Task difficulty of visually guided gait modifications involves differences in central drive to spinal motor neurons.

Walking in natural environments requires visually guided modifications, which can be more challenging when involving sideways steps rather than longer steps. This exploratory study investigated whether these two types of modifications involve different changes in the central drive to spinal motor neurons of leg muscles. Fifteen adults [age: 36 ± 6 (SD) years] walked on a treadmill (4 km/h) while observing a screen displaying the real-time position of their toes. At the beginning of the swing phase, a visual target appeared in front (forward) or medial-lateral (sideways) of the ground contact in random step cycles (approximately every third step). We measured three-dimensional kinematics and electromyographic activity from leg muscles bilaterally. Intermuscular coherence was calculated in the alpha (5-15 Hz), beta (15-30 Hz), and gamma bands (30-45 Hz) approximately 230 ms before and after ground contact in control and target steps. Results showed that adjustments toward sideways targets were associated with significantly higher error, lower foot lift, and higher cocontraction between antagonist ankle muscles. Movements toward sideways targets were associated with larger beta-band soleus (SOL): medial gastrocnemius (MG) coherence and a more narrow and larger peak of synchronization in the cumulant density before ground contact. In contrast, movements toward forward targets showed no significant differences in coherence or synchronization compared with control steps. Larger SOL:MG beta-band coherence and short-term synchronization were observed during sideways, but not forward, gait modifications. This suggests that visually guided gait modifications may involve differences in the central drive to spinal ankle motor neurons dependent on the level of task difficulty.NEW & NOTEWORTHY This exploratory study suggests a specific and temporally restricted increase of central (likely corticospinal) drive to ankle muscles in relation to visually guided gait modifications. The findings indicate that a high level of visual attention to control the position of the ankle joint precisely before ground contact may involve increased central drive to ankle muscles. These findings are important for understanding the neural mechanisms underlying visually guided gait and may help develop rehabilitation interventions.

Behavioural Responses of Beef Cattle to Hot Conditions.

Cattle are increasingly exposed to hot temperatures as a result of climate change, and a better understanding of behavioural responses could be beneficial for the diagnosis of heat loads. The changes in the positioning of key body parts, feeding behaviour, body maintenance, and respiratory dynamics were assessed in 24 Black Angus steers individually exposed to hot conditions and fed a finisher diet based on cereal grain or a substituted diet (8% of the grain replaced by an isoenergetic amount of lucerne hay). Increased respiration rate during the heat load period, compared to the recovery period, was associated with increased stepping, especially by left limbs. Cattle also reduced eating, grooming, and scratching during the heat load period. The lowered head, backward ear, vertical or raised tail, and increased respiration rate and panting persisted in cattle during the heat load period. Cattle on the cereal grain diet stood for longer and were more likely to hold their ears backward and tail vertical than those on the substituted diet. We conclude that these behaviours could be used to detect animals that are most affected and that changing from a cereal-based diet to a substituted diet containing a higher amount of fibre, such as lucerne hay, can reduce hyperthermic behavioural responses to a heat load.

Exploring the effects of increased socket-residual limb coupling integrity via vacuum assisted suspension on prosthetic control: a preliminary study in transtibial prosthesis users.

PURPOSE: The prosthetic socket provides the critical interface between prosthesis and residuum. The purpose of this pilot study was to explore the effect of altering socket-residuum coupling integrity on limb and body control, through the use of vacuum-assisted suspension. A secondary purpose was to explore the potential use of two measurement tools designed to assess mobility in a clinical context. MATERIALS AND METHODS: Individuals with unilateral transtibial amputation performed intentional sway (n = 7) and treadmill walking (n = 6) tasks at three vacuum levels. Sway deviation from a straight-line path to peripheral targets was measured using an instrumented balance platform. Step width variability and targeting accuracy were measured using an augmented reality treadmill. RESULTS: There was a significant difference in intentional sway performance toward the target on the anterior diagonal toward the prosthetic side (p = 0.036); higher vacuum levels tended toward less deviation from a straight-line path. We found no group differences between total intentional sway deviation, step width variability or stepping accuracy across vacuum levels. CONCLUSIONS: Improved socket-residuum coupling integrity via vacuum may have measurable effects on functional control that warrant further investigation. We highlight limitations of the clinical testing paradigms to inform future work.Implications for rehabilitationThe fit of the socket is a critical factor in the success of lower limb prosthesis use.Vacuum-assisted suspension modifies the coupling between the residuum and socket.Changes in socket-residuum coupling may lead to measurable differences in control; however, these may be activity and person-specific.Clinically intended instrumented tests of movement function derived for an intact anatomy should be used with caution when assessing prosthesis users.

