Possible factors related to increased strain of the iliotibial band in recreational female runners

Increased strain of the iliotibial band (ITB) is a key factor of ITBS aggravation. There are several internal risk factors contributing to increased ITB strain; gender (female), knee malalignment (genu varum > genu valgus), deteriorated muscle strength and/or muscle activation. However, running biomechanics as an inciting movement of ITBS should be included in the clarification of the ITBS mechanism. The purpose of this study was to clarify the change of the ITB strain during running and to identify differences in muscle activity between runners with or without genu varum. A total of 17 healthy recreational women runners [genu varum group (GV) = 8; normal group (N) = 9] volunteered in this study. Participants performed 30 minutes of running, and muscle activity of gluteus maximus (GMAX), gluteus medius (GMED), and tensor fascia latae (TFL) were recorded every 10 minutes of the running. Before and after running, the strain of the ITB and hip muscle strength were measured. The results showed a significantly increased ITB strain in standing after 30-min running for the participants with genu varum alignment. Also, there was a significant difference between the groups. And the muscle activities of the TFL and GMAX in the GV group were greater than those in the N group. These findings indicate that genu varum alignment may induce more tensile stress on the ITB as a result of greater activation of the TFL during running, thus increasing the strain of the ITB.