In the case of the arms inward, forearms placed on the back of the armrest, elbow flexion of about 90 ° is normal. If the armrest is too high, the shoulders are easily fatigued, and pushing the wheel ring will easily cause abrasions on the upper arms. If the armrests are too low, driving the wheelchair can easily cause the upper body to lean forward, causing the torso to lean out of the wheelchair, and long-term operation of the wheelchair in a leaning position can lead to spinal deformation and chest compression, resulting in breathing difficulties.