Papers by Daina Sturnieks
Gait & posture, 2018
Reduced ability to adapt gait, particularly under challenging conditions, may be an important rea... more Reduced ability to adapt gait, particularly under challenging conditions, may be an important reason why older adults have an increased risk of falling. This study aimed to identify cognitive, psychological and physical mediators of the relationship between impaired gait adaptability and fall risk in older adults. Fifty healthy older adults (mean±SD: 74±7years) were categorised as high or low fall risk, based on past falls and their performance in the Physiological Profile Assessment. High and low-risk groups were then compared in the gait adaptability test, i.e. an assessment of the ability to adapt gait in response to obstacles and stepping targets under single and dual task conditions. Quadriceps strength, concern about falling and executive function were also measured. The older adults who made errors on the gait adaptability test were 4.76 (95%CI=1.08-20.91) times more likely to be at high risk of falling. Furthermore, each standard deviation reduction in gait speed while appro...
Investigative ophthalmology & visual science, 2015
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...
Background. Studies comparing the effects of spatial and nonspatial secondary tasks on balance ha... more Background. Studies comparing the effects of spatial and nonspatial secondary tasks on balance have produced conflicting results. However, in most of these studies the difficulty levels of the secondary tasks have not been matched. In this study, we compared the effects of carefully matched visuospatial (VS) and nonspatial (NS) secondary tasks on choice stepping reaction time (CSRT). Methods. Forty-one older
BMJ open, 2014
Falling in older age is a serious and costly problem. At least one in three older people fall ann... more Falling in older age is a serious and costly problem. At least one in three older people fall annually. Although exercise is recognised as an effective fall prevention intervention, low numbers of older people engage in suitable programmes. Health and exercise professionals play a crucial role in addressing fall risk in older adults. This trial aims to evaluate the effect of participation in a fall prevention educational programme, compared with a wait-list control group, on health and exercise professionals' knowledge about fall prevention and the effect on fall prevention exercise prescription behaviour and confidence to prescribe the exercises to older people. A randomised controlled trial involving 220 consenting health and exercise professionals will be conducted. Participants will be individually randomised to an intervention group (n=110) to receive an educational workshop plus access to internet-based support resources, or a wait-list control group (n=110). The two prima...
Repeatability of traditional kinematic and kinetic models is affected by the ability to accuratel... more Repeatability of traditional kinematic and kinetic models is affected by the ability to accurately locate anatomical landmarks (ALs) to define joint centres and anatomical coordinate systems. Numerical methods that define joint centres and axes of rotation independent of ALs may also improve the repeatability of kinematic and kinetic data. The purpose of this paper was to compare the repeatability of
International Journal of MS Care, 2014
The aims of this study were 1) to examine postural sway in the eyes open (EO) and eyes closed (EC... more The aims of this study were 1) to examine postural sway in the eyes open (EO) and eyes closed (EC) conditions in people with multiple sclerosis (MS) with moderate levels of disability compared with controls and 2) to examine relationships between postural sway and total Expanded Disability Status Scale (EDSS) scores, functional system subscores, and clinical measures of strength and spasticity in the MS group. Thirty-four people with moderate MS and ten matched controls completed measures of postural sway with EO and EC, knee extension and ankle dorsiflexion isometric strength, EDSS total score and subscores, and spasticity levels. Participants with MS swayed significantly more with EO and EC and had reduced knee extension and ankle dorsiflexion strength compared with controls (P < .001). In the MS group, increased sway was associated with higher total EDSS scores and cerebellar function subscores, whereas increased sway ratio (EC/EO) was associated with reduced sensory function subscores. Postural sway was not significantly associated with strength or spasticity. Participants with MS swayed more and were significantly weaker than controls. Cerebellar dysfunction was identified as the EDSS domain most strongly associated with increased sway, and sensory loss was associated with a relatively greater dependence on vision for balance control. These findings suggest that exercise interventions targeting sensory integration and cerebellar ataxia may be beneficial for enhancing balance control in people with MS.
