Can we use peripheral vision to create a visuospatial map for compensatory reach-to-grasp reactions?

Perturbation-induced reach-to-grasp reactions are dependent on vision to capture environmental features of potential support surfaces. Previous research proposed the use of an intrinsic visuospatial map of the environment to reduce delays in motor responses (e.g.

Exploring the role of applied force eccentricity after foot-contact in managing anterior instability among older adults during compensatory stepping responses.

Background: The specific mechanisms responsible for age-related decline in forward stability control remain unclear. Previous work has suggested reactive control of net ground reaction force (GRF) eccentricity may be responsible for age-related challenges in mediolateral stability control during the restabilisation phase of forward compensatory stepping responses.

Research Questions: Does reactive control of GRF eccentricity play a role in managing forward stability control during the restabilisation phase of a forward stepping response to external balance perturbation?

Methods: Healthy younger (YA) (n = 20) and older adults (OA) (n = 20) were tethered to a rigid frame, via adjustable cable.

Local dynamic stability of the lower extremity in novice and trained runners while running intraditional and minimal footwear.

Background: Understanding how footwear cushioning influences movement stability may be helpful in reducing injuries related to repetitive loading.

Research Question: The purpose of this study was to identify the relationship between running experience and midsole cushioning on local dynamic stability of the ankle, knee and hip.

Methods: Twenty-four trained and novice runners were recruited to run on a treadmill for five minutes at the same relative intensity.

Age-related challenges in reactive control of mediolateral stability during compensatory stepping: A focus on the dynamics of restabilisation.

Age-related mediolateral instability during forward stepping reactions evoked by whole-body perturbation is believed to occur independent of the initial temporospatial parameters prior to step-contact. Recent research is beginning to explore the restabilisation phase, following step-contact, as the origin of such instability. This work sought to uncover potential mechanisms underlying age-related mediolateral instability during restabilisation by examining whole-body centre of mass (COM) kinematics and the orientation of the net ground reaction force relative to the COM.

Control of standing balance while using constructions stilts: comparison of expert and novice users.

Unlabelled: This study examined the control of standing balance while wearing construction stilts. Motion capture data were collected from nine expert stilt users and nine novices. Three standing conditions were analysed: ground, 60 cm stilts and an elevated platform.

Kinetic measures of restabilisation during volitional stepping reveal age-related alterations in the control of mediolateral dynamic stability.

Research examining age-related changes in dynamic stability during stepping has recognised the importance of the restabilisation phase, subsequent to foot-contact. While regulation of the net ground reaction force (GRFnet) line of action is believed to influence dynamic stability during steady-state locomotion, such control during restabilisation remains unknown. This work explored the origins of age-related decline in mediolateral dynamic stability by examining the line of action of GRFnet relative to the centre of mass (COM) during restabilisation following voluntary stepping.

The influence of ankle muscle activation on postural sway during quiet stance.

Although balance during quiet standing is postulated to be influenced by multiple factors, including ankle stiffness, it is unclear how different mechanisms underlying increases in stiffness affect balance control. Accordingly, this study examined the influence of muscle activation and passive ankle stiffness increases on the magnitude and frequency of postural sway. Sixteen young adults participated in six quiet stance conditions including: relaxed standing, four muscle active conditions (10%, 20%, 30% and 40% maximum voluntary contraction (MVC)), and one passive condition wearing an ankle foot orthotic (AFO).

Age-related changes in mediolateral dynamic stability control during volitional stepping.

The control of mediolateral dynamic stability during stepping can be particularly challenging for older adults and appears to be related to falls and hip fracture. The specific mechanisms or control challenges that lead to mediolateral instability, however, are not fully understood. This work focussed on the restabilisation phase of volitional forward stepping, subsequent to foot contact, which we believe to be a principal determinant of mediolateral dynamic stability.

Dynamic stability control during volitional stepping: a focus on the restabilisation phase at movement termination.

