At two o 'clock in the afternoon to between exercise is better at 7 o 'clock. This is because: sunny day in winter, the changing rule of the temperature is usually in the morning and cold in the morning and afternoon is warmer. And human activities by the 'biological clock' control, temperature of human body oneself also follow the rule of 'high' low in the morning, afternoon, so winter fitness time choose afternoon PM - This number is ideal. At this point, the outdoor temperature is higher, has a high body temperature, physical strength is abundant, easily excited, are more likely to enter into the state of motion. In the morning or before 9:00 in the morning exercise, due to the low temperature, low temperature damage to human body is mainly caused by local frostbite and hypothermia. In a cold environment movement (for a long time Such as long-distance running, etc. ) , heat loss too much, can appear giddy, loss of coordination, gait instability, such as signs. At this time, must not lie down and rest, or body temperature will reduce further, so as to cause coma and even death. Winter exercise correct method is more calories food, wear, appropriate control movement time, in order to maintain body temperature level, and the body's normal functions, make exercise really achieve the goal of physical fitness.