Yang JF, Norton J, Nevett-Duchcherer J, Roy FD, Gross DP, and Gorassini MA
Physical Therapy [Phys Ther] 2011 Jun; Vol. 91 (6), pp. 931-43. Date of Electronic Publication: 2011 Apr 21.
Adult, Aged, Ankle physiopathology, Electromyography, Female, Hip physiopathology, Humans, Knee physiopathology, Leg physiopathology, Male, Middle Aged, ROC Curve, Young Adult, Exercise Therapy, Muscle Strength, Spinal Cord Injuries physiopathology, Spinal Cord Injuries rehabilitation, and Walking physiology
Background: It is unclear which individuals with incomplete spinal cord injury best respond to body-weight-supported treadmill training. Objective: The purpose of this study was to determine the factors that predict whether a person with motor incomplete spinal cord injury will respond to body-weight-supported treadmill training. Design: This was a prognostic study with a one-group pretest-posttest design. Methods: Demographic, clinical, and electrophysiological measurements taken prior to training were examined to determine which measures best predicted improvements in walking speed in 19 individuals with chronic (>7 months postinjury), motor-incomplete spinal cord injuries (ASIA Impairment Scale categories C and D, levels C1-L1). Results: Two initial measures correlated significantly with improvements in walking speed: (1) the ability to volitionally contract a muscle, as measured by the lower-extremity manual muscle test (LE MMT) (r=.72), and (2) the peak locomotor electromyographic (EMG) amplitude in the legs (r=.56). None of the demographics (time since injury, age, body mass index) were significantly related to improvements in walking speed, nor was the clinical measure of balance (Berg Balance Scale). Further analysis of LE MMT scores showed 4 key muscle groups were significantly related to improvements in walking speed: knee extensors, knee flexors, ankle plantar flexors, and hip abductors (r=.82). Prediction using the summed MMT scores from those muscles and peak EMG amplitude in a multivariable regression indicated that peak locomotor EMG amplitude did not add significantly to the prediction provided by the LE MMT alone. Change in total LE MMT scores from the beginning to the end of training was not correlated with a change in walking speed over the same period. Limitations: The sample size was limited, so the results should be considered exploratory. Conclusions: The results suggest that preserved muscle strength in the legs after incomplete spinal cord injury, as measured by MMT, allows for improvements in walking speed induced by locomotor training.
Intensive treadmill training after incomplete spinal cord injury can improve functional walking abilities. To determine the changes in muscle activation patterns that are associated with improvements in walking, we measured the electromyography (EMG) of leg muscles in 17 individuals with incomplete spinal cord injury during similar walking conditions both before and after training. Specific differences were observed between subjects that eventually gained functional improvements in overground walking (responders), compared with subjects where treadmill training was ineffective (nonresponders). Although both groups developed a more regular and less clonic EMG pattern on the treadmill, it was only the tibialis anterior and hamstring muscles in the responders that displayed increases in EMG activation. Likewise, only the responders demonstrated decreases in burst duration and cocontraction of proximal (hamstrings and quadriceps) muscle activity. Surprisingly, the proximal muscle activity in the responders, unlike nonresponders, was three- to fourfold greater than that in uninjured control subjects walking at similar speeds and level of body weight support, suggesting that the ability to modify muscle activation patterns after injury may predict the ability of subjects to further compensate in response to motor training. In summary, increases in the amount and decreases in the duration of EMG activity of specific muscles are associated with functional recovery of walking skills after treadmill training in subjects that are able to modify muscle activity patterns following incomplete spinal cord injury.
Clinical Neurophysiology: Official Journal Of The International Federation Of Clinical Neurophysiology [Clin Neurophysiol] 2008 Dec; Vol. 119 (12), pp. 2675-6. Date of Electronic Publication: 2008 Oct 05.
Humans, Central Nervous System cytology, Motor Neurons physiology, and Walking physiology