Multiple Sclerosis and Related Disorders, 2014
Walking ability and fatigue are often reported as the most disabling symptoms in Multiple Scleros... more Walking ability and fatigue are often reported as the most disabling symptoms in Multiple Sclerosis (MS). Motor fatigue may contribute to reduced mobility, and is likely caused by both central and peripheral deterioration in neuromuscular function. Simple and choice stepping reaction time (RT) measures have the potential to detect walking induced changes in motor impairment. The aim of this study was to assess the effect of six minutes of walking on simple and choice stepping RT in people with MS. 31 people with moderate walking disability and a diagnosis of MS completed simple and choice stepping RT tasks, and rated their levels of fatigue on a 100mm visual analogue scale before and after a modified six minute walk test. Subjects walked an average of 368(±110)m in six minutes. Perceived fatigue increased following the six minute walk, as indicated by a 25(±19.7)mm increase on the 100mm visual analogue scale (p<0.001). There was a significant increase in both hand (p=0.003) and foot (p=0.006) simple RT following the six minute walk. For choice stepping RT, response time was significantly slower (p=0.006) following the six minute walk, while movement time was unchanged (p=0.506). Simple and choice stepping reaction times are slower following six minutes of walking in people with MS. These findings suggest that walking-induced fatigue might lead to central slowing and slowed stepping performance. Further studies are needed to investigate the clinical relevance of these RT measures in relation to fall risk and therapeutic interventions to improve mobility and manage fatigue in people with MS.
Parkinsonism & Related Disorders, 2008
Archives of physical medicine and rehabilitation, 2015
To evaluate the effect of wearing a dorsiflexion assist orthosis (DAO) on walking distance, physi... more To evaluate the effect of wearing a dorsiflexion assist orthosis (DAO) on walking distance, physiological cost, fatigue, and strength and balance measures after a modified 6-minute walk test (6MWT) in people with multiple sclerosis (MS). Randomized crossover trial. Hospital Movement Laboratory. People with moderate MS and Expanded Disability Status Scale score of 3.7±0.7 (N=34; 26 women). Modified 6MWT with and without a DAO worn on the weaker leg. Distance walked, perceived fatigue, and the physiological cost of walking were compared between walking conditions. Pre- and postwalk changes in knee extensor and ankle dorsiflexor isometric strength and standing postural sway with eyes open and closed were compared between walking conditions. There were no differences in distance walked or perceived fatigue between the 2 walking conditions. However, there was a reduced physiological cost of walking (P<.05), a smaller reduction in knee extensor strength (P<.05), and a smaller increa...
PloS one, 2014
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...
The Journal of rheumatology, 2004
To investigate physiological risk factors for falls in people with self-reported lower limb arthr... more To investigate physiological risk factors for falls in people with self-reported lower limb arthritis. Six hundred eighty-four community-dwelling men and women aged 75-98 years (mean 80.0, SD 4.4), categorized with and without lower limb arthritis, underwent quantitative tests of strength, peripheral sensation, vision, reaction time, balance, and pain. A 12-month history of falls was also obtained. Subjects with self-reported lower extremity arthritis performed significantly worse in tests of knee and ankle muscular strength, lower limb proprioception, postural sway, and leaning balance than subjects without lower extremity arthritis, while being comparable in vision, tactile sensitivity, and reaction time. This pattern of specific impairments was also evident when group results for the arthritis subjects were compared with community normative values and presented as a physiological profile. The arthritis group suffered significantly more falls [relative risk (RR) 1.22, 95% CI 1.03-...
The Journal of Physiology, 2007
To detect joint movement, the brain relies on sensory signals from muscle spindles that sense the... more To detect joint movement, the brain relies on sensory signals from muscle spindles that sense the lengthening and shortening of the muscles. For single-joint muscles, the unique relationship between joint angle and muscle length makes this relatively straightforward. However, many muscles cross more than one joint, making their spindle signals potentially ambiguous, particularly when these joints move in opposite directions. We show here that simultaneous movement at adjacent joints sharing biarticular muscles affects the threshold for detecting movements at either joint whereas it has no effect for non-adjacent joints. The angular displacements required for 70% correct detection were determined in 12 subjects for movements imposed on the shoulder, elbow and wrist at angular velocities of 0.25-2 deg s −1 . When moved in isolation, detection thresholds at each joint were similar to those reported previously. When movements were imposed on the shoulder and wrist simultaneously, there were no changes in the thresholds for detecting movement at either joint. In contrast, when movements in opposite directions at velocities greater than 0.5 deg s −1 were imposed on the elbow and wrist simultaneously, thresholds increased. At 2 deg s −1 , the displacement threshold was approximately doubled. Thresholds decreased when these adjacent joints moved in the same direction. When these joints moved in opposite directions, subjects more frequently perceived incorrect movements in the opposite direction to the actual. We conclude that the brain uses potentially ambiguous signals from biarticular muscles for kinaesthesia and that this limits acuity for detecting joint movement when adjacent joints are moved simultaneously.
