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Background. The purpose of this study was to determine if the prioritization of postural control over secondary task performance is altered in younger and older adults under different conditions of postural threat. Methods. Fifteen healthy older adults (mean age = 69.53 +/- 5.78) and 15 younger adults (mean age = 22.00 +/- 2.17) performed Brooks' Spatial Letter Task (BST) while standing in four conditions of postural threat. Galvanic skin conductance (GSC) was collected to measure changes in physiological arousal. BST task duration was used to measure changes in cognitive performance, and center of pressure (COP) area was used to determine changes in postural stability across each of the testing conditions. A prioritization index was calculated based on the relative change in BST and COP across testing conditions. This measure was used to quantify changes in the relationship between postural control and secondary task performance under conditions of postural threat. Results. Measures of GSC increased in younger and older adults in response to conditions of increased postural threat. Prioritization index scores revealed that a greater number of older adults than younger adults prioritized postural control over secondary task performance under conditions of increased postural threat. Conclusions. Environmental contexts that alter postural threat may lead to modifications in the prioritization between postural control and secondary task performance among older adults. This relationship may have implications for postural control under situations that do not afford deterioration in secondary task performance. [ABSTRACT FROM AUTHOR]

[Purpose] We document the significant improvement in posturography and spinal deformity by Chiropractic BioPhysics ® (CBP ® ) technique methods. [Participant and Methods] A 78-year-old male presented with 20 years of chronic hip and lower back pain and stiffness. The pain was 5/10 and disability was 38%. The patient also complained of walking difficulty and balance problems. Radiographic assessment demonstrated a significant thoracolumbar kyphosis and anterior C7-S1 sagittal vertical axis (SVA). Force plate posturography showed high centre of pressure (COP) parameter values including the total path length, particularly for the vestibular condition of the modified clinical test of sensory integration and balance (mCTSIB). [Results] The patient was treated with 36 sessions of CBP corrective exercises and spinal traction as well as PowerPlate balance and gait exercises. Assessment after 4-months showed improvements in sleep, pain, disability, and mobility. There was a 79 mm reduction in SVA and improved postural control in many parameters including a 49 cm and 22 cm reduction in COP total path length for the vestibular and visual trials on the mCTSIB, respectively. The pain and disability were reduced to 0/10 and 22%. [Conclusion] This case demonstrates the significant improvement in postural control as quantified by the mCTSIB with the reduction of excessive SVA as demonstrated on post-treatment x-rays., Competing Interests: P.A.O. is a paid consultant for CBP NonProfit, Inc. D.E.H. teaches continuing education conferences to health care providers, is the CEO of Chiropractic BioPhysics, teaches rehabilitation methods, and distributes products for patient rehabilitation to physicians in the USA. W.H.G. and G.M. have no competing interests to declare., (2024©by the Society of Physical Therapy Science. Published by IPEC Inc.)

Smartphones, with embedded accelerometers, may be a viable method to monitor gait variability in the free-living environment. However, measurements estimated using smartphones must first be compared to known quantities to ensure validity. This study assessed the validity and reliability of smartphone-derived gait measures compared to a gold-standard footswitch system during overground walking. Seventeen adults completed three 8-minute overground walking trials during 3 separate visits. The stride time series was calculated as the time difference between consecutive right heel contact events within the footswitch and smartphone-accelerometry signals. Linear (average stride time, stride time standard deviation, and stride time coefficient of variation) and nonlinear (fractal scaling index, approximate entropy, and sample entropy) measures were calculated for each stride time series. Bland-Altman plots with 95% limits of agreement assessed agreement between systems. Intraclass correlation coefficients assessed reliability across visits. Bland-Altman plots revealed acceptable limits of agreement for all measures. Intraclass correlation coefficients revealed good-to-excellent reliability for both systems, except for fractal scaling index, which was moderate. The smartphone system is a valid method and performs similarly to gold-standard research equipment. These findings suggest the development and implementation of an inexpensive, easy-to-use, and ubiquitous telehealth instrument that may replace traditional laboratory equipment for use in the free-living environment.

Background: The nonlinear variability present during steady-state gait may provide a signature of health and showcase one's walking adaptability. Although treadmills can capture vast amounts of walking data required for estimating variability within a small space, gait patterns may be misrepresented compared to an overground setting. Smartphones may provide a low-cost and user-friendly estimate of gait patterns among a variety of walking settings. However, no study has investigated differences in gait patterns derived from a smartphone between treadmill walking (TW) and overground walking (OW)., Research Question: This study implemented a smartphone accelerometer to compare differences in temporal gait variability and gait dynamics between TW and OW., Methods: Sixteen healthy adults (8F; 24.7 ± 3.8 years) visited the laboratory on three separate days and completed three 8-minute OW and three TW trials, at their preferred speed, during each visit. The inter-stride interval was calculated as the time difference between right heel contact events located within the vertical accelerometery signals recorded from a smartphone while placed in participants front right pant pocket during walking trials. The inter-stride interval series was used to calculate stride time standard deviation (SD) and coefficient of variation (COV), statistical persistence (fractal scaling index), and statistical regularity (sample entropy). Two-way analysis of variance compared walking condition and laboratory visits for each measure., Results: Compared to TW, OW displayed significantly (p < 0.01) greater stride time SD (0.014 s, 0.020 s), COV (1.26 %, 1.82 %), fractal scaling index (0.70, 0.79) and sample entropy (1.43, 1.63). No differences were found between visits for all measures., Significance: Smartphone-based assessment of gait provides the ability to distinguish between OW and TW conditions, similar to previously established methodologies. Furthermore, smartphones may be a low-cost and user-friendly tool to estimate gait patterns outside the laboratory to improve ecological validity, with implications for free-living monitoring of gait among various populations., Competing Interests: Declaration of Competing Interest None, (Copyright © 2024 Elsevier B.V. All rights reserved.)

