Spinal Stiffness: Reliability And Validity Of A Novel Tool To Evaluate Weight Lifters With Low Back Pain

Assessment of core strength is often used as a way for clinicians to determine injury risk and predict athletic performance in weightlifting athletes. Current literature shows weak, non-linear relationships depending on the type of core assessment. Most core assessments measure resistance of spinal sheer force in the perpendicular plane (planks, Sorensen, side planks etc.) but those tests fail to capture axial compression forces. Spinal stiffness is necessary for energy transfer from the lower extremities to the bar in squats, deadlifts, and Olympic lifting, however there are currently no core assessments that adequately measure an athlete’s ability to actively stiffen/brace their spine. PURPOSE: To perform reliability and validity testing on a novel assessment tool for measuring active spinal stiffness, hereby referred to as abdominal hoop stress (AHS). METHODS: A load cell was fitted to a traditional weightlifting belt via a modified strap which allowed the lifter to wear the belt as they normally would while lifting. The load cell output force measurements to give live read-outs of AHS while the athlete actively braced. Subjects were fitted with the belt, it was zeroed, and they were asked to perform a series of increasingly weighted squats/deadlifts. The peak force was measured for each lift as the primary outcome variable and validity was established using Pearson correlation with max deadlift/squat. Intra-rater reliability was established using ICC for the first 10 subjects. RESULTS: Results from the Pearson correlation showed a statistically significant (p = 0.013), strong positive relationship between peak AHS and max squat/deadlift with an r value of 0.624. Intra-rater reliability for AHS was good, with an ICC value of 0.922. CONCLUSION: Measuring AHS with a load cell affixed to a traditional weightlifting belt is a reliable and valid measurement in the weightlifting population. More research is needed to determine correlation with low back pain and/or other injury risk factors.