|（1.School of Physical Education & Health，East China Normal University，Shanghai 200241，China；2.Laboratory of Laser Sports Medicine，South China Normal University，Guangzhou 510006，China）
Abstract: It is inevitable for aerobic metabolism to produce active oxygen (OA). Although excessive OA is toxic, a certain level of OA plays an important role in cell signal transduction and antioxidase gene expression. Sports train-ing can establish and maintain a homeostasis between oxidation and antioxidation (HO-A), which can maintain OA to a certain level. There is a certain range (RH) in which the HO-A is able to resist the fluctuation of the OA level. The maximum value and minimum value of RH are denoted as maxRH and minRH respectively. The OA level that is just high enough to cause an oxidation reaction is called the reactive active oxygen (ROA) level. If the OA level is fre-quently lower than the minRH, the HO-A will degenerate. When the OA level exceeds the maxRH to reach the ROA level, the existing HO-A can be broken, and a more powerful new HO-A will be established. If the OA level causes the decease or damage of cells, supplementing an exogenous antioxidant is helpful. If the OA level is lowered to a level below the minRH, the maintenance of the HO-A will be affected, and the supplementation of an exogenous antioxi-dant is harmful. If the ROA level is lowered to a level within the RH, the establishment of a new HO-A will be af-fected, and the supplementation of an exogenous antioxidant is useless.
Key words: sports biochemistry；active oxygen；antioxidant；oxidative reaction；homeostasis；overview