Influence of Fatigue in Neuromuscular Control of Spinal Stability

Lifting-induced fatigue may influence neuromuscular control of spinal stability. Stability is primarily controlled by muscle recruitment, active muscle stiffness, and reflex response. Fatigue has been observed to affect each of these neuromuscular parameters and may therefore affect spinal stability. A biomechanical model of spinal stability was implemented to evaluate the effects of fatigue on spinal stability. The model included a 6-degree-of-freedom representation of the spine controlled by 12 deformable muscles from which muscle recruitment was determined to simultaneously achieve equilibrium and stability. Fatigue-induced reduction in active muscle stiffness necessitated increased antagonistic cocontraction to maintain stability resulting in increased spinal compression with fatigue. Fatigue induced reduction in force-generating capacity limited the feasible set of muscle recruitment patterns, thereby restricting the estimated stability of the spine. Electromyographic and trunk kinematics from 21 healthy participants were recorded during sudden-load trials in fatigued and unfatigued states. Empirical data supported the model predictions, demonstrating increased antagonistic cocontraction during fatigued exertions. Results suggest that biomechanical factors including spinal load and stability should be considered when performing ergonomic assessments of fatiguing lifting tasks. Potential applications of this research include a biomechanical tool for the design of administrative ergonomic controls in manual materials handling industries.

[1]  J. Cholewicki,et al.  Stabilizing Function of Trunk Flexor‐Extensor Muscles Around a Neutral Spine Posture , 1997, Spine.

[2]  A. Bergmark.  Stability of the lumbar spine. A study in mechanical engineering. , 1989, Acta orthopaedica Scandinavica. Supplementum.

[3]  K P Granata,et al.  Female and male trunk geometry: size and prediction of the spine loading trunk muscles derived from MRI. , 2001, Clinical biomechanics.

[4]  P J Sparto,et al.  Neuromuscular trunk performance and spinal loading during a fatiguing isometric trunk extension with varying torque requirements. , 1997, Journal of spinal disorders.

[5]  G A Mirka,et al.  The quantification of EMG normalization error. , 1991, Ergonomics.

[6]  Katsuhiko Ogata,et al.  Modern Control Engineering , 1970 .

[7]  B. Jones,et al.  Intrinsic risk factors for exercise-related injuries among male and female army trainees , 1993, The American journal of sports medicine.

[8]  M Nordin,et al.  Reduced servo‐control of fatigued human finger extensor and flexor muscles. , 1995, The Journal of physiology.

[9]  David G. Wilder,et al.  Muscular Response to Sudden Load: A Tool to Evaluate Fatigue and Rehabilitation , 1996, Spine.

[10]  P. Brinckmann,et al.  Fatigue fracture of human lumbar vertebrae. , 1988, Clinical biomechanics.

[11]  Manohar M. Panjabi,et al.  Lumbar spine stability can be augmented with an abdominal belt and/or increased intra-abdominal pressure , 1999, European Spine Journal.

[12]  I. Stokes,et al.  The Effects of Abdominal Muscle Coactivation on Lumbar Spine Stability , 1998, Spine.

[13]  M I Jayson,et al.  Employment and Physical Work Activities as Predictors of Future Low Back Pain , 1997, Spine.

[14]  J. Laible,et al.  Role of muscles in lumbar spine stability in maximum extension efforts , 1995, Journal of orthopaedic research : official publication of the Orthopaedic Research Society.

[15]  D. Morgan.  Separation of active and passive components of short-range stiffness of muscle. , 1977, The American journal of physiology.

[16]  T Hortobágyi,et al.  Voluntary and reflex responses to fatigue with stretch-shortening exercise. , 1991, Canadian journal of sport sciences = Journal canadien des sciences du sport.

[17]  P V Komi,et al.  Altered reflex sensitivity after repeated and prolonged passive muscle stretching. , 1999, Journal of applied physiology.

[18]  Paavo V. Komi,et al.  Reduced stretch reflex sensitivity and muscle stiffness after long-lasting stretch-shortening cycle exercise in humans , 1998, European Journal of Applied Physiology and Occupational Physiology.

[19]  J Cholewicki,et al.  Biomechanical basis for stability: an explanation to enhance clinical utility. , 2001, The Journal of orthopaedic and sports physical therapy.

[20]  Carlo J. De Luca,et al.  The Use of Surface Electromyography in Biomechanics , 1997 .

[21]  P. Komi,et al.  Interaction between muscle stiffness and stretch reflex sensitivity after long‐term stretch‐shortening cycle exercise , 1998, Muscle & nerve.

[22]  James A. Ashton-Miller,et al.  Spine instability and segmental hypermobility biomechanics: A call for the definition and standard use of terms , 1991 .

[23]  M Hallett,et al.  Central fatigue as revealed by postexercise decrement of motor evoked potentials , 1994, Muscle & nerve.

[24]  A Shirazi-Adl,et al.  Mechanical Response of a Lumbar Motion Segment in Axial Torque Alone and Combined with Compression , 1986, Spine.

[25]  K P Granata,et al.  Changes in Trunk Dynamics and Spine Loading During Repeated Trunk Exertions , 1997, Spine.

[26]  K. Granata,et al.  Trunk posture and spinal stability. , 2001, Clinical biomechanics.

[27]  W. S. Marras,et al.  Changes in trunk and spine biomechanics during repetitive fatiguing exertions , 1996, Proceedings of the 1996 Fifteenth Southern Biomedical Engineering Conference.

