Physical activity and protein requirements

Research shows that protein requirements during exercise are 0.8 kg per day greater than the recommended dietary allowances.

Endurance load

Endurance exercise induces training adaptations that alter protein metabolism. Increased amino acid oxidation increases mitochondrial protein content, which may require more protein than recommended dietary allowances (RDAs). Exercise intensity and duration contribute to increased amino acid oxidation. This may help identify endurance athletes who engage in different training intensities, as their protein requirements vary.

• Low intensity. Athletes who regularly train at V02max below 50% (slow walking, cycling, dancing) do not require additional protein. Indeed, this level of exercise can provide a positive stimulus for protein utilization without increasing the body's need for it.
• High Intensity. Athletes who train regularly and vigorously (running, swimming, cycling) require more protein than the RDI - 1.2 to 1.4 g-kg per day (140-160% RDI). It is assumed that this increased protein requirement is most important during the first two weeks of an intense exercise program.

Load to overcome resistance

Lifting weights increases protein requirements. Maintaining muscle mass requires significantly less protein than increasing it. Research shows that with adequate energy intake, muscle mass can be maintained with protein intakes of 5-10 g-kg per day. However, bodybuilders and weightlifters rarely want to just maintain their existing muscle mass. Most of them try to build additional muscle mass through training.

Current recommendations for muscle gain during resistance exercise are in the range of 1.4-1.8 g-kg/day (160-200% RDI). Adequate energy intake also helps improve protein utilization during muscle gain. Energy should be adequate or slightly higher than the energy needed to maintain body weight (by 200 kcal/day or 3 kcal-kg/day).

Timing of Protein Consumption

Studies have shown that a certain amount of protein and carbohydrate (recommended ratio 1:3) after exercise promotes increased glycogen resynthesis by stimulating insulin release. The combination of protein and carbohydrate in a meal after intense exercise may also stimulate an increase in muscle mass by releasing insulin and growth hormone. It has been suggested that a carbohydrate supplement, immediately or within 1 hour after resistance exercise, produces a more positive nitrogen balance than several hours after exercise.

An important topic for discussion is the improvement of training methods. Resistance training and endurance training are rarely mutually exclusive. Bodybuilders and weightlifters engage in aerobic exercise, but not at the level of endurance athletes. The latter recognize the benefits of weight training. Since many athletes engage in strength and endurance training, their protein requirements are 1.2-1.8 g-kg per day. Each athlete's protein requirements must be calculated individually.

Calculating protein requirements

Protein requirements can be determined by identifying the level of physical activity for different groups of people. It is important to consider whether an athlete is starting an individual training program and/or is already involved in strength and endurance training. Thus, a football player who regularly trains for endurance and strength will have the highest protein requirements, while other athletes who only perform aerobic exercise without lifting weights may have lower protein requirements.

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