Physical exercise can enhance immunity. However, according to Hong Kong's "Ta Kung Newspaper" May 13, Hong Kong Medical experts pointed out that in order to resist diseases, sudden increase of physical activity and exercise frequency will increase the risk of getting disease.

The researchers from the Department of Social Medical Science and the Department of Microbiology of Hong Kong University conducted the survey.

They invested 24,650 people in Hong Kong who died over the age of 30 years old during the period from 1998 to 2008. They studied the information about the exercise habit they owned ten years before they die. The results showed that the possibility of suffering from influenza and other infectious diseases of those who adhered to the 1-3 times of exercise a month is significantly lower. As to those who do not exercise frequently but suddenly increased their exercise amount up to over four times a week, the risk of dying of infectious disease for them is about 6 percent higher. The researchers said that too much frequent sports and a sudden increase in the amount of the exercise would weaken the body's immune function and increase the risk of infection.

The researchers suggested that those who exercise very little should cultivate the habit of regular exercise and avoid sudden increase in exercise during the period of disease prevalence "Exercise three times a week is enough to strengthen the resistance and a good rest after exercise is needed.”