The accelerometers embedded within smartphones may be a promising tool to capture gait patterns outside the laboratory and for extended periods of time. The current study evaluated the agreement and reliability of gait measures derived from a smartphone accelerometer system, compared to reference motion capture and footswitch systems during treadmill walking. Seventeen healthy young adults visited the laboratory on three separate days and completed three 8-minute treadmill walking trials, during each visit, at their preferred walking speed. The inter-stride interval series was calculated as the time difference between consecutive right heel contacts, located within the signals of the smartphone accelerometer, motion capture, and footswitch systems. The inter-stride interval series was used to estimate common linear gait measures and nonlinear measures, including fractal scaling index, approximate entropy, and sample entropy. Bland Altman plots with 95% limits of agreement and intraclass correlation coefficients assessed agreement and reliability, respectively. The smartphone system was found to be within the acceptable limits of agreement when compared to either reference system. The intraclass correlation coefficients values revealed moderate-to-excellent reliability for the smartphone system, with greater reliability found for linear compared to nonlinear measures and were similar to both reference systems, except for the fractal scaling index. These findings suggest the smartphone accelerometer system is a valid and reliable method for estimating linear and nonlinear gait measures during treadmill walking., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Balance-correcting responses are fast, accurate, and functionally- and directionally-specific. However, there remains a lack of clarity in the literature as to how balance-correcting responses are organized, perhaps due to use of various perturbation methods. This study investigated the differences in neuromuscular organization of balance-correcting responses induced with platform-translation (PLAT) and upper body cable-pull (PULL) methods. Healthy males ( n  =  15; age: 24.3 ± 3.0 years) underwent unexpected forward and backward PLAT and PULL perturbations of equivalent intensity. EMG of leg, thigh, and trunk anterior and posterior muscles was recorded bilaterally during forward-stepping trials. Muscle activation latencies were calculated with respect to perturbation initiation. Repeated measures ANOVAs tested for differences in muscle activation latencies between perturbation methods and body sides (anterior/posterior muscles, swing/stance limb sides); Holm-Bonferroni sequentially rejective procedure adjusted alpha during multiple comparisons. Anterior muscle activation latencies were similar between methods (∼210 ms). During PLAT trials, posterior muscles demonstrated symmetrical distal-proximal activation between 70 ms and 260 ms, bilaterally. During PULL trials, stance-limb side posterior muscles demonstrated proximal-distal activation 70-130 ms; the activation latencies (∼80 ms) were not different between the stance-limb side posterior muscles. Previous examinations of method comparisons have examined results across publications, and generally have not accounted for different stimulus characteristics. This study revealed markedly different neuromuscular organization of balance-correcting responses to two different perturbation methods that utilized, importantly, equivalent perturbation intensity. Interpretation of functional balance recovery responses requires clear understanding of the intensity and nature of the perturbation., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (©2023PublishedbyElsevierLtd.)

Current research is unclear with respect to whether pole walking (PW) reduces lower limb loading when compared to regular walking (RW). Contradictory findings in the literature may be related to the relative timing between pole and foot contact events, which were examined in the current study among naïve pole walkers. Fourteen young (4 F; 25.3 ± 5.4 years) and 8 older adults (4 F; 68.5 ± 3.2 years) performed PW and RW trials along a force plate embedded walkway at two different visits. The time difference between pole and foot contact during both the onset of ground contact and the peak force application was calculated. Several kinetic measures were calculated for the lower limbs and poles. A significant decrease during PW, compared to RW, was found for foot impulse (2.1%; p < 0.01), peak vertical ground reaction force (vGRF) (3.4%; p < 0.01), rate of loading (5.2%; p =0.02), and peak push-off vGRF (2.1%; p =0.01). No difference in pole loading was found between age groups and visits. No significant correlations were found between the relative timing and foot loading measures. Significant low-to-moderate negative correlations were found between peak foot and pole vGRFs ( p =0.04), peak foot vGRF and pole strike impulse ( p =0.01), peak foot vGRF and pole impulse ( p =0.02), and peak foot push-off vGRF and pole impulse ( p =0.01), suggesting that as pole loading increased, foot loading decreased. Findings suggest timing between pole and heel contact may not be related to unloading the lower limbs but may be related to other aspects of pole use since PW reduced lower limb loading., Competing Interests: The authors have no conflicts of interest to declare., (Copyright © 2022 Vincenzo E. Di Bacco et al.)

Negative age-stereotypes can have widespread effects on older adult functionality; however, no research has explored psychophysical aspects of stair navigation after exposure to stereotype priming. The present study examined self-efficacy and biomechanics related to stair navigation in older adults ( N = 90). Between-groups analyses revealed positively primed older adults ascended and descended the stairs significantly faster with greater velocity in the medio-lateral plane than older adults who received a negative prime or controls ( p < .017). Moreover, negatively primed older adults rated their stair self-efficacy significantly lower compared with the control and positively primed groups ( p < .017). These results suggest positively primed older adults can navigate stairs with more confidence, quickness, and efficiency. With implications for interventions aimed at maintaining older adult functionality, the present study highlights the potential benefits of positive age-stereotypes, especially related to challenging physical tasks.

Identifying the optimal approach for motivating faculty to adopt teaching innovation is important, given that broad-scale initiatives can utilize an inordinate amount of time and resources. Using a quantitative approach, we evaluate policy actions that are most strongly associated with the adoption of either e-learning or community-focused experiential learning, over a five-year period in a single institution. Comparisons between adopters and non-adopters affirm the relevance of previously documented facilitators and barriers. However, a logistic regression analysis demonstrates that actions that promote a supportive institutional culture (such as, an institutional plan, committee involvement, professional development and logistical support) as well as faculty perceptions and beliefs (i.e., "using new methods is not risky for student learning"; confidence and self-efficacy with respect to implementation), is strongly associated with the adoption of either e-learning ( n = 118) or community-focused experiential learning ( n = 97). In contrast, funding and professional dimensions (i.e., workload, historical precedence, and the institutional promotion of the innovation with respect to academic freedom) is weakly associated with adoption. The results not only provide a fine-grained analysis of current assumptions regarding the necessary conditions for implementing organizational change in the university context, but also suggest an approach that reinforces and sustains the adoption of teaching innovation over the long term. Theoretical and practical implications are discussed in reference to models of organizational change, faculty motivation and approaches to institutionalizing teaching innovation., Competing Interests: The authors declare no conflict of interest., (© 2021 The Author(s).)

