Isokinetic Strength of the Trunk and Hip in Female Runners By: Laurie L. Tis, MEd, ATC

A plethora of research has examined bilateral and reciprocal concentric strength relationships of the thigh musculature in a variety of athletic populations. However, little research has reported strength values of the trunk and hip musculature. Thus, the purpose of this investigation was to examine concentric and eccentric strength of the trunk and hip flexor and extensor muscle groups in female runners. Twenty-one habitual female runners were assessed for trunk and hip strength via isokinetic dynamometry (KinCom, Chattecx Corp.). Strength was reported in newtons (N) and calculated as the average force over the range of motion in which the joint was tested. Eccentric strength at the trunk was greater than concentric strength. Similar results were found at the hip. Reciprocal muscle group ratios revealed that concentric trunk flexion was 52% of extension. Eccentric trunk flexion was 39% of extension. Concentric hip flexion was 98% of extension. Eccentric hip flexion was 103% of extension. The ratios were not significantly different. These findings establish previously unreported isokinetic strength values for the trunk and hip in female runners. Article: A plethora of research has examined bilateral and reciprocal concentric strength relationships of the thigh musculature in a variety of athletic populations. However, minimal research has reported isokinetic strength of the trunk and hip in any athletic population. Several studies have examined concentric trunk extensor and flexor strength via isokinetic dynamometry in sedentary males and females.[2-4,7,12] However, no data have been reported on hip strength or eccentric trunk strength. Langrana et al.[4] established male and female concentric strength values, and compared isometric versus isokinetic strength values of the trunk musculature. Hasue et al.[2] examined trunk flexor and extensor strength in sedentary males and females and in patients with low back pain. Langrana and Lee[3] examined trunk musculature testing protocols and concluded that a sitting position was the most effective method of isolating the trunk flexors and extensors and stabilizing the hip flexors and extensors. * Doctoral student in Sports Medicine, University of Virginia, Charlottesville, VA 22903. † Assistant Professor and Director, Sports Medicine Research Laboratory and Graduate Athletic Training Education, University of Virginia, Charlottesville, VA 22903. ‡ Postdoctoral student in Exercise Physiology, Washington University, St. Louis, MO 63110. § Associate Professor and Director, Exercise Physiology Research Laboratory, University of Virginia, Charlottesville, VA 22903. The purpose of this study was to examine the maximal concentric and eccentric force produced by the trunk and hip musculature in runners. In addition, reciprocal muscle group relationships were established from strength values obtained during both concentric and eccentric contractions.