Gait signatures of endurance runners with low back pain: A case controlled cross sectional study.

BACKGROUND: Low back pain (LBP) is an understudied condition among runners, and it is unclear what biomechanical features could be targeted for gait retraining to mitigate pain. RESEARCH QUESTION: How do running biomechanics differ between healthy individuals and those with running-related LBP? METHODS: This was a case-controlled, comparative study design of community runners: running-related LBP (n=52) and healthy controls (n=52). All runners completed running history forms and performed a 3-dimensional gait analysis. Kinematic data were collected using a motion capture system and normalized to a gait cycle, while participants ran on a level grade at self-selected speed on an instrumented treadmill. Current running volume, temporal-spatial, kinetic and kinematic features were compared between groups. RESULTS: The LBP group had 39.5 % lower weekly distance and 15.4 % fewer were currently training for a race (all p<.05). Runners with LBP demonstrated lower cadence (166±10 step/min vs. 171±9 step/min; p=.05), greater center of gravity lateral displacement (1.4±0.5 cm vs. 1.2 ±.3 cm; p=.044) and greater stride width variability (1.3±0.4 cm versus 1.0 ± 0.04 cm; p=.008). Runners with LBP had a greater Vertical Average Loading Rate ([VALR] 67.7±22.2 bodyweights [BW]/s vs. 62.2±21.5 BW/s; p=.022), and higher joint moments (N*m/(kg*m)) at the knee in the sagittal plane (2.13±0.50 vs. 1.87±0.56; p <.001), frontal plane (1.44±0.39 vs. 1.29±0.29; p=.013), and at the hip in the frontal plane (2.04±0.51 vs. 1.84±0.41; p=.024). No differences were found between groups in the pelvis, hip, knee, and ankle joint excursions in any plane of motion during a typical gait cycle. SIGNIFICANCE: These collective motion signature may reflect challenges with control of motion and VALR in the presence of back pain. Cadence training to increase step rate, coupled with core/hip muscle activation, may be an important strategy to reduce motion variability, impact loading rate and pain symptoms while running.

Considerations beyond spine pain: do different co-occurring lower body joint pains differentially influence physical function and quality of life ratings?

BACKGROUND: Patients seeking medical care for back pain often have coexisting painful joints and the effects of different combinations and number of coexisting pain sites (hip, knee, foot/ankle) to back pain on physical function domains and quality of life rating are not yet established. The purpose of this study was to determine the differences in functional outcomes and QOL among individuals with back pain who have concurrent additional pain sites or no pain sites. METHODS: Data from the Osteoarthritis Initiative (OAI) cohort were used for this cross-sectional analysis. Men and women aged 45-79 years with back pain were binned into nine groups by presence or not of coexisting hip, knee, ankle/foot pain and combinations of these sites (N = 1,642). Healthy controls reported no joint pain. Main outcomes included Knee Injury and Osteoarthritis Outcome score (KOOS; quality of life and function-sports-and-recreation), Western Ontario McMaster Universities Osteoarthritis Index (WOMAC; Activities of Daily Living, Pain), Medical Outcomes Short Form-12 (SF-12) Physical Component score, and self-reported function in last 7-30 days (lifting 25-pound objects, housework). 20-m and 400-m walk times and gait speed and repeated chair rise test times were collected. RESULTS: Compared to back pain alone, pain at all five sites was associated with 39%-86% worse KOOS, WOMAC, and SF-12 scores (p < .0001). Back-Hip and Back-Knee did not produce worse scores than Back pain alone, but Back-Hip-Knee and Back-Knee-Ankle/Foot did. The 20-m, 400-m walk, and repeated chair times were worse among individuals with pain at all five sites. Additional hip and knee sites to back pain, but not ankle/foot, worsened performance-based walk times and chair rise scores. CONCLUSIONS: The number and type of coexistent lower body musculoskeletal pain among patients with back pain may be associated with perceived and performance-based assessments. Management plans that efficiently simultaneously address back and additional coexistent pain sites may maximize treatment functional benefits, address patient functional goals in life and mitigate disability.