請用中文大幅度改寫以下內容：

"The purpose of this study was to investigate the effects of exercise on cardiovascular health in middle-aged adults. A total of 100 participants were recruited and randomly assigned to either an exercise group or a control group. The exercise group participated in a 12-week aerobic exercise program, while the control group maintained their usual level of physical activity. Pre- and post-intervention assessments were conducted to measure participants' blood pressure, heart rate, and cholesterol levels. The results showed that the exercise group had significantly lower blood pressure and heart rate, and higher levels of HDL cholesterol, compared to the control group. These findings suggest that regular aerobic exercise can improve cardiovascular health in middle-aged adults."