title: Differences in motor recruitment and resulting kinematics between low back pain patients and asymptomatic participants during lifting exertions.
abstract: BACKGROUND
  Low back disorders are a prevalent problem in society today and may lead to chronic debilitating low back pain. Developing our understanding of temporal muscle and kinematic patterns during manual material handling tasks may provide insight for preventing the cascading series of events leading to chronic low back pain.
  
  
  METHODS
  Sixty-two low back pain patients and 61 asymptomatic participants performed a variety of lifting exertions that varied in lift origin horizontal and vertical distance, lift asymmetry, and weight. Electromyographic activity of 10 trunk muscles as well as trunk and pelvic kinematics was recorded during each exertion. Differences in muscle activation and kinematic parameters were compared between low back pain patients and asymptomatic participants as a function of experimental conditions.
  
  
  RESULTS
  Both the left and right erector spinae activated significantly earlier and were on significantly longer in low back pain patients compared to asymptomatic participants. The horizontal and vertical location of the lift influenced the EMG and kinematic differences between the low back pain patients and asymptomatic participants.
  
  
  CONCLUSIONS
  These finding indicate that low back pain patients would be exposed to increase muscle activity resulting in higher spine loads for a greater length of time compared to asymptomatic participants. The longer exposure time to increased spine load may lead to greater risk of future low back injury and cascading events leading to debilitating low back pain. The longer muscle activation time suggests that low back pain patients have changed their motor program from an open to a closed loop system.
authors.affiliation: Biodynamics Laboratory, The Ohio State University, 210 Baker Systems Engineering, 1971 Neil Avenue, Columbus OH, 43210, USA. ferguson.4@osu.edu
authors.forename: Sue A
authors.initials: SA
authors.lastname: Ferguson
authors.forename: William S
authors.initials: WS
authors.lastname: Marras
authors.forename: Deborah L
authors.initials: DL
authors.lastname: Burr
authors.forename: Kermit G
authors.initials: KG
authors.lastname: Davis
authors.forename: Purnendu
authors.initials: P
authors.lastname: Gupta
mesh_terms: D000328:Adult; D001415:Back / Q000503:physiopathology; D001696:Biomechanical Phenomena / Q000379:methods; D004576:Electromyography / Q000379:methods*; D005260:Female; D006801:Humans; D017116:Low Back Pain / Q000175:diagnosis / Q000503:physiopathology*; D008297:Male; D009068:Movement; D009119:Muscle Contraction; D018482:Muscle, Skeletal / Q000503:physiopathology*; D005082:Physical Exertion; D012016:Reference Values; D013647:Task Performance and Analysis; D016474:Weight-Bearing