Which of the following concepts pertains to the capability of the body’s systems to be altered favorably through exercise?

The concept that pertains to the capability of the body’s systems to be altered favorably through exercise is metabolic fitness. This term focuses on how exercise can positively influence various metabolic functions, including how the body processes carbohydrates and fats, regulates blood sugar, and maintains healthy cholesterol levels. Metabolic fitness reflects the overall efficiency of the body's metabolic processes, which can be improved with regular physical activity, leading to enhanced health and reduced risk of diseases.

While the other concepts are important aspects of physical fitness, they do not specifically encompass the broad metabolic changes that occur through exercise. Body composition relates more to the proportion of fat and non-fat mass in the body, while flexibility refers to the range of motion in joints and muscles. Balance involves the ability to maintain control of body position, both statically and dynamically. Each of these elements contributes to overall fitness but does not directly capture the idea of favorable alterations in the body's systems through exercise as accurately as metabolic fitness does.