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Biomedical subjects

R L Craik

Publications and source records attributed to R L Craik.

10 recordsLinked to original sources
PubMed1994

Disability following hip fracture.

Risks for hip fractures are greater for women than for men and increase with age. Individuals who sustain hip fractures exhibit higher mortality than age-matched cohorts, and survivors often demonstrate permanent disability and dependency despite successful surgical repair. This review explores de scriptions of the extent of residual disability following hip fracture and details the multiple variables that account for the discrepancy between surgical and functional outcome. Although outcome has been described traditionally in terms of mortality, ability to perform activities of daily living, and ambulatory status, the need to assess functional disability as a measure of recovery is emphasized. The complexities of the recovery process and the current lack of complete descriptions of disability emphasize the need for national research studies. Research is needed to describe the extent of functional disability present following fracture, to develop a meaningful classification scheme, and to decide the effect of intervention on reducing functional disability.

Activities of Daily Living↗
PubMed1994

Effects of electrical stimulation or voluntary contraction for strengthening the quadriceps femoris muscles in an aged male population.

Since musculoskeletal impairment increases with age, it is important to determine if exercise changes age-related muscle weakness. This study compared the training effects of electrical stimulation and voluntary isometric contraction, the traditional exercise, on the quadriceps femoris in males 65 years and older. Eighteen informed, nondisabled males, 72 +/- 4 years of age, participated in 12 training sessions over 4 weeks. Maximal voluntary isometric contraction (MVIC) torque was measured with a Cybex II dynamometer prior to and following training. An interclass correlation coefficient (3,1) of 0.982 demonstrated repeated reliable torque measurement. The electrical stimulation group trained at an average of 36% of pretest MVIC; the traditional exercise group trained at an average of 42% MVIC. Average (F = 14.06, p = 0.004) and peak (F = 14.32, p = 0.004) torque values were increased with both modes of training. Both methods of training using a low training load were effective in increasing torque in this older male sample. Electrical stimulation has the same potential as traditional exercise to provide improved strength for aged males. Future research should examine electrical stimulation in older persons with compromised ability to exercise using traditional methods.

Aged↗
PubMed1991

Relationships between physical activity and temporal-distance characteristics of walking in elderly women.

The purpose of this study was to investigate the relationships between physical activity and walking speed in women 64 years of age and over. Data were gathered from 81 nondisabled women ranging from 64.0 to 94.5 years of age. The women were categorized as sedentary, community active, or exercisers based on a combination of their living situation and level of daily activity. Subjects walked over a 3.84-m recording surface at five different paces, ranging from walking as slowly as possible to walking as quickly as possible. Actual walking speed and length of steps were measured. Stepping frequency and step length relative to leg length were derived measures. Mean walking speeds ranged from 0.43 m/s at the very slow pace to 1.42 m/s at the very fast pace. The walking speeds at the very slow pace were significantly different among the three physical activity groups. At the very slow pace, women who exercised were able to walk significantly more slowly than the other women. The groups were not significantly different at any other pace. Normal walking speeds for all groups were slower than those previously reported for younger women, with the walking speed of the fastest pace of the elderly women being closer to the normal walking speed of younger women. The results of this study indicate that physical therapists need to utilize age-appropriate values as the standard when evaluating performance. [Leiper CI, Craik RL. Relationships between physical activity and temporal-distance characteristics of walking in elderly women.

Activities of Daily Living↗
PubMed1988

The role of norepinephrine in adult rat somatosensory (SmI) cortical metabolism and plasticity.

Stimulation of rat facial vibrissae increases glucose utilization in the corresponding barrels (lamina IV) and associated columns in laminae I-VIa of the contralateral first somatosensory (SmI) cortex as assessed autoradiographically by the uptake of [14C]2-deoxy-glucose (2-DG). Chronic deafferentation (2 months) by bilateral vibrissectomy with sparing of the C3 vibrissa (SC3) in adult Sprague-Dawley rats produced no change in the rate of LCGU but led to an increased areal extent of the metabolic representation of the SC3 barrel (39%, P less than 0.001) and column (31%, P less than 0.003) as compared to rats with fully intact vibrissae. In other rats with intact facial vibrissae, 6-hydroxydopamine lesions of the locus coeruleus (LC) depleted ipsilateral cortical norepinephrine (NE) by more than 90% and, 2 months later, led to an 11% and 21% increase in C3 barrel and column metabolic representations, respectively, as compared to the contralateral SmI cortex with intact NE levels (P less than 0.05). When bilateral vibrissectomy was combined with a unilateral LC lesion, the SC3 barrel and column metabolic representation on the LC-intact side enlarged as expected but no enlargement occurred on the NE-depleted side (20% difference; P less than 0.05). Therefore, the effect of NE on the SmI cortex depends on the status of its afferent input. NE inhibits the spread of metabolic activity beyond the activated barrel and column in the intact cortex, but independently modulates plastic enlargement in the partially deafferented SmI cortex.

