| 1. |
- Adlerton, Anna Karin, et al.
(författare)
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Forceplate and accelerometer measures for evaluating the effect of muscle fatigue on postural control during one-legged stance.
- 2003
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Ingår i: Physiotherapy Research International. - 1358-2267. ; 8:4, s. 99-187
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND AND PURPOSE: The control of balance is vital in many sporting activities as well as in activities of daily life. In order to treat deficiencies properly valid and reliable methods are needed to evaluate different aspects of stability. Muscle fatigue has been proposed to cause a change in postural control strategy, and the use of different tools and variables might therefore elucidate these changes. The aims of the present study were: to investigate if forceplate and accelerometer measurements about postural control during one-legged stance indicate changes in postural control strategy after fatiguing exercise; and to investigate the correlation between forceplate and accelerometer measurements obtained before and after fatiguing exercise. METHOD: The study used an experimental design. Twenty-three healthy women (mean age 26.8 years; range 20-34 years) were studied. Forceplate and accelerometer data were obtained simultaneously and consisted of measures of centre of pressure movements and horizontal trunk acceleration in medio-lateral and antero-posterior directions. The calf muscles of the right leg were fatigued by repeated heel rises. RESULTS: The average amplitude of centre of pressure movements and trunk acceleration increased, whereas the average velocity of centre of pressure movements decreased during fatigue. These changes indicate a change of movement strategy. Moderate correlation between trunk acceleration and centre of pressure movements was seen, confirming the link between the variables, but indicating that different aspects of the ability to control balance were measured. CONCLUSIONS: Calf muscle fatigue has a short-lasting effect on body balance, with measurements indicating a change in postural control strategy. Different tools and variables are needed to identify different balance control strategies. The procedures used in the present study may be modified to identify subjects with inadequate capacity to choose between balance control strategies; they are also applicable in clinical settings outside a laboratory environment.
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| 2. |
- Blomqvist, Sven
(författare)
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Postural balance, physical activity and capacity among young people with intellectual disability
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The overall aim of this thesis was to investigate postural balance, physical activity, physical capacity and their associations in young people (16-20 years) with intellectual disability (ID), mild to moderate. The aim was also to study the reliability and concurrent validity of postural balance tests.To evaluate postural balance, one assessor used five common postural balance tests and one new test. The tests were performed twice for 89 young people with ID (one to twelve days apart). Intraclass correlation coefficients greater than 0.80 were achieved for four of the common balance tests: Extended Timed Up and Go Test (ETUGT), Modified Forward Reach Test (MFRT), One-Leg Stance Test (OLS), and a Force Platform Test (FPT). The smallest real difference ranged from 12% to 40%; less than 20% is considered to be low. For the six balance tests, the concurrent validity varied between none to low.Falls are more common for young people with ID compared to young people without ID. One reason could be impaired postural balance. The postural balance for young people with ID has not been thoroughly investigated. Therefore, five balance tests and three muscle strength tests were used to compare young people with ID with an age-matched control group without ID (n=255). The young people with ID had significantly lower scores on most of the postural balance tests and muscle strength tests of the trunk and lower limbs. Muscle strength, height, and body mass index had no strong association with postural balance. The results also illustrated that young people with ID did not rely more on vision for their balance ability compared to peers without ID.It seems that postural balance is impaired for young people with ID when evaluated with common tests. An everyday situation is to react to unexpected balance disturbances to avoid falls by using different postural responses. Since young people with ID seem to fall more often than peers without ID, it is valuable to investigate if those postural responses are different between the groups. Therefore, young people with and without ID (n=99) were exposed to six backward surface translations and several postural muscle responses were evaluated: muscle