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Biomedical subjects

N B Alexander

Publications and source records attributed to N B Alexander.

43 records · Page 3Linked to original sources
PubMed1992

Quantitative assessment of bed rise difficulty in young and elderly women.

OBJECTIVE: To describe the motions which occur during rising from bed, specifically the motions that appeared to characterize difficulty in rising from a bed in older adults. DESIGN: Development of a Mobility assessment tool. SETTING: Retirement center and two university laboratories. PARTICIPANTS: Three groups of female volunteers: young controls (n = 17, mean age 24), community-dwelling older adults (n = 12, mean age 71), and retirement center-dwelling older adults who admitted to difficulty in rising from a bed (n = 15, mean age 86). INTERVENTION: Videotaping of motions occurring during controlled rises from a supine to sitting position. MAIN OUTCOME MEASURES: These motions were rated on the specially developed Bed Rise Difficulty (BRD) scale, a scale designed to measure movements that characterize difficulty in rising from a bed in older adults. Subject groups were compared in total BRD score, individual BRD item score, and total time to rise. Item relationships and scale reliability were also assessed. RESULTS: Older adults with no apparent difficulty in rising based on total time to rise or on the BRD score nevertheless showed differences in upper extremity use when compared to young controls. Older adult subjects with difficulty in rising from a bed, when compared to other older adults with no apparent difficulty, differed more often in their upper extremity and leg use to facilitate the rise. Five BRD scale items, including use of extremity pushes, discontinuity of trunk and leg motion, multiple shoulder/pelvic adjustments, multiple leg adjustments, and poor vertical heel clearance may have best indicated true bed rise difficulty. CONCLUSIONS: These data provide a reliable and valid method to characterize difficulty in rising from a bed and provide the basis for biomechanical analyses of the strength and joint ranges of motion required to rise from a bed.

Activities of Daily Living↗
PubMed1991

Rising from a chair: effects of age and functional ability on performance biomechanics.

Although difficulty in rising from a chair is common to elderly people, few studies have compared chair rise performance in young and elderly adults with differing functional abilities. Using an instrumented chair and a videotape analysis, controlled chair rise performances were quantified in three groups of volunteers: young adults (Young, n = 17, mean age 23 years), elderly adults able to rise without the use of armrests (Old Able, n = 23, mean age 72 years), and elderly adults unable to rise without the use of armrests (Old Unable, n = 11, mean age 84 years). Rises both with and without the use of hands were observed. The total time to rise and the percent of that time spent in the two distinct phases of the rise, the body segment rotations used, and the hand forces exerted were measured. Despite no apparent functional impairment, the Old Able compared to the Young spent a larger percent time in the first phase of the rise and rotated their body segments by different amounts. When rising with use of hands, the Old Unable compared to the Old Able group took more time and used different body segment rotations and larger ratios of hand force to body weight. These data quantify chair rise performance in young adults and in elderly adults with differing functional abilities and enable biomechanical analyses of the importance of joint torque strengths and postural stability in that performance.

Adult↗
PubMed1991

Stepping over obstacles: gait patterns of healthy young and old adults.

Falls associated with tripping over an obstacle can be devastating to elderly individuals, yet little is known about the strategies used for stepping over obstacles by either old or young adults. The gait of gender-matched groups of 24 young and 24 old healthy adults (mean ages 22 and 71 years) was studied during a 4 m approach to and while stepping over obstacles of 0, 25, 51, or 152 mm height and in level obstacle-free walking. Optoelectronic cameras and recorders were used to record approach and obstacle crossing speeds as well as bilateral lower extremity kinematic parameters that described foot placement and movement trajectories relative to the obstacle. The results showed that age had no effect on minimum swing foot clearance (FC) over an obstacle. For the 25 mm obstacle, mean FC was 64 mm, or approximately three times that used in level gait; FC increased nonlinearly with obstacle height for all subjects. Although no age differences were found in obstacle-free gait, old adults exhibited a significantly more conservative strategy when crossing obstacles, with slower crossing speed, shorter step length, and shorter obstacle-heel strike distance. In addition, the old adults crossed the obstacle so that it was 10% further forward in their obstacle-crossing step. Although all subjects successfully avoided the riskiest form of obstacle contact, tripping, 4/24 healthy old adults stepped on an obstacle, demonstrating an increased risk for obstacle contact with age.

Adult↗
PubMedDate not supplied

Bed mobility task performance in older adults.

Difficulty in transferring, the ability to rise in and out of a bed and chair, is a common problem in older adults, particularly those residing in skilled nursing facilities. Focusing on one aspect of transferring, rising from supine to sitting position, we devised a set of bed mobility tasks to test key arm, leg, and trunk movements that likely contribute to successful rising from bed. Healthy young controls (YC, n=22, mean age 23), and older adults (aged 60 and over) either residing independently in congregate housing (CH, n=29, mean age 84) or undergoing rehabilitation in a skilled nursing facility (SNF, mean age 77) were assessed in the time to rise from supine to sitting and in the ability or inability to perform 16 other bed mobility tasks. Trunk function-related tasks, specifically those requiring trunk elevation and trunk balance, were most difficult for the SNF, followed by CH, and then YC. Tasks focusing on trunk flexion strength (sit up arms crossed, bilateral heel raise) and lateral trunk strength/balance were the most difficult for both SNF and CH, although there was minimal difference in the percent unable to complete each task. The major CH-SNF differences occurred in trunk elevation tasks where the upper limb was important in facilitating trunk elevation (sit up with head of bed elevation with use of arms, sit up with the use of a trapeze, or sit up with use of arms from a flat bed position). These findings suggest that to improve frail older adult performance on bed mobility tasks, and specifically in rising from supine to sitting, training should move beyond improving trunk function (i.e., trunk strength). There should be an additional focus, either through therapy or bed design modifications, on how upper limb movements and positioning can be used to assist in trunk elevation.

Activities of Daily Living↗