Test-Retest Reliability of Movement Displacement during a 20-s Stepping-in-Place Test in Community-Dwelling Older Adults with and without Supportive Care.

INTRODUCTION: Our recent reports have shown that movement pattern and displacement assessed with an infrared depth sensor during a 20-s stepping-in-place test (ST) correlates with measures of balance and need for assistance in older individuals. This study investigated ST test-retest reliability in community-dwelling older adults with and without supportive care. METHODS: Two groups were included: those not participating (HO: n = 25, 74.7 ± 5.2 years) and those participating (DSU: n = 41, 78.8 ± 5.8 years) in regular senior day services (supportive care). HO completed three ST trials, separated by 1 week, while DSU completed two ST trials during the same half-day supportive care visit. Testing was conducted with eyes open. ST measures included head movement path distance (TMD), maximum movement displacement (MMD), knee movement path length (KMD), and stepping rate (STEP). TMD×KMD-1 ratio indicated upper-body sway relative to lower-body. Test-retest reliability (intra-class correlation coefficients, ICCs) and between-trial and between group differences (ANCOVA, adjusting for age) were assessed. RESULTS: After adjusting for age, TMD, KMD, TMD×KMD-1 were lesser and STEP was greater in HO than DUS. HO ST variables did not differ across testing days. HO ICC (1, 3) for TMD (0.911 [95% confidence interval: 0.827-0.958]), MMD (0.918 [0.814-0.961]), KMD (0.838 [0.685-0.923]), and TMD×KMD-1 (0.940 [0.884-0.872]) showed strong to very strong reliability. Similarly, DSU ST variables did not differ across same day trials and ICC (1, 2) for TMD, KMD, and TMD×KMD-1 displayed very strong reliability. CONCLUSION: These ST variables exhibited excellent test-retest reliability of discriminating between community-dwelling older adults with and without supportive care.

Process evaluation of a parenting intervention for pre-schoolers with intellectual disabilities who display behaviours that challenge in the UK.

BACKGROUND: Stepping Stones Triple P (SSTP) is a complex parent-mediated intervention aimed to reduce behaviours that challenge in children with moderate to severe intellectual disabilities, aged 30-59 months. METHODS: To formulate a comprehensive understanding of SSTP implementation in the UK, we conducted a process evaluation collecting stakeholder views and considering intervention fidelity, dose, reach, delivery adaptations, and acceptability. RESULTS: Fidelity and quality of delivery ratings were high. Parents perceived SSTP as valuable, reporting increased parental confidence and understanding of the child's behaviours. However, only 30% of families received an adequate dose of the intervention. Parents who only received treatment as usual described feeling abandoned by current services. Service managers emphasised the importance of availability of resources and therapist training for successful intervention delivery. CONCLUSIONS: SSTP supports effective management of early-onset behaviours that challenge. Further work is needed to ensure equitable access to the intervention across health and social care services. TRIAL REGISTRATION: NCT03086876 - https://www. CLINICALTRIALS: gov/ct2/show/NCT03086876?term=Hassiotis+Angela&draw=1&rank=1.

Normalization of the hip abductors rate of activation during a voluntary step task in older adults: Reliability and differences among approaches.