synergies and strategies, muscle onset latency, time-to-peak amplitude, and adaptation. The responses of the investigated muscles – the gastrocnemius, the biceps femoris, and the erector spinae L4 level – were measured using electromyography. The results showed that there were no differences between the two groups with respect to synergies or strategies, muscle onset latency, and time-to-peak amplitude. An overall pattern was seen, that young people with ID adapted their muscle response slower in all three muscles than peers without ID, but this pattern was not statistically significant.Studies have shown that people with ID have impaired postural balance, a lower level of physical activity, and lower aerobic capacity compared to people without ID. The association is however not investigated. Therefore, postural balance (postural sway indirectly measured with the subjects standing on a force platform), physical activity (measured with a pedometer), and aerobic capacity (measured with a sub-maximal ergometer cycle test) were used to assess young people with and without ID (n=106). To investigate the subjects’ view of their own health, the subjects completed an adapted questionnaire that addressed their perceived health. The analysis showed no significant associations between postural balance, level of physical activity, and aerobic capacity. The subjects in the ID group, both men and women, had significantly lower aerobic capacity compared to subjects without ID. The answers from the health questionnaire did not correspond to the measured outcomes from the physical tests for young people with ID.In conclusion, ETUGT and MFRT can be used to evaluate change in postural balance over time in young people with mild to moderate ID. The low concurrent validity suggests that the postural balance tests probably challenge various subsystems. Young people with ID have impaired postural balance and perform lower on muscle strength tests than age-matched controls. Postural muscle responses after external perturbations seem to be similar for young people with and without ID, but the ability to adapt muscle responses after repeated perturbations appears to be slower for young people with ID. The studies in the thesis also indicate that young people with ID have reduced level of physical activity and lower aerobic capacity. The lack of association between the different physical functions indicates that they should be evaluated and exercised separately. Young persons with ID might have more difficulty realising the health advantage of being physically active, as they do not seem to make this connection. Because of this, it is important that parents/guardians, school staff, physiotherapists, and others encourage them to participate in physical activity.
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| 3. |
- Moe-Nilssen, Rolf, et al.
(författare)
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Criteria for evaluation of measurement properties of clinical balance measures for use in fall prevention studies
- 2007
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Ingår i: Journal of Evaluation In Clinical Practice. - : Blackwell Publishing. - 1356-1294 .- 1365-2753. ; 14:2, s. 236-240
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Tidskriftsartikel (refereegranskat)abstract
- Work Package 3 of the Prevention of Falls Network Europe has evaluated measurement properties of clinical balance measures to be used to: (1) select participants for interventions with the goal to prevent falls in older people, and (2) assess the results of such intervention on balance function.Inclusion in a fall prevention study may be based on measures identifying subjects who have impaired balance or increased risk of future falls. We propose that an appropriate statistical method to analyse discriminative ability of a balance measure is discriminant analysis or logistic regression analysis. The optimal cut‐off score is best determined by plotting a receiver‐operating‐characteristic curve for different cut‐off values. The evaluation of predictors for risk of future falls should be based on a study design with a prospective data collection of falls.Sensitivity to change is a measurement property needed to evaluate the outcome of an intervention. The standardized response mean is frequently encountered in the literature and is recommended as a statistical measure of sensitivity to change in the context of an intervention study.Adequate reliability is a prerequisite for consistent measurement. Relative reliability may be reported as an intraclass correlation coefficient and absolute reliability as the within‐subject standard deviation (sw), also called standard error of measurement. When measurement error is proportional to the score, calculation of a coefficient of variation can be considered.In a second paper, the authors will evaluate clinical balance measures for use in fall prevention studies based upon criteria recommended in this report.
