Continuous exercise for several days suddenly feel very tired, may be due to nutritional imbalance, low blood potassium, too much lactic acid, cold and other reasons. 1. Unbalanced nutrition. It may be that during exercise, the intake of carbohydrates is too low and other foods contain less carbohydrates, thus leading to unbalanced nutrition and causing the feeling of being very tired. You should improve the three meals and balance the nutrition. 2. Low blood potassium. Usually less exercise, suddenly continuous exercise for several days, resulting in body fatigue, sweat after exercise, if the diet is no oil and little salt, it is easy to cause hypokalemia, which will lead to symptoms of generalized weakness. 3. Excessive lactic acid. Usually exercise less, suddenly exercise, muscle glycogen consumption is too much, and in anaerobic state, easy to produce too much lactic acid, accumulation in the muscle, resulting in muscle stimulation, thus causing the above symptoms. 4. Cold and flu. Patients who exercise after catching a cold may experience symptoms of feeling tired. Serious cases are recommended to actively seek medical attention to clarify the cause of the disease and to carry out targeted treatment.