Yoked prisms are used by some optometrists to adjust posture, but evidence to support this practi... more Yoked prisms are used by some optometrists to adjust posture, but evidence to support this practice is sparse and low level. The aim of this research was to investigate whether vertical yoked prisms have an impact on posture in healthy adults. Posture was assessed objectively in 20 healthy adults, by recording a range of joint angles or body segment locations at the ankle, hip, torso, neck, and head during participant observation of a straight-ahead target, and subsequently with eyes closed. Recording occurred before, during, and after wearing goggles with control plano lenses, and 5-diopter (D) base-up and 5-D base-down yoked prisms. In each viewing condition, the goggles were worn for 30 minutes. Interaction effects of lens/prism condition by time on joint angles and body orientation were determined. In the eyes-open and eyes-closed conditions, no significant lens/prism × time interaction effects were found at the torso, neck, hip, or ankle (P > 0.1). However, in both eyes-open...
... Visual determinants of instability and falls in older people. Jasmine C Menant, Stuart Smith... more ... Visual determinants of instability and falls in older people. Jasmine C Menant, Stuart Smith & Stephen R Lord Author for correspondence. Sections: ... 26 . Anand V, Buckley J, Scally A, Elliott DB: The effect of refractive blur on postural stability. Ophthalmic Physiol. ...
The aim of this study was to systematically investigate the influence of various walking surfaces... more The aim of this study was to systematically investigate the influence of various walking surfaces and footwear characteristics on the ability to terminate gait rapidly in 10 young and 26 older people. Subjects walked at a self-selected speed in eight randomized shoe conditions (standard versus elevated heel, soft sole, hard sole, high-collar, flared sole, bevelled heel and tread sole) on
Hand grip strength (GS) is a predictor of mortality in older adults and is moderately to highly h... more Hand grip strength (GS) is a predictor of mortality in older adults and is moderately to highly heritable, but no genetic variants have been consistently identified. We aimed to identify single nucleotide polymorphisms (SNPs) associated with GS in middle-aged to older adults using a genome-wide association study (GWAS). GS was measured using handheld dynamometry in community-dwelling men and women aged 55-85 from the Hunter Community Study (HCS, N = 2088) and the Sydney Memory and Ageing Study (Sydney MAS, N = 541). Genotyping was undertaken using Affymetrix microarrays with imputation to HapMap2. Analyses were performed using linear regression. No genome-wide significant results were observed in HCS nor were any of the top signals replicated in Sydney MAS. Gene-based analyses in HCS identified two significant genes (ZNF295, C2CD2), but these results were not replicated in Sydney MAS. One out of eight SNPs previously associated with GS, rs550942, located near the CNTF gene, was significantly associated with GS (p = 0.005) in the HCS cohort only. Study differences may explain the lack of consistent results between the studies, including the smaller sample size of the Sydney MAS cohort. Our modest sample size also had limited power to identify variants of small effect. Our results suggest that similar to various other complex traits, many genetic variants of small effect size may influence GS. Future GWAS using larger samples and consistent measures may prove more fruitful at identifying genetic contributors for GS in middle-aged to older adults.
Poor vision impairs balance and increases the risk of falls and fractures in older people. Multif... more Poor vision impairs balance and increases the risk of falls and fractures in older people. Multifocal glasses can add to this risk by impairing contrast sensitivity, depth perception, and ability to negotiate obstacles. Vision assessment and provision of new spectacles may not reduce, and may even increase, the risk of falls. Restriction of the use of multifocal glasses may reduce falls in active older people. Other effective fall prevention strategies include maximizing vision through cataract surgery and occupational therapy interventions in visually impaired older people.
