To facilitate stable trunk kinematics, humans must generate appropriate motor patterns to effectively control muscle force and stiffness and respond to biomechanical perturbations and/or neuromuscular control errors. Thus, it is important to understand physiological variables such as muscle force and stiffness, and how these relate to the downstream production of stable spine and trunk movements. This study was designed to assess the local dynamic stability of spine muscle activation and rotational stiffness patterns using Lyapunov analyses, and relationships to the local dynamic stability of resulting spine kinematics, during repetitive lifting and lowering at varying combinations of lifting load and rate. With an increase in the load lifted at a constant rate there was a trend for decreased local dynamic stability of spine muscle activations and the muscular contributions to spine rotational stiffness; although the only significant change was for the full state space muscle activation stability (p < 0.05). With an increase in lifting rate with a constant load there was a significant decrease in the local dynamic stability of spine muscle activations and the muscular contributions to spine rotational stiffness (p ≤ 0.001 for all measures). These novel findings suggest that the stability of motor inputs and the muscular contributions to spine rotational stiffness can be altered by external task demands (load and lifting rate), and therefore are important variables to consider when assessing the stability of the resulting kinematics.

References

1.
Panjabi
,
M. M.
,
1992
, “
The Stabilizing System of the Spine. Part I. Function, Dysfunction, Adaptation, and Enhancement
,”
J. Spinal Disord.
,
5
(
4
), pp.
383
389
.10.1097/00002517-199212000-00001
2.
Reeves
,
N. P.
,
Narendra
,
K. S.
, and
Cholewicki
,
J.
,
2007
, “
Spine Stability: The Six Blind Men and the Elephant
,”
Clin. Biomech.
,
22
(
3
), pp.
266
274
.10.1016/j.clinbiomech.2006.11.011
3.
Kang
,
H. G.
, and
Dingwell
,
J. B.
,
2009
, “
Dynamics and Stability of Muscle Activations During Walking in Healthy Young and Older Adults
,”
J. Biomech.
,
42
(
14
), pp.
2231
2237
.10.1016/j.jbiomech.2009.06.038
4.
McGill
,
S. M.
,
Grenier
,
S.
,
Kavcic
,
N.
, and
Cholewicki
,
J.
,
2003
, “
Coordination of Muscle Activity to Assure Stability of the Lumbar Spine
,”
J. Electromyogr. Kinesiol.
,
13
(
4
), pp.
353
359
.10.1016/S1050-6411(03)00043-9
5.
Cholewicki
,
J.
, and
McGill
,
S. M.
,
1996
, “
Mechanical Stability of the In Vivo Lumbar Spine: Implications for Injury and Chronic Low Back Pain
,”
Clin. Biomech.
,
11
(
1
), pp.
1
15
.10.1016/0268-0033(95)00035-6
6.
Granata
,
K. P.
, and
Gottipati
,
P.
,
2008
, “
Fatigue Influences the Dynamic Stability of the Torso
,”
Ergonomics
,
51
(
8
), pp.
1258
1271
.10.1080/00140130802030722
7.
Potvin
,
J. R.
, and
Brown
,
S. H. M.
,
2005
, “
An Equation to Calculate Individual Muscle Contributions to Joint Stability
,”
J. Biomech.
,
38
(
5
), pp.
973
980
.10.1016/j.jbiomech.2004.06.004
8.
Brown
,
S. H. M.
, and
McGill
,
S. M.
,
2005
, “
Muscle Force-Stiffness Characteristics Influence Joint Stability: A Spine Example
,”
Clin. Biomech.
,
20
(
9
), pp.
917
922
.10.1016/j.clinbiomech.2005.06.002
9.
Granata
,
K. P.
, and
England
,
S. A.
,
2006
, “
Stability of Dynamic Trunk Movement
,”
Spine
,
31
(
10
), pp.
E271
E276
.10.1097/01.brs.0000216445.28943.d1
10.
Graham
,
R. B.
,
Sadler
,
E. M.
, and
Stevenson
,
J. M.
,
2012
, “
Local Dynamic Stability of Trunk Movements During the Repetitive Lifting of Loads
,”
Hum. Mov. Sci.
,
31
(
3
), pp.
592
603
.10.1016/j.humov.2011.06.009
11.
Graham
,
R. B.
, and
Brown
,
S. H. M.
,
2012
, “
A Direct Comparison of Spine Rotational Stiffness and Dynamic Spine Stability During Repetitive Lifting Tasks
,”
J. Biomech.
,
45
(
9
), pp.
1593
1600
.10.1016/j.jbiomech.2012.04.007
12.
Bergmark
,
A.
,
1989
, “
Stability of the Lumbar Spine. A Study in Mechanical Engineering
,”
Acta Orthop. Scand. Suppl.
,
230
(
230
), pp.
