Posts Tagged ‘endurance’

Protein Needs for Training . . .

nutrition | Posted by admin July 26th, 2009

Protein has been considered a key nutrient for sporting success by athletes of all eras and in all sports. Whereas ancient Olympians were reported to eat unusually large amounts of meat, today’s athletes are provided with a vast array of protein and amino acid supplements to increase their protein intakes.

Protein plays an important role in the response to exercise. Amino acids from proteins form building blocks for the manufacture of new tissue including muscle, and the repair of old tissue. They are also the building blocks for hormones and enzymes that regulate metabolism and other body functions. Protein provides a small source of fuel for the exercising muscle.

Some scientists have suggested that endurance and resistance-trained athletes in heavy training may have increased daily protein needs – up to a maximum of 1.2-1.7 g per kg body weight (BW), compared to the recommended intake of 0.8 g/kg BW for a sedentary person. However, the evidence for this increase in protein needs is not clear or universal. Part of the confusion is caused by problems involved in scientific techniques used to measure protein requirements. The debate over the precise protein needs of athletes is largely unnecessary.

Dietary surveys show that most athletes already consume diets providing protein intakes above the maximum recommended level, even without the use of protein supplements. Therefore, most athletes do not need to be encouraged or educated to increase their protein intakes. These surveys, however, relate mostly to athletes eating typical Western-style diets, and more information is urgently needed on athletes eating different food types.

Athletes most at risk of failing to meet their protein needs are those who severely restrict their energy intake or dietary variety. An adequate energy intake is important in promoting protein balance or increasing protein retention.

Although some resistance-trained athletes and body builders consume more than 2-3 g/kg BW, there is no evidence that these high daily protein intakes enhance the response to training or increase the gains in muscle mass and strength. Such diets are not necessarily harmful, but they are expensive and can fail to meet other nutritional goals, such as providing the fuel needed to optimize training and performance.

Recent studies have focused on the acute response to workouts of both endurance and resistance training. Enhanced protein balance is a desirable goal of the recovery phase – to overturn the increased rates of protein breakdown that occur during exercise, and to promote muscle growth, repair and adaptation following the exercise stimulus. These studies have found that eating a small amount of high-quality protein, combined with carbohydrate, enhances protein synthesis during the recovery period.

There is some evidence that the response is enhanced when these nutrients are provided soon after exercise, or in the case of a resistance workout, perhaps before training. Further work is required to fine-tune guidelines for the optimal amount, type and timing of intake of these nutrients, and to confirm that these eating strategies lead to an enhancement of the goals of training. In the light of this information, it appears sensible to focus on the total balance of the diet and the timing of protein-carbohydrate meals and snacks in relation to training, rather than on high protein intakes per se.

Special sports foods such as sports bars and liquid meal supplements can provide a compact and convenient way to consume carbohydrate and protein when everyday foods are unavailable or are too bulky and impractical to consume. However, the additional cost of these products, and the fact that they contain only a limited range of nutrients, must be taken into account. There is little justification for using very expensive protein-only powders or amino acid supplements. Everyday foods are likely to be just as effective.