Although simple assessments of gait speed have been shown to predict falls as well as hospitalisa... more Although simple assessments of gait speed have been shown to predict falls as well as hospitalisation, functional decline and mortality in older people, dual task gait speed paradigms have been increasingly evaluated with respect to fall prediction. Some studies have found that dual task walking paradigms can predict falls in older people. A systematic review and meta-analysis was conducted to determine whether dual task walking paradigms involving a secondary cognitive task have greater ability to predict falls than single walking tasks. The meta-analytic findings indicate single and dual task tests of gait speed are equivalent in the prediction of falls in older people and sub-group analyses revealed similar findings for studies that included only cognitively impaired participants, slow walkers or used secondary mental-tracking or verbal fluency tasks.
Previous research has shown that visuospatial processing requiring working memory is particularly... more Previous research has shown that visuospatial processing requiring working memory is particularly important for balance control during standing and stepping, and that limited spatial encoding contributes to increased interference in postural control dual tasks. However, visuospatial involvement during locomotion has not been directly determined. This study examined the effects of a visuospatial cognitive task versus a nonspatial cognitive task on gait speed, smoothness and variability in older people, while controlling for task difficulty. Thirty-six people aged ≥75 years performed three walking trials along a 20 m walkway under the following conditions: (i) an easy nonspatial task; (ii) a difficult nonspatial task; (iii) an easy visuospatial task; and (iv) a difficult visuospatial task. Gait parameters were computed from a tri-axial accelerometer attached to the sacrum. The cognitive task response times and percentage of correct answers during walking and seated trials were also co...
Background: Unsteady gait and falls are major problems for people with Parkinson's disease (P... more Background: Unsteady gait and falls are major problems for people with Parkinson's disease (PD). Symmetric auditory cues at altered cadences have been used to improve walking speed or step length. However, few people are exactly symmetric in terms of morphology or movement patterns and effects of symmetric cueing on gait steadiness are inconclusive. Objectives: To investigate if matching auditory cue a/symmetry to an individual's intrinsic symmetry or asymmetry affects gait steadiness, gait symmetry, and comfort to cues, in people with PD, healthy age-matched controls (HAM) and young. Methods: Thirty participants; 10 with PD, 11 HAM (66 years), and 9 young (30 years), completed five baseline walks (no cues) and twenty-five cued walks at habitual cadence but different a/symmetries. Outcomes included; gait steadiness (step time variability and smoothness by harmonic ratios), walking speed, symmetry, comfort, and cue lag times. Results: Without cues, PD participants had slower ...
To examine whether arterial stiffness is a risk factor for falls in community-dwelling older peop... more To examine whether arterial stiffness is a risk factor for falls in community-dwelling older people. Prospective cohort study. Community population, Sydney, Australia. Community-dwelling older adults (mean age 79.8±4.4, 52.2% female; N=481). Carotid-femoral pulse wave velocity (PWV) was measured in the supine position after lying for 10 minutes. Demographic, medical, and medication characteristics and levels of physical activity were obtained in clinical interviews and questionnaires, and falls were recorded with monthly falls diaries for 12 months. Participants in the top quintile of PWV (high PWV) were more likely to have higher seated systolic blood pressure (SBP) and heart rate, unsatisfactory control of blood pressure, diabetes mellitus, and lower physical activity levels. These participants were also more likely to be male and taking cardiovascular medications. Of the 473 participants available for follow-up, 212 (44.8%) reported one or more falls. In modified Poisson regressi...
Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference, 2014
An exploratory analysis was conducted into how simple features, from acceleration at the lower ba... more An exploratory analysis was conducted into how simple features, from acceleration at the lower back and ankle during simulated free-living walking, stair ascent and descent, correlate with age, the overall fall risk from a clinically validated Physiological Profile Assessment (PPA), and its sub-components. Inertial data were captured from 92 older adults aged 78-95 (42 female, mean age 84.1, standard deviation 3.9 years). The dominant frequency, peak width from Welch's power spectral density estimate, and signal variance along each axis, from each sensor location and for each activity were calculated. Several correlations were found between these features and the physiological risk factors. The strongest correlations were from the dominant frequency at the ankle along the mediolateral direction during stair ascent (Spearman's correlation coefficient p = - 0.45) with anterioposterior sway, and signal variance of the anterioposterior acceleration at the lower back during stair...