BACKGROUND: Voluntary stepping tasks are used to measure the ability of an individual to step and has been associated with fall risk in older adults. Although electromyography (EMG) amplitude is measured during stepping tasks, there is no consensus about the reference EMG value that should be used to normalize the signal. The purpose of the present study was to 1) investigate the impact of using different EMG parameters as a reference to normalize the rate of activation (RoA) of the hip abductor muscles across lateral voluntary step trials and the differences between trials, and 2) to investigate the reliability among trials of the reference EMG values. METHODS: Nineteen older adults (>65 years of age) performed ten lateral choice reaction stepping test (CRST), while the gluteus medius and tensor fascia latae EMG were recorded. Three reference EMG values were calculated and used to normalize RoA during the stepping task. A repeated-measures ANOVA was used (normalized RoA[3] x trial[3]) to compare normalized EMG across trials, and an intraclass correlation coefficient and coefficient of variation were used for the inter-trial reliability of the reference EMG values. RESULTS: The present study showed that gluteus medius and tensor fascia latae RoA normalized values from the stance and stepping leg (right or left side) measured during CRST are different according to the reference EMG value(P<0.001), with no differences across trials. Overall, the EMG procedures showed high inter-trial reliability, with a few exceptions. SIGNIFICANCE: Therefore, after careful examination of our results, the peak and mean EMG amplitudes showed consistently higher intraclass correlation coefficients; however, the former may provide a more intuitive reference value.

Functional lower extremity strength influences stepping strategy in community-dwelling older adults during single and dual-task walking.

As age increases, a decline in lower extremity strength leads to reduced mobility and increased fall risks. This decline outpaces the age-related reduction in muscle mass, resulting in mobility limitations. Older adults with varying degrees of mobility-disability use different stepping strategies. However, the link between functional lower extremity strength and stepping strategy is unknown. Therefore, understanding how age-related reductions in functional lower extremity strength influence stepping strategy is vital to unraveling mobility limitations. Twenty participants (17F, 72 ± 6 years) were recruited and tested at a local community event. Participants were outfitted with inertial measurement units (IMU) and walked across a pressurized walkway under single and dual motor task conditions (walking with and without carrying a tray with water) at their usual and fast speeds. Participants were dichotomized into normal (11) or low functional strength groups (9) based on age-specific normative cutoffs using the instrumented 5-repetition Sit-to-Stand test duration. Our study reveals that older adults with normal strength prefer adjusting their step time during walking tasks, while those with reduced strength do not exhibit a preferred stepping strategy. This study provides valuable insights into the influence of functional lower extremity strength on stepping strategy in community-dwelling older adults during simple and complex walking tasks. These findings could aid in diagnosing gait deviations and developing appropriate treatment or management plans for mobility disability in older adults.

Walking with increased step length variability increases the metabolic cost of walking.

Older adults and neurological populations tend to walk with slower speeds, more gait variability, and a higher metabolic cost. This higher metabolic cost could be related to their increased gait variability, but this relationship is still unclear. The purpose of this study was to determine how increased step length variability affects the metabolic cost of waking. Eighteen healthy young adults completed a set of 5-minute trials of treadmill walking at 1.20 m/s while we manipulated their step length variability. Illuminated rectangles were projected onto the surface of a treadmill to cue step length variabilities of 0, 5 and 10% (coefficient of variation). Actual step lengths and their variability were tracked with reflective markers on the feet, while metabolic cost was measured using indirect calorimetry. Changes in metabolic cost across habitual walking (no projections) and the three variability conditions were analyzed using a linear mixed effects model. Metabolic power was largest in the 10% condition (4.30 ± 0.23 W/kg) compared to 0% (4.16 ± 0.18 W/kg) and habitual (3.98 ± 0.25 W/kg). The participant's actual step length variability did not match projected conditions for 0% (3.10%) and 10% (7.03%). For every 1% increase in step length variability, there is an 0.7% increase in metabolic cost. Our results demonstrate an association between the metabolic cost of walking and gait step length variability. This suggests that increased gait variability contributes to a portion of the increased cost of walking seen in older adults and neurological populations.

Incidence and Importance of Peripheral Vestibular Dysfunction in Adolescent Idiopathic Scoliosis.