Afferent Pathways↗
PubMed1987

Locus coeruleus input affects glucose metabolism in activated rat barrel cortex.

Significant depletion (greater than 50%) of neocortical norepinephrine (NE), 2 weeks after unilateral 6-hydroxydopamine lesions of the locus coeruleus, led to a small (8%), ipsilateral decrease in total C3 vibrissa column 14C-2-deoxyglucose uptake, but a larger (24-32%) increase in the areal extent of this uptake into the metabolic representation of both the C3 column and barrel of the rat somatosensory (SmI) cortex during stimulation of the contralateral C3 facial vibrissae. This suggests a predominantly inhibitory role for NE in modulating SmI oxidative metabolism during physiologic stimulation.

Animals↗
PubMed1982

The role of sensory conflict on stair descent performance in humans.

Electromyographic (EMG) activity produced in the triceps surae (TS) and subsequent landing were examined under various visual conditions during stair descent with the following results: The amount of precontact TS EMG was reduced during each visual perturbation. Perturbations corresponded to no knowledge or visualization of stairs (B), no stair visualization during descent (A) and vertical movement of the surround during descent (M). Erroneous visual information was primarily responsible for altered EMG activity. The only known difference between the M data sets was that the surround moved up (U) or down (D) as the subject descended. However, TS EMG characteristics were different under these two conditions. Specific visual information appeared necessary for vision to override the other sensory systems. There was no difference in EMG when the room moved up (U) compared to the room not moving (NM). However, EMG activity was significantly different when the room moved down (D) compared to the room not moving (NM). The relationship between TS EMG activity and subsequent landing appeared related to landing strategy. Although the EMG was reduced during both the B and M test conditions compared to the control, the landing was "softer" for B and harder for M. The pre-contact EMG is apparently part of a preprogrammed movement pattern which can be modified by sensory information during task execution. Future studies should examine the neuronal mechanisms which provide the visual system access to the center controlling lower limb muscle activity during dynamic movement.

Adolescent↗
PubMed1982

Clinical correlates of neural plasticity.

The purpose of this article is to relate the concepts of mammalian nervous system plasticity to clinical practice. The clinical relevance of Dr. Bishop's four-part review of prenatal and postnatal maturation, function-induced plasticity, and nervous system regeneration is discussed. The scope of this paper is limited to the relationship between plasticity and 1) the pathogenesis of congenital malformations, 2) skill acquisition in the infant, and 3) functional recovery and treatment. Limitations in current clinical evidence for functional recovery are examined, and research questions that must be answered are presented. Clinical evidence of functional recovery coupled with current concepts of neural plasticity will provide information to determine the efficacy of treatment intervention for the neurologically handicapped. It is hoped that this discussion will encourage clinicians to renew their efforts to accurately document the clinical course of recovery and the treatment methods used to achieve this recovery and to report their findings.

Anencephaly↗
PubMed1978

Clinical evaluation of a sensory feedback device: the limb load monitor.

Based on records of 81 patients who used the LLM, and on questionnaire answers and comments from clinicians, the following can be concluded: 1. The LLM can be operated easily after a minimum of training. It does not break down with extended clinical use when handled properly. 2. The LLM manual provides sufficient information for proper operation and clinical use of the device. 3. The number of patients in a clinic who can benefit from LLM training can be predicted, if consideration is given to the type of facility and the size of the patient population and physical therapy staff. 4. The largest diagnostic group of patients who can benefit from LLM therapy are lower-limb amputees, followed by hemiplegic and orthopedic patients. 5. The general selection criteria outlined initially proved sufficient. A patient who is selected properly can be expected to respond to the feedback signal (i.e., make a weight-bearing adjustment) within the first or second session.

Adolescent↗