This study investigated the effects of various shoe features and surfaces on step time variabilit... more This study investigated the effects of various shoe features and surfaces on step time variability and pelvis accelerations (RMS) during walking in six younger and 22 older adults. Participants walked at a self-selected speed in five shoe conditions (standard, elevated heel, soft sole, hard sole, and high collar) on two surfaces: level and irregular. Results showed an age-related reduction in step time variability on the irregular surface and increased medio-lateral (ML) acceleration RMS in older people walking on the irregular versus the level surface. When wearing the elevated heel shoes, both young and old participants displayed significant reductions in pelvis ML accelerations, suggesting a compensatory strategy to counteract for lateral instability resulting from heel elevation. Overall, the findings demonstrate that older people are less able than younger ones to meet the stepping adaptability required for negotiating an irregular surface and, as a possible consequence, have more difficulty maintaining frontal plane stability on such a surface.
Although Parkinson&am... more Although Parkinson's disease (PD) is a well recognised risk factor for falls, how this disease and its therapy affect postural stability and leaning balance remains unclear. The aim of this study was to examine the effects of PD and levodopa on postural sway and leaning balance. Performances of 28 PD participants {median [inter-quartile range (IQR)] duration of PD: 10 (6-13) years, median (IQR) UPDRS motor score "off": 22 (14-31) "on" and "off" levodopa were compared with 28 age- and gender-matched healthy controls on two measures of controlled leaning balance [ratio of anterior-posterior (AP) sway to maximal balance range (MBR) and coordinated stability]. PD participants had greater ratio of AP sway to MBR than controls (P < 0.001), indicating that they swayed more as a proportion of their limits of stability, both "off" and "on" levodopa (P < 0.001). They also performed poorer in the coordinated stability test both "off" and "on" levodopa compared to controls (P < 0.001, for both), suggesting greater difficulty in controlling the center of mass at or near the limits of stability. Levodopa improved PD "participants" leaning balance (P < 0.001) and reduced the AP sway to MBR ratio (P < 0.001), although not to the level of controls. PD participants perform poorer than controls in leaning balance tests but significantly improve when "on" levodopa. Regardless of medication state, PD participants sway markedly more as a percentage of their limits of stability than controls suggesting a higher risk of falling.
To identify medical, psychological, and physiological mediators of the relationship between dizzi... more To identify medical, psychological, and physiological mediators of the relationship between dizziness and falls in older adults. Secondary analysis of a prospective cohort study. Community. Five hundred sixteen community-dwelling adults aged 73 to 92. Participants completed questionnaires related to health and psychological well-being and underwent a tilt table blood pressure test, the Physiological Profile Assessment (PPA; vision, reaction time, proprioception, postural sway, and quadriceps strength), and leaning balance tests. Prospective falls data were collected using monthly calendars for 12 months. Participants were categorized into dizzy and nondizzy groups based on self-report of dizziness, vertigo, and light-headedness. Two hundred seventeen (42%) participants reported vertigo or dizziness (10%), light-headedness (16%), or both (16%). The dizzy participants were significantly more likely to report neck and back pain, past transient ischemic attacks, and feeling dizzy upon upright tilting. They also had poorer balance and less strength and scored higher on measures of depression and anxiety (P < .05). There were no blood pressure measurement-related differences between the groups. Dizziness increased the risk of multiple falls in an unadjusted analysis (relative risk (RR) = 1.55, 95% confidence interval = 1.08-2.23). After controlling for PPA scores, neck and back pain and anxiety were mediators that reduced the RR of the relationship between dizziness and faller status the most (14%) in a modified Poisson regression model. Suffering from neck and back pain and anxiety were mediators of the relationship between dizziness and falls after controlling for poor sensorimotor function and balance. Older people with dizziness might benefit from interventions targeting these mediators such as pain management and cognitive behavioral therapy.
