Quick Facts - Protein Intake

Why?

The US Dietary Reference recommend a daily protein intake for all individuals 19 years and older to be 0.8g of protein per kilogram of body weight. However, athletes (including endurance athletes) have been demonstrated to have an increased protein requirement. Tarnopolsky et al., (1992), found that for athletes, daily protein intake of 0.86g per kilogram of body weight was insufficient to allow maximal rates of protein synthesis, whereas a daily intake of 1.4g per kilogram of body weight allowed for maximal synthesis. This was supported by Moore (2009), who demonstrated that muscle protein synthesis may be optimally stimulated by protein intake of 15-25kg depending on the weight of the athlete.

To optimise the ratio of fat-to-learn muscle loss, it is recommended that athletes lower their carbohydrate intake to approximately 40% of their total energy intake and increase their protein intake to 20-30% (Abete et al., 2010).

When?

The recommended timing for protein intake for optimal adaptation and recovery is after exercise (Koopman et al., 2007; Phillips, Tang & Moore,2009). While there is some evidence that intake pre-exercise of during exercise may have some beneficial effects, these results have not been successfully replicated (Cernak et al.,2009).

While there is some debate about the “critical” nature of the timing of postexercise protein consumption, a simple message may be that the earlier after exercise an athlete consumes protein the better.

How?

Protein quality is most commonly evaluated using the PDCAAS. This tool measures a protein’s ability to provide adequate levels of essential amino acids for human needs and a human’s ability to digest it. Animal-source proteins such as eggs, milk (including casein and whey) and most meats are considered the highest quality proteins and evidence supports their relationship with greater hypertrophy when consumed by athletes compared to soy-based proteins (Wilkinson, 2007).

Milk proteins in particular have been suggested to be the most effective for supporting muscle protein synthesis, due to their particular richness in the essential amino acid leucine (Atherton et al., 2010). In their literature review, Phillips & Van Loon (2011) recommend milk or flavoured milk as the most effective and economical option for athletes who wish to optimise their muscle protein synthesis.