Tired legs and heavy legs may be symptoms caused by muscle strain, osteoporosis and lower limb vascular diseases. 1. Muscle strain: If walking or running is carried out for a long time, or over-exercising the lower limbs, it may lead to excessive fatigue of the lower limb muscles and formation of invisible damage to the muscle fibers of the legs, at which time there will be obvious fatigue and heaviness in the legs. 2. Osteoporosis: For people with calcium deficiency, bone density will be affected, resulting in osteoporosis. People with severe osteoporosis will have tired legs and heavy legs. 3. Lower limb vascular disease: If there is lower limb vascular disease, such as lower limb arterial embolism, or even complete occlusion, it will lead to insufficient blood circulation in the lower limbs. At this time, in the process of activity will obviously feel the lower extremity ischemia caused by leg tiredness, leg heavy and other symptoms. If you often feel tired and heavy legs, you should go to the hospital as soon as possible to determine the cause of the discomfort and get timely treatment to avoid aggravation of the symptoms.