Which of the following is a key function of exercise in relation to health?

A key function of exercise in relation to health is the decreased risk of chronic disease. Regular physical activity plays a vital role in enhancing overall health and wellness by strengthening the heart, improving circulation, and regulating various body functions. Engaging in exercise can lower the chances of developing chronic conditions such as heart disease, type 2 diabetes, hypertension, and certain types of cancer by promoting better metabolic health and improving bodily functions.

Additionally, exercise helps in weight management, strengthens the immune system, and can aid in the prevention and management of chronic diseases. It also fosters better mental health by reducing symptoms of anxiety and depression, linking physical fitness to a well-rounded approach to health.

In contrast, the other options do not represent positive outcomes associated with exercise. Increased stress levels is not a desirable effect and runs counter to the mental health benefits of physical activity. Decreased muscle mass typically indicates a lack of physical activity rather than an effect of regular exercise, which should promote muscle growth and strength. Improved isolation doesn't relate to the benefits of exercise, which often encourages social interaction and engagement through organized activities or group workouts.