Relationship between double leg lowering test and core strength test of the lumbar spine in normal healthy individuals

Introduction: Core stability relies on the effectiveness of abdominal muscle function in their stabilizing role. A wide variety of tests are available to quantify the strength of trunk muscles. Aim: The objective of this study was to determine the relationship between double-leg-lowering (DLL) test and core strength test in normal healthy individuals. Materials and Methods: This study was conducted on 843 volunteers between the ages of 18 and 60 years. Assessment of core strength was done using a pressure biofeedback unit. The actual task, i.e., abdominal draw-in the test was performed with the subject lying in a prone position. Then, pressure reduction which was held up to at least 10 s was noted. The DLL test was performed with the subject lying in supine position with hands folded across the body on a plinth. The therapist passively raised both the lower limbs simultaneously to 90° hip flexion with the knees kept straight. Subjects then performed a posterior pelvic tilt and maintained this position while slowly lowering the legs to horizontal. The angle at which the back arched was noted. Grading was done in a similar manner for three times with a rest-period of 1 min in between the repeats. The best of the three repetitions was used for the analysis. Results: Spearman's correlation coefficient (ρ) between core strength test and DLL test was found to be 0.24. The median for DLL test was 4 and pressure reduction on the pressure biofeedback unit was 9 mmHg. Conclusions: We found that there is weak positive correlation between the core strength test and DLL test.