Final answer:
Carbohydrates are the macronutrient most affected by an individual's training volume, as they are consumed in larger amounts to meet the increased energy needs during extensive training. Proteins also play a role, particularly for muscle repair and growth, but carbohydrates are vital for energy supply and recovery.
Step-by-step explanation:
Macronutrient Most Affected by Training Volume
The macronutrient that is most affected by an individual's training volume is carbohydrates. Carbohydrates are the primary energy source for both the brain and muscles during exercise. When an athlete's training volume increases, their need for carbohydrates also escalates to ensure sufficient energy for performance and recovery. For instance, carbohydrate requirements can rise approximately 3-10 g/kg/day depending on exercise intensity. This increase aids in replenishing glycogen stores in the liver and muscles, which are finite and can be exhausted through prolonged or intensive training.
In contrast, athletes may also focus on protein to support muscle repair and growth, especially in sports where increased muscle mass is beneficial, such as football and weightlifting. However, it is carbohydrates that play the most critical role in supporting increased energy demands due to intensified training.
Finally, while body weight and composition are important for athletes, and can be influenced by dietary intake, the unique energy requirements of different types of training and sports make carbohydrates the standout macronutrient that adjusts the most in response to training volume changes.