Preliminary study on MRI quantitative assessment of calf muscle cross-sectional area and fat fraction in amateur marathon runners / 中华放射学杂志

ABSTRACT

Objective:To evaluate the calf muscle cross-sectional area (CSA) and fat fraction (FF) in amateur marathon runners based on T 2WI-Flex fat-suppression sequence and iterative decomposition of water and fat with echo asymmetrical and least-squares estimation quantitation sequence (IDEAL-IQ) technique, and to explore the correlation between them and age, body mass index (BMI), running age, speed exercise, and monthly exercise. Methods:From September to November 2022, 37 amateur marathon group (marathon group) and 12 healthy volunteers (control group) who did not often exercise were recruited in Shijiazhuang. T 2WI-Flex fat-suppression sequence and IDEAL-IQ sequence were performed on all subjects. The anterior group of the right calf (tibialis anterior, extensor hallucis longus, extensor digital longus), external group of the calf (peroneus longus, peroneus brevis), soleus, medial head and lateral head of the gastrocnemius were delineated along the edge of the muscle contour as regions of interest, and the CSA and FF values of the muscles were obtained. Twelve subjects matched with the clinical data of the control group were selected from the marathon group (marathon matched group), and the differences in CSA and FF were compared by independent sample t test or Mann-Whitney U test. Spearman correlation analysis was used to evaluate the correlation between CSA and FF values of the right calf and running-related indicators including age, BMI, running age, speed exercise, and monthly exercise in 37 amateur marathon runners. Results:The CSA of the right calf soleus muscle in the marathon matched matched group was larger than that in the control group ( t=-2.09, P=0.048). There was no significant difference in CSA of other calf muscles between the two groups ( P>0.05). The FF values of the right calf anterior group, the outer group, the soleus muscle, the medial head and the lateral head of the gastrocnemius muscle in the marathon matched group were lower than those in the control group ( P<0.05). The BMI of 37 amateur marathon runners was positively correlated with the CSA and FF values of the anterior group, the outer group, the soleus, the medial head and the lateral head of the gastrocnemius muscle (CSA r=0.628, 0.468, 0.680, 0.566, 0.615, respectively, all P<0.05; FF value r=0.395, 0.567, 0.631, 0.482, 0.516, respectively, all P<0.05). The FF values of the anterior group, the outer group, the soleus, the medial head and the lateral head of the gastrocnemius muscle were negatively correlated with monthly exercise ( r=-0.337, -0.405, -0.437, -0.338, -0.446, respectively, all P<0.05). Conclusions:Long-term running training can reduce the FF value of each calf muscle group, and the FF value of calf muscles is negatively correlated with the amount of running each month. Long-term running training has the greatest effect on the CSA of soleus muscle.