Final answer:
Our caloric/energy expenditure is greatest during intense physical activities compared to the basal metabolic rate (BMR) at rest. Energy needs are higher when the body is in an active state, particularly during vigorous exercise when the Respiratory Exchange Ratio (RER) can exceed 1.0, corresponding with high rates of carbohydrate metabolism.
Step-by-step explanation:
At which Respiratory Exchange Ratio (RER) is our caloric/energy expenditure the greatest? Our caloric or energy expenditure is greatest when engaging in vigorous physical activities, where the metabolic rate increases substantially compared to the basal metabolic rate (BMR) at rest. BMR is a measure of the energy expended by our body to maintain basic functions in a restful state and is influenced by factors such as age, gender, body weight, and muscle mass; with athletes tending to have a higher BMR due to a greater muscle mass.
Energy expenditure during activities far exceeds the BMR, and caloric burn is highest during these periods. This is because during exercise, the skeletal muscles and heart's energy consumption increases dramatically. Different activities will have varying RER values, with more intense activities causing the RER to exceed 1.0, indicating a high rate of carbohydrates metabolism, and consequently high caloric expenditure.