Adolescent idiopathic scoliosis (AIS) is a common form of scoliosis. As the name suggests, etiopathogenesis is not clearly defined, so treatment is still anchored in the musculoskeletal theory and correction/prevention of high Cobb angle values. This study aimed to determine whether there is any connection between developing scoliotic curvature and a positive history of motion sickness as a symptom of a peripheral vestibular dysfunction/deficit, and if vestibular rehabilitation exercises could be integrated into the treatment plan. The study was conducted over 12 months on a selected population of 159 patients to evaluate or treat scoliotic curvatures in a private clinic. The collected data were analyzed using IBM SPSS Statistics 25 and illustrated using Microsoft Office Excel/Word 2021. Patients with peripheral vestibular dysfunction had significantly higher Cobb angle values when compared to patients with a negative result in an instrumental test for peripheral vestibular dysfunction. Motion sickness was considerably more associated with peripheral vestibular dysfunction, and a positive Fukuda stepping test was associated with a positive history of motion sickness. Adolescent idiopathic scoliosis with higher Cobb angles is related to positive motion sickness history as part of peripheral vestibular dysfunction. Conservative treatment for scoliosis could incorporate sensory integration techniques, and a positive history of motion sickness could be an indicator of a higher risk of progression in adolescent idiopathic scoliosis.

Representation of rhythmic chunking in striatum of mice executing complex continuous movement sequences.

We used a step-wheel system to examine the activity of striatal projection neurons as mice practiced stepping on complexly arranged foothold pegs in this Ferris-wheel-like device to receive reward. Sets of dorsolateral striatal projection neurons were sensitive to specific parameters of repetitive motor coordination during the runs. They responded to combinations of the parameters of continuous movements (interval, phase, and repetition), forming "chunking responses"-some for combinations of these parameters across multiple body parts. Recordings in sensorimotor cortical areas exhibited notably fewer such responses but were documented for smaller neuron sets whose heterogeneity was significant. Striatal movement encoding via chunking responsivity could provide insight into neural strategies governing effective motor control by the striatum. It is possible that the striking need for external rhythmic cuing to allow movement sequences by Parkinson's patients could, at least in part, reflect dysfunction in such striatal coding.

New insight of square stepping exercise in immune fine-tuning for anticipating emerging pandemics.

The COVID-19 pandemic has significantly impacted human life, posing serious physical and psychological threats, particularly to the elderly. While individuals of all ages are susceptible to contracting COVID-19, older people face a heightened risk of developing various diseases due to age-related immunophysiological changes and preexisting health conditions. The interplay between immune health and physical activity is believed to hold even greater significance during a pandemic. Recent findings from our research indicate that the intervention of square stepping exercise (SSE), characterized by a rhythmic and controlled stepping pattern, resulted in increased levels of Brain-Derived Neurotrophic Factor (BDNF) in the elderly. BDNF, known to influence not only nerve cells but also immune cells, suggests a potential link between SSE and immune system modulation. Consequently, this exercise regimen holds promise in counteracting age-related immunophysiological changes, fine-tuning immune responses, and mitigating the severity of potential new virus outcomes, such as 'Disease X.' This review aims to underscore the significance of integrating SSE as a home-based program, serving as a potent tool to enhance immune resilience, prepare for future potential pandemics, and empower older individuals during challenging times. Through the practice of SSE, older adults may strengthen their ability to navigate the challenges posed by pandemics and maintain a sense of control over their well-being.

Cross-sectional associations between temporal patterns and composition of upright and stepping events with physical function in midlife: Insights from the 1970 British Cohort Study.

