You can wear a single long-sleeved trousers, but don't take off your clothes, because the capillaries are open during exercise, and it is very easy to catch a cold if it is cold, so be sure to pay attention.
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Besides going to the gym, you can also exercise outdoors when the weather is good, and the outdoor air is fresher. Wear clothes properly when running, because the temperature is low before running, some people will wear more clothes. As a result, it became hotter and hotter as I ran, and I took off while running. This is particularly easy to catch a cold.
A better way is to warm up indoors and put on appropriate clothes according to the principle of running dress. If the temperature is low, you can tie a windproof thin coat around your waist and put it on and off at any time according to the temperature.
In winter, muscle viscosity increases and elasticity decreases, so sudden exercise is easy to cause muscle strain. So before you do formal exercise, you should try to raise your temperature a little. Warm up for 3-5 minutes before running. You can do some simple stretching or walking.