Purpose To investigate the changes in quadriceps femoris microcirculatory perfusion level after low-load blood flow restriction training and its relationship with muscle strength.Materials and Methods Twenty-five healthy subjects were prospectively recruited in the First Affiliated Hospital of Kunming Medical University from September to November 2022.A 200 mmHg pressure cuff was applied at the root of the left thigh for blood flow restriction,and the subjects completed regular knee extension training within 4 weeks.Before the first training session and within 24 hours after the last training session,all subjects underwent scanning with the 3.0T MRI intravoxel incoherent motion sequence and the multi-echo steady-state acquisition three-dimentional imaging sequence.After image post-processing,the quadriceps femoris cross-sectional area,perfusion fraction and pseudo-diffusion coefficient were obtained,and the peak torque was measured using an isokinetic dynamometer.The MRI and muscle strength test parameters before and after training were compared,and correlation analyses were performed between the change of peak torque and the change of perfusion fraction,cross-sectional area,and pseudo-diffusion coefficient respectively.Results After low-load blood flow restriction training,the cross-sectional area of the left quadriceps femoris in subjects increased(t=-4.515,P<0.05).Among its components,the cross-sectional area of the left rectus femoris,vastus intermedius and vastus lateralis all increased(t=-3.302,-2.877,-3.207,all P<0.05).The perfusion fraction value of the left quadriceps femoris increased(t=-5.447,P<0.05);the perfusion fraction values of the left rectus femoris,vastus intermedius,vastus lateralis and vastus medialis all increased(t=-5.723,-4.621,-3.767,-4.682,all P<0.05);the muscle strength of the left quadriceps femoris increased(t=-3.983,P<0.05).There was a highly positive correlation between change of perfusion fraction and peak torque of the left quadriceps femoris in subjects(r=0.708,P<0.05).Conclusion After low-load blood flow restriction training,the changes in quadriceps femoris muscle microperfusion quantified by intravoxel incoherent motion are related to muscle strength,which is helpful for formulating rehabilitation training strategies for young patients.

Purpose To investigate the changes in quadriceps femoris microcirculatory perfusion level after low-load blood flow restriction training and its relationship with muscle strength.Materials and Methods Twenty-five healthy subjects were prospectively recruited in the First Affiliated Hospital of Kunming Medical University from September to November 2022.A 200 mmHg pressure cuff was applied at the root of the left thigh for blood flow restriction,and the subjects completed regular knee extension training within 4 weeks.Before the first training session and within 24 hours after the last training session,all subjects underwent scanning with the 3.0T MRI intravoxel incoherent motion sequence and the multi-echo steady-state acquisition three-dimentional imaging sequence.After image post-processing,the quadriceps femoris cross-sectional area,perfusion fraction and pseudo-diffusion coefficient were obtained,and the peak torque was measured using an isokinetic dynamometer.The MRI and muscle strength test parameters before and after training were compared,and correlation analyses were performed between the change of peak torque and the change of perfusion fraction,cross-sectional area,and pseudo-diffusion coefficient respectively.Results After low-load blood flow restriction training,the cross-sectional area of the left quadriceps femoris in subjects increased(t=-4.515,P<0.05).Among its components,the cross-sectional area of the left rectus femoris,vastus intermedius and vastus lateralis all increased(t=-3.302,-2.877,-3.207,all P<0.05).The perfusion fraction value of the left quadriceps femoris increased(t=-5.447,P<0.05);the perfusion fraction values of the left rectus femoris,vastus intermedius,vastus lateralis and vastus medialis all increased(t=-5.723,-4.621,-3.767,-4.682,all P<0.05);the muscle strength of the left quadriceps femoris increased(t=-3.983,P<0.05).There was a highly positive correlation between change of perfusion fraction and peak torque of the left quadriceps femoris in subjects(r=0.708,P<0.05).Conclusion After low-load blood flow restriction training,the changes in quadriceps femoris muscle microperfusion quantified by intravoxel incoherent motion are related to muscle strength,which is helpful for formulating rehabilitation training strategies for young patients.