The understanding of reactive balance control mechanisms in humans emanates from studies utilizing a variety of perturbation methods, instructions, and sensory conditions. The use of different perturbation methods may produce method-specific balance-correcting responses. This study evaluated balance-correcting responses induced with platform-translation and shoulder-pull methods with equilibrated perturbation intensities, and whether the absence of vision affects balance-correcting responses differently between perturbation methods. Fifteen healthy young males participated. Unexpected forward and backward platform-translation and shoulder-pull perturbations were induced with eyes-open and eyes-closed. Participants were asked to behave naturally. Forward stepping trials were analyzed. Margin of stability (MOS) was calculated from the position data of reflective markers placed strategically around the body. MOS was reported at step onset and at foot contact. MOS was smaller at step onset (0.01 ± 0.01 m) and at foot contact (0.09 ± 0.01 m) during platform-translation trials and at both time points during shoulder-pull trials (0.04 ± 0.01 m and 0.17 ± 0.01 m, respectively). The absence of vision did not affect MOS at step onset. At foot contact during platform-translation with eyes-closed MOS was larger (0.11 ± 0.01 m) than with eyes-open (0.08 ± 0.01 m), but not different between eyes-open (0.17 ± 0.01 m) and eyes-closed (0.18 ± 0.01 m) during shoulder-pull. Participants required a second step to recover balance in 14% of the platform-translation and 3% of the shoulder-pull trials. During platform-translation trials participants demonstrated smaller MOS which placed them in a less favorable circumstance for balance recovery. Platform-translation appears to be more challenging than shoulder-pull perturbation in terms of balance recovery. This study underscores that caution is required when interpreting results of studies utilizing different perturbation paradigms., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Study Design: Descriptive phenomenological approach., Objectives: This study explored the lived experience of sexuality for men after spinal cord injury (SCI) and described the current state of tools and resources available to assist with sexual adjustment from the perspective of men living with SCI., Setting: Men living in the community in Ontario, Canada., Methods: Six men (age 24-49 years) with complete or incomplete SCI (C4-T12; <1-29 years post injury) participated in one individual, in-depth, standardized, open-ended interview (68-101 min). Analysis was conducted using Giorgi's method, and involved within case analysis followed by cross-case analysis., Results: All participants reported that resources available to support sexual adjustment after SCI were inadequate, and the majority of men felt their healthcare providers lacked knowledge regarding, and comfort discussing sexuality after SCI. Men reported sexuality was not a priority of the rehabilitation centers and felt that healthcare providers did not understand the importance of addressing sexuality. Existing resources were described as too clinical and not necessarily relevant given changes in sensation and mobility post injury. Participants provided recommendations for the effective delivery of relevant sexual education information., Conclusions: To improve quality of life for men after SCI, suitable resources must be available to support sexual rehabilitation post injury. Future research should focus on developing strategies to facilitate discussions about sexuality between individuals with SCI and healthcare providers, and on developing resources that are effective and relevant for these men.

Background: Experts of the Krav Maga (KM) self-defense system propose that KM techniques are based on simple body movements which are suggested to be learned rapidly and retained. This study investigated the acquisition, retention, and further improvement with additional training of two KM strike techniques among novice female practitioners: straight punch and defensive kick., Methods: Sixteen healthy females (age: 23 ± 3.7 years) without any previous martial arts/self-defense experience volunteered to participate. All participants received an initial 30-min instruction session (AQ), taught by a certified KM instructor, where each technique was deconstructed into three checkpoints (defined as a component of the entire movement) for learning. Participants were divided into two groups, one of which received additional training. Several kinematic and kinetic measures were recorded at four timepoints: immediately before AQ, immediately after AQ, 5 days after AQ, and 12 days after AQ., Results: Results suggest that both techniques were learned rapidly, as checkpoint performance was significantly improved after AQ. Kick velocity and impact force also increased significantly after AQ; however, these measures did not change after AQ for the punch technique. Additional training did not improve either punch or kick performance beyond that learned during AQ., Conclusion: The findings from this study suggest that a single training session may be sufficient to learn and retain KM strike techniques relatively permanently; and the acquisition of the kick technique may lead to concomitant improvements in kick velocity and impact force., Competing Interests: The authors declare that they have no competing interests., (© 2020 Di Bacco et al.)

Variability in the temporal structure of gait patterns, measured by "Fractal Index" (FI), is thought to represent abundancy of movement patterns facilitating adaptive control of walking. However we do not know how FI changes according to different walking rhythms or if this is repeatable, as needed to exploit the paradigm for rehabilitation. Fourteen healthy young adults synchronised heel contact to an auditory metronome twice each in four conditions (uncued, white noise, pink noise, and red noise) and three sessions. FI differed based on the walking condition while no effect of session was revealed. The results of this study suggest gait fractality changes systematically with different stimuli and can be consistently prescribed in a desired direction within a group of healthy young individuals.

The type of balance recovery, feet-in-place or stepping, is predicated on the perturbation intensity, often defined by the combination of applied force and displacement. Few studies examined the relationship between characteristics required to produce a stepping response with one of the postural perturbation methods. The purpose of this study was to investigate the relationship between perturbation characteristics (applied force and displacement) required to elicit a forward stepping response with platform-translation and shoulder-pull methods, and to establish whether a common set of perturbation characteristics existed across both perturbation methods. Fourteen young healthy males participated. Temporally unexpected platform translations and shoulder pulls were induced by release of free weights, which fell a controlled height exerting a pull on the platform or on the participant via a shoulder harness. Participants responded with either feet-in-place or stepping responses. The force and displacement were varied to investigate the range of force-displacement combinations required to elicit stepping responses. Force-displacement combinations that elicited stepping responses were recorded and normalized to the participant's body weight (BW) and the base of support (BOS; participant's foot length). The lowest force and associated displacement that elicited stepping responses showed an inverse linear relationship during both platform-translation and shoulder-pull trials. The lowest force-displacement combination common to both perturbation methods was found to be 8.75%BW and 105%BOS, which, in the future work, could enable a direct comparison of the neuromuscular and biomechanical responses to different perturbation methods in a manner that attempts to equilibrate the perturbation stimulus across the methods., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

