Sore and tired legs may be caused by physiological reasons such as over-exercise, prolonged standing and sedentary activities, as well as pathologic factors such as lumbar disorders and synovitis of the knee. 1. Physiological reasons: there is an abundance of muscle tissue present in the legs, which is responsible for supporting body weight and movement, etc.. Long-term strain or large amount of physical activity may cause fatigue injury or anaerobic metabolism of muscle tissue, resulting in accumulation of metabolic products and symptoms of sore legs; people who have been standing for a long time and sitting for a long time may also experience the above symptoms due to the soft tissues of the legs being in a state of tension for a long period of time. 2. Pathological factors: patients with basic lumbar diseases may have symptoms of soreness and weakness of the lower limbs due to the stimulation of the intervertebral discs on the nerve tissues or spinal stenosis, such as lumbar disc herniation and lumbar spondylolisthesis. Synovitis of the knee joint may present with symptoms such as swelling and pain in the knee joint, and may also radiate to the lower part of the femur, upper part of the tibia, etc., presenting with symptoms such as soreness and tiredness in the legs. There may be other reasons for the soreness and tiredness of the legs, it is recommended to go to the hospital in time, improve the examination to clarify the cause of the disease, and then give targeted treatment or treatment under the guidance of the doctor.