Longitudinal Relationship Between Intramuscular Fat in the Quadriceps and Gait Independence in Convalescent Stroke Patients

•The link between intramuscular fat and gait independence is unclear post-stroke.•Changes in gait independence are related to changes in intramuscular fat.•Improved gait independence may be requisite for decreasing intramuscular fat. In a cross-sectional study, intramuscular fat in the quadriceps of stroke patients has been associated with gait independence. However, the longitudinal relationship between intramuscular fat and gait independence remain unclear. If these relationships are clarified, it can be demonstrated that improvement in gait independence eventually contributes to improved intramuscular fat in the quadriceps of stroke patients. The aim of this study was to investigate the longitudinal relationship between intramuscular fat in the quadriceps and gait independence in convalescent stroke patients. Eleven stroke patients participated in this study. Gait independence was assessed using the Functional Independence Measure (FIM) gait score. The intramuscular fat in the quadriceps was assessed using ultrasound echo intensity, whereas higher echo intensity indicated greater intramuscular fat. The baseline and discharge assessment values for the echo intensity of the quadriceps were compared using a paired t-test. Correlation analysis of the FIM gait score gain and echo intensity changes in the quadriceps on the paretic and non-paretic sides was performed using Kendall's rank correlation coefficient. For quadriceps on the paretic side, echo intensity values at discharge were significantly lower than those at admission. However there was no significant difference for quadriceps on the non-paretic side (paretic side: 19.9% decrease; non-paretic side: 8.0% decrease). We observed that the change in the echo intensity of quadriceps on the non-paretic side was negatively corelated with FIM gait score gain. Our results revealed a strong correlation between longitudinal change in intramuscular fat in the quadriceps and gait independence, implying that improved gait independence in convalescent stroke patients might have a positive effect on improvements in intramuscular fat.