1
54
.10.3109/17453678909154177
13.
Rodrick
,
D.
, and
Quesada
,
P. M.
,
2013
, “
Non-Linear Dynamics of Lower Leg Muscle Surface Electromyogram During Repeated Plantar Flexion
,”
Theor. Issues Ergonomics Sci.
,
14
(
2
), pp.
37
41
.10.1080/1464536X.2011.584582
14.
Graham
,
R. B.
,
Oikawa
,
L. Y.
, and
Ross
,
G. B.
,
2014
, “
Comparing the Local Dynamic Stability of Trunk Movements Between Varsity Athletes With and Without Non-Specific Low Back Pain
,”
J. Biomech.
,
47
(
6
), pp.
1459
1464
.10.1016/j.jbiomech.2014.01.033
15.
McGill
,
S. M.
,
1991
, “
Electromyographic Activity of the Abdominal and Low Back Musculature During the Generation of Isometric and Dynamic Axial Trunk Torque: Implications for Lumbar Mechanics
,”
J. Orthop. Res.
,
9
(
1
), pp.
91
103
.10.1002/jor.1100090112
16.
McGill
,
S. M.
,
1992
, “
A Myoelectrically Based Dynamic Three-Dimensional Model to Predict Loads on Lumbar Spine Tissues During Lateral Bending
,”
J. Biomech.
,
25
(
4
), pp.
395
414
.10.1016/0021-9290(92)90259-4
17.
Kingma
,
I.
,
Staudenmann
,
D.
, and
van Dieën
,
J. H.
,
2007
, “
Trunk Muscle Activation and Associated Lumbar Spine Joint Shear Forces Under Different Levels of External Forward Force Applied to the Trunk
,”
J. Electromyogr. Kinesiol.
,
17
(
1
), pp.
14
24
.10.1016/j.jelekin.2005.12.001
18.
Brown
,
S. H. M.
, and
McGill
,
S. M.
,
2010
, “
The Relationship Between Trunk Muscle Activation and Trunk Stiffness: Examining a Non-Constant Stiffness Gain
,”
Comput. Methods Biomech. Biomed. Eng.
,
13
(
6
), pp.
829
835
.10.1080/10255841003630652
19.
McGill
,
S. M.
, and
Norman
,
R. W.
,
1986
, “
Partitioning the L4–L5 Dynamic Moment Into Disc, Ligamentous, and Muscular Components
,”
Spine
,
11
(
7
), pp.
666
678
.10.1097/00007632-198609000-00004
20.
Cholewicki
,
J.
, and
McGill
,
S. M.
,
1995
, “
Relationship Between Muscle Force and Stiffness in the Whole Mamallian Muscle: A Simulation Study
,”
ASME J. Biomech. Eng.
,
117
(
3
), pp.
339
342
.10.1115/1.2794189
21.
Crisco
,
J. J.
, and
Panjabi
,
M. M.
,
1991
. “
The Intersegmental and Multisegmental Muscles of the Lumbar Spine: A Biomechanical Model Comparing Lateral Stabilizing Potential
,”
Spine
,
16
(
7
), pp.
793
799
.10.1097/00007632-199107000-00018
22.
Bruijn
,
S. M.
,
van Dieën
,
J. H.
,
Meijer
,
O. G.
, and
Beek
,
P. J.
,
2009
, “
Statistical Precision and Sensitivity of Measures of Dynamic Gait Stability
,”
J. Neurosci. Methods
,
178
(
2
), pp.
327
333
.10.1016/j.jneumeth.2008.12.015
23.
Abarbanel
,
H. D. I.
,
Brown
,
R.
,
Sidorowich
,
J. J.
, and
Tsimring
,
L. S.
,
1993
, “
The Analysis of Observed Chaotic Data in Physical Systems
,”
Rev. Mod. Phys.
,
65
(
4
), pp.
1331
1392
.10.1103/RevModPhys.65.1331
24.
Kennel
,
M. B.
,
Brown
,
R.
, and
Abarbanel
,
H. D. I.
,
1992
, “
Determining Embedding Dimension for Phase-Space Reconstruction Using a Geometrical Construction
,”
Phys. Rev. A
,
45
(
6
), pp.
3403
3411
.10.1103/PhysRevA.45.3403
25.
Rosenstein
,
M. T.
,
Collins
,
J. J.
, and
De Luca
,
C. J.
,
1993
, “
A Practical Method for Calculating Largest Lyapunov Exponents From Small Data Sets
,”
Phys. D
,
65
(
1–2
), pp.
117
134
.10.1016/0167-2789(93)90009-P
26.
Bruijn
,
S. M.
,
van Dieën
,
J. H.
,
Meijer
,
O. G.
, and
Beek
,
P. J.
,
2009
, “
Is Slow Walking More Stable?
