Speed-dependent reductions of force output in people with poststroke hemiparesis.

BACKGROUND AND PURPOSE Movement is slow in people with poststroke hemiparesis. Moving at faster speeds is thought by some researchers to exacerbate abnormal or unwanted muscle activity. The purpose of this study was to quantify the effects of increased speed on motor performance during pedaling exercise in people with poststroke hemiparesis. SUBJECTS Twelve elderly subjects with no known neurological impairment and 15 subjects with poststroke hemiparesis of greater than 6 months' duration were tested. METHODS Subjects pedaled at 12 randomly ordered workload and cadence combinations (45-, 90-, 135-, and 180-J workloads at 25, 40, and 55 rpm). Pedal reaction forces were used to calculate work done by each lower extremity. Electromyographic activity was recorded from 7 lower-extremity muscles. RESULTS The main finding was that net mechanical work done by the paretic lower extremity decreased as speed increased in all subjects. The occurrence of inappropriate muscle activity on the paretic side, however, was not exacerbated in that the vastus medialis muscle on the paretic side did not show a consistent further increase in its prolonged activity at higher speeds. The mechanics of faster pedaling resulted in greater net negative mechanical work because, at higher pedaling rates, the prolonged vastus medialis muscle activity is present during a greater portion of the cycle. CONCLUSION AND DISCUSSION The lessened force output by the paretic limb is mainly the result of the inherent mechanical demands of higher-speed pedaling and not due to exacerbation of impaired neural control.

[1]  R. Nordlinger,et al.  How do we decide? , 1980, Journal of Thai Association for Voluntary Sterilization.

[2]  H. Barbeau,et al.  A dynamic EMG profile index to quantify muscular activation disorder in spastic paretic gait. , 1989, Electroencephalography and clinical neurophysiology.

[3]  M. Dimitrijevic,et al.  Studies of spasticity in man. I. Some features of spasticity. , 1967, Brain : a journal of neurology.

[4]  E. Roth,et al.  Hemiplegic gait. Relationships between walking speed and other temporal parameters. , 1997, American journal of physical medicine & rehabilitation.

[5]  J. Desmedt.  Motor control mechanisms in health and disease , 1983 .

[6]  J Perry,et al.  The Mechanics of Walking in Hemiplegia , 1969, Clinical orthopaedics and related research.

[7]  D. Corcos,et al.  Movement deficits caused by hyperexcitable stretch reflexes in spastic humans. , 1986, Brain : a journal of neurology.

[8]  JoAnne K. Gronley,et al.  Classification of walking handicap in the stroke population. , 1995, Stroke.

[9]  S A Kautz,et al.  Relationships between timing of muscle excitation and impaired motor performance during cyclical lower extremity movement in post-stroke hemiplegia. , 1998, Brain : a journal of neurology.

[10]  Philip E. Martin,et al.  The relationship between cadence and lower extremity EMG in cyclists and noncyclists. , 1995, Medicine and science in sports and exercise.

[11]  S A Kautz,et al.  Muscle activity adapts to anti-gravity posture during pedalling in persons with post-stroke hemiplegia. , 1997, Brain : a journal of neurology.

[12]  Shuji Suzuki,et al.  EMG activity and kinematics of human cycling movements at different constant velocities , 1982, Brain Research.

[13]  T L Chelette,et al.  The acceleration-velocity relationship: Identification of normal and spastic upper extremity movement , 1997, Comput. Biol. Medicine.

[14]  S A Kautz,et al.  Muscle activity patterns altered during pedaling at different body orientations. , 1996, Journal of biomechanics.

[15]  M L Hull,et al.  A theoretical basis for interpreting the force applied to the pedal in cycling. , 1993, Journal of biomechanics.

[16]  K Potempa,et al.  Physiological outcomes of aerobic exercise training in hemiparetic stroke patients. , 1995, Stroke.

[17]  Alan J. McComas,et al.  Skeletal Muscle: Form and Function , 1996 .

[18]  Norton Bj,et al.  The relationship of voluntary movement to spasticity in the upper motor neuron syndrome. , 1977 .

[19]  M L Hull,et al.  A mechanically decoupled two force component bicycle pedal dynamometer. , 1988, Journal of biomechanics.

[20]  R. Neptune,et al.  The effect of pedaling rate on coordination in cycling. , 1997, Journal of biomechanics.

[21]  W. J. Beek,et al.  Hemiplegic gait: a kinematic analysis using walking speed as a basis. , 1992, Journal of biomechanics.

[22]  C. Gowland,et al.  Hemiplegic gait: analysis of temporal variables. , 1983, Archives of physical medicine and rehabilitation.

[23]  E Knutsson,et al.  Different types of disturbed motor control in gait of hemiparetic patients. , 1979, Brain : a journal of neurology.

[24]  J. Charles.  [The profession mourns anew]. , 1975, Cahiers d'odonto-stomatologie.

[25]  B Conrad,et al.  Electromyographic analysis of bicycling on an ergometer for evaluation of spasticity of lower limbs in man. , 1983, Advances in neurology.

[26]  R W Bohannon,et al.  Nature, reliability, and predictive value of muscle performance measures in patients with hemiparesis following stroke. , 1992, Archives of physical medicine and rehabilitation.

[27]  B. Bobath.  Adult hemiplegia: Evaluation and treatment , 1978 .

[28]  A. Fugl-Meyer,et al.  The post-stroke hemiplegic patient. 1. a method for evaluation of physical performance. , 1975, Scandinavian journal of rehabilitation medicine.

[29]  D. Ma,et al.  Relationships among walking performance, postural stability, and functional assessments of the hemiplegic patient. , 1987 .

[30]  R W Bohannon,et al.  Correlation of knee extensor muscle torque and spasticity with gait speed in patients with stroke. , 1990, Archives of physical medicine and rehabilitation.

[31]  P. Nathan.  Factors affecting spasticity. , 1980, International rehabilitation medicine.

[32]  S A Kautz,et al.  Increased workload enhances force output during pedaling exercise in persons with poststroke hemiplegia. , 1998, Stroke.

[33]  S. G. Nelson,et al.  Reliability of the Fugl-Meyer assessment of sensorimotor recovery following cerebrovascular accident. , 1983, Physical therapy.

[34]  S. Sahrmann,et al.  The relationship of voluntary movement of spasticity in the upper motor neuron syndrome , 1977, Transactions of the American Neurological Association.

[35]  L Gransberg,et al.  Influences of muscle stretch reflexes on voluntary, velocity-controlled movements in spastic paraparesis. , 1997, Brain : a journal of neurology.