake. Firstly, eating more protein than your body needs for building muscle will just mean that the extra protein is burned for energy, or converted straight into fat. Secondly, excessively high intakes (more than 20 per cent of the total energy in the diet) have been linked to various medical problems, such as increased loss of calcium from the body, kidney stones and gout