Final answer:
During exercise, dietary proteins are broken down into amino acids, which are used to repair and grow new proteins or serve as an energy source. The body cannot store amino acids; therefore, excess is converted to urea and excreted. Essential amino acids must be obtained from the diet, and a healthy balanced diet is usually more beneficial than supplements.
Step-by-step explanation:
Amino acids, the building blocks of proteins, are a crucial part of our diet and play a significant role during exercise. When an individual exercises, the body uses dietary proteins by breaking them down into amino acids. These amino acids can then be reassembled into new proteins necessary for muscle repair and growth, or they can be used for energy if needed. This process occurs because the body cannot store amino acids for later use. As a result, any excess amino acids are degraded, and the nitrogen within them is excreted as urea in the urine.
Dietary proteins are essential, as they are hydrolyzed into amino acids to contribute to the body's amino acid pool. This pool is utilized not only for synthesizing new proteins but also for creating non-protein nitrogenous substances (such as hormones and neurotransmitters) and, when necessary, for energy production through oxidative degradation. Moreover, the demand for amino acids increases during strenuous activities, and they may be used more liberally for energy, especially when the body's usual sources of energy, like carbohydrates and fats, are in short supply.
Essential amino acids cannot be synthesized by the body and must be obtained from food. In the context of exercise, especially at competitive levels, proper dietary intake of these amino acids is critically important for athletic performance. Supplements are often marketed to athletes under the guise of muscle-building; however, maintaining a healthy, balanced diet is typically more beneficial.