Yoked prisms are used by some optometrists to adjust posture, but evidence to support this practi... more Yoked prisms are used by some optometrists to adjust posture, but evidence to support this practice is sparse and low level. The aim of this research was to investigate whether vertical yoked prisms have an impact on posture in healthy adults. Posture was assessed objectively in 20 healthy adults, by recording a range of joint angles or body segment locations at the ankle, hip, torso, neck, and head during participant observation of a straight-ahead target, and subsequently with eyes closed. Recording occurred before, during, and after wearing goggles with control plano lenses, and 5-diopter (D) base-up and 5-D base-down yoked prisms. In each viewing condition, the goggles were worn for 30 minutes. Interaction effects of lens/prism condition by time on joint angles and body orientation were determined. In the eyes-open and eyes-closed conditions, no significant lens/prism × time interaction effects were found at the torso, neck, hip, or ankle (P > 0.1). However, in both eyes-open...
... Visual determinants of instability and falls in older people. Jasmine C Menant, Stuart Smith... more ... Visual determinants of instability and falls in older people. Jasmine C Menant, Stuart Smith & Stephen R Lord Author for correspondence. Sections: ... 26 . Anand V, Buckley J, Scally A, Elliott DB: The effect of refractive blur on postural stability. Ophthalmic Physiol. ...
The aim of this study was to systematically investigate the influence of various walking surfaces... more The aim of this study was to systematically investigate the influence of various walking surfaces and footwear characteristics on the ability to terminate gait rapidly in 10 young and 26 older people. Subjects walked at a self-selected speed in eight randomized shoe conditions (standard versus elevated heel, soft sole, hard sole, high-collar, flared sole, bevelled heel and tread sole) on
Hand grip strength (GS) is a predictor of mortality in older adults and is moderately to highly h... more Hand grip strength (GS) is a predictor of mortality in older adults and is moderately to highly heritable, but no genetic variants have been consistently identified. We aimed to identify single nucleotide polymorphisms (SNPs) associated with GS in middle-aged to older adults using a genome-wide association study (GWAS). GS was measured using handheld dynamometry in community-dwelling men and women aged 55-85 from the Hunter Community Study (HCS, N = 2088) and the Sydney Memory and Ageing Study (Sydney MAS, N = 541). Genotyping was undertaken using Affymetrix microarrays with imputation to HapMap2. Analyses were performed using linear regression. No genome-wide significant results were observed in HCS nor were any of the top signals replicated in Sydney MAS. Gene-based analyses in HCS identified two significant genes (ZNF295, C2CD2), but these results were not replicated in Sydney MAS. One out of eight SNPs previously associated with GS, rs550942, located near the CNTF gene, was significantly associated with GS (p = 0.005) in the HCS cohort only. Study differences may explain the lack of consistent results between the studies, including the smaller sample size of the Sydney MAS cohort. Our modest sample size also had limited power to identify variants of small effect. Our results suggest that similar to various other complex traits, many genetic variants of small effect size may influence GS. Future GWAS using larger samples and consistent measures may prove more fruitful at identifying genetic contributors for GS in middle-aged to older adults.
Poor vision impairs balance and increases the risk of falls and fractures in older people. Multif... more Poor vision impairs balance and increases the risk of falls and fractures in older people. Multifocal glasses can add to this risk by impairing contrast sensitivity, depth perception, and ability to negotiate obstacles. Vision assessment and provision of new spectacles may not reduce, and may even increase, the risk of falls. Restriction of the use of multifocal glasses may reduce falls in active older people. Other effective fall prevention strategies include maximizing vision through cataract surgery and occupational therapy interventions in visually impaired older people.
