| 1. |
- Falk, Jimmy, et al.
(författare)
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Increased co-contraction reaction during a surface perturbation is associated with unsuccessful postural control among older adults
- 2022
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Ingår i: BMC Geriatrics. - : Springer Nature. - 1471-2318. ; 22:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: As a strategy to maintain postural control, the stiffening strategy (agonist-antagonist co-contractions) is often considered dysfunctional and associated with poor physical capacity. The aim was to investigate whether increased stiffening is associated with unsuccessful postural control during an unpredictable surface perturbation, and which sensory and motor variables that explain postural stiffening.Methods: A sample of 34 older adults, 75.8 ± 3.8 years, was subjected to an unpredicted surface perturbation with the postural task to keep a feet-in-place strategy. The participants also completed a thorough sensory- and motor test protocol. During the surface perturbation, electromyography was measured from tibialis anterior and gastrocnemius to further calculate a co-contraction index during the feed-forward and feedback period. A binary logistic regression was done with the nominal variable, if the participant succeeded in the postural task or not, set as dependent variable and the co-contraction indexes set as independent variables. Further, the variables from the sensory and motor testing were set as independent variables in two separate Orthogonal Projections of Latent Structures (OPLS)-models, one with the feed-forward- and the other with the feedback co-contraction index as dependent variable.Results: Higher levels of ankle joint stiffening during the feedback, but not the feed-forward period was associated with postural task failure. Feedback stiffening was explained by having slow non-postural reaction times, poor leg muscle strength and being female whereas feed-forward stiffening was not explained by sensory and motor variables.Conclusions: When subjected to an unpredicted surface perturbation, individuals with higher feedback stiffening had poorer postural control outcome, which was explained by poorer physical capacity. The level of feed-forward stiffening prior the perturbation was not associated with postural control outcome nor the investigated sensory and motor variables. The intricate causal relationships between physical capacity, stiffening and postural task success remains subject for future research.
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| 2. |
- Falk, Jimmy, et al.
(författare)
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What Explains Successful or Unsuccessful Postural Adaptations to Repeated Surface Perturbations among Older Adults?
- 2021
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Ingår i: International Journal of Environmental Research and Public Health. - : MDPI. - 1661-7827 .- 1660-4601. ; 18:22
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Tidskriftsartikel (refereegranskat)abstract
- As we age there are natural physiological deteriorations that decrease the accuracy and flexibility of the postural control system, which increases the risk of falling. Studies have found that there are individual differences in the ability to learn to manage repeated postural threats. The aim of this study was to investigate which factors explain why some individuals are less proficient at adapting to recurrent postural perturbations. Thirty-five community dwelling older adults performed substantial sensory and motor testing and answered surveys regarding fall-related concerns and cognitive function. They were also subjected to three identical surface perturbations where both kinematics and electromyography was captured. Those that were able to adapt to the third perturbation were assigned to the group “Non-fallers” whereas those that fell during all perturbations were assigned to the group “Fallers”. The group designation dichotomized the sample in a hierarchical orthogonal projection of latent structures— the discriminant analysis model. We found that those who fell were older, had poorer physical performance, poorer strength and longer reaction times. The Fallers’ postural control strategies were more reliant on the stiffening strategy along with a more extended posture and they were less skillful at making appropriate feedforward adaptations prior to the third perturbation.
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| 3. |
- Forsberg, Karin, et al.
(författare)
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Concurrent Validity of Cervical Movement Tests Using VR Technology—Taking the Lab to the Clinic
- 2023
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Ingår i: Sensors. - : MDPI. - 1424-8220. ; 23:24
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Tidskriftsartikel (refereegranskat)abstract
- Reduced cervical range of motion (ROM) and movement velocity are often seen in people with neck pain. Objective assessment of movement characteristics is important to identify dysfunction, to inform tailored interventions, and for the evaluation of the treatment effect. The purpose of this study was to investigate the concurrent validity of a newly developed VR technology for the assessment of cervical ROM and movement velocity. VR technology was compared against a gold-standard three-dimensional optical motion capture system. Consequently, 20 people, 13 without and 7 with neck pain, participated in this quantitative cross-sectional study. ROM was assessed according to right/left rotation, flexion, extension, right/left lateral flexion, and four diagonal directions. Velocity was assessed according to fast cervical rotation to the right and left. The correlations between VR and the optical system for cervical ROM and velocity were excellent, with intraclass correlation coefficient (ICC) values > 0.95. The mean biases between VR and the optical system were ≤ 2.1° for the ROM variables, <12°/s for maximum velocity, and ≤3.0°/s for mean velocity. In conclusion, VR is a useful assessment device for ROM and velocity measurements with clinically acceptable biases. It is a feasible tool for the objective measurement of cervical kinematics in the clinic.
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| 4. |
- Jafari, Hedyeh, et al.
