Effects of Sternocleidomastoid Muscle Fatigue on Cervical Spine Kinematics and Postural Responses to Trunk Perturbation

This thesis investigated the effects of sternocleidomastoid (SCM) fatigue on cervical spine kinematics and postural responses to trunk perturbation in upright standing. We hypothesized that SCM fatigue would result in greater motion of the head, and that postural control would be impaired as a result. Our findings indicate that SCM fatigue catalyzed a change in postural set that increased trunk joint stiffness. We propose that this change reduced the transfer of momentum from the pendulum to the body to facilitate control of the body's centre of mass. Increased trunk joint stiffness, along with attenuated contractile capacity of the fatigued SCM, resulted in greater magnitudes of head acceleration. Despite the increase in head acceleration, the postural control system effectively controlled motion of the body's centre of mass. The neuromuscular system is highly versatile and can modify a control strategy according to different forms of threat to the maintenance of postural equilibrium.

Year	Entry
1990	Winter DA. Biomechanics and Motor Control of Human Movement. 2nd ed. New York, NY: Inc., John Wiley & Sons; 1990.
2006	Wilson EL, Madigan ML, Davidson BS, Nussbaum MA. Postural strategy changes with fatigue of the lumbar extensor muscles. Gait Post. April 2006;23(3):348-354.
1986	Horak FB, Nashner LM. Central programming of postural movements: adaptation to altered support-surface configurations. J Neurophysiol. June 1986;55(6):1369-1381.
2003	Blouin J-S, Descarreaux M, Bélanger-Gravel A, Simoneau M, Teasdale N. Attenuation of human neck muscle activity following repeated imposed trunk-forward linear acceleration. Exp Brain Res. June 2003;150(4):458-464.
2006	Madigan ML, Davidson BS, Nussbaum MA. Postural sway and joint kinematics during quiet standing are affected by lumbar extensor fatigue. Hum Mov Sci. December 2006;25(6):788-799.
2002	Kumar S, Narayan Y, Amell T. An electromyographic study of low-velocity rear-end impacts. Spine. May 15, 2002;27(10):1044-1055.
1998	Kamibayashi LK, Richmond FJR. Morphometry of human neck muscles. Spine. June 15, 1998;23(12):1314-1323.
1995	Wu G, Cavanagh PR. ISB recommendations for standardization in the reporting of kinematic data. J Biomech. 1995;28(10):1257-1261.
1998	Vasavada AN, Li S, Delp SL. Influence of muscle morphometry and moment arms on the moment-generating capacity of human neck muscles. Spine. February 15, 1998;23(4):412-422.
2000	Brault JR, Siegmund GP, Wheeler JB. Cervical muscle response during whiplash: evidence of a lengthening muscle contraction. Clin Biomech (Bristol, Avon). July 2000;15(6):426-435.
2003	Siegmund GP, Sanderson DJ, Myers BS, Inglis JT. Rapid neck muscle adaptation alters the head kinematics of aware and unaware subjects undergoing multiple whiplash-like perturbations. J Biomech. April 2003;36(4):473-482.

Year

Entry

1990

Winter DA. Biomechanics and Motor Control of Human Movement. 2nd ed. New York, NY: Inc., John Wiley & Sons; 1990.

2006

Wilson EL, Madigan ML, Davidson BS, Nussbaum MA. Postural strategy changes with fatigue of the lumbar extensor muscles. Gait Post. April 2006;23(3):348-354.

1986

Horak FB, Nashner LM. Central programming of postural movements: adaptation to altered support-surface configurations. J Neurophysiol. June 1986;55(6):1369-1381.

2003

Blouin J-S, Descarreaux M, Bélanger-Gravel A, Simoneau M, Teasdale N. Attenuation of human neck muscle activity following repeated imposed trunk-forward linear acceleration. Exp Brain Res. June 2003;150(4):458-464.

2006

Madigan ML, Davidson BS, Nussbaum MA. Postural sway and joint kinematics during quiet standing are affected by lumbar extensor fatigue. Hum Mov Sci. December 2006;25(6):788-799.