Barbell squat shoulder pain may be caused by overloading, shoulder muscle spasm, cold shoulders, physiological reasons and other reasons. 1. Excessive weight: when the barbell squatting, if the barbell is too heavy, resulting in excessive shoulder weight, it will increase the burden and stimulation of the shoulders, which can lead to shoulder pain. 2. Shoulder muscle spasm: during the barbell squatting process, due to the persistent use of poor posture of the upper limbs, can lead to shoulder muscle spasm, which can lead to shoulder pain symptoms. 3. Cold shoulders: In the process of barbell squatting, the shoulders will produce a lot of sweat, if the shoulders are cold in the process, it can also lead to shoulder pain. 4. Physiological reasons:Excessive lactic acid buildup due to excessive shoulder activity can also lead to shoulder pain. When shoulder pain occurs in barbell squatting, it is recommended to consult a professional doctor in time and take the correct treatment to avoid damage to the shoulders.