INTRODUCTION: Age-related decline in physical functioning has significant implications for health in later life but declines begin earlier in midlife. Physical activity (PA) volume is associated with physical function, but the importance of the pattern in which PA is accumulated is unclear. This study investigates associations between patterns of PA accumulation, including the composition, variation, and temporal distribution of upright and stepping events, with physical function in midlife. METHODS: Participants (n = 4378) from the 1970 British Cohort Study wore an activPAL3 accelerometer on the thigh for 7 consecutive days. Exposure measures included a suite of metrics describing the frequency, duration, and composition of upright events, as well as the duration and volume (total steps) of stepping events. In addition, patterns of accumulation of upright and sedentary events were examined including how fragmented/transient they were (upright-to-sedentary transition probability [USTP]) and their burstiness (the tendency for events to be clustered together followed by longer interevent times). Physical function outcomes included grip strength (GS), balance, and SF-36 physical functioning subscale (SF-36pf). Cross-sectional analyses included multivariable linear regression models to assess associations, adjusting for covariates including overall PA volume (mean daily step count). RESULTS: Higher upright event burstiness was associated with higher GS, and higher USTP was associated with lower GS. Duration and step volume of stepping events were positively associated with SF-36pf in females. Step-weighted cadence was positively associated with SF-36pf and balance. Contradictory findings were also present (e.g., more transient stepping events were associated with better GS) particularly for GS in males. Inconsistencies between sexes were observed across some associations. CONCLUSION: Our study reveals that diverse patterns of PA accumulation exhibit distinct associations with various measures of physical function in midlife, irrespective of the overall volume. Contradictory findings and inconsistency between sexes warrant further investigation. Patterns of PA accumulation, in addition to volume, should be considered in future PA research. Longitudinal studies are required to determine whether a given volume of activity accumulated in different patterns, impacts associations between PA and health outcomes.

Functional Lower Extremity Strength Influences Stepping Strategy in Community-Dwelling Older Adults During Single and Dual-Task Walking.

As age increases, a decline in lower extremity strength leads to reduced mobility and increased fall risks. This decline outpaces the age-related reduction in muscle mass, resulting in mobility limitations. Older adults with varying degrees of mobility-disability use different stepping strategies. However, the link between functional lower extremity strength and stepping strategy is unknown. Therefore, understanding how age-related reductions in functional lower extremity strength influence stepping strategy is vital to unraveling mobility limitations. Participants were recruited and tested at a local community event, where they were outfitted with IMUs and walked across a pressurized walkway. Our study reveals that older adults with normal strength prefer adjusting their step time during walking tasks, while those with reduced strength do not exhibit a preferred stepping strategy. This study provides valuable insights into the influence of functional lower extremity strength on stepping strategy in community-dwelling older adults during simple and complex walking tasks. These findings could aid in diagnosing gait deviations and developing appropriate treatment or management plans for mobility disability in older adults.

Personal communication as a strategy to improve the quality of household organic waste - Does it work? results from a quasi-experimental study in Northern Hesse, Germany.

Household organic waste has great potential for closing nutrient cycles in agriculture. This requires proper waste separation by households. Personal communication at the doorstep potentially improves household waste separation behaviour but it is expensive and findings from existing research are mixed. Based on results of previous studies and from a quasi-experiment with non-equivalent groups design in two German municipalities, this paper argues that efficiency of personal communication depends on its context. It can positively influence behaviour when recycling is voluntary and participation rates are low. However, it has no significant effects if recycling is mandatory. One explanation could be different perceptions of recycling in mandatory and voluntary schemes. In voluntary schemes door stepping can activate the intrinsic motivation of households. In mandatory schemes, all households need to participate irrespective of intrinsic motivation. This research shows that this creates a situation in which a small share of households is responsible for almost all contamination. This can be overcome by considering extrinsic factors that affect recycling behaviour. The paper recommends further research to understand which combination of incentives, sanctions and information is efficient in affecting behaviour change in mandatory recycling schemes.

Age-related changes in muscle coordination patterns of stepping responses to recover from loss of balance.

