The Importance of Protein for Muscles This article will help you understand the important role of protein in bodybuilding and fitness. There are dozens of nutrients needed by the human body, which can be summarized into six categories: protein, lipids, carbohydrates, inorganic salts, vitamins and water. Protein is an organic polymer nitrogen-containing compound, and the basic unit of protein is amino acid. It is the most important nitrogen source in the body and the material basis for life and movement.
Physiological functions of proteins
1. Protein is an important component of body tissue. The protein content in the human body accounts for 16-19% of the body weight. About 3% of the daily protein participates in the body's metabolism.
2. It consists of a variety of substances with important physiological functions in the body, such as enzymes and hormones that have catalytic and regulatory effects in the metabolic process, hemoglobin that transports oxygen and antibodies that have immune functions, muscle fiber proteins, collagen, etc.
3. Maintain acid-base balance in the body
4. Participate in the body's energy metabolism. Part of the energy consumed by the human body every day comes from protein.
Nitrogen balance
Protein is broken down into amino acids and small molecule peptides in the digestive tract and absorbed. Most of it is used to synthesize tissue proteins for the repair and growth of damaged muscle tissue after exercise. Some of it is used to synthesize various functional proteins and other proteins. of nitrogenous compounds such as purine and creatine. After some amino acids are absorbed, they are broken down in the body to provide energy.
When the body does not consume protein at all, protein in the body is still decomposing and synthesizing. An adult man weighing 60 kilograms will still excrete 3.2 grams of nitrogen from urine, feces, skin and secretions every day, which is equivalent to 20 grams of protein. This amount of nitrogen that the body inevitably consumes when protein is not taken in at all is called "necessary nitrogen loss." This means a 6An adult man weighing 0 kg should consume at least 20 grams of high-quality protein every day. Only then can normal protein metabolism in the body be maintained.
Within a certain period of time, the relationship between the amount of nitrogen ingested and the amount of nitrogen excreted is called "nitrogen balance", which is used to measure the human body's protein requirements and evaluate the condition of human muscle protein.
There are three situations of nitrogen balance:
1. Nitrogen balance: Within a certain period of time, the amount of nitrogen taken in is equal to the amount of nitrogen discharged. It means that the synthesis and decomposition of proteins in the human body are in balance, and the muscle circumference of the human body is at its original circumference and level.
2. Positive nitrogen balance: the amount of nitrogen taken in is greater than the amount of nitrogen excreted, the synthesis of protein is greater than the amount of decomposition, and the muscle fibers that are damaged after exercise will be quickly repaired and grown.
3. Negative nitrogen balance: The amount of nitrogen taken in is less than the amount of nitrogen eliminated, and the synthesis of protein is less than the decomposition. At this time, the body's muscle protein is decomposed to provide energy to ensure the body's activities. Muscles are in a state of wasting.
Amino acids
Protein in the human body (human muscle) is composed of more than 20 kinds of amino acids in different combinations. The human body obtains various amino acids needed to synthesize body proteins (human muscles) by eating protein.
1. Essential amino acids: The human body cannot synthesize them or the synthesis rate is far from meeting the needs of the body. They must be supplemented from diet or sports nutrition. A total of 9 types: leucine, isoleucine, lysine, methionine, phenylalanine, threonine, tryptophan, valine, and histidine.
2. Semi-essential amino acids: Cystine and methionine can be converted from methionine and phenylalanine respectively. When cystine and methionine are abundant, 30% of methionine and 50% of phenylalanine can be saved. This amino acid is also called a "semi-essential amino acid".
3. Non-essential amino acids: Non-essential amino acids are not required for protein synthesis in the body, but can be synthesized in the human body. When the total nitrogen is insufficient, the synthesis of non-essential amino acids in the body will be limited, thus restricting the synthesis of human protein and egg (human muscle). .