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| 4. |
- Månsson, Linda, 1973-
(författare)
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Digital fall prevention for older adults : Feasibility of a self-managed exercise application and development of a smartphone self-test for balance and leg strength
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- As the numbers of older adults grow, fall prevention is vital to reduce health care needs due to falls and to increase quality of life. Balance and strength exercises have been found to be effective in fall prevention, however, long-term adherence is often poor. The growth of digital technology in society has generated opportunities for fall prevention with eHealth. The aim of this thesis was to evaluate the feasibility and use of a new digital fall prevention exercise programme, and to develop and investigate a smartphone self-test application for balance and leg strength. Three different studies included community-dwelling older adults ≥ 70 years, who were able to rise from a chair and stand without support. A feasibility study evaluated a new digital exercise programme (DP) compared to a paper booklet exercise programme (PB) for self-managed fall prevention in a four-month controlled participant preference trial (n = 67) (Paper I & II). Self-reported data on adherence, falls efficacy, and functional ability were collected and analysed, along with performance-based measures of gait speed, balance, and chair stand test. In Paper II the feasibility was explored of using the self-reported scales and performance-based outcome measures. A self-test application was also developed (Paper III) in co-creation with 10 participants, who met during five sessions to design the application’s instructions and user interface. The participants’ preference for and their contribution to the application design was analysed with qualitative content analysis with a deductive-inductive approach. A concurrent validity study (n = 31) (Paper IV) assessed the correlations between variables from the self-test prototype and outcome measures from clinical instruments. Results from the feasibility study show that 43% chose the DP and 57% PB, and the attrition rate was 17% and 37% respectively. Both groups had similar adherence, but for the subgroup that exercised most, participants in the DP group reported significantly more exercise time (Paper I). Participants in both groups reported a boost in balance after the intervention, and in the DP group also improved leg strength. Significantly more participants continued to use the DP at 12 months. The self-managed exercise intervention (Paper II) resulted in improvements in functional leg strength, which positively correlated with exercise time, but no other performance-based outcomes showed any significant improvements. Performance-based measurements of balance as well as the self- reported balance confidence and fear of falling revealed ceiling effects. Pre-assessments of self-reported outcomes and performance-based measures showed significant but low correlations, no such correlations were seen in change scores. The deductive-inductive analysis of the co-creation process resulted in 17 subcategories within the seven facets of the Optimized Honeycomb model for iii user experience (Paper III). The main results were that participants desired clear and appropriate information to understand why things were done in a certain way, and their contributions enhanced the user experience of the self-test. The concurrent validity testing of the self-test prototype (IV) showed low to moderate correlations for the strength test but limited correlations for the balance test. In conclusion the DP group showed comparable adherence to the programme as the PB group, as well as to previous studies, indicating it was feasible to use the new DP. DP participants also reported better exercise maintenance after 12 months. Positive self-reported effects were expressed in addition to leg strength improvement. Outcome measures for balance and falls efficacy revealed ceiling effects, consequently, these instruments might not be suitable for assessments in all community-dwelling older adults. In particular, for balance related outcomes there is a need for new more sensitive measurements. The co-creation of the smartphone self-test was feasible and valuable for user experience, but further validity and reliability testing are needed before it can serve as an independent assessment tool.
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| 5. |
- Rennie, Linda, et al.
(författare)
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The reliability of gait variability measures for individuals with Parkinson's disease and healthy older adults - The effect of gait speed.
- 2018
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Ingår i: Gait & posture. - : Elsevier BV. - 1879-2219 .- 0966-6362. ; 62, s. 505-509
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Tidskriftsartikel (refereegranskat)abstract
- Step-to-step variability is a marker of reduced motor control and a frequently studied outcome measure in neurodegenerative disorders such as Parkinson's disease (PD) as compared to healthy older adults (HOA). To challenge motor control of gait, walking should be tested at different gait speeds. Good reliability is essential, and gait variability estimates show good reproducibility when sampled at normal gait speed. The aim was therefore to investigate if gait variability could be reliably sampled at slow and fast speeds for individuals with PD and HOA by evaluating test-retest reliability.29 (14 males) subjects with idiopathic PD, Hoehn &Yahr 2 (n=18) and 3,≥60years, and 25 age matched HOAwere included. Spatiotemporal gait data was collected (GAITRite) during slow, normal, and fast walking on two occasions.Measurement error was lowest for gait variability estimates based on 40 steps in both groups. This was true across all speeds in HOA, but only for normal and fast gait speeds in the PD cohort. Due to increased homogeneity in the variability estimates intraclass correlation coefficients (ICC) were low for HOA, except for step width variability. In the PD cohort ICCs were good to excellent for temporal- and step width gait variability across speeds.HOA demonstrated reliable gait variability estimates across all speeds, whereas Individuals with PD were reliable at normal and fast gait speeds only Estimates should be based on at least 40 steps. Step width variability was overall the most reliable variable across groups and speed conditions.
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| 6. |
- Rennie, Linda, et al.
(författare)
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The validity of the Gait Variability Index for individuals with mild to moderate Parkinson's disease.
