The body does not sweat even if there is a lot of activity, which may be caused by the cold environment, congenital anhidrosis, ichthyosis and other reasons. 1. Cold environment: if the environment around the activity is cold, the sweat glands of the human body will not be easy to open, which leads to the phenomenon that the body does not sweat even if the activity is big. 2. Congenital anhidrosis: it is caused by the underdevelopment of sweat glands, often combined with sebaceous glands, hair, nail plate and other aspects of underdevelopment or defects, which will result in the phenomenon of the body does not sweat even if the activity is large. 3. Ichthyosis: Sweat consists of oil secreted by sebaceous glands in the skin and sweat secreted by sweat glands. After the attack of ichthyosis, the speed of skin keratinization is greatly accelerated, resulting in a large number of scales. Along with the keratinization of the skin, the hair follicles and sweat ducts are also blocked, leading to disorders in the secretion of sebaceous glands and sweat glands, which prevents them from secreting oil and sweat, resulting in no sweating. If the body does not sweat even with a lot of activity is a pathological condition, it is important to seek medical attention in time for professional judgment and targeted treatment by a doctor.