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Biomedical subjects

R Cromwell

Publications and source records attributed to R Cromwell.

6 recordsLinked to original sources
PubMed2001

Sagittal plane head stabilization during level walking and ambulation on stairs.

BACKGROUND AND PURPOSE: Head stabilization in space provides a stable reference frame for visual and vestibular systems during locomotor tasks. The purpose of the present study was to examine upper body movement patterns used to maintain head stability in response to the increased challenge of stair ambulation. METHOD: A repeated-measures study design was used and the order of conditions was randomized for each subject. Eight healthy, non-disabled, young adults walked 10 metres on a level surface, ascended and descended four steps. Head, neck and trunk angular positions in space were obtained for three trials of each condition. Significant differences in mean head, neck and trunk angular orientation in space and segment excursions were determined. Cross-correlation analyses between head and neck, neck and trunk, and head and trunk determined movement patterns used for maintaining head stability. The chi-square test examined the homogeneity of movement pattern distributions for each segment pair across conditions. RESULTS: Head in space flexion orientation and angular excursions were greater during stair ascent and greater still during stair descent as compared to level walking. This indicates a progressively significant increase in the challenge to head stability. Neck flexion orientation in space and angular excursion were greater during stair descent as compared to level walking. Movement patterns between segment pairs demonstrated phase leads and lags between segments when threats to head stability were minimal. With increased challenge to head stability, segments moved synchronously in opposite directions to maintain balance. With further challenges to head stability, segments moved synchronously in the same direction to maintain body segment alignment. CONCLUSIONS: Head stabilization was significantly challenged when ascending stairs and is further challenged while descending stairs. Movement patterns reflected changes associated with challenges to head stability. Increased head excursion during stair ambulation may reflect the need to orient vision for foot placement. Results suggest that individuals with visual or vestibular deficits may be at risk for falls during stair ambulation.

Adult↗
PubMed1989

Loads on the lumbar trunk during level walking.

The goal of this study was to estimate the loads internal to the lumbar trunk that arise during level walking. To do this, (a) trunk muscle activities were calibrated in terms of muscle contraction force levels in a set of isometric exertions; (b) trunk muscle myoelectric activities were measured during level walking; and then (c) the muscle contraction forces that arose during walking were calculated from these measurements and calibrations. Lumbar trunk muscle myoelectric activities were quantified in 10 healthy young males. Myoelectric activities were monitored using eight bipolar surface electrode pairs placed around the trunk at the level of the third lumbar vertebrae. The subjects first performed four static weight-resisting tasks to calibrate muscle force/activity relationships. They then traversed a 8.25 m walkway three times each at cadences of 72 and 120 steps/min. A biomechanical model incorporating 22 lumbar trunk muscles was used to predict muscle contraction forces for the calibration tasks. Predicted forces were linearly correlated with the measured myoelectric activities for these tasks. The regression equations were then interpolated to estimate the muscle contraction forces from the myoelectric data during gait. Peak contraction forces for the iliocostalis muscles were calculated to be approximately 55 N per side, corresponding to total erector spinae peak contractions on the order of 140 N per side. For the other six muscles that were monitored, contraction forces were less than 15 N per side. This suggests that peak net reaction moments and peak spine compressions on the lumbar trunk during these walking tasks were on the order of 15 Nm and 1.2 times body weight, respectively.

Abdominal Muscles↗
PubMed1987

Lumbar trunk muscle use in standing isometric heavy exertions.

A study was conducted to see whether a biomechanical model previously validated for predicting the lumbar spine internal loads imposed by the performance of easy and moderately strenuous physical tasks was also adequate for predicting loads imposed by heavy exertions. Lumbar trunk muscle myoelectric activities were measured in 10 healthy young adult men performing a variety of less strenuous and more strenuous tasks while standing upright, and these were compared to the lumbar muscle contraction magnitudes predicted by the model. For the less strenuous tasks, measured activities and predicted forces showed strong linear correlations, confirming the validity of the model at those load levels. Model predictions for the more strenuous tasks were often found to be inadequate. Contrary to model-incorporated assumptions, substantial antagonistic muscle contractions sometimes occurred, intraabdominal pressurization may sometimes have contributed substantially to the maintenance of structural equilibrium, and the ligamentous tissues of the trunk seemed sometimes to develop substantial passive resistances to bending and twisting moments.

Adult↗
PubMed1980

Reducing the use of full-leather restraints on an acute adult inpatient ward.

The authors describe a program to reduce the use of full-leather restraints on an acute adult inpatient psychiatric ward of a large community mental health center. It included the introduction of a multipurpose pipe-frame bed, which can be used for seclusion only or seclusion with restraints. Use of the bed, coupled with a seclusion-first policy and rapid tranquilization programs, reduced the time the patients spent in full-leather restraints from 360 hours in the month before the program was introduced to 30 hours two months later.

Community Mental Health Centers↗
PubMedDate not supplied

The Adult Sensory Profile: measuring patterns of sensory processing.

OBJECTIVE: This article describes a series of studies designed to evaluate the reliability and validity of the Adult Sensory Profile. METHOD: Expert judges evaluated the construct validity of the items. Coefficient alpha, factor analysis, and correlations of items with subscales determined item reliability, using data from 615 adult sensory profiles. A subsample of 20 adults furnished skin conductance data. A heterogeneous group of 93 adults completed the revised Adult Sensory Profile, and item reliability was reexamined. RESULTS: Expert judgment indicated that items could be categorized according to Dunn's Model of Sensory Processing. Results suggested reasonable item reliability for all subscales except for the Sensation Avoiding subscale. Skin conductance measures detected distinct patterns of physiological responses consistent with the four-quadrant model. Revision of the Adult Sensory Profile resulted in improved reliability of the Sensation Avoiding subscale. CONCLUSION: The series of studies provides evidence to support the four subscales of the Adult Sensory Profile as distinct constructs of sensory processing preferences.

Adolescent↗