Although simple assessments of gait speed have been shown to predict falls as well as hospitalisa... more Although simple assessments of gait speed have been shown to predict falls as well as hospitalisation, functional decline and mortality in older people, dual task gait speed paradigms have been increasingly evaluated with respect to fall prediction. Some studies have found that dual task walking paradigms can predict falls in older people. A systematic review and meta-analysis was conducted to determine whether dual task walking paradigms involving a secondary cognitive task have greater ability to predict falls than single walking tasks. The meta-analytic findings indicate single and dual task tests of gait speed are equivalent in the prediction of falls in older people and sub-group analyses revealed similar findings for studies that included only cognitively impaired participants, slow walkers or used secondary mental-tracking or verbal fluency tasks.
Previous research has shown that visuospatial processing requiring working memory is particularly... more Previous research has shown that visuospatial processing requiring working memory is particularly important for balance control during standing and stepping, and that limited spatial encoding contributes to increased interference in postural control dual tasks. However, visuospatial involvement during locomotion has not been directly determined. This study examined the effects of a visuospatial cognitive task versus a nonspatial cognitive task on gait speed, smoothness and variability in older people, while controlling for task difficulty. Thirty-six people aged ≥75 years performed three walking trials along a 20 m walkway under the following conditions: (i) an easy nonspatial task; (ii) a difficult nonspatial task; (iii) an easy visuospatial task; and (iv) a difficult visuospatial task. Gait parameters were computed from a tri-axial accelerometer attached to the sacrum. The cognitive task response times and percentage of correct answers during walking and seated trials were also co...
Background: Unsteady gait and falls are major problems for people with Parkinson's disease (P... more Background: Unsteady gait and falls are major problems for people with Parkinson's disease (PD). Symmetric auditory cues at altered cadences have been used to improve walking speed or step length. However, few people are exactly symmetric in terms of morphology or movement patterns and effects of symmetric cueing on gait steadiness are inconclusive. Objectives: To investigate if matching auditory cue a/symmetry to an individual's intrinsic symmetry or asymmetry affects gait steadiness, gait symmetry, and comfort to cues, in people with PD, healthy age-matched controls (HAM) and young. Methods: Thirty participants; 10 with PD, 11 HAM (66 years), and 9 young (30 years), completed five baseline walks (no cues) and twenty-five cued walks at habitual cadence but different a/symmetries. Outcomes included; gait steadiness (step time variability and smoothness by harmonic ratios), walking speed, symmetry, comfort, and cue lag times. Results: Without cues, PD participants had slower ...
To examine whether arterial stiffness is a risk factor for falls in community-dwelling older peop... more To examine whether arterial stiffness is a risk factor for falls in community-dwelling older people. Prospective cohort study. Community population, Sydney, Australia. Community-dwelling older adults (mean age 79.8±4.4, 52.2% female; N=481). Carotid-femoral pulse wave velocity (PWV) was measured in the supine position after lying for 10 minutes. Demographic, medical, and medication characteristics and levels of physical activity were obtained in clinical interviews and questionnaires, and falls were recorded with monthly falls diaries for 12 months. Participants in the top quintile of PWV (high PWV) were more likely to have higher seated systolic blood pressure (SBP) and heart rate, unsatisfactory control of blood pressure, diabetes mellitus, and lower physical activity levels. These participants were also more likely to be male and taking cardiovascular medications. Of the 473 participants available for follow-up, 212 (44.8%) reported one or more falls. In modified Poisson regressi...
Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference, 2014
An exploratory analysis was conducted into how simple features, from acceleration at the lower ba... more An exploratory analysis was conducted into how simple features, from acceleration at the lower back and ankle during simulated free-living walking, stair ascent and descent, correlate with age, the overall fall risk from a clinically validated Physiological Profile Assessment (PPA), and its sub-components. Inertial data were captured from 92 older adults aged 78-95 (42 female, mean age 84.1, standard deviation 3.9 years). The dominant frequency, peak width from Welch's power spectral density estimate, and signal variance along each axis, from each sensor location and for each activity were calculated. Several correlations were found between these features and the physiological risk factors. The strongest correlations were from the dominant frequency at the ankle along the mediolateral direction during stair ascent (Spearman's correlation coefficient p = - 0.45) with anterioposterior sway, and signal variance of the anterioposterior acceleration at the lower back during stair...
