Leg preference associated with protective stepping responses in older adults.

BACKGROUND: Asymmetries in dynamic balance stability have been previously observed. The goal of this study was to determine whether leg preference influenced the stepping response to a waist-pull perturbation in older adult fallers and non-fallers. METHODS: 39 healthy, community-dwelling, older adult (>65 years) volunteers participated. Participants were grouped into non-faller and faller cohorts based on fall history in the 12 months prior to the study. Participants received 60 lateral waist-pull perturbations of varying magnitude towards their preferred and non-preferred sides during quiet standing. Outcome measures included balance tolerance limit, number of recovery steps taken and type of recovery step taken for perturbations to each side. FINDINGS: No significant differences in balance tolerance limit (P ≥ 0.102) or number of recovery steps taken (η(2)partial ≤ 0.027; P ≥ 0.442) were observed between perturbations towards the preferred and non-preferred legs. However, non-faller participants more frequently responded with a medial step when pulled towards their non-preferred side and cross-over steps when pulled towards their preferred side (P=0.015). INTERPRETATION: Leg preference may influence the protective stepping response to standing balance perturbations in older adults at risk for falls, particularly with the type of recovery responses used. Such asymmetries in balance stability recovery may represent a contributing factor for falls among older individuals and should be considered for rehabilitation interventions aimed at improving balance stability and reducing fall risk.

Voluntary changes in step width and step length during human walking affect dynamic margins of stability.

"Cautious" gait is generally characterized by wider and shorter steps. However, we do not clearly understand the relationship between step characteristics and individuals' stability. Here, we examined the effects of voluntarily altering step width (SW) and step length (SL) on individuals' margins of stability. Fourteen participants completed three 3-min treadmill walking trials during three SL (short, normal with metronome, and long) and three SW (narrow, normal and wide) manipulation conditions. SL manipulations yielded significant changes in mean anterior-posterior (AP) margins of stability (MOS(ap)) (p<0.0005) but not mediolateral (ML) margins of stability (MOS(ml)) (p≥0.0579). Taking wider steps increased mean MOS(ml) while decreasing MOS(ap) (p<0.0005). Walking with either wider or long steps, each of which increases the base of support, yielded increased AP and ML MOS variability (p≤0.0468). Step-to-step analysis of MOS(ml) indicated that subjects took stable steps followed immediately by stable steps. Overall, short-term, voluntary adoption of wider steps may help increase instantaneous lateral stability but shorter steps did not change lateral stability during unperturbed walking. We suggest that the observed changes in stability margins be considered in gait training programs which recommend short-term changes in step characteristics to improve stability.

Dynamic margins of stability during human walking in destabilizing environments.

Understanding how humans maintain stability when walking, particularly when exposed to perturbations, is key to preventing falls. Here, we quantified how imposing continuous, pseudorandom anterior-posterior (AP) and mediolateral (ML) oscillations affected the control of dynamic walking stability. Twelve subjects completed five 3-minute walking trials in the Computer Assisted Rehabilitation ENvironment (CAREN) system under each of 5 conditions: no perturbation (NOP), AP platform (APP) or visual (APV) or ML platform (MLP) or visual (MLV) oscillations. We computed AP and ML margins of stability (MOS) for each trial. Mean MOS(ml) were consistently slightly larger during all perturbation conditions than during NOP (p≤0.038). Mean MOS(ap) for the APP, MLP and MLV oscillations were significantly smaller than during NOP (p<0.0005). Variability of both MOS(ap) and MOS(ml) was significantly greater during the MLP and MLV oscillations than during NOP (p<0.0005). We also directly quantified how the MOS on any given step affected the MOS on the following step using first-return plots. There were significant changes in step-to-step MOS(ml) dynamics between experimental conditions (p<0.0005). These changes suggested that subjects may have been trying to control foot placement, and consequently stability, during the perturbation conditions. Quantifying step-to-step changes in margins of dynamic stability may be more useful than mean MOS in assessing how individuals control walking stability.

Voluntarily changing step length or step width affects dynamic stability of human walking.

Changes in step width (SW), step length (SL), and/or the variability of these parameters have been prospectively related to risk of falling. However, it is unknown how voluntary changes in SW and SL directly alter variability and/or dynamic stability of walking. Here, we quantified how variability and dynamic stability of human walking changed when individuals voluntarily manipulated SW and SL. 14 unimpaired, young adults walked on a treadmill at their preferred walking speed with normal gait, with a metronome and with narrower, wider, shorter and longer steps than normal. Taking narrower steps caused increased SL variability while mediolateral (ML) movements of the C7 vertebra (i.e., trunk) became locally more stable (p<0.05) and anterior-posterior (AP) C7 movements became locally less stable (p<0.05). Taking wider steps caused increased SW and SL variability, while ML C7 movements became both locally and orbitally less stable (p<0.05). Any change in SL caused increased SW, SL, and stride time variability. When taking shorter steps, ML C7 movements exhibited greater short-term local and orbital instability, while AP C7 movements exhibited decreased short-term and long-term local instability (p<0.05). When taking longer steps, AP, ML, and vertical C7 movements all exhibited increased long-term local instability and increased orbital instability (p<0.05). Correlations between mean SW, SL and dynamic stability of C7 marker motions were weak. However, short-term voluntary changes in SW and SL did significantly alter local and orbital stability of trunk motions.

Child disability case studies: an interprofessional learning opportunity for medical students and paediatric nursing students.

CONTEXT: We describe an interprofessional learning (IPL) opportunity for pre-qualification medical and paediatric nursing students using community-based case studies of disabled children and their families. METHODS: A total of 160 students were randomly allocated into interprofessional and uniprofessional pairs. Each pair visited a disabled child at home and school and presented their experience to the rest of the group. Quantitative and qualitative evaluation methods were used to explore the learning experience. Data collection tools included a scale measuring attitudes towards IPL, which was completed by all students before and after their visits and focus groups. RESULTS: The value of the community setting and independent working of the case study was appreciated by the students. The intimacy involved in working in IP pairs demonstrated both positive and negative features. Nursing students showed more open and positive attitudes towards IPL than medical students. Nursing students in IP pairs appear to have benefited most from the exercise, notably in terms of confidence and self-esteem. Professional differences in communication skills and approach were identified as particular learning points for all students. CONCLUSIONS: The added value of combining quantitative and qualitative research methods is well demonstrated by this study. Learning opportunities from the case study were greater as a result of working interprofessionally. Student attitudes towards IPL and professional stereotyping changed as a result of this IPL exercise. The importance of the social context of learning and the contact hypothesis are supported by our findings.