AFAA Personal Trainer Certification Practice Exam 2025 - Free Personal Trainer Practice Questions and Study Guide

The component of energy expenditure that accounts for the energy used for basic bodily functions at rest is the Basal Metabolic Rate (BMR). BMR represents the minimum amount of energy required to maintain vital physiological functions while the body is in a state of rest. These functions include breathing, circulation of blood, cell production, nutrient processing, and temperature regulation, among others.

BMR is a critical component of total energy expenditure, making up a significant portion of the calories burned during the day, especially when an individual is not engaging in physical activity. Understanding BMR is essential for personal trainers in order to tailor nutritional and exercise programs that fit the individual needs of their clients based on their metabolic rates.

The other components, such as physical activity, the thermic effect of food, and exercise metabolism, all add to energy expenditure but do not relate to simply maintaining the body's basic functions at rest like BMR does. Physical activity involves energy used during movement, the thermic effect of food refers to the calories burned through digestion and metabolism of food, and exercise metabolism pertains specifically to energy used during structured exercise sessions.