This module explores how various body systems (respiratory, cardiovascular, and musculoskeletal) function during physical activity. Students will learn about the major muscle groups and how physical activity affects energy expenditure. Concepts like the Metabolic Equivalent of Task (MET), the exercise continuum, and different types of physical activity (aerobic and anaerobic) are introduced. The FITT principle for exercise program design and components of health-related physical fitness are also discussed.