While physical activity is increasingly promoted for older adults, there is a paucity of sport promotion, which has distinct benefits from exercise and remains stereotypically associated with younger age. Curling is a moderately intense and safe sport that continues to gain popularity; however, no research has investigated psychophysical benefits of curling for older adults. The present study compares high-experience (20+ years; n = 63) and low-experience (<20 years; n = 53) curlers (aged 60+ years) with older adult noncurlers (n = 44) on measures of daily functionality, balance confidence, and perceptions of the aging process. While no significant differences were found between high- and low-experience curlers, any level of experience reported significantly better functionality, physical confidence, and aging attitudes compared to noncurlers (p ≤ .05). Although further research is necessary, the results suggest that any level of curling experience can enhance older adult psychophysical well-being, and warrants consideration for physical activity promotion and falls prevention programs.

Background: Mechanical loading during exercise has been shown to promote tissue remodeling. Safe and accessible exercise may be beneficial to populations at risk of diminished bone and joint health. We examined the effect of drop height and instruction on knee loading during a drop-landing task and proposed a task that makes use of drop heights that may be appropriate for rehabilitation purposes and functional in daily life to examine transient knee joint loads., Methods: Twenty males (22.0 ± 2.8 years) performed drop landings from 22 cm (low) and 44 cm (high) heights, each under three instructions: "land naturally" (natural), "softly" (soft), and "stiffly" (stiff). Knee compression force and external flexion moment were estimated using three-dimensional inverse dynamics and normalized to body mass., Results: Peak knee compression force was larger (p < 0.001) for high (17.8 ± 0.63 N/kg) than low (14.8 ± 0.61 N/kg) heights. There was an increase (p < 0.001) in the knee compression force across soft (11.8 ± 0.40 N/kg), natural (17.0 ± 0.62 N/kg), and stiff (20.2 ± 0.67 N/kg) instructions. Peak knee flexion moment in high-natural (2.12 ± 0.08 Nm/kg) was larger (p < 0.001) than in high-soft (1.88 ± 0.08 Nm/kg), but lower than in high-stiff (2.23 ± 0.08 Nm/kg). No differences in peak knee flexion moment were observed across instructions for the low height., Conclusions: We propose a drop-landing task that creates a scalable increase in knee compression loading. The absence of increased knee flexion moment with drop from the low height, compared to high, suggests that individuals could perform the task without incremental risk of knee injury. This task could be used in future studies to examine the effect of acute bouts of mechanical loading on bone and cartilage metabolism.

Background: Balance impairments, falls, and spasticity are common after stroke, but the effect of spasticity on balance control after stroke is not well understood., Methods: In this cross-sectional study, twenty-seven participants with stroke were divided into two groups, based on ankle plantar flexor spasticity level. Fifteen individuals with high spasticity (Modified Ashworth Scale (MAS) score of ≥2) and 12 individuals with low spasticity (MAS score <2) completed quiet standing trials with eyes open and closed conditions. Balance control measures included centre of pressure (COP) root mean square (RMS), COP velocity, and COP mean power frequency (MPF) in anterior-posterior and mediolateral (ML) directions. Trunk sway was estimated using a wearable inertial measurement unit to measure trunk angle, trunk velocity, and trunk velocity frequency amplitude in pitch and roll directions., Results: The high spasticity group demonstrated greater ML COP velocity, trunk roll velocity, trunk roll velocity frequency amplitude at 3.7 Hz, and trunk roll velocity frequency amplitude at 4.9 Hz, particularly in the eyes closed condition ( spasticity by vision interaction). ML COP MPF was greater in the high spasticity group., Conclusion: Individuals with high spasticity after stroke demonstrated greater impairment of balance control in the frontal plane, which was exacerbated when vision was removed.

The current study quantified lumbar loading while carrying an anterior load mass and navigating an obstacle. Eight healthy male participants walked down a walkway and crossed an obstacle under three randomised LOAD conditions; empty-box (2 KG), five kilogram (5 KG) and ten kilogram (10 KG). Each walk was assessed at two events: left foot mid-stance (LMS) and right toe-crossing (TC) to characterise any changes from approach to crossing. Measures of interest included: trunk pitch, L4/L5 joint moment, compression, joint anterior-posterior shear and erector spinae activation. Findings demonstrate that obstacle crossing extended posture by 50, 41, 44%, respectively for each carried load magnitude. Further, these results indicate that shear rather than compressive loading may be an important consideration during crossing due to increase by 8, 9, 22% from LMS to TC for each load magnitude tested. These results provide insight into sagittal lumbar loading when navigating an obstacle while carrying a load. Practitioner Summary: The risk of carrying while navigating obstacles on the lumbar spine is not completely understood. The forces at the lumbar spine while simultaneously carrying and obstacle crossing were analysed. Data indicate that carrying and obstacle crossing influence lumbar shear loads, thereby moderately increasing the relative risk at lumbar spine.

Objective: To develop a video-based system, mounted on a rollator to quantify the step width values of rollator users in the community., Subjects: A total of 5 able-bodied young adults, age range 24-28 years., Methods: A digital video camera system was mounted on the rollator frame to capture the position of the participant's feet during overground walking. A method of estimating step width from the video data was developed and evaluated against the output from a concurrently recording Vicon MX motion capture system., Results: Mean step widths of the rollator and motion capture systems were 14.40 cm (standard deviation (SD) 4.64) and 14.37 cm (SD 4.34), respectively, revealing a strong level of agreement; intra-class correlation coefficient 0.999 (95% confidence interval (95% CI) 0.987-1.000; and root-mean-square difference 0.70 cm., Conclusion: The video-based system mounted on a rollator to collect foot placement data enabled accurate measurement of step width during rollator use. The ability to record foot placement measurements outside the laboratory setting, characterizing foot placement patterns occurring in the community, will enable research into how these assistive devices influence mobility during everyday use.

