Knees always feel sore, no strength is common in the following aspects of the reasons: 1, patellofemoral joint wear, patellofemoral joint is composed of the patella and the distal end of the femur joint, if often squatting, running, hiking, climbing stairs, etc., may lead to wear and tear of the cartilage surface, the emergence of soreness as well as fatigue of the knee anteriorly. 2, tibiofemoral joint cartilage wear is the distal end of the femur and the proximal end of the tibia joints composed of the joints, if often jumping, long term If the cartilage is worn out due to frequent jumping or long-term overweight, there will be soreness in the knee joint space and weakness of the knee. 3. Tear of the meniscus, synovitis in the joints, and intra-articular free radicals can cause soreness as well as weakness of the knee. Overall, this symptom is a lesion within the knee, which can be further investigated by X-ray or MRI.