Because you often take things with your right hand first and join them with your left hand behind, your hands are of course very powerful, which makes you feel that your left hand is more powerful or your right hand is very tired. If you change your left hand to hold a heavy object, you will also have the illusion that your left hand is more powerful. You know, exertion is dominated by the nervous system. The strength of the dominant hand is generally greater, not the muscle is stronger, but the nervous system is more likely to mobilize more muscles to participate in the force. When both hands exercise with the same weight, the left hand will be stronger to make up for the weakness of the nervous system. At this time, when you are tired, the function of the nervous system will be weakened, and the advantage of stronger left hand muscles will be shown.