Effects of experimentally induced pain and fear of pain on trunk coordination and back muscle activity during walking.
OBJECTIVE
To examine the effects of experimentally induced pain and fear of pain on trunk coordination and erector spinae EMG activity during gait.


METHODS
In 12 healthy subjects, hypertonic saline (acute pain) and isotonic saline (fear of pain) were injected into erector spinae muscle, and unpredictable electric shocks (fear of impending pain) were presented during treadmill walking at different velocities, while trunk kinematics and EMG were recorded.


BACKGROUND
Chronic low back pain patients often have disturbed trunk coordination and enhanced erector spinae EMG while walking, which may either be due to the pain itself or to fear of pain, as is suggested by studies on both low back pain patients and healthy subjects.


METHODS
The effects of the aforementioned pain-related manipulations on trunk coordination and EMG were examined. Results. Trunk kinematics was not affected by the manipulations. Induced pain led to an increase in EMG variability and induced fear of pain to a decrease in mean EMG amplitude during double stance.


CONCLUSIONS
Induced pain and fear of pain have subtle effects on erector spinae EMG activity during walking while leaving the global pattern of EMG activity and trunk kinematics unaffected. This suggests that the altered gait observed in low back pain patients is probably a complex evolved consequence of a lasting pain, rather than a simple immediate effect.


CONCLUSIONS
Variability of EMG data and kinematics may explain pain-dependent alterations of motor control, which in turn might contribute to a further understanding of the development of movement impairments in low back pain.
Lamoth
Claudine J C
CJ
Faculty of Human Movement Sciences, Vrije Universiteit, Van der Boechorststraat 9, 1081 BT Amsterdam, The Netherlands. c_lamoth@fbw.vu.nl
Daffertshofer
Andreas
A
Meijer
Onno G
OG
Lorimer Moseley
G
G
Wuisman
Paul I J M
PI
Beek
Peter J
PJ
D000222:Adaptation, Physiological; D000293:Adolescent; D000328:Adult; D001415:Back / Q000503:physiopathology*; D004576:Electromyography / Q000379:methods; D005239:Fear; D005684:Gait; D006801:Humans; D008297:Male; D009068:Movement; D009119:Muscle Contraction; D018482:Muscle, Skeletal / Q000503:physiopathology*; D010146:Pain / Q000139:chemically induced / Q000503:physiopathology*; D004856:Postural Balance; D012965:Sodium Chloride; D013909:Thorax / Q000503:physiopathology*; D016138:Walking
D012965:Sodium Chloride