Neurophysiologie Clinique/Clinical Neurophysiology, 2008
Good balance is an imperative skill for daily life that requires the complex integration of senso... more Good balance is an imperative skill for daily life that requires the complex integration of sensory information regarding the position of the body relative to the surroundings and the ability to generate appropriate motor responses to control body movement. Balance calls upon contributions from vision, vestibular sense, proprioception, muscle strength and reaction time. With increased age, there is a progressive loss of functioning of these systems which can contribute to balance deficits. Balance disorders represent a growing public health concern due to the association with falls and fall-related injuries, particularly in regions of the world in which high proportions of the population are elderly. Falls present one of the most serious and costly problems associated with older adulthood. Falls can mark the beginning of a decline in function and independence and are the leading cause of injury-related hospitalisation in older people. One in three people over the age of 65 years who are living in the community experience at least one fall each year and 10-15% of these falls are associated with serious injury. In economic terms, the direct and indirect costs associated with falls are large and will grow as the proportion of older people increases. Consequently, understanding age-related changes in the physiological systems imperative to balance is of utmost importance to prevent falls in older people and reduce the injury-related burden on individuals and society.
Journal of Science and Medicine in Sport, 2005
Balance calls upon contributions from vision, peripheral sensation, vestibular sense, muscle stre... more Balance calls upon contributions from vision, peripheral sensation, vestibular sense, muscle strength, neuromuscular control and reaction time. With increased age, there is a progressive loss of functioning of these systems and an increased likelihood of falls. Falls cml mark the beginning of a decline in function and independence and are the leading cause of injury-related hospitalisation in older people. By using simple tests of vision, leg sensation, muscle strength, reaction time and standing balance, it is possible to identify accurately older people at risk of falls and assess intervention outcomes. This approach overcomes the limitations associated with traditional methods of assessing falls risk via medical diagnoses, including varied severity between individuals. Using a physiological approach provides information at the impairment and functional capacity levels to assist in understanding fails and developing and evaluating optimal falls prevention strategies for older people. (J Sci Med Sport 2005;8:1:35-42)
The Journals of Gerontology Series A: Biological Sciences and Medical Sciences, 2009
Background. Previous studies have indicated that gait patterns in older people may be affected by... more Background. Previous studies have indicated that gait patterns in older people may be affected by concern about falling. The aim of this study was to examine the effects of concern about falling and physiological falls risk on gait performance using a paradigm in which concern about falling was experimentally induced.
The Journals of Gerontology Series A: Biological Sciences and Medical Sciences, 2008
Background. Studies comparing the effects of spatial and nonspatial secondary tasks on balance ha... more Background. Studies comparing the effects of spatial and nonspatial secondary tasks on balance have produced conflicting results. However, in most of these studies the difficulty levels of the secondary tasks have not been matched. In this study, we compared the effects of carefully matched visuospatial (VS) and nonspatial (NS) secondary tasks on choice stepping reaction time (CSRT).
Journal of Biomechanics, 2003
Repeatability of traditional kinematic and kinetic models is affected by the ability to accuratel... more Repeatability of traditional kinematic and kinetic models is affected by the ability to accurately locate anatomical landmarks (ALs) to define joint centres and anatomical coordinate systems. Numerical methods that define joint centres and axes of rotation independent of ALs may also improve the repeatability of kinematic and kinetic data. The purpose of this paper was to compare the repeatability of gait data obtained from two models, one based on ALs (AL model), and the other incorporating a functional method to define hip joint centres and a mean helical axis to define knee joint flexion/extension axes (FUN model). A foot calibration rig was also developed to define the foot segment independent of ALs. The FUN model produced slightly more repeatable hip and knee joint kinematic and kinetic data than the AL model, with the advantage of not having to accurately locate ALs. Repeatability of the models was similar comparing within-tester sessions to between-tester sessions. The FUN model may also produce more repeatable data than the AL model in subject populations where location of ALs is difficult. The foot calibration rig employed in both the AL and FUN model provided an easy alternative to define the foot segment and obtain repeatable data, without accurately locating ALs on the foot. r
Journal of Biomechanics, 2006
Gait & Posture, 2005
Chapter 5. Multi-sensory integration 33 normal subjects and 80 subacute patients with a first hem... more Chapter 5. Multi-sensory integration 33 normal subjects and 80 subacute patients with a first hemisphere stroke (54 left, 26 right). On the basis of the Scale for Contraversive Pushing (SCP) (Karnath et al., 2000), 45 were considered as upright in sitting and standing, and 35 showed a contralesional lateropulsion. Among these latter 6 showed a contralesional lateropulsion plus pushing. The four groups of subjects were compared: normals, upright patients, patients with lateropulsion but no pushing, pushers.
Gait & Posture, 2005
Introduction: Choice stepping reaction time (CSRT) combined with a cognitive task is a useful str... more Introduction: Choice stepping reaction time (CSRT) combined with a cognitive task is a useful strategy for investigating the attentional requirements of balance [1]. In this study we compared the effects of a visuospatial working memory task (VS) and a non-spatial backward counting task (NS) on CSRT.
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Papers by Daina Sturnieks