Final answer:
The claim that physical activity can decrease stress hormones and increase immunity is true. Exercise reduces the physiological effects of stress, enhances immune system functions, and offers a plethora of benefits including improved cardiovascular health, stress reduction, and a lower risk of major illnesses.
Step-by-step explanation:
The statement that physical activity reduces unhelpful stress hormones that can dampen resistance to disease and enhances the circulation of natural killer cells that fight off viruses and bacteria is true. Physical activity has a broad range of beneficial effects on the body, including the enhancement of the immune system's efficiency. Regular physical exercise not only helps in reducing the risk of disease but also supports overall health by improving cardiovascular and muscular fitness, increasing bone density, aiding cognitive function, and helping with weight maintenance.
One of the mechanisms by which exercise may be especially beneficial is its ability to moderate the physiological impacts of stress. Exercise can reduce hypothalamic-pituitary-adrenal responsiveness to stress, help prevent telomere shortening associated with the aging process, and minimize stress impacts on cognitive functions such as memory. Furthermore, physical activity has been correlated with lower incidences of upper respiratory tract infections, reduced cancer mortality, and a decreased risk for type 2 diabetes and obesity.
The cardiovascular benefits of exercise are well established, as well as its ability to reduce stress. Increased physical fitness can reduce stress and protect against stress-related health issues. In contrast, chronic stress without the buffer of physical exercise may inhibit immune responses, thereby increasing susceptibility to certain diseases. This underscores the importance of physical activity as part of a healthy lifestyle, to maintain the balance of the body's immune system and to cope with stress effectively.