Final answer:
Regular aerobic exercise decreases susceptibility to illness by buffering stress responses, improving heart efficiency, reducing blood pressure, and promoting cardiovascular health. It also releases myokines with anti-inflammatory effects and strengthens the immune system. Therefore, the correct option is b.
Step-by-step explanation:
Regular, aerobic exercise helps to decrease susceptibility to illness through several mechanisms. Primarily, it buffs the physiological response to stress, which might be a factor in decreasing the risk of illness. For example, studies have shown that exercise can mitigate the effects of stress on the hypothalamic-pituitary-adrenal axis, reducing its reactivity. This can lead to lower cortisol levels and a decreased stress response. Moreover, regular exercise maintains cardiovascular health, increasing the efficiency of the heart and lowering blood pressure. This can lead to a reduced rate of plaque formation in the arteries. In addition, exercise also releases myokines from muscles during contractions, which are hormones that have reparative and anti-inflammatory effects.
Another way exercise decreases the likelihood of illness is by improving the immune system function, evidenced by a decrease in incidences of upper respiratory tract infections among those who engage in moderate exercise. Physical exercise is also correlated with reduced death rates from certain cancers and has been employed as a treatment modality for major depressive disorder and attention deficit hyperactivity disorder, showcasing its broad health benefits.