(författare)
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Predicting balance impairments in older adults: a wavelet-based center of pressure classification approach
- 2023
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Ingår i: Biomedical engineering online. - : Springer Nature. - 1475-925X. ; 22
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Tidskriftsartikel (refereegranskat)abstract
- Background: Aging is associated with a decline in postural control and an increased risk of falls. The Center of Pressure (CoP) trajectory analysis is a commonly used method to assess balance. In this study, we proposed a new method to identify balance impairments in older adults by analyzing their CoP trajectory frequency components, sensory inputs, reaction time, motor functions, and Fall-related Concerns (FrC).Methods: The study includes 45 older adults aged 75.2(±4.5)75.2(±4.5) years who were assessed for sensory and motor functions. FrC and postural control in a quiet stance with open and closed eyes on stable and unstable surfaces. A Discrete Wavelet Transform (DWT) was used to detect features in frequency scales, followed by the K-means algorithm to detect different clusters. The multinomial logistic model was used to identify and predict the association of each group with the sensorimotor tests and FrC.Results: The study results showed that by DWT, three distinct groups of subjects could be revealed. Group 2 exhibited the broadest use of frequency scales, less decline in sensorimotor functions, and lowest FrC. The study also found that a decline in sensorimotor functions and fall-related concern may cause individuals to rely on either very low-frequency scales (group 1) or higher-frequency scales (group 3) and that those who use lower-frequency scales (group 1) can manage their balance more successfully than group 3.Conclusions: Our study provides a new, cost-effective method for detecting balance impairments in older adults. This method can be used to identify people at risk and develop interventions and rehabilitation strategies to prevent falls in this population.
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| 5. |
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| 6. |
- Pauelsen, Mascha, et al.
(författare)
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Frequency domain shows : Fall-related concerns and sensorimotor decline explain inability to adjust postural control strategy in older adults
- 2020
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Ingår i: PLOS ONE. - : PLOS. - 1932-6203. ; 15:11
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Tidskriftsartikel (refereegranskat)abstract
- Human postural control is a complex system and changes as we age. Frequency based analyses have been argued to be useful to identify altered postural control strategies in balance tasks. The aim of this study was to explore the frequency domain of the quiet stance centre of pressure of older adults with various degrees of fall-related concerns and sensorimotor functioning. We included 45 community dwelling older adults and used a force plate to register 30 seconds of quiet stance with eyes open and closed respectively. We also measured sensory and motor functions, as well as fall-related concerns and morale. We analysed the centre of pressure power spectrum density and extracted the frequency of 4 of its features for each participant. Orthogonal projection of latent structures–discriminant analysis revealed two groups for each quiet stance trial. Group 1 of each trial showed less sensory and motor decline, low/no fall-related concerns and higher frequencies. Group 2 showed more decline, higher fall-related concerns and lower frequencies. During the closed eyes trial, group 1 and group 2 shifted their features to higher frequencies, but only group 1 did so in any significant way. Higher fall-related concerns, sensory and motor decline, and explorative balancing strategies are highly correlated. The control system of individuals experiencing this seems to be highly dependent on vision. Higher fall-related concerns, and sensory and motor decline are also correlated with the inability to adjust to faster, more reactive balancing strategies, when vision is not available.
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| 7. |
- Pauelsen, Mascha
(författare)
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Losing control and developing concerns : The complexities of ageing postural control and fall-related concerns
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- With the world population shifting its proportions towards higher ages, it is imperative to increase healthspan rather than lifespan, both for the sakes of community sustainability as well as individual quality of life. One of the main means to obtain healthy ageing, is a concept called active ageing, as activity has shown to slow down the natural ageing process. Active ageing is threatened by a decline in balance performance and an increase of fall-related concerns, as activity curtailment is a major consequence. Fall-related concerns are prevalent in a large portion of the older population. Current understanding of its mechanisms is largely hypothesised, based on few observational studies in which single factors – mostly psychological – are researched. Postural control is the system that helps us maintain balance and control while moving or being still. Yet, the interactions between fall-related concerns and postural control are not very well described. Sensory input and processing have been identified as possibly an important part, but more in-depth investigations are needed.To investigate the prevalence and factors that may play a part in fall-related concerns, 153 older adults (70 years and over) were visited in their home. During these visits questionnaires and clinical tests were administered (among them FES-I, PGCM, SPPB, MMSE). To investigate the relationship between fall-related concerns and postural control more thoroughly, 45 of the original sample were also tested in the movement laboratory. Several modalities of sensory function were recorded, as well as lower limb strength and quiet stance centre of pressure. The home visits showed that 70% of people 70 years and older, living in the community experience at least one of the constructs of fall-related concerns and that associated factors are of both psychological and physical nature (fear, morale, and physical performance). Large and significant differences between men and women were discovered not only in prevalence, but also for the associated factors. Hierarchical multivariate modelling of the laboratory data showed that an increase in sway size and velocity during open eyes quiet stance can explain a rise in fall-related concerns and that that relationship in turn can be explained by declines in specific parts of the postural control system (lower limb strength, reaction time, vision, and proprioception of the ankle, knee, and neck). The more in-depth methods of frequency domain and multivariate discriminant analysis revealed that older participants could be grouped in ‘declined and concerned’ and ‘not declined and not concerned.’ The first showing power in lower frequencies of the postural sway signal than the latter and showing an inability to adjust control strategy when closing their eyes. Finally, the changing and adapting postural control of older people was successfully modelled by applying dimension reduction, neural networks, and an internal feedback of 150ms. The model can predict postural corrections up to 1 second ahead of time. This gave more insight in key features of successful adaptation to an ageing system and provides a virtual environment for future model and theory testing. In conclusion, I have gained more understanding of the complexity and interaction of the different systems involved in the concern-and-balance relationship and have contributed to the field by showing methods that will improve the quality of analyses when testing, evaluating, and researching these phenomena.
