Optimal Protein Intake for High-Performing Athletes

June 9, 2023


Protein plays an important role in helping athletes perform at their best. Not only does it aid in muscle repair and growth, but it also has many other functions that support athletic performance and recovery.


How does protein work?

How does protein help recovery?

Protein is known for its role in muscle recovery and growth. During intense exercise, micro-tears develop in the muscles, which can lead to muscle soreness. To repair those tears and get stronger, the body needs amino acids, which are the building blocks of protein.

When an athlete consumes protein, the body breaks it down into amino acids, which are then used to repair muscle damage from exercise. This is how muscles get bigger and stronger. Therefore, post-exercise protein intake promotes muscle repair and thus recovery, which increases strength and performance over time.

How does protein promote muscle growth?

Protein doesn't just help with muscle repair, it is also important for muscle growth. During muscle protein synthesis (MPS), the body makes new muscle proteins, which increases muscle size and strength.

MPS rates are stimulated when athletes exercise, especially resistance or strength training. Consumption of a complete protein, including all essential amino acids, enhances this MPS response, leading to increased muscle mass and strength. It's important to note that without sufficient protein, the body's ability to stimulate MPS is reduced, limiting muscle growth.

How does protein benefit hormone balance?

Hormonal balance is another key area where protein plays an important role. Several hormones are critical to athletic performance, such as insulin-like growth factor 1 (IGF-1) and human growth hormone (HGH). These hormones support various bodily functions, including cell growth and regeneration, all of which contribute to an athlete's overall performance. By providing the necessary raw materials for these hormones, protein helps maintain an optimal hormonal environment to support performance and recovery.

How does protein benefit your immune system?  

The immune system is another key area that may be affected by an athlete's protein intake. It relies on proteins to produce antibodies, which are needed to fight infection and disease. When athletes follow a high-intensity training program, they often have an increased risk of disease, which can stress their immune system. By ensuring they get enough protein, athletes can help support their immune function and reduce the effect of diseases that can disrupt their training and performance.

Is protein a source of energy?  

While carbohydrates and fats are the body's preferred sources of energy, protein can also be used as a fuel source when necessary. During long endurance races, or when overall calorie intake is low, the body can convert protein into glucose through a process called gluconeogenesis. This provides a steady supply of energy to support sustained physical activity, further emphasizing the importance of protein in athletic performance. Unfortunately, the main amino acids used for this process are essential amino acids. Which must be consumed in the diet.


The role of protein in promoting satiety cannot be overstated, especially for athletes who need to control their weight or energy intake. Protein-rich foods have been shown to enhance feelings of fullness after meals, which can help regulate energy intake and maintain a healthy bodyweight. A healthy weight can greatly affect an athlete's performance, from improving speed, power to weight ratios, and agility to reducing injury risk.

Is protein important for strong bones?   

The role of protein in bone health is also important. While protein's role in muscle health is often discussed, it's just as important for maintaining bone health. Adequate protein intake can help athletes maintain bone mass, which reduces the risk of injuries such as stress fractures.


Finally, protein plays a vital role in optimising the body's adaptations to training. When an athlete is exercising, various changes will occur in the body due to the pressure of training. By providing the necessary building blocks, protein helps the body rebuild itself and grow stronger in response to this training stimulus, improving performance over time.

What types of protein are there?


Not all proteins are created equal.

Complete protein sources are foods that contain all nine essential amino acids that the body cannot produce on its own. These essential amino acids include histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine.


A complete source of protein is crucial because our bodies need these essential amino acids to perform a variety of functions. The body can produce non-essential amino acids on its own, but it relies on essential amino acids from the diet.


Most complete proteins are found in animal foods such as meat, fish, eggs, and dairy products. However, some plant foods, such as quinoa and soy beans, are also complete proteins. Other plant foods, such as rice and beans, can be cleverly combined to create a meal that together provides all the essential amino acids, even though they may individually be deficient in one or two.


For athletes, the presence of all essential amino acids in the diet is critical to supporting peak performance. Essential amino acids, especially leucine, are key drivers of muscle protein synthesis, the process by which the body builds new muscle protein. Regular exercise, especially resistance and endurance training, can cause muscle damage that the body needs to repair to recover and adapt. A complete source of protein provides essential amino acids for this repair and growth process.


In addition to supporting muscle health, essential amino acids contribute to a variety of other functions that affect athletic performance. For example, some amino acids, such as tryptophan, are precursors to neurotransmitters involved in mood and sleep regulation. Others, such as methionine, play a role in the synthesis of molecules involved in energy metabolism.


Additionally, adequate intake of all essential amino acids ensures that the body produces essential protein-based hormones and antibodies.This is important for maintaining a healthy hormonal balance and strong immune function, both of which affect an athlete's training and performance.


Leucine is one of the nine essential amino acids that cannot be synthesised by humans and must be obtained from the diet. It plays an especially important role in MPS, the process by which the body builds new muscle proteins, ultimately leading to muscle growth and repair.


What distinguishes leucine from other amino acids is its ability to independently stimulate MPS. Research has shown that leucine activates a complex called the mammalian target of rapamycin (mTOR), which is a key regulator of cell growth, including muscle growth. Once activated, mTORinitiates the MPS process, which leads to muscle repair and growth.


In addition to its role as an mTOR activator and MPS stimulator, leucine also acts as a signal of the state of nutrient availability to the body. When leucine levels are high, as is the case after eating protein-rich foods, it signals to the body that enough dietary protein is available for the MPS process to occur without risk of preventing other essential processes. Conversely, low leucine levels indicate a state of nutrient deficiency and can inhibit the process of MPS even when other essential amino acids are available.


Additionally, leucine has been shown to reduce muscle protein breakdown, the process by which the body breaks down muscle protein into individual amino acids. By stimulating MPS and reducing muscle protein breakdown, Leucine can help muscle protein gains, resulting in net muscle growth.


Therefore, leucine is essential for athletes and individuals who engage in regular resistance training as it can help maximise muscle recovery, growth, and adaptation to training. However, it's worth noting that while leucine plays a key role in MPS, a balanced intake of all essential amino acids is necessary for optimal muscle health and athletic performance.


To calculate your own protein requirements, you need to consider the needs of your sport, your performance improvement goals, and how protein contributes to your overall energy intake. The majority of recreational athletes would benefit from using their age as a guide to their protein portion e.g. a 25 year old should aim for 25g of protein in each meal as a minimum. The human body becomes less efficient at processing protein as it ages, so increasing the size of the protein portion as you get older helps you to support your muscles. Over the age of 40 you can continue with a 40g per portion target as this has been shown to be beneficial even in the elderly so there is little point in increasing the target further.