,”
J. Biomech.
,
42
(
10
), pp.
1506
1512
.10.1016/j.jbiomech.2009.03.047
27.
Marras
,
W. S.
,
Lavender
,
S. A.
,
Ferguson
,
S. A.
,
Splittstoesser
,
R. E.
, and
Yang
,
G.
,
2010
, “
Quantitative Dynamic Measures of Physical Exposure Predict Low Back Functional Impairment
,”
Spine
,
35
(
8
), pp.
914
923
.10.1097/BRS.0b013e3181ce1201
28.
Gardner-Morse
,
M. G.
, and
Stokes
,
I. A.
,
2001
, “
Trunk Stiffness Increases With Steady-State Effort
,”
J. Biomech.
,
34
(
4
), pp.
457
463
.10.1016/S0021-9290(00)00226-8
29.
Granata
,
K. P.
, and
Marras
,
W. S.
,
1995
, “
The Influence of Trunk Muscle Coactivity on Dynamic Spinal Loads
,”
Spine
,
20
(
8
), pp.
913
919
.10.1097/00007632-199504150-00006
30.
van Dieën
,
J. H.
,
Kingma
,
I.
, and
van der Bug
,
J. C. E.
,
2003
, “
Evidence for a Role of Antagonistic Cocontraction in Controlling Trunk Stiffness During Lifting
,”
J. Biomech.
,
36
(
12
), pp.
1829
1836
.10.1016/S0021-9290(03)00227-6
31.
Newell
,
K. M.
, and
Carlton
,
L. G.
,
1988
, “
Force Variability in Isometric Responses
,”
J. Exp. Pscyhol. Hum. Percept. Perform
,
14
(
1
), pp.
37
44
.10.1037/0096-1523.14.1.37
32.
Slifkin
,
A. B.
, and
Newell
,
K. M.
,
2000
, “
Variability and Noise in Continuous Force Production.
,”
J. Mot. Behav.
,
32
(
2
), pp.
141
150
.10.1080/00222890009601366
33.
Hamilton
,
A. F. D. C.
,
Jones
,
K. E.
, and
Wolpert
,
D. M.
,
2004
, “
The Scaling of Motor Noise With Muscle Strength and Motor Unit Number in Humans
,”
Exp. Brain Res.
,
157
(
4
), pp.
417
430
.10.1007/s00221-004-1856-7
34.
Reeves
,
N. P.
, and
Cholewicki
,
J.
,
2010
, “
Expanding Our View of the Spine System
,”
Eur. Spine J.
,
19
(
2
), pp.
331
332
.10.1007/s00586-009-1220-5
35.
Brown
,
S. H. M.
, and
Potvin
,
J. R.
,
2007
, “
Exploring the Geometric and Mechanical Characteristics of the Spine Musculature to Provide Rotational Stiffness to Two Spine Joints in the Neutral Posture
,”
Hum. Mov. Sci.
,
26
(
1
), pp.
113
123
.10.1016/j.humov.2006.09.006
36.
Houk
,
J. C.
,
1979
, “
Regulation of Stiffness by Skeletomotor Reflexes
,” Annu Rev Physiol,
41
, pp.
99
114
.
37.
Axelson
,
H. W.
, and
Hagbarth
,
K. E.
,
2001
, “
Human Motor Control Consequences of Thixotropic Changes in Muscular Short-Range Stiffness
,”
J. Physiol.
,
535
(
1
), pp.
279
288
.10.1111/j.1469-7793.2001.00279.x
38.
Campbell
,
K. S.
,
2010
, “
Short-Range Mechanical Properties of Skeletal and Cardiac Muscles
,”
Adv. Exp. Med. Biol.
,
682
, pp.
223
246
.10.1007/978-1-4419-6366-6
39.
Stein
,
R.
,
1982
, “
What Muscle Variable(s) Does the Nervous System Control in Limb Movements?
,”
Behav. Brain Sci.
,
5
(
4
), pp.
535
541
.10.1017/S0140525X00013327
40.
Karayannis
,
N. V.
,
Smeets
,
R. J. E. M.
,
van den Hoorn
,
W.
, and
Hodges
,
P. W.
,
2013
, “
Fear of Movement is Related to Trunk Stiffness in Low Back Pain
,”
PLoS One
,
8
(
6
), p.
e67779
.10.1371/journal.pone.0067779
41.
Cacciatore
,
T.
,
Gurfinkel
,
V.
,
Horak
,
F.
,
Cordo
,
P.
, and
Ames
,
K.
,
2011
, “
Increased Dynamic Regulation of Postural Tone Through Alexander Technique Training
,”
Hum. Mov. Sci.
,
30
(
1
), pp.
74
89
.10.1016/j.humov.2010.10.002
You do not currently have access to this content.