Category: Research and Articles

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Mobility status and bone density in cerebral palsy.

date: 08/01/1996
author: Wilmshurst S, Ward K, Adams JE, Langton CM, Mughal MZ.
publication: Arch Dis Child. 1996 Aug;75(2):164-5.
pubmed_ID: 8869203

The spinal bone mineral density (SBMD) and calcaneal broadband ultrasound attenuation (BUA) was measured in 27 children with cerebral palsy. They were categorised into four mobility groups: mobile with an abnormal gait, mobile with assistance, non-mobile but weight bearing, non-mobile or weight bearing. Mean SD scores for BUA and SBMD differed among mobility groups (analysis of variance, p < 0.001 and p = 0.078, respectively).

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Effect of prolonged bed rest on bone mineral.

date: 12/19/1970
author: Donaldson CL, Hulley SB, Vogel JM, Hattner RS, Bayers JH, McMillan DE.
publication: Metabolism. 1970 Dec; 19(12): 1071-84
pubmed_ID: 4321644
Outside_URL: http://www.ncbi.nlm.nih.gov/pubmed/4321644
Bone mineral is lost during immobilization. This disuse osteopenia occurs locally in patients with fracture or hemiplegia and is generalized in quadriplegia.

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Bone loss and muscle atrophy in spinal cord injury: epidemiology, fracture prediction, and rehabilitation strategies.

date: 01/01/2006
author: Giangregorio L, McCartney N.
publication: J Spinal Cord Med. 2006;29(5):489-500.
pubmed_ID: 17274487

Individuals with spinal cord injury (SCI) often experience bone loss and muscle atrophy. Muscle atrophy can result in reduced metabolic rate and increase the risk of metabolic disorders. Sublesional osteoporosis predisposes individuals with SCI to an increased risk of low-trauma fracture. Fractures in people with SCI have been reported during transfers from bed to chair, and while being turned in bed. The bone loss and muscle atrophy that occur after SCI are substantial and may be influenced by factors such as completeness of injury or time post injury. A number of interventions, including standing, electrically stimulated cycling or resistance training, and walking exercises have been explored with the aim of reducing bone loss and/or increasing bone mass and muscle mass in individuals with SCI. Exercise with electrical stimulation appears to increase muscle mass and/or prevent atrophy, but studies investigating its effect on bone are conflicting. Several methodological limitations in exercise studies with individuals with SCI to date limit our ability to confirm the utility of exercise for improving skeletal status. The impact of standing or walking exercises on muscle and bone has not been well established. Future research should carefully consider the study design, skeletal measurement sites, and the measurement techniques used in order to facilitate sound conclusions.

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Skeletal adaptations to alterations in weight-bearing activity: a comparison of models of disuse osteoporosis.

date: 01/01/2001
author: Giangregorio L, Blimkie CJ.
publication: Sports Med. 2002;32(7):459-76.
pubmed_ID: 12015807

The removal of regular weight-bearing activity generates a skeletal adaptive response in both humans and animals, resulting in a loss of bone mineral. Human models of disuse osteoporosis, namely bed rest, spinal cord injury and exposure to micro-gravity demonstrate the negative calcium balance, alterations in biochemical markers of bone turnover and resultant loss of bone mineral in the lower limbs that occurs with reduced weight-bearing loading. The site-specific nature of the bone response is consistent in all models of disuse; however, the magnitude of the skeletal adaptive response may differ across models. It is important to understand the various manifestations of disuse osteoporosis, particularly when extrapolating knowledge gained from research using one model and applying it to another. In rats, hindlimb unloading and exposure to micro-gravity also result in a significant bone response. Bone mineral is lost, and changes in calcium metabolism and biochemical markers of bone turnover similar to humans are noted. Restoration of bone mineral that has been lost because of a period of reduced weight bearing may be restored upon return to normal activity; however, the recovery may not be complete and/or may take longer than the time course of the original bone loss. Fluid shear stress and altered cytokine activity may be mechanistic features of disuse osteoporosis. Current literature for the most common human and animal models of disuse osteoporosis has been reviewed, and the bone responses across models compared.

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Physical rehabilitation as an agent for recovery after spinal cord injury.

date: 05/18/2007
author: Behrman AL, Harkema SJ.
publication: Phys Med Rehabil Clin N Am. 2007 May;18(2):183-202, v.
pubmed_ID: 17543768

The initial level of injury and severity of volitional motor and clinically detectable sensory impairment has been considered the most reliable for predicting neurologic recovery of function after spinal cord injury (SCI). This consensus implies a limited expectation for physical rehabilitation interventions as important in the facilitation of recovery of function. The development of pharmacologic and surgical interventions has always been pursued with the intent of altering the expected trajectory of recovery after SCI, but only recently physical rehabilitation strategies have been considered to improve recovery beyond the initial prognosis. This article reviews the recent literature reporting emerging activity-based therapies that target recovery of standing and walking based on activity-dependent neuroplasticity. A classification scheme for physical rehabilitation interventions is also discussed to aid clinical decision making.

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Moving the arms to activate the legs.

date: 07/01/2006
author: Ferris DP, Huang HJ, Kao PC.
publication: Exerc Sport Sci Rev. 2006 Jul;34(3):113-20.
pubmed_ID: 16829738

Recent studies on neurologically intact individuals and individuals with spinal cord injury indicate that rhythmic upper limb muscle activation has an excitatory effect on lower limb muscle activation during locomotor-like tasks. This finding suggests that gait rehabilitation therapy after neurological injury should incorporate simultaneous upper limb and lower limb rhythmic exercise to take advantage of neural coupling.