This study investigated the effects of various shoe features and surfaces on step time variabilit... more This study investigated the effects of various shoe features and surfaces on step time variability and pelvis accelerations (RMS) during walking in six younger and 22 older adults. Participants walked at a self-selected speed in five shoe conditions (standard, elevated heel, soft sole, hard sole, and high collar) on two surfaces: level and irregular. Results showed an age-related reduction in step time variability on the irregular surface and increased medio-lateral (ML) acceleration RMS in older people walking on the irregular versus the level surface. When wearing the elevated heel shoes, both young and old participants displayed significant reductions in pelvis ML accelerations, suggesting a compensatory strategy to counteract for lateral instability resulting from heel elevation. Overall, the findings demonstrate that older people are less able than younger ones to meet the stepping adaptability required for negotiating an irregular surface and, as a possible consequence, have more difficulty maintaining frontal plane stability on such a surface.
Although Parkinson&am... more Although Parkinson's disease (PD) is a well recognised risk factor for falls, how this disease and its therapy affect postural stability and leaning balance remains unclear. The aim of this study was to examine the effects of PD and levodopa on postural sway and leaning balance. Performances of 28 PD participants {median [inter-quartile range (IQR)] duration of PD: 10 (6-13) years, median (IQR) UPDRS motor score "off": 22 (14-31) "on" and "off" levodopa were compared with 28 age- and gender-matched healthy controls on two measures of controlled leaning balance [ratio of anterior-posterior (AP) sway to maximal balance range (MBR) and coordinated stability]. PD participants had greater ratio of AP sway to MBR than controls (P < 0.001), indicating that they swayed more as a proportion of their limits of stability, both "off" and "on" levodopa (P < 0.001). They also performed poorer in the coordinated stability test both "off" and "on" levodopa compared to controls (P < 0.001, for both), suggesting greater difficulty in controlling the center of mass at or near the limits of stability. Levodopa improved PD "participants" leaning balance (P < 0.001) and reduced the AP sway to MBR ratio (P < 0.001), although not to the level of controls. PD participants perform poorer than controls in leaning balance tests but significantly improve when "on" levodopa. Regardless of medication state, PD participants sway markedly more as a percentage of their limits of stability than controls suggesting a higher risk of falling.
To identify medical, psychological, and physiological mediators of the relationship between dizzi... more To identify medical, psychological, and physiological mediators of the relationship between dizziness and falls in older adults. Secondary analysis of a prospective cohort study. Community. Five hundred sixteen community-dwelling adults aged 73 to 92. Participants completed questionnaires related to health and psychological well-being and underwent a tilt table blood pressure test, the Physiological Profile Assessment (PPA; vision, reaction time, proprioception, postural sway, and quadriceps strength), and leaning balance tests. Prospective falls data were collected using monthly calendars for 12 months. Participants were categorized into dizzy and nondizzy groups based on self-report of dizziness, vertigo, and light-headedness. Two hundred seventeen (42%) participants reported vertigo or dizziness (10%), light-headedness (16%), or both (16%). The dizzy participants were significantly more likely to report neck and back pain, past transient ischemic attacks, and feeling dizzy upon upright tilting. They also had poorer balance and less strength and scored higher on measures of depression and anxiety (P < .05). There were no blood pressure measurement-related differences between the groups. Dizziness increased the risk of multiple falls in an unadjusted analysis (relative risk (RR) = 1.55, 95% confidence interval = 1.08-2.23). After controlling for PPA scores, neck and back pain and anxiety were mediators that reduced the RR of the relationship between dizziness and faller status the most (14%) in a modified Poisson regression model. Suffering from neck and back pain and anxiety were mediators of the relationship between dizziness and falls after controlling for poor sensorimotor function and balance. Older people with dizziness might benefit from interventions targeting these mediators such as pain management and cognitive behavioral therapy.
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