Question

Describe four factors that affect the metabolic rate of an active person. (pp. 408,411 )

Short answer

Answer: Four factors that affect the metabolic rate of an active person are age, body size and composition, physical activity, and gender. Age affects metabolism as it tends to decrease with age due to factors like loss of muscle mass and hormonal changes. Body size and composition play a role as individuals with a larger body mass and higher percentage of lean muscle mass typically have a higher metabolic rate. Physical activity influences metabolism since more active individuals require more energy for their activities and high-intensity activities can significantly increase metabolic rate. Lastly, gender affects metabolism as men generally have a higher metabolic rate than women due to greater lean muscle mass, lower body fat percentage, and hormonal differences.

Step-by-step solution

Factor 1: Age

As a person gets older, their metabolic rate tends to decrease. This is due to a variety of reasons, including the loss of muscle mass as a person ages, hormonal changes that lower metabolism, and a generally less active lifestyle.

Factor 2: Body size and composition

Metabolic rate is influenced by body size and composition. Individuals with a larger body mass and a higher percentage of lean muscle mass typically have a higher metabolic rate than smaller individuals or those with a higher percentage of body fat. This is because muscle tissue is more metabolically active than fat tissue, requiring more energy to maintain its function.

Factor 3: Physical activity

It is intuitive that an increase in physical activity would increase a person's metabolic rate. More active individuals require more energy to fuel their activities and maintain proper body functions. The type and intensity of the activity also play a role in determining the overall impact on metabolism. High-intensity activities such as sprinting or weight lifting can significantly increase metabolic rate, even after the activity has been completed.

Factor 4: Gender

On average, men tend to have a higher metabolic rate than women. This is mainly due to the fact that men typically have a greater percentage of lean muscle mass and a lower percentage of body fat than women. Additionally, hormonal differences between the sexes can also influence metabolism, as testosterone (found in higher amounts in men) can promote muscle growth and increase metabolic rate.