INTRODUCTION: Reactive stepping capacity to recover from a loss of balance declines with aging, which increases the risk of falling. To gain insight into the underlying mechanisms, we investigated whether muscle coordination patterns of reactive stepping differed between healthy young and older individuals. METHODS: We performed a cross-sectional study between 15 healthy young and 14 healthy older adults. They recovered from 200 multidirectional platform translations that evoked reactive stepping responses. We determined spatiotemporal step variables and used muscle synergy analysis to characterize stance- and swing-leg muscle coordination patterns from the start of perturbation until foot landing. RESULTS: We observed delayed step onsets in older individuals, without further spatiotemporal differences. Muscle synergy structure was not different between young and older individuals, but age-related differences were observed in the time-varying synergy activation patterns. In anterior-posterior directions, the older individuals demonstrated significantly enhanced early swing-leg synergy activation consistent with non-stepping behavior. In addition, around step onset they demonstrated increased levels of synergy coactivation (mainly around the ankle) in lateral and anterior directions, which did not appear to hamper foot clearance. CONCLUSION: Although synergy structure was not affected by age, the delayed step onsets and the enhanced early synergy recruitment point at a relative bias towards non-stepping behavior in older adults. They may need more time for accumulating information on the direction of perturbation and making the corresponding sensorimotor transformations before initiating the step. Future work may investigate whether perturbation-based training improves these age-related deficits.

Square-stepping exercise in older inpatients in early geriatric rehabilitation. A randomized controlled pilot study.

BACKGROUND: Preservation of mobility and fall prevention have a high priority in geriatric rehabilitation. Square-Stepping Exercise (SSE) as an evaluated and standardized program has been proven to be an effective training for older people in the community setting to reduce falls and improve subjectively perceived health status. This randomized controlled trial (RCT), for the first time, examines SSE in the context of inpatient early geriatric rehabilitation compared to conventional physiotherapy (cPT). METHODS: Data were collected in a general hospital in the department of acute geriatric care at admission and discharge. Fifty-eight inpatients were randomized to control (CG, n = 29) or intervention groups (IG, n = 29). CG received usual care with cPT five days per week during their hospital stay. For the IG SSE replaced cPT for at least six sessions, alternating with cPT. Physical function was measured with the Short Physical Performance Battery (SPPB) and Timed "Up & Go" (TUG). Gait speed was measured over a distance of 10 m. In a subgroup (n = 17) spatiotemporal gait parameters were analyzed via a GAITRite® system. RESULTS: Both the SPPB total score improved significantly (p = < 0.001) from baseline to discharge in both groups, as did the TUG (p < 0.001). In the SPPB Chair Rise both groups improved with a significant group difference in favor of the IG (p = 0.031). For both groups gait characteristics improved: Gait speed (p = < 0.001), walk ratio (p = 0.011), step length (p = < 0.001), stride length (p = < 0.001) and double support (p = 0.009). For step length at maximum gait speed (p = 0.054) and stride length at maximum gait speed (p = 0.060) a trend in favor of the IG was visible. CONCLUSIONS: SSE in combination with a reduced number of sessions of cPT is as effective as cPT for inpatients in early geriatric rehabilitation to increase physical function and gait characteristics. In the Chair Rise test SSE appears to be superior. These results highlight that SSE is effective, and may serve as an additional component for cPT for older adults requiring geriatric acute care. TRIAL REGISTRATION: DRKS00026191.

Wearing a back-support exoskeleton alters lower-limb joint kinetics during single-step recovery following a forward loss of balance.

We assessed the effects of a passive, back-support exoskeleton (BSE) on lower-limb joint kinetics during the initiation and swing phases of recovery from a forward loss of balance. Sixteen (8M, 8F) young, healthy participants were released from static forward-leaning postures and attempted to recover their balance with a single-step while wearing a BSE (backXTM) with different levels of support torque and in a control condition. The BSE provided âˆ¼ 15-20 Nm of external hip extension torque on the stepping leg at the end of initiation and beginning of swing phases. Participants were unable to generate sufficient hip flexion torque, power, and work to counteract this external torque, although they sustained hip flexion torque for a more prolonged period, resulting in slightly increased hip contribution to positive leg work (compared to control). However, net positive leg work, and the net contribution of hip joint (human + BSE) to total leg work decreased with BSE use. While all participants had changes in hip joint kinetics, a significant compensatory increase in ankle contribution to positive leg work was observed only among females. Our results suggest that BSE use adversely affects reactive stepping by decreasing the stepping leg kinetic energy for forward propulsion, and that the relative contributions of lower-limb joints to total mechanical work done during balance recovery are altered by BSE use. BSEs may thus need to be implemented with caution for dynamic tasks in occupational settings, as they may impair balance recovery following a forward loss of balance.

