Rebecca L. Craik

Determinants of recovery 12 months after hip fracture: the importance of psychosocial factors.

The independent contributions to recovery from hip fracture of psychosocial factors including depression, personality, social connectedness, and self-rated health were studied in 219 women age 59 and older (mean age 78.5) who were community dwelling prior to fracture. Initial assessments were conducted shortly after surgery and follow up assessments 2, 6, and 12 months later. By 12 months, 15 patients had died and 15 had entered a nursing home. Substantial declines in physical functioning though not psychosocial status were observed. Only 21 per cent (compared to 81 per cent prefracture) reported walking independently; fewer than 30 per cent had regained reported prefracture levels of physical function. The proportion with elevated depression scores at 12 months was 20 per cent, down from 51 per cent following surgery; 64 per cent rated their health excellent or good at 12 months, up from 43 per cent after surgery. Poor cognitive status and post-surgical self-rated health were predictive of mortality. Among survivors, age, prefracture physical functioning, and cognitive status were associated with recovery in physical function but not psychosocial status. High post-surgery depression scores, but not the other psychosocial factors, were associated with poorer recovery in both functional and psychosocial status. These findings demonstrate the importance of depressive symptoms as one determinant of recovery from hip fracture and support the need to attend to the affective status of hip fracture patients following surgery.

Gait Variability in Community-Dwelling Older Adults

OBJECTIVES: To describe gait variability at usual and fast walking speeds in community‐dwelling older adults and to describe the effects of increasing gait speed on gait variability.

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.

Detectable Changes in Physical Performance Measures in Elderly African Americans

Background African American older adults have higher rates of self-reported disability and lower physical performance scores compared with white older adults. Measures of physical performance are used to predict future morbidity and to determine the effect of exercise. Characteristics of performance measures are not known for African American older adults. Objective The purpose of this study was to estimate the standard error of measurement (SEM) and minimal detectable change (MDC) for the Short Physical Performance Battery (SPPB), Timed “Up & Go” Test (TUG) time, free gait speed, fast gait speed, and Six-Minute Walk Test (6MWT) distance in frail African American adults. Design This observational measurement study used a test-retest design. Methods Individuals were tested 2 times over a 1-week period. Demographic data collected included height, weight, number of medications, assistive device use, and Mini-Mental Status Examination (MMSE) scores. Participants then completed the 5 physical performance tests. Results Fifty-two participants (mean age=78 years) completed the study. The average MMSE score was 25 points, and the average body mass index was 29.4 kg/m2. On average, participants took 7 medications, and the majority used assistive devices. Intraclass correlation coefficients (ICC [2,1]) were greater than .90, except for the SPPB score (ICC=.81). The SEMs were 1.2 points for the SPPB, 1.7 seconds for the TUG, 0.08 m/s for free gait speed, 0.09 m/s for fast gait speed, and 28 m for 6MWT distance. The MDC values were 2.9 points for the SPPB, 4 seconds for the TUG, 0.19 m/s for free gait speed, 0.21 m/s for fast gait speed, and 65 m for 6MWT distance. Limitations The entire sample was from an urban area. Conclusions The SEMs were similar to previously reported values and can be used when working with African American and white older adults. Estimates of MDC were calculated to assist in clinical interpretation.

Home-Based Leg-Strengthening Exercise Improves Function 1 Year After Hip Fracture: A Randomized Controlled Study

OBJECTIVES: To compare the effectiveness of a short‐term leg‐strengthening exercise program with that of attentional control on improving strength, walking abilities, and function 1 year after hip fracture.

Meaningful improvement in gait speed in hip fracture recovery.

OBJECTIVES: To estimate meaningful improvements in gait speed observed during recovery from hip fracture and to evaluate the sensitivity and specificity of gait speed changes in detecting change in self‐reported mobility.

The role of sensory conflict on stair descent performance in humans

SummaryElectromyographic (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.

Human Solutions for Locomotion II. Interlimb Coordination

Interlimb coordination is presented as a temporal and phase relationship between peak hip extension (HE) in one limb and (1) peak hip extension in the contralateral limb (LHE to RHE), and (2) peak shoulder flexion (SF) and extension (SE) in both the homolateral (e.g., LHE to LSF) and the diagonal (e.g., LHE to RSE) limbs. In the normal subjects studied, a cycle-by-cycle analysis of a series of strides at various rates of free walking reveals an abrupt shift of the frequency relationship between the motion of upper and lower limbs from 1:1 to 2:1 at approximately 0.75 Hz. This relation persists through the complete range of slow frequencies investigated (i.e., 0.5 – 0.75 Hz). The commonly observed characteristics of in-phase coupling between the homo-lateral HE-SF and the diagonal HE-SE limbs and of alternate phase coupling between both upper limbs are altered at frequencies below 0.75 Hz. At these rhythms, HE couples in-phase with homolateral SE and remains coupled in-phase with the diagonal SE. Thus, below 0.75 Hz, each hip extensor peak during a stride cycle is “locked” to SE bilaterally. The analysis of shoulder motion and associated EMG discharges (e.g., M. posterior deltoid, M. anterior deltoid) indicates that each muscle may change its functional role when the rhythm of upper limb motion is altered. Additional investigation of muscle function suggests that one or more muscles with common segmental innervation have differing functional activities during the gait cycle, activities that vary in accordance with the tactics and strategies employed.

Validity of the StepWatch Step Activity Monitor: preliminary findings for use in persons with Parkinson disease and multiple sclerosis.

Background:One goal for older adults with Parkinson disease (PD) and multiple sclerosis (MS) is community ambulation; however, the best way for clinicians to measure this has not been established. Self-report questionnaires rely on the participants cognitive function and reporting accuracy, while the association between clinical timed walk tests and community ambulation may not be strong. Progress toward the identification of an appropriate clinical tool to measure strides in PD and MS populations is hampered by the lack of meaningful research and reference standards in this area. Purpose:The objective of the present study was to explore the validity of the StepWatch Step Activity Monitor (SAM) in assessing stride count in persons with PD or MS. The SAM is a 2-dimensional accelerometer that counts strides and is calibrated for individual participants. Methods:A convenience sample of 20 participants completed a health history interview. Participants ambulated approximately 15 m while wearing the SAM to establish appropriate baseline calibrations, matching their stride with the device settings. Next, participants took 3 passes over the GaitMat II (GM II) while wearing the SAM. Strides counted by the GM were compared with the strides counted by the SAM. Results:The Pearson correlation coefficients (r) for MS and PD, respectively, were 0.99 and 1.0. Conclusions:Our investigation presents preliminary data that shows the concurrent validity of the SAM when compared with the gold standard GM. The SAM appears to be a valid tool for use in persons with PD and MS. The validity was apparent in a population of widely varying impairment levels.

Timing, Intensity, and Duration of Rehabilitation for Hip Fracture and Stroke: Report of a Workshop at the National Center for Medical Rehabilitation Research

This article summarizes the proceedings of an NIH workshop on timing, intensity, and duration of rehabilitation for acute stroke and hip fracture. Participants concentrated on methodological issues facing investigators and suggested priorities for future research in this area.