Magnetic Resonance Diffusion Tensor Imaging To Evaluate The Effects Of Long-distance Running On Thigh Muscle In Amateur Marathon Runners

Objective: Diffusion tensor imaging was used to observe the effects of long-term running training on human thigh muscles,and DTI was used to observe the effects of a half marathon on thigh muscles.Methods: There were 35 subjects with 70 thighs in this study.Among them,17 local male amateur marathoners were selected as the experimental group,and 18 matched men who were not regular exercisers were selected as the control group.All subjects in the experimental group received 1.5 T MRI scans of bilateral thigh muscles 1 week before(Pre),3 hours after(T1),3 days after(T2)and 7 days after(T3)of a half marathon.The scanning sequence includes the transverse axis fast spin echo T1 WI sequence,the fast spin echo T2-FS-Dixon sequence,and the planar echo based DTI sequence.Using Siemens Neuro 3 d DTI post-processing software for the anteromedial thigh muscles(rectus femoris,vastus medialis,vastus lateralis,vastus intermedius),the posterior compartment muscles(biceps femoris long head,semitendinosus,semimembranosus),the medial compartment muscles(adductor magnus,adductor longus),a total of 18 muscles for areas of interest for each muscle FA.Friedman’s nonparametric test was used to compare FA values of bilateral thigh muscles of amateur marathon runners before and after half-marathon distance running,and Kruskal-Wallis H test was used to compare muscle groups.Results: The FA values of muscles in the front,medial and rear groups of the control group were 0.256(0.222,0.322)、0.233(0.216,0.268)、0.304(0.273,0.346),respectively,and those in the experimental group were 0.220(0.194,0.244)、0.217(0.198,0.239)、0.273(0.245,0.302),respectively.The FA values of muscles in the experimental group were all lower than those in the control group.There were significant difference in FA values among muscle groups in the control group.There was no significant difference in the FA value between the anterior muscle and the medial muscle of the experimental group,and there was significant difference between the posterior muscle and the anterior muscle and the medial muscle of the experimental group.The overall thigh muscle FA values of amateur marathon runners were 0.245(0.214,0.285)、0.236(0.203,0.277)、0.241(0.210,0.285)、0.248(0.215,0.284)before(PRE),3 h,3 d,and 7 d,respectively,which were significantly lower than the baseline values before(P < 0.001),while there was no significant difference between the baseline values after 3 h and 7 d.In amateur marathon runners,FA values of vastus intermediates,vastus medius and adductor magnus were significantly lower at 3 h after running than before running(P < 0.001),but there was no significant difference between baseline values at 3 d and 7 d after running and before running.There was no significant difference between the baseline values of other thigh muscles at 3 h,3 d and 7 d after running and those before running.Conclusion: DTI technology can reflect the internal structural changes of human thigh muscle fibers after long-term running training,and such changes mainly exist in the anterior and medial muscles.Male amateur marathoners had microscopic changes in thigh muscles that were difficult to be observed by conventional MR sequences after running a half marathon.Such changes were not continuous,and could be restored to the baseline level after resting for 3 days after running.During running,it mainly activates the anteromedial thigh muscles and the medial compartment muscles.