Effects of Hip Position on Conventional Isokinetic Knee Flexion/Extension Ratios: A Critically Appraised Topic

Clinical Scenario: The traditional knee flexion/extension isokinetic testing position has the hip flexed to ∼90°, which deviates from hip positions during many functional activities and affects the length-tension balance of the hamstrings disproportionately compared with the quadriceps. Clinical Question: What is the effect of a more extended hip position compared with the traditional flexed hip position on isokinetic conventional hamstrings to quadriceps (H:Q) peak torque ratios across the velocity spectrum in healthy adults? Summary of Key Findings: Three studies were identified as meeting the criteria for inclusion. Compared with the traditional hip flexion position, two studies reported no significant H:Q changes in 30° and 45° of hip flexion, whereas two investigations reported significantly lower H:Q in <10° hip flexion test positions. Clinical Bottom Line: Consistent moderate evidence exists that H:Q are lower in test positions with <10° hip flexion compared with the traditional 90° hip flexion. In addition to deviating from many functional activity kinematics, the traditional 90° hip flexion position may overestimate the strength of the hamstrings relative to the quadriceps. There is low, less consistent evidence related to hip testing position effects across the isokinetic velocity spectrum. Strength of Recommendation: Level 2 evidence is available.