SITTING VS STANDING ISOKINETIC TRUNK EXTENSION/FLEXION JOINT ANGLE AT PEAK TORQUE

Abstract

239 Isokinetic saggital-plane trunk muscle performance has been traditionally measured in either the sitting or standing position. However, dissimilar hip angles in these positions produce disparate length tension relationships resulting in physiological ROM that has been shown to produce significantly different levels of peak torque, power and work in flexion. Therefore, if incongruous torque production characteristics exist, it should be expected that the angle at which torque is greatest should also differ between positions. The purpose of this investigation was to determine if differences in joint angle at peak torque (JAPT) exist between sitting and standing isokinetic trunk extension and flexion exercise. Sixteen subjects (8 males & 8 females, age 30.8 (6.4) yrs, ht 170.2 (11.1) cm, wt 68.1 (13.8) kg) performed three maximal repetitions of isokinetic trunk extension and flexion at 60 and 120 d/s in the sitting and standing positions. A repeated measures ANOVA was used to analyze the data. The results, mean (SEM), demonstrated a significant (p<0.05) difference in JAPT between sitting 14.12 deg (16.06) and standing 25.75 deg (15.87) for extension at 120 d/s only. Although different physiological ROM between sitting and standing alters joint angle, no changes in JAPT were evident in flexion. These results appear to document a machine bias towards JAPT stability irrespective of physiological ROM. Therefore, JAPT may not be a reliable variable to consider during strength test interpretation.