Abstract: Objective: To investigate the changes of metabolites of teenage football players after exercise-induced fatigue. Methods: Twelve male teenage football players (14～16 yrs) were selected as experimental subjects in this study. And an exercise model including aerobic and anaerobic exercise as one group exercise was established by using power bicycle: completion 6 min 150 W load, 60～65 r/min of riding exercise and 30 s of riding exercise which load was the maximum speed set by the tester's weight. The rest took 1 min in the middle of one group exercise, and repeat 3 times of one group exercise, then rest for 3 min after one group exercise. The maximum oxygen uptake (VO₂ max) and average anaerobic power were measured after each group exercise. Their urine samples were collected before and after the whole exercise model, and gas chromatograph-mass spectrometer (GC-MS) was used to detect the differential metabolites. Results: The teenage football players had a significant decrease in anaerobic capacity after fatigue. Compared with pre-exercise, a total of 25 differential metabolites were screened out, of which 3 metabolites were significantly higher and 22 metabolites were markedly lower. The related metabolic pathways of above differential metabolites were classified as glycine-serine-threonine metabolism, tricarboxylic acid cycle, tyrosine metabolism, nitrogen metabolism and glycerophospholipid metabolism, respectively. Conclusion: After exercise-induced fatigue occurs in teenage football players, the body's metabolites: sarcosine, L-allothreonine, creatine, serine, succinic acid, citric acid, 4-hydroxyphenylacetic acid, hydroxylamine, and ethanolamine produce significant changes. The above-mentioned differential metabolites can be used as indicators for teenage football players' exercise-induced fatigue evaluation.

Key words: teenages, football players, exercise fatigue, urine, metabolomics, metabolic pathway