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Neural coupling between upper and lower limbs during recumbent stepping.

date: 10/01/2004
author: Huang HJ, Ferris DP.
publication: J Appl Physiol. 2004 Oct;97(4):1299-308. Epub 2004 Jun 4.
pubmed_ID: 15180979
Outside_URL: http://www.ncbi.nlm.nih.gov/pubmed/15180979
During gait rehabilitation, therapists or robotic devices often supply physical assistance to a patient’s lower limbs to aid stepping. The expensive equipment and intensive manual labor required for these therapies limit their availability to patients. One alternative solution is to design devices where patients could use their upper limbs to provide physical assistance to their lower limbs (i.e., self-assistance). To explore potential neural effects of coupling upper and lower limbs, we investigated neuromuscular recruitment during self-driven and externally driven lower limb motion. Healthy subjects exercised on a recumbent stepper using different combinations of upper and lower limb exertions. The recumbent stepper mechanically coupled the upper and lower limbs, allowing users to drive the stepping motion with upper and/or lower limbs. We instructed subjects to step with 1) active upper and lower limbs at an easy resistance level (active arms and legs); 2) active upper limbs and relaxed lower limbs at easy, medium, and hard resistance levels (self-driven); and 3) relaxed upper and lower limbs while another person drove the stepping motion (externally driven). We recorded surface electromyography (EMG) from six lower limb muscles. Self-driven EMG amplitudes were always higher than externally driven EMG amplitudes (P < 0.05). As resistance and upper limb exertion increased, self-driven EMG amplitudes also increased. EMG bursts during self-driven and active arms and legs stepping occurred at similar times. These results indicate that active upper limb movement increases neuromuscular activation of the lower limbs during cyclic stepping motions. Neurologically impaired humans that actively engage their upper limbs during gait rehabilitation may increase neuromuscular activation and enhance activity-dependent plasticity.

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Locomotor training after human spinal cord injury: a series of case studies.

date: 07/01/2000
author: Behrman AL, Harkema SJ.
publication: Phys Ther. 2000 Jul;80(7):688-700.
pubmed_ID: 10869131

Many individuals with spinal cord injury (SCI) do not regain their ability to walk, even though it is a primary goal of rehabilitation. Mammals with thoracic spinal cord transection can relearn to step with their hind limbs on a treadmill when trained with sensory input associated with stepping. If humans have similar neural mechanisms for locomotion, then providing comparable training may promote locomotor recovery after SCI. We used locomotor training designed to provide sensory information associated with locomotion to improve stepping and walking in adults after SCI. Four adults with SCIs, with a mean postinjury time of 6 months, received locomotor training. Based on the American Spinal Injury Association (ASIA) Impairment Scale and neurological classification standards, subject 1 had a T5 injury classified as ASIA A, subject 2 had a T5 injury classified as ASIA C, subject 3 had a C6 injury classified as ASIA D, and subject 4 had a T9 injury classified as ASIA D. All subjects improved their stepping on a treadmill. One subject achieved overground walking, and 2 subjects improved their overground walking. Locomotor training using the response of the human spinal cord to sensory information related to locomotion may improve the potential recovery of walking after SCI.

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Physiologic responses to electrically assisted and frame-supported standing in persons with paraplegia.

date: 12/01/2003
author: Jacobs PL, Johnson B, Mahoney ET.
publication: J Spinal Cord Med. 2003 Winter;26(4):384-9.
pubmed_ID: 14992341

BACKGROUND: Systems of functional electrical stimulation (FES) have been demonstrated to enable some persons with paraplegia to stand and ambulate limited distances. However, the energy costs and acute physiologic responses associated with FES standing activities have not been well investigated. OBJECTIVE: To compare the physiologic responses of persons with paraplegia to active FES-assisted standing (AS) and frame-supported passive standing (PS). METHODS: Fifteen persons with paraplegia (T6-T11) previously habituated to FES ambulation, completed physiologic testing of PS and AS. The AS assessments were performed using a commercial FES system (Parastep-1; Altimed, Fresno, Calif); the PS tests used a commercial standing frame (Easy Stand 5000; Altimed, Fresno, Calif). Participants also performed a peak arm-cranking exercise (ACE) test using a progressive graded protocol in 3-minute stages and 10-watt power output increments to exhaustion. During all assessments, metabolic activity and heart rate (HR) were measured via open-circuit spirometry and 12-lead electrocardiography, respectively. Absolute physiologic responses to PS and AS were averaged over 1-minute periods at 5-minute intervals (5, 10, 15, 20, 25, and 30 minutes) and adjusted relative to peak values displayed during ACE to determine percentage of peak (%pk) values. Absolute and relative responses were compared between test conditions (AS and PS) and across time using two-way analysis of variance. RESULTS: The AS produced significantly greater values of VO2 (43%pk) than did PS (20%pk). The mean HR responses to PS (100-102 beats per minute [bpm] throughout) were significantly lower than during AS, which ranged from 108 bpm at 5 minutes to 132 bpm at test termination. CONCLUSION: Standing with FES requires significantly more energy than does AS and may provide a cardiorespiratory stress sufficient to meet minimal requirements for exercise conditioning.

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Standing and its importance in spinal cord injury management.

date: 01/01/1987
author: Axelson P, Gurski D, Lasko-Harvill A.
publication: RESNA 10th Annual Conference San Jose, California 1987
pubmed_ID:
Outside_URL:
A broad spectrum of physiological problems are associated with lack of gravitational stress in the individual with spinal cord injury. Prolonged immobilization results in systemic de-adaptations which include cardiovascular changes, the alteration of calcium homeostasis which leads to bone de-mineralization and risk of urinary calculi.

Weight bearing in the standing posture has been shown to ameliorate many of these problems and offers physiological advantages for the individual with spinal card injury.

There are also significant psychological and social benefits to standing, including improved self-image, and eye-to-eye interpersonal contact. Increased vocational, recreational and daily living independence are additional benefits of standing.