Force plate targeting has been referenced as a confounding factor in gait research, but the literature is sparse. Asking participants to target force plates is a convenient strategy to increase the number of acceptable trials, but may inadvertently alter the motor control of gait and limit external validity. This study aimed to investigate the effect of visual targeting on spatiotemporal, kinematic, and kinetic measures of gait and their variability. Young healthy participants were asked to traverse a walkway with three embedded hidden force plates. Starting from a participant-specific initial position and leading with the same foot each time, participants performed series of natural walking trials (no targeting and unaware of the hidden force plates), followed by targeting walking trials. For the targeting trials, participants were asked to step completely within the bounds of a tape outline (∼50cm×45cm), which coincided with the position of the last hidden force plate. The results demonstrated evidence of targeting during targeting trials; compared to natural walking trials, mean heel-target distance variability for targeting trials decreased progressively for the steps approaching the targeting step, reaching significance (p<0.05) for the target (41%), and post-target steps (39%). Despite visual targeting, no significant differences between targeting and natural trials were detected in spatiotemporal, kinematic, and kinetic gait measures, or the variability of the measures. When the experimental set-up was tailored to the individual participant's gait variables (step/stride length), visual targeting of the force plates appeared to have no effect on the magnitude or variability of any gait measures., (Copyright © 2014 Elsevier B.V. All rights reserved.)

While assisting with balance is a primary reason for rollator use, few studies have examined how the upper limbs are used for balance. This study examines upper limb contributions to balance control during rollator-assisted walking. We hypothesized that there would be an increased upper limb contribution, measured by mean vertical loading (Fz) and variation in frontal plane center-of-pressure (COPhigh), when walking balance is challenged/impaired. Experiment 1 compared straight-line and beam-walking in young adults (n = 11). As hypothesized, Fz and COPhighincreased in beam-walking compared to baseline (mean Fz: 13.7 vs. 9.1% body weight (BW), p < 0.001, RMS COPhigh: 1.35 vs. 1.07 cm, p < 0.001). Experiment 2 compared older adults who regularly use rollators (RU, n = 10) to older adult controls (CTL, n = 10). The predicted higher upper limb contribution in the RU group was not supported. However, when individuals were grouped by balance impairment, those with the lowest Berg Balance scores (< 45) demonstrated greater speed-adjusted COPhigh than those with higher scores (p = 0.013). Furthermore, greater COPhigh and Fz were correlated to greater reduction in step width, supporting the role of upper limb contributions to frontal plane balance. This work will guide studies assessing reliance on rollators by providing a basis for measurement of upper limb balance contributions.

Background: The purpose of this study was to describe professional soccer players' perceptions towards injuries, physical recovery and the effect of surface related factors on injury resulting from soccer participation on 3rd generation artificial turf (FT) compared to natural grass (NG)., Methods: Information was collected through a questionnaire that was completed by 99 professional soccer players from 6 teams competing in Major League Soccer (MLS) during the 2011 season., Results: The majority (93% and 95%) of the players reported that playing surface type and quality influenced the risk of sustaining an injury. Players believed that playing and training on FT increased the risk of sustaining a non-contact injury as opposed to a contact injury. The players identified three surface related risk factors on FT, which they related to injuries and greater recovery times: 1) Greater surface stiffness 2) Greater surface friction 3) Larger metabolic cost to playing on artificial grounds. Overall, 94% of the players chose FT as the surface most likely to increase the risk of sustaining an injury., Conclusions: Players believe that the risk of injury differs according to surface type, and that FT is associated with an increased risk of non-contact injury. Future studies should be designed prospectively to systematically track the perceptions of groups of professional players training and competing on FT and NG.

Despite the importance of regaining independent ambulation after stroke, the amount of daily walking completed during in-patient rehabilitation is low. The purpose of this study is to determine if (1) walking-related heart rate responses reached the minimum intensity necessary for therapeutic aerobic exercise (40%-60% heart rate reserve) or (2) heart rate responses during bouts of walking revealed excessive workload that may limit walking (>80% heart rate reserve). Eight individuals with subacute stroke attending in-patient rehabilitation were recruited. Participants wore heart rate monitors and accelerometers during a typical rehabilitation day. Walking-related changes in heart rate and walking bout duration were determined. Patients did not meet the minimum cumulative requirements of walking intensity (>40% heart rate reserve) and duration (>10 minutes continuously) necessary for cardiorespiratory benefit. Only one patient exceeded 80% heart rate reserve. The absence of significant increases in heart rate associated with walking reveals that patients chose to walk at speeds well below a level that has meaningful cardiorespiratory health benefits. Additionally, cardiorespiratory workload is unlikely to limit participation in walking. Measurement of heart rate and walking during in-patient rehabilitation may be a useful approach to encourage patients to increase the overall physical activity and to help facilitate recovery.

Purpose: The objective of this study was to investigate the relationship between medio-lateral foot placement characteristics and environmental context when individuals with Multiple Sclerosis (MS) walk with a rollator (four-wheeled walker)., Method: Ten women diagnosed with MS, who used rollators regularly, participated in this study. First, a rollator-based technique of calculating step width (SW) was validated in this patient population by comparing the output of an instrumented rollator (iWalker) to a laboratory-based Vicon Motion Capture System. Secondly, the iWalker-based technique was used to calculate the participants' SW and SW variability as they used the iWalker in four common outdoor community environments., Results: There was a strong level of agreement between the iWalker and Vicon SW calculations, with an intra-class correlation coefficient of 0.993 and a root-mean-square difference of 0.71 cm. Furthermore, SW variability (P = 0.002), but not SW (P = 0.288), was influenced by the walking environment (i.e. between the in-lab vs. up-ramp and up-ramp vs. down-ramp conditions)., Conclusions: Foot placement variability appears to be influenced by the walking environment of MS patients. Therefore, an enhanced understanding of walker-user interactions in relation to the environment must be established in order to improve mobility.