Associating white matter microstructural integrity and improvements in reactive stepping in people with Parkinson's Disease.

Reactive steps are rapid responses after balance challenges. People with Parkinson's Disease (PwPD) demonstrate impaired reactive stepping, increasing fall-risk. Although PwPD can improve steps through practice, the neural mechanisms contributing to improved reactive stepping are poorly understood. This study investigated white-matter correlates of responsiveness to reactive step training in PwPD. In an eighteen-week multiple-baseline study, participants (n = 22) underwent baseline assessments (B1 and B2 two-weeks apart), a two-week training protocol, and post-training assessments immediately (P1) and two-months (P2) post-training. Assessments involved three backward reactive step trials, measuring anterior-posterior margin of stability (AP MOS), step length, and step latency. Tract-Based Spatial Statistics correlated white-matter integrity (fractional anisotropy (FA) and radial diffusivity (RD)) with retained (P2-B2) and immediate improvements (P1-B2) in stepping. Significant and sustained improvements in step length and AP MOS were observed. Greater retention of step length improvement correlated with increased FA in the left anterior thalamic radiation (ATR), left posterior thalamic radiation (PTR), left superior longitudinal fasciculus (SLF), and right inferior longitudinal fasciculus (ILF). Step latency retention was associated with lower RD in the left posterior corona radiata and left PTR. Immediate improvements in AP MOS correlated with increased FA of the right ILF, right SLF, and right corticospinal tract. Immediate step length improvements were associated with increased FA in right and left ATR and right SLF. These findings highlight the importance of white-matter microstructural integrity in motor learning and retention processes in PD and could aid in identifying individuals with PD who would benefit most from balance rehabilitation.

Utilising dynamic motor control index to identify age-related differences in neuromuscular control.

PURPOSE: Considering the relationship between aging and neuromuscular control decline, early detection of age-related changes can ensure that timely interventions are implemented to attenuate or restore neuromuscular deficits. The dynamic motor control index (DMCI), a measure based on variance accounted for (VAF) by one muscle synergy (MS), is a metric used to assess age-related changes in neuromuscular control. The aim of the study was to investigate the use of one-synergy VAF, and consecutively DMCI, in assessing age-related changes in neuromuscular control over a range of exercises with varying difficulty. METHODS: Thirty-one subjects walked on a flat and inclined treadmill, as well as performed forward and lateral stepping up tasks. Motion and muscular activity were recorded, and muscle synergy analysis was conducted using one-synergy VAF, DMCI, and number of synergies. RESULTS: Difference between older and younger group was observed for one-synergy VAF, DMCI for forward stepping up task (one-synergy VAF difference of 2.45 (0.22, 4.68) and DMCI of 9.21 (0.81, 17.61), p = 0.033), but not for lateral stepping up or walking. CONCLUSION: The use of VAF based metrics and specifically DMCI, rather than number of MS, in combination with stepping forward exercise can provide a low-cost and easy to implement approach for assessing neuromuscular control in clinical settings.

Created stepping-stone configurations depend on task constraints.

Previous studies have shown that choices about how to configure stepping-stones to be used as playground or exercise equipment reflect a person's action capabilities. In two experiments, we investigated whether choices about how to configure stepping-stones to be used as a path for locomotion additionally reflect the goals for which or the constraints under which the path is to be used. In Experiment 1, participants created stepping-stone configurations (with rubber mats) that would allow them to cross a given space quickly, comfortably, or carefully. Configurations in the "Quickly" condition consisted of fewer mats, and longer mean (linear) distances between mats, and greater "challenge" (relative to maximum stepping distance) than in the other two conditions. In Experiment 2, participants created stepping-stone configurations that would be fun to use or that would be easy to use to cross a given space. Configurations in the "Fun" condition consisted of more mats, longer linear distances between mats, and greater "challenge" than those in the "Easy" condition. Moreover, paths in the "Fun" condition were also wider, longer, and exhibited larger changes in distances and angles between consecutive mats than in the "Easy" condition. The results are discussed both in terms of implications for understanding affordances and for the design of stepping-stone paths.