Journal of the International Society of Sports Nutrition (JISSN) focused on the acute and chronic effects of sports nutrition and supplementation strategies on body composition, physical performance, and metabolism has given their official position about protein intake in the context of athletic training.
Based on the literature currently available, the society presented an objective and critical review related to protein intake by such individuals as athletes/sportsmen.
- Heavy physical activity, particularly strength training, and the intake of dietary protein, stimulates the synthesis of muscle protein (MPS), this interaction has a greater synergistic effect when protein intake occurs before or after strength training.
- To ensure the growth and maintenance of muscle mass, by providing a positive balance of muscle protein [MPB], the total daily protein intake should be in the range of 1.4-2.0 g/kg body weight/day (g/kg/day), which is sufficient for the majority of trainees [for a low-calorie diet] that fits optimally within the permissible range of distribution of macro-elements, according to the information published by the Institute of Medicine on the protein.
- Higher protein intake (2.3-3.1 g/kg/day) may be necessary to maximize lean muscle mass for athletes practicing strength training, during periods of low-calorie diets.
- There is evidence that higher protein intake (> 3.0 g/kg/day) can have a positive effect on body composition among athletes. Thus, it contributes to a greater loss of fat tissue.
- What about optimal single intake of protein in order to maximize MPS, common recommendations are about the absorption of ~ 0.25 g of high-quality protein per kg of body weight.
- Most likely, physically active people, should provide their daily protein norm by consuming ordinary food. The use of protein supplementation can allow athletes to provide the necessary amount of protein, while minimizing the consumption of accompanying calories, especially for athletes practicing high-volume training.
- Quickly digestible proteins that contain high concentrations of essential amino acids (EAAs) and an adequate amount of leucine are most effective in stimulating MPS.
- Athletes training their endurance should seek to consume adequate amounts of carbohydrates, in order to optimize training performance; adding protein, can help compensate for muscle damage and provide a quicker recovery.
- Consumption of 30-40 g of casein protein before bedtime, apparently, provides an increase in MPS metabolic processes during the night period, but without any significant effect on lipolysis (the breakdown of lipids and hydrolysis of triglycerides into glycerol and free fatty acids).