3-4 times a week is enough, keep the intensity low, jog or go fast. Because the time is too short, the warm-up exercise of the body is insufficient, the cardiopulmonary function is not strengthened, the heart rate can't go up, the oxygen supply of the body can't keep up with the demand of exercise, and anaerobic exercise only consumes sugar. Time is too short, fat mobilization hasn't started yet. Generally, after 20 minutes of warm-up, the heart rate rises, the cardiopulmonary function is strengthened, the oxygen supply can meet the needs of the body, and the body begins to mobilize fat. At this time, the body enters the stage of aerobic exercise.
If the time is too long, exceeding 1 hour, you will consume too much sugar, protein and fat after continuous exercise. If nutrition cannot keep up, the negative nitrogen balance of the body will lead to malnutrition. Unless obesity deliberately wants to spend.
Running for too long for middle-aged and elderly friends will aggravate the cartilage wear and meniscus injury of weight-bearing joints, especially the knee joint, resulting in degeneration of the knee joint, leading to osteoarthritis and affecting daily life. So be sure to run moderately and do what you can.