Vector coding reveals the underlying balance control strategies used by humans during translational perturbation.

Postural control research has focused on standing balance experiments on platforms moving with relatively large amplitudes (0.1-0.2 m). This study investigated balance strategies while standing on a platform moving 4 mm in anterior-posterior direction with frequency scaled linearly from 0.4 to 6 Hz. Platform motion and kinematic and kinetic information for nine healthy participants were recorded using motion capture and force plate systems. Coordination between hip, knee and ankle joint torque, and centre of mass (COM) and centre of pressure (COP) motion was quantified by vector coding. Significant main effect of platform frequency for knee-ankle and COP-COM phase relationship was observed (p = 0.023, p = 0.016). At frequencies below 2.11 and 2.34 Hz, ankle strategy was recruited. With ankle strategy, in-phase COP-COM motion with COP dominancy occurred at frequencies below 2.19 and 2.23 Hz during scaling up and down, respectively. As platform frequency passed these values, COM dominated over COP which was followed by anti-phase knee-ankle torque, called a knee strategy, and anti-phase motion between the COP and COM that allowed COP to regain dominance over COM. Collectively, we reveal knee strategy as a new and relevant strategy in real-life settings, and transition between ankle and knee strategies that underpinned transition between COP-COM relative motion.

Innovative solutions to enhance safe and green environments for ageing well using co-design through patient and public involvement.

BACKGROUND: There is a need to develop innovative solutions to enhance safe and green physical environments, which optimise health, wellbeing and community participation among older adults. To develop solutions that meet the needs of a diverse ageing population, an interdisciplinary approach is needed. Our aim was to identify the needs of older people in relation to ageing well in the environment by bringing together knowledge from different perspectives using Patient and Public Involvement. METHODS: An international consortium (Retrofit living For ageing well through Understanding and Redesign of Built environments consortium: ReFURB) was established in April 2018, including ten core members, to (i) explore cutting-edge solutions to safe living for ageing populations and (ii) develop innovative approaches to everyday physical environments, which bring about health benefits. We used a co-design, interdisciplinary framework involving older adults, carers, physiotherapists, geriatricians, engineers, human movement experts, geographers and psychologists from the UK and Australia. This engaged people in a 1 day workshop that comprised a series of presentations from international speakers on urban design, social connectedness, hazards and injury prevention, and the physical environment. Small group discussions (facilitated by consortium members) followed presentations to consider the opportunities, challenges and barriers encountered with ageing, which included the use of creative engagement activities (LEGO® Serious Play, mind maps, poster gallery walk), to help participants share personal stories and reflect on the issues raised. Thematic coding was used to synthesise the outputs of the small group work. RESULTS: Five themes were identified across the workshops: access and transport; involvement of the whole community; restoration rather than redesign; assistive and digital technology; and intergenerational approaches. These dimensions related to the physical, social and nature-based qualities of everyday environments, as they pertain to ageing well. CONCLUSIONS: Co-design was a valuable tool that helped understand the perceptions of participants and essential to develop effective interventions and solutions. Participants highlighted several issues affecting people as they age and key environmental considerations to promote wellbeing, activity, and participation. The consortium identified gaps in the existing evidence base and are now planning activities to further develop research ideas in collaboration with our co-design participants.

Real-Life Measurement of Tri-Axial Walking Ground Reaction Forces Using Optimal Network of Wearable Inertial Measurement Units.

Monitoring natural human gait in real-life environment is essential in many applications including the quantification of disease progression, and monitoring the effects of treatment and alteration of performance biomarkers in professional sports. Nevertheless, reliable and practical techniques and technologies necessary for continuous real-life monitoring of gait is still not available. This paper explores in detail the correlations between the acceleration of different body segments and walking ground reaction forces GRF(t) in three dimensions and proposes three sensory systems, with one, two, and three inertial measurement units (IMUs), to estimate GRF(t) in the vertical (V), medial-lateral (ML), and anterior-posterior (AP) directions. The nonlinear autoregressive moving average model with exogenous inputs (NARMAX) non-linear system identification method was utilized to identify the optimal location for IMUs on the body for each system. A simple linear model was then proposed to estimate GRF(t) based on the correlation of segmental accelerations with each other. It was found that, for the three-IMU system, the proposed model estimated GRF(t) with average peak-to-peak normalized root mean square error (NRMSE) of 7%, 16%, and 18% in V, AP, and ML directions, respectively. With a simple subject-specific training at the beginning, these errors were reduced to 7%, 13%, and 13% in V, AP, and ML directions, respectively. These results were found favorably comparable with the results of the benchmark NARMAX model, with subject-specific training, with 0% (V), 4% (AP), and 1% (ML) NRMSE difference.