Wearing two pairs of pants, for example, causes an unnatural running stance, which increases your chance of injury. Wearing more layers during your run can keep you warm in cold weather, but excessive layers might make you too hot in hot weather. Not only that, but wearing multiple sets of clothes is just plain messy. The best way to stay safe while running is to use common sense. If you feel like you're about to catch fire, take off some clothes or jump into a body of water. There are many other ways to prevent injuries while running, so be sure to use caution and listen to your body.