[28]  W. Marras,et al.  An EMG-assisted model of trunk loading during free-dynamic lifting. , 1995, Journal of biomechanics.

[29]  M. Panjabi,et al.  Euler stability of the human ligamentous lumbar spine. Part II: Experiment. , 1992, Clinical biomechanics.

[30]  J. Cholewicki,et al.  Mechanical stability of the in vivo lumbar spine: implications for injury and chronic low back pain. , 1996, Clinical biomechanics.

[31]  W. Marras,et al.  The Influence of Trunk Muscle Coactivity on Dynamic Spinal Loads , 1995, Spine.

[32]  P J Sparto,et al.  Estimation of Trunk Muscle Forces and Spinal Loads During Fatiguing Repetitive Trunk Exertions , 1998, Spine.

[33]  S. McGill,et al.  Intervertebral disc herniation: studies on a porcine model exposed to highly repetitive flexion/extension motion with compressive force. , 2001, Clinical biomechanics.

[34]  K P Granata,et al.  MRI-derived moment-arms of the female and male spine loading muscles. , 2001, Clinical biomechanics.

[35]  P. V. Komi,et al.  Stretch shortening cycle fatigue: interactions among joint stiness, reflex, and muscle mechanical performance in the drop jump , 2006, European Journal of Applied Physiology and Occupational Physiology.

[36]  T. Horita,et al.  Stretch shortening cycle fatigue: interactions among joint stiness, reflex, and muscle mechanical performance in the drop jump , 2004, European Journal of Applied Physiology and Occupational Physiology.

[37]  P. Komi.  Stretch-shortening cycle: a powerful model to study normal and fatigued muscle. , 2000, Journal of biomechanics.

[38]  T E Milner,et al.  The effect of eccentric exercise on intrinsic and reflex stiffness in the human hand. , 2000, Clinical biomechanics.

[39]  S. Garland,et al.  Role of small diameter afferents in reflex inhibition during human muscle fatigue. , 1991, The Journal of physiology.

[40]  M. Nordin,et al.  1988 Volvo Award in Biomechanics: The Triaxial Coupling of Torque Generation of Trunk Muscles during Isometric Exertions and the Effect of Fatiguing Isoinertial Movements on the Motor Output and Movement Patterns , 1988, Spine.

[41]  Simo Taimela,et al.  Psychomotor Speed in Chronic Low-Back Pain Patients and Healthy Controls: Construct Validity and Clinical Significance of the Measure , 1998, Perceptual and motor skills.

[42]  Toshio Moritani,et al.  Electromyographic evidence of selective fatigue during the eccentric phase of stretch/shortening cycles in man , 2004, European Journal of Applied Physiology and Occupational Physiology.

[43]  R. Hughes,et al.  Evaluating the effect of co-contraction in optimization models. , 1995, Journal of biomechanics.

[44]  Karl F. Orishimo,et al.  Response of trunk muscle coactivation to changes in spinal stability. , 2001, Journal of biomechanics.

[45]  Stuart M. McGill,et al.  Low Back Stability: From Formal Description to Issues for Performance and Rehabilitation , 2001, Exercise and sport sciences reviews.

[46]  S. Garland,et al.  Reflex inhibition of human soleus muscle during fatigue. , 1990, The Journal of physiology.

[47]  P V Komi,et al.  Electromyographic and mechanical characteristics of human skeletal muscle during fatigue under voluntary and reflex conditions. , 1983, Electroencephalography and clinical neurophysiology.

[48]  Kevin P. Granata.  An EMG-assisted model of biomechanical trunk loading during free- dynamic lifting / , 1993 .

[49]  J. Cholewicki,et al.  Postural control of trunk during unstable sitting. , 2000, Journal of biomechanics.

[50]  S. Taimela,et al.  The effect of lumbar fatigue on the ability to sense a change in lumbar position. A controlled study. , 1999, Spine.

[51]  A Gollhofer,et al.  Fatigue during stretch-shortening cycle exercises: changes in mechanical performance of human skeletal muscle. , 1987, International journal of sports medicine.

[52]  J R Potvin,et al.  Trunk Muscle Co‐contraction Increases During Fatiguing, Isometric, Lateral Bend Exertions: Possible Implications for Spine Stability , 1998, Spine.

[53]  G D Herrin,et al.  Prediction of overexertion injuries using biomechanical and psychophysical models. , 1986, American Industrial Hygiene Association journal.

[54]  Broberg Kb,et al.  On the Mechanical Behaviour of Intervertebral Discs , 1983 .

[55]  M M Panjabi,et al.  Euler stability of the human ligamentous lumbar spine. Part I: Theory. , 1992, Clinical biomechanics.

[56]  R. Gorman,et al.  Decline in spindle support to alpha‐motoneurones during sustained voluntary contractions. , 1991, The Journal of physiology.

[57]  M. H. Pope,et al.  European Spine Society —The Acromed Prize for Spinal Research 1995 Unexpected load and asymmetric posture as etiologic factors in low back pain , 2004, European Spine Journal.

[58]  R F Kirsch,et al.  Neural compensation for fatigue-induced changes in muscle stiffness during perturbations of elbow angle in human. , 1992, Journal of neurophysiology.

[59]  H. Alaranta,et al.  Long psychomotor reaction time in patients with chronic low-back pain: preliminary report. , 1993, Archives of physical medicine and rehabilitation.