- 2017
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Ingår i: Gait & posture. - : Elsevier BV. - 1879-2219 .- 0966-6362. ; 54, s. 311-317
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Tidskriftsartikel (refereegranskat)abstract
- Increased step-to-step variability is a feature of gait in individuals with Parkinson's disease (PD) and is associated with increased disease severity and reductions in balance and mobility. The Gait Variability Index (GVI) quantifies gait variability in spatiotemporal variables where a score ≥100 indicates a similar level of gait variability as the control group, and lower scores denote increased gait variability. The study aim was to explore mean GVI score and investigate construct validity of the index for individuals with mild to moderate PD. 100 (57 males) subjects with idiopathic PD, Hoehn & Yahr 2 (n=44) and 3, and ≥60 years were included. Data on disease severity, dynamic balance, mobility and spatiotemporal gait parameters at self-selected speed (GAITRite) was collected. The results showed a mean overall GVI: 97.5 (SD 11.7) and mean GVI for the most affected side: 94.5 (SD 10.6). The associations between the GVI and Mini- BESTest and TUG were low (r=0.33 and 0.42) and the GVI could not distinguish between Hoehn & Yahr 2 and 3 (AUC=0.529, SE=0.058, p=0.622). The mean GVI was similar to previously reported values for older adults, contrary to consistent reports of increased gait variability in PD compared to healthy peers. Therefore, the validity of the GVI could not be confirmed for individuals with mild to moderate PD in its current form due to low associations with validated tests for functional balance and mobility and poor discriminatory ability. Future work should aim to establish which spatiotemporal variables are most informative regarding gait variability in individuals with PD.
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| 7. |
- Stenlund, Tobias, 1975-
(författare)
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Seated postural reactions to mechanical shocks : laboratory studies with relevance for risk assessment and prevention of musculoskeletal disorders among drivers
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Professional drivers of off-road vehicles, driving on irregular terrain such as in forestry, agriculture and mining, are exposed to whole-body vibration and mechanical shocks. These driver groups have reported severe musculoskeletal problems in the spine, but the association to seated postural reactions is not fully understood. One assumption is that unexpected shocks may create excessive load on spinal joints. The driver’s posture and exposure to mechanical shocks are required to be included in work risk assessments, but muscle activity and body kinematics are not included. The overall aim of this thesis was to describe and analyse seated postural reactions to mechanical shocks and to evaluate measuring of seated postures with relevance for risk assessment and the prevention of musculoskeletal disorders among drivers.The thesis includes four studies, all laboratory-based using a repeated-measures design. Postural reactions were recorded from 23 (Paper I) and 20 (Paper II & III) young, healthy male participants who were seated on a movable platform. The platform delivered mechanical shocks with peak accelerations up to 14 m/s2 in lateral directions during different conditions. Furthermore, twenty participants (Paper IV) were tested by four testers for analysis of test-retest reliability within and between testers measuring seated postures. Kinematics were here detected by means of a motion analysis system (MoLabTM) and described for the spine as angular displacements or range of motion (ROM) using a three-segment model of neck, trunk and pelvis (Paper I–III) and as a more specific model (Paper IV). Surface electromyography (EMG) was recorded bilaterally on the following muscles; trapezius upper part, upper neck, erector spinae and external oblique (Paper I–III).The general findings show that EMG amplitudes normalised to maximum voluntary contractions (MVC) did not exceed 2% in the trapezius, 8% in the upper neck and erector spinae and 18% in the external oblique. The EMG amplitudes and the angular displacements in the neck were significantly reduced from the first compared to the fifth mechanical shock. Adding a cognitive task significantly increased angular displacements. The largest ROM with approximately 20° in each segment was found during a double-sided mechanical shock (shock that changes direction). The reliability within one tester measuring seated postures was mostly considered good and superior to the reliability between several testers, but still insensitive to changes of less than 10°.Exposure to single-sided or double-sided mechanical shocks with accelerations up to 14 m/s2 seem not to cause postural reactions to such an extent that overload of muscles or joint structures should be expected. There seems to be a quick adaptation that causes an improved readiness. The external obliques were most active when restoring equilibrium and seem important for stabilising the whole spinal column. Stability training, in order to improve neuromuscular control of the external obliques could, therefore, be a possible recommendation. The angular displacement in the neck increases if the subject solves a cognitive task of why such activities should be avoided when driving in difficult terrains. Since accurate descriptions of the spinal posture seems difficult even when advanced technical equipment is used, simpler models seem more appropriate. The results show that postural control is maintained even when exposed to considerable mechanical shocks. On the basis of these results, there is no need to change established risk assessment models.
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