In order to investigate the changes of temporal function metabolism of lumbar and back muscles after exercise, a magnetic resonance imaging- (MRI-) based assessment of fatigue injury during exercise was proposed. A total of 100 healthy adult volunteers were selected, including 48 males and 52 females, aged from 19 to 30 years, with an average age of 24.8 + 2.3 years. They were divided into four groups according to the different time points of 0, 15, 30, and 45 minutes after exercise, with 25 persons in each group. PHILIPS Achieva 3.0 T Tx MRI scanner was used to perform BOLD and T2-mapping before and after exercise in four groups of healthy volunteers. All data were analyzed by statistical software. The results showed that the total CSA of the dorsi extensor muscle group and the CSA value of the dorsi extensor muscle group at different levels at different time points before and after exercise increased slowly in exercise period and decreased rapidly in recovery period. It was verified that BOLD MRI and T2-mapping imaging can indirectly evaluate the trend of CSA water metabolism and blood oxygen level in healthy adults after exercise.