This is the case of adolescents and young people who often do very strenuous physical activities, resulting in fatigue of the muscles of the lower limbs, which may lead to muscle spasms. 2. The muscle spasms of the lower limbs can be caused by fatigue after doing light physical exercise activities. 3, osteoporosis, adolescents are in a period of rapid growth and development, if the nutritional intake is insufficient, resulting in a lack of calcium in the body, it is very easy to produce muscle spasms of the lower limbs. 4, cold, there are many adolescents used to have lower limbs The fact that many teenagers are not adequately dressed, such as often wear shorts or short skirts, once the lower limbs are cold, then it may also cause cramps.