Background: Ankylosing spondylitis is a chronic inflammatory disorder that can lead to increased axial and peripheral joint stiffness, impairing joint mobility. Impaired axial mobility due to vertebral ankylosis may result in changes in standing postural control. Little research has addressed changes in standing postural control in the ankylosing spondylitis population, nor how these issues might affect clinical understanding and treatment., Methods: Sixteen ankylosing spondylitis patients, and 17 healthy controls participated. Each individual completed two 120-second quiet standing trials with eyes open and eyes closed, while standing upon two force platforms. Net center of pressure displacement and mean power frequency in the frontal and sagittal planes were calculated. A Spearman's rank correlation analysis was performed between net center of pressure measures and several clinical measures of disease activity., Findings: Frontal plane net center of pressure displacement and frequency content, and sagittal plane net center of pressure displacement were significantly greater within the ankylosing spondylitis patient group. Ankylosing spondylitis patients demonstrated a significant increase in frontal plane net center of pressure displacement in the eyes-closed condition. Net center of pressure displacement and frequency were significantly correlated to the Bath Ankylosing Spondylitis Functional Index, and individual components of the Bath Ankylosing Spondylitis Metrology Index., Interpretation: Quiet standing postural control was altered particularly so in the frontal plane in patients with ankylosing spondylitis, which may be associated with increased fall risk. Posturographic measures of postural control may serve as valuable clinical tools for the monitoring of disease progression and disease status in ankylosing spondylitis., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Despite widespread acceptance of clinical benefits, empirical evidence to evaluate the advantages and limitations of ambulation aids for balance control is limited. The current study investigates the upper limb biomechanical contributions to the control of frontal plane stability while using a 4-wheeled walker in quiet standing. We hypothesized that: (1) upper limb stabilizing moments would be significant, and (2) would increase under conditions of increased stability demand. Factors influencing upper limb moment generation were also examined. Specifically, the contributions of upper limb center-of-pressure (COP(hands)), vertical and horizontal loads applied to the assistive device were assessed. The results support a significant mechanical role for the upper limbs, generating 27.1% and 58.8% of overall stabilizing moments under baseline and challenged stability demand conditions, respectively. The increased moment was achieved primarily through the preferential use of phasic upper limb control, reflected by increased COP(hands) (baseline vs. challenged conditions: 0.29 vs. 0.72cm). Vertical, but not horizontal, was the primary force direction contributing to stabilizing moments in quiet standing. The key finding that the upper limbs play an important role in effecting frontal plane balance control has important implications for ambulation aid users (e.g., elderly, stroke, and traumatic brain injury)., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Background: Promoting whole body activities, such as walking, can help improve recovery after stroke. However, little information exists regarding the characteristics of daily walking in patients enrolled in rehabilitation poststroke. The objectives of this study were to: (1) examine the quantity of walking and duration of individual bouts of walking during an inpatient day, (2) compare standard laboratory symmetry measures with measures of symmetry captured throughout the day, and (3) investigate the association between quantity of walking and indices of stroke severity., Methods: The study examined ambulatory activity among 16 inpatients with subacute stroke who were bilaterally instrumented with a wireless accelerometer above the ankle for approximately 8 continuous hours., Results: On average, patients demonstrated 47.5 minutes (standard deviation [SD] = 26.6 minutes) of total walking activity and walking bout durations of 54.4 s (SD = 21.5 s). A statistically significant association was found between the number of walking bouts to total walking time (r = .76; P = .006) and laboratory gait speed (r = .51; P = .045) and between laboratory gait speed and balance impairment (r = .60; P = .013). Also, a significant increase in gait asymmetry was observed during day-long measurement compared with the standard laboratory-based assessment (P = .006)., Conclusions: Rather modest amounts of daily walking were found for these ambulatory inpatients, consistent with previous reports about patients after stroke. Bouts of walking were short in duration, and the gait was more asymmetrical, compared with a standard gait assessment. Unobtrusive monitoring of daily walking exposes the characteristics and temporal qualities of poststroke ambulation.

The extent to which different locomotor tasks require cognitive control is not well characterized. In this article, the authors consider the potential increase in attentional demands associated with carrying an anterior load while clearing an obstacle. Nine healthy male volunteers participated in 80 walking trials, 20 in each of 4 conditions: 1 no load condition (NL) and 3 carrying conditions (2KG, 5KG, and 10KG). Of the 20 trials in each condition, 12 included a probe reaction time (PRT) test during lead limb obstacle crossing, which was used to measure cognitive load. A load-dependent increase in PRT was observed, with PRT in the 2KG condition being significantly greater than in the NL condition, and PRT in the 5KG and 10KG conditions being significantly greater than in the 2KG condition. These results suggested that cognitive load was increased when: (a) the obstacle was occluded from vision by the load, and (b) the magnitude of load was increased.

Background: There is little information about the quality of gait in the years following stroke. Long-term changes in mobility, using global indices of function, suggest a decline well after initial rehabilitation. However, global indices of mobility do not reveal more specific changes in walking competency or underlying gait-specific impairment., Objectives: The authors used a cross-sectional design with gait-specific measures (velocity and symmetry) to investigate whether deterioration in gait occurs over the long term poststroke., Methods: Data were abstracted from a standardized database containing clinical assessments and spatiotemporal gait analyses for 171 individuals with stroke. Velocity and 3 expressions of symmetry ratios (swing time, stance time, and step length) were calculated for each individual; they were then assigned to 1 of the 5 following groups: 0 to 3, 3 to 12, 12 to 24, 24 to 48, and >48 months poststroke., Results: Swing time, stance time, and step length symmetry demonstrated a systematic linear trend toward greater asymmetry in groups in the later stages poststroke, whereas velocity, neurological deficit, and lower-extremity (LE) motor impairment did not., Conclusions: The quality of gait, as measured by spatial and temporal symmetry, appears to worsen in later years. These results suggest a dissociation between quantitative measures of gait, such as velocity versus symmetry, and that these parameters may measure independent features. A longitudinal study is needed to confirm the presence and to interpret the clinical meaning of a long-term decline in specific parameters of poststroke gait.

