Recurring Back Injuries

Despite an abstract which conveys no information [and is not worthy of summary], this publication from Lumbar Motion Monitor central contains important information. Comparing Low Back Pain victims to controls, “the LBP patients experienced higher risk under the same lifting conditions because the patients generated increased spine loading. The increased spine loading in LBP patients compared to asymptomatic controls was due to increased levels of ‘‘guarding’’ or muscle co-activity.”

This provides a physiological explanation, as opposed to psychosocial, for the pattern of recurring back injury among workers.

BrooklynDodger is not sure the investigators have solved the problem of whether the LBP victims showed higher spine loading with similar lifts before their injury, compared to the asymptomatic controls. Other studies show that most injuries arise from “moderate” risk jobs, and that most workers return to the same moderate risk job after return to work.


Applied Ergonomics 36 (2005) 85–95
Workplace design guidelines for asymptomatic vs.
low-back-injured workers
Sue A. Fergusona,_, William S. Marrasa, Deborah Burrb
aBiodynamics Laboratory, Institute for Ergonomics, The Ohio State University, 210 Baker Systems, 1971 Neil Avenue, Columbus, OH 43210, USA
bPublic Health, B110 Star Loving, 320 West 10th Ave, Columbus, OH 43210, USA

One hundred and twenty-three subjects participated in the study. Sixty-two LBP patients and 61 age and gender matched controls. In the patient population there were 32 males and 30 females. The LBP group was diagnosed with muscular LBP and no radiculopathy (diagnosed by their orthopedic surgeon). The median duration of pain symptoms was 5.5 months. Forty-eight percent of the patients had a history of previous LBP. Eighty-eight percent of the patients had returned to work at the time of testing and the median number of lost days from work was 14.

…the LBP patients experienced higher risk under the same lifting conditions because the patients generated increased spine loading (Marras et al., 2001a; Marras et al., 2004a). The increased spine loading in LBP patients compared to asymptomatic controls was due to increased levels of ‘‘guarding’’ or muscle co-activity. The difference influenced the lifting guidelines because in several cases the co-activity in patients created A/P shear levels exceeding 1000N resulting in high-risk classification. Hence, practitioners must be sensitive to the greater loading to which LBP patients are exposed when returning to the workplace. Ergonomists have long argued that it