flex one's muscles

This is a world that reveres martial arts, where the internal energy techniques and moves created by the legendary masters Zhang Sanfeng and Yang Luchan have brought Eastern martial arts to their pinnacle. As we enter an era where genetic technology and neural networks are becoming increasingly widespread... Jiang Yaoyang, who is completely incapable of cultivating internal energy, is knocked unconscious by a backpack filled with martial arts manuals! The Bone-Marrow Washing Classic! The Muscle-Tendon Changing Classic! The Star-Sucking Technique! The Light-Step and Six-Meridian Divine Sword! And even the Dual Cultivation Joyful Zen! His journey of martial glory begins here!