The purpose of this study was to assess the effect of anterior load carriage on obstacle-crossing behaviour, with a focus on lower limb gait parameters. Nine male participants (age 23+/-1.8 years, height 176+/-5.0cm) volunteered. Participants either walked without a load (No Load), or carried a load (2KG (empty box), 5KG, 10KG), and stepped over a 20cm obstacle. Vision of the obstacle was obscured 1.0m to 1.3m prior to the obstacle. Significant correlations were found between trail limb toe distance and lead limb toe clearance, in the 2KG, 5KG, and 10KG conditions. Toe clearance increased with load (No Load, 147.3+/-13.9mm; 2KG, 162.5+/-15.6mm; 5KG, 167.6+/-17.6mm; 10KG, 173.9+/-17.5mm; p<0.0001). Trail limb toe distance, trail limb toe distance variability, lead heel distance variability, and lead limb toe clearance variability were greater in the 2KG, 5KG, and 10KG conditions, compared with the No Load condition. Participants adopted a conservative gait pattern during obstacle crossing when carrying a load, evidenced by increasing toe clearance, which may have been influenced by availability of visual information regarding obstacle position. In contrast with previous literature, increased lead limb toe clearance may have been associated with absence of relative surface height difference pre- and post-obstacle crossing., (Copyright 2010 Elsevier B.V. All rights reserved.)

Symmetry is a gait characteristic that is increasingly measured and reported, particularly in the stroke patient population. However, there is no accepted standard for assessing symmetry making it difficult to compare across studies and establish criteria to guide clinical decision making. This study compares the most common expressions of spatiotemporal gait symmetry to describe post-stroke gait and makes recommendations regarding the most suitable measure for standardization. The following symmetry equations were compared: symmetry ratio, symmetry index, gait asymmetry and symmetry angle using step length, swing time, stance time, double support time and an intra-limb ratio of swing: stance time. Comparisons were made within a group of 161 community-dwelling, ambulatory individuals with stroke and 81 healthy adults as a reference group. Our analysis supports the recommendations of the symmetry ratio as the equation for standardization and step length, swing time and stance time as the gait parameters to be used in the equation. Future work should focus on establishing the intra-individual variability of these measures and linking them to mechanisms of gait dysfunction., (Copyright 2009 Elsevier B.V. All rights reserved.)

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. Patients demonstrated changes in onset latency of rectus femoris and gluteus medius, and in amplitude of muscle activity in tibialis anterior, gastrocnemius, rectus femoris, and gluteus medius, for both perturbation directions, and for both the surgical and sound limbs. Peak knee joint angular velocity was reduced among the patients for both perturbation directions and both the surgical and sound limbs, and patients demonstrated greater peak center of mass displacement. The CNS appears to alter the response to postural perturbation of both lower limbs, based on the reduced capacities of the surgical limb. Impaired detection of the valgus-varus loading of the knee joints may lead to the changes in muscle activity and resultant kinematics. Clinically, these findings are relevant in understanding that fully recovered TKA patients may continue to demonstrate balance impairments, and that balance training during physical rehabilitation may be advantageous to these patients.

Background: There is an important need to better understand the activities of individual patients with stroke outside of structured therapy since this activity is likely to have a profound influence on recovery. A case-study approach was used to examine the activity levels and associated physiological load of patients with stroke throughout a day., Methods: Activities and physiologic measures were recorded during a continuous 8 hour period from 4 individuals in the sub-acute stage following stroke (ranging from 49 to 80 years old; 4 to 8 weeks post-stroke) in an in-patient rehabilitation hospital., Results: Both heart rate (p = 0.0207) and ventilation rate (p < 0.0001) increased as intensity of activity increased. Results revealed individual differences in physiological response to daily activities, and large ranges in physiological response measures during 'moderately' and 'highly' therapeutic activities., Conclusion: Activity levels of individuals with stroke during the day were generally low, though task-related changes in physiologic measures were observed. Large variability in the physiological response to even the activities deemed to be greatest intensity suggests that inclusion of such extended measurement of physiologic measures may improve understanding of physiological profile that could guide elements of the physical therapy prescription.

To determine the potential differences in control underlying compensatory and voluntary reach-to-grasp movements the current study compared the kinematic and electromyographic profiles associated with upper limb movement. Postural perturbations were delivered to evoke compensatory reach-to-grasp in ten healthy young adult volunteers while seated on a chair that tilted as an inverted pendulum in the frontal plane. Participants reached to grasp a laterally positioned stable handhold and pulled (or pushed) to return the chair to vertical. The distinguishing characteristic between the two behaviors was the onset latency and speed of movement. Consistent with compensatory balance reactions, the perturbation-evoked reach response was initiated very rapidly (137 vs. 239 ms for voluntary). As well the movement time was shorter, and peak velocity was greater for PERT movements. In spite of the profound differences in timing, the sequence of muscle activity onsets and the order of specific kinematic events were not different between maximum velocity voluntary (VOL) and perturbation-evoked (PERT) reach-to-grasp movements. Peak velocity and grasp aperture occurred prior to hand contact with the target for PERT and VOL movements, and wrist trajectory was influenced by the direction of perturbation relative to the target. To achieve such target specific control for responses initiated within 100 ms of the perturbation, and when characteristics of body movement were unpredictable, the perturbation-evoked movements would need to incorporate sensory cues associated with body movement relative to the target into the earliest aspects of the movement. This suggests reliance on an internal spatial map constructed prior to the onset of perturbation. Parallels in electromyographic and kinematic profiles between compensatory and voluntary reach-to-grasp movements, in spite of temporal differences, lead to the view they are controlled by common neural mechanisms.