This work sought to advance the understanding of dynamic stability control during stepping. The specific intention was to better understand the control of the centre of mass during voluntary stepping, by characterizing its trajectory and intertrial variability. Young participants (n=10) performed five different stepping tasks to vary the challenge to COM control: (1) preferred step, (2) long step, (3) wide step, (4) long and wide step and (5) rapid step.

Locomotor strategies in response to altered lower limb segmental mechanical properties.

The present study sought to use stilt walking as a model to uncover modifications to gait dynamics caused by changes in lower limb anthropometrics. We examined 10 novice and 10 expert stilt walkers, each walking with and without stilts, to determine the specific adaptations brought about by experience. Three-dimensional kinematics and force platform data were used to calculate the intersegmental forces, net joint moments and moment powers at the ankle, knee and hip.

Intersegmental coordination while walking up inclined surfaces: age and ramp angle effects.

The lower-limb segment elevation angles during human locomotion have been shown to co-vary in a manner such that they approximate a plane when plotted against each other over a gait cycle. This relationship has been described as the Planar Co-Variation Law and has been shown to be consistent across various modes of locomotion on level ground. The goal of this study is to determine whether the Planar Co-Variation Law will hold in situations where the orientation of the walking surface is altered and if aging will have an effect on this intersegmental coordination during these locomotor tasks.

Postural responses following a rotational support surface perturbation, following knee joint replacement: frontal plane rotations.

Total knee arthroplasty (TKA) is associated with altered sensory and motor functions of the knee which may impair balance control when standing and walking. This study examined the organization of electromyographic and kinematic postural responses to frontal plane support surface rotations, after TKA. Eight TKA patients and nine control participants volunteered.

Organization of postural responses following a rotational support surface perturbation, after TKA: sagittal plane rotations.

Proprioceptive dysfunction, related to osteoarthritis and total knee arthroplasty (TKA) may be related to changes in gait, and may result in balance impairment. This study examined the organization of postural responses to rotational support surface perturbations after TKA. Eight TKA patients and nine control participants volunteered.

Adaptation to unilateral change in lower limb mechanical properties during human walking.

To produce successful and safe walking movements, the locomotor control system must have a detailed awareness of the mechanical properties of the lower limbs. Flexibility of this control comes from an ability to identify and accommodate any changes in limb mechanics by updating its internal representation of the lower limb. To explore the ability of the locomotor control system to tune its representation of the lower limb, eight participants performed three 5 min trials (PRE, WEIGHT and POST) of treadmill walking.

Locomotor adaptations for changes in the slope of the walking surface.

The goal of this study was to examine the transition of walking from a level surface onto different inclined surfaces. Kinematic data of limb and trunk segments were recorded from individuals as they approached and stepped onto four different ramped surfaces (slopes= 3 degrees , 6 degrees , 9 degrees , 12 degrees ). This transition introduced significant adaptations to the swing limb trajectory that were evident in even the lowest ramp condition and appear to be scaled to the ramp inclination although the nature of this scaling seemed to change between the 6 degrees and 9 degrees conditions.

Swing phase kinetics and kinematics of knee replacement patients during obstacle avoidance.

Proper knee joint function is essential for safe and effective mobility within a complex environment. Following knee joint replacement, joint structure and function are altered, often requiring individuals to adjust normal movement patterns in order to adapt to these changes. Such adaptations may either improve function or lead to movement patterns that may potentially be unsafe for individuals.

Bilateral lower limb strategies used during a step-up task in individuals who have undergone unilateral total knee arthroplasty.

Objective: The purpose of this study was to determine how bilateral lower limb joint function is altered by the combined effects of osteoarthritis and its treatment by total knee arthroplasty.

Design: Lower limb joint work of age-matched healthy, control participants was compared to surgical and non-surgical limb work in individuals who had undergone total knee arthroplasty.

Background: Research investigating outcomes following total knee arthroplasty has focussed primarily on the surgical knee, identifying deficits in surgical knee function.