Acute changes in diffusion tensor imaging parameters of the quadriceps femoris muscle after stretching and their relationship with intramuscular adipose tissue.

PURPOSE

Whether stretch exercise improves muscle anisotropy in relation to intramuscular adipose tissue (IntraMAT) is unclear. This study aimed to compare the diffusion tensor imaging (DTI) parameters of the quadriceps before and after stretching and to investigate correlations between the magnitudes of changes and IntraMAT ratios.

METHODS

Twenty young males were included. Single axial DTI and T1-weighted imaging of the right mid-thigh region were conducted before and after rest and stretching. Individual quadriceps were segmented, λ and fractional anisotropy (FA) were measured using DTI, and the IntraMAT ratios were measured using T1-weighted imaging. To test an intervention-by-time interaction effect, two-way repeated-measures analysis of variance was conducted. The correlation coefficients between the changing λ and FA magnitude by stretching and the IntaMAT ratio were assessed.

RESULTS

There was a significant interventions-by-time interaction effect in the λ and FA in the vastus medialis (VM). After stretching, in the VM, the λ values significantly decreased (mean difference, 0.07 mm∙s∙10 for λ), and the FA significantly increased (mean difference, 0.021). Furthermore, the decreasing λ and λ in the VM were significantly inversely correlated with the IntraMAT ratio (r = - 0.50 for both), and the increasing FA magnitude was significantly positively correlated with the IntraMAT ratio (r = 0.45).

CONCLUSION

Stretching the quadriceps acutely decreased λ and increased FA in the VM, and the magnitude of the λ, λ, and FA changes were correlated with the IntraMAT ratio. Stretching the quadriceps could improve VM function, particularly in overweight and obese people.