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. EMG was collected bilaterally from lower limb muscles. Kinematic data were collected using an OPTOTRAK system. The temporal pattern of muscle activation was preserved in both the surgical and sound limbs of the patient groups, while muscle activation amplitude was reduced. Knee joint angular displacement was reduced in both limbs among patients. COM displacement was not different. Patients demonstrated a different method in recovering posture control following a postural perturbation. Bilateral changes appear to reflect a simplification in the organization of the motor response, in response to the needs of the injured, or previously injured limb.

Movements of the whole-body center of mass during quiet standing have been estimated from measurements of body segment movements. These whole-body center of mass movements have been compared with movements of the center of mass as predicted from a simple inverted-pendulum model of standing. However, the total body center of mass is a weighted average of the center of mass of all individual body segments. The question arises as to how well the total body center of mass represents the individual segments and lower limb joint angles. This study focuses on the validity of how well the individual segments and lower limb angles temporally and spatially synchronize with the total body center of mass. Eleven healthy university students volunteered to participate. Kinematic data were collected using a 3D optoelectronic camera system; kinetic data were collected using a 3D force plate. Participants stood quietly, with eyes open, for 120 s. Segment and whole body centers of mass were calculated from a 14 segment, 3D bilateral model. Segment and joint angles were calculated for the lower limbs, bilaterally, and the trunk. Segment center of mass root-mean-square displacements were strongly correlated with center of mass height relative to the ankle joint and were synchronized, or temporally locked, to the movement of the whole body center of mass. Sagittal plane ankle angular displacements were highly correlated to sagittal plane center of mass movement; stronger correlations between body center of mass and lower limb angular displacement were observed, the result of compensatory knee joint angular displacements. These data support and extend the use of an inverted pendulum model to represent quiet standing postural control.

We tested the hypotheses that: (1) anxiety regarding the possibility of falling alters the attentional demands of gait; and (2) this alteration in the attentional requirements of gait occurs independently of gait pattern accommodations. Sixteen younger and 15 older adults participated in this study. Subjects walked at a self-determined velocity along a 7.2-m walkway under four conditions of postural threat; the walking conditions varied depending on the width constraints of the walkway (60 cm vs 15 cm) and the height of the walking surface (0 cm vs 60 cm). Attentional demands of locomotion in each condition of testing were assessed using the dual-task methodology, in which participants verbally responded to an auditory cue as quickly as possible while continuing to walk. Our findings revealed that: (1) participants were successful in verbally responding to the auditory cue without modifying their gait pattern; (2) reaction times increased for all subjects when walking in the condition of greatest postural threat; (3) the attentional demands for locomotion varied with the phase of the gait cycle for younger adults but not for older adults; (4) the phase-dependent effect for younger adults disappeared in the condition of greatest postural threat, while reaction time scores for older adults systematically increased; and (5) increases in reaction time persisted despite significant changes in gait kinematics. Our findings confirm that anxiety increases the attentional demands for locomotion and provide further explanation for age-dependent increases in the attentional demands of gait. Furthermore, our findings confirm that fall-related anxiety predicates an increase in the allocation of attention to locomotor control that is independent of gait pattern adjustments.

The purpose of this paper is to highlight the motor mechanisms involved in balance as the human, as a biped, continuously defends against gravitational and internal forces to maintain a safe posture. The search for these mechanisms needs precise and valid 3D measurements including both limbs plus valid biomechanical models. The literature shows the need for two force platforms to separate the mechanisms at the ankle and hip (load/unload mechanism). Also, precise measures ( approximately 0.03 mm) of markers on a multi-segment 3D bilateral model are required to record the minute trajectories of all segments and joints. The controlled variable, center-of-mass, is seen to be virtually in phase with the controlling variable, the center-of-pressure, which suggests a 0th order system where a simple series elastic spring could maintain balance. The first model involves a mass/spring/damper of medial/lateral balance: the stiffness was varied with stance width and the predicted sway from a spring controlled inverted pendulum closely matched the experimentally measured stiffness and sway. The second was a non-linear model of the plantarflexor series elastic elements which resulted in three closely validated predictions of anterior/posterior balance: the locus of the gravitational load line, the predicted ankle moment and the ankle stiffness at the operating point.

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. The existence of additional lower limb deficits and adjustments made by unaffected joints to complement these deficits, has yet to be examined., Methods: Joint moments, power and work were calculated using bilateral lower limb force and kinematic data collected during a step-up to heights of 11.25 and 20 cm., Results: Fifty percent of patients were unable to step onto the 20 cm step. At both step heights, when the surgical limb led the step-up, surgical knee work was less than controls. When the non-surgical limb led, deficits in non-surgical lead knee work were observed. In both cases, lead hip work increased., Conclusions: Work done by both surgical and non-surgical knees in a step-up task was lower than that done by healthy controls. This deficit was balanced by increased lead hip extensor work., Relevance: These findings highlight the importance of including exercises that optimize bilateral knee and hip function in rehabilitation programs used following knee replacement. Clinicians working with this population can use this information to assist in the design of evidenced based treatment programs.

We tested the hypothesis that anxiety regarding the potential consequences of a possible fall would alter gait patterns differently between younger and older adults. Sixteen younger and fifteen older adults participated in this study. Participants walked at a self-determined velocity along a 7.2-m walkway under 4 different conditions of postural threat; the walking conditions varied depending on the width constraints of the walkway (0.60 m vs 0.15 m) and the height of the walking surface (floor vs elevated: 0 m vs 0.60 m). Results indicated that although both younger and older adults altered their gait patterns under conditions of increased postural threat, the movement adaptations observed among older adults were substantially different to those adopted by younger adults. These age-dependent differences were strongly evidenced in the joint kinematics and the variability of the gait pattern within each condition. Our findings also indicated that when postural threat increased, the level of muscle activation throughout the gait cycle was altered in the distal musculature (gastrocnemius m. and tibialis anterior m.) among older adults only. Based on the age-related differences observed, we believe that the gait pattern alterations observed among younger and older adults reflect central set modifications to postural control that are mediated by a heightened anxiety imposed by the constraints of the testing conditions. Based on the age-dependent differences in the observed gait pattern modifications, it appears that the effects of anxiety on the control of locomotion are more pervasive for older adults than for younger adults.