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| 8. |
- Rissen, Dag, et al.
(författare)
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Psychosocial work environment, stress symptoms and musculoskeletal pain among professional Swedish big band musicians
- 2022
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Konferensbidrag (refereegranskat)abstract
- Background: The psychosocial work environment among musicians can be demanding due to factors such as high job demands, low control, and lack of social support. At the same time, musical performance is physically demanding, and musculoskeletal pain is common. However, few studies have investigated health situation among jazz musicians. Research questions: How do Swedish big band musicians perceive the psychosocial work environment? What are the levels of stress symptoms? Are there any differences in these variables between those with or without playing related musculoskeletal pain? Methods: Three professional big bands in Sweden participated in this cross-sectional questionnaire study. Thirty-two of 35 musicians (mean age 45.4years (SD 10.1); 30 male) participated. A questionnaire including the Nordic Musculoskeletal Questionnaire, additional questions about playing related musculoskeletal pain (PRMD), Demand-Control-Support Questionnaire, and The Copenhagen-Psychosocial-Questionnaire, was used. Mann-Whitney U test was used to compare musicians with or without PRMD. P-value was set at <.05. Results: Level of demands at work (median: 11.5, IQR: 2) was lower than control (median: 18.0, IQR:3). Job strain (i.e. demands/control) had a median value of 0.65 (IQR: 0.14). Level of social support was 19.5 (IQR: 4). Emotional- (median: 7.0, IQR 2), cognitive- (median: 6.0, IQR: 3) and somatic- (median: 6.0, IQR: 3) stress symptoms were approximately at the same levels. Eight of 32 musicians had PRMD during the last 7 days. The groups did not differ significantly in any of the studied variables. Summary of content: The psychosocial work environment of these jazz musicians seems to be favorable since the perceived control is higher than the demands. Compared with professional symphony orchestra musicians, the stress symptoms are similar to (1), who used percent scores. No significant differences were foundation between musicians with or without PRMD. Significance: The psychosocial work environment may differ between different groups of musicians. More research is warranted to explore these potential differences, with a special focus on groups less investigated.
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| 9. |
- Röijezon, Ulrik, et al.
(författare)
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Deep and superficial cervical muscles respond differently to unstable motor skill tasks
- 2021
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Ingår i: Human Movement Science. - : Elsevier. - 0167-9457 .- 1872-7646. ; 80
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Tidskriftsartikel (refereegranskat)abstract
- Biomechanical modelling and physiological studies suggest that various spinal muscle layers differ in their contribution to spine movement and stiffness. This study aimed to investigate the activation of deep and superficial muscles in stable and unstable task conditions. Nine healthy participants performed a task of controlling a metal ball on a plate fixed to the head in seated position. In unstable tasks, visual feedback was provided by mirrors to move the ball to the centre of the plate by small head movements and maintain the position for 3 s. Task difficulty was adjusted in a stepwise progression of difficulty using five surfaces with materials of decreasing resistance. In the stable condition, the ball was fixed to the plate's centre. EMG was recorded with surface (sternocleidomastoid, anterior scalenes, upper trapezius) and fine-wire electrodes (rectus capitis posterior major, obliquus inferior, multifidus, semispinalis cervicis, splenius capitis). The outcome variable was root mean square (RMS) EMG during the part of the task when the ball was maintained in the centre position. Results revealed greater cervical muscle activity in the unstable than stable conditions (p < 0.001, ηp2 = 0.746). Control of deep and superficial cervical muscles differed (p = 0.003, ηp2 = 0.354). Deep cervical muscle activity was greater with unstable tasks, but did not differ with task difficulty. In contrast, superficial cervical muscle activity increased in a stepwise manner with increasing challenge. These results support the notion that the central nervous system uses different strategies for control of deep versus superficial muscle layers of the cervical spine in association with instability.
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| 10. |
- Röijezon, Ulrik, et al.
(författare)
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Proprioceptive Disturbance in Chronic Neck Pain: Discriminate Validity and Reliability of Performance of the Clinical Cervical Movement Sense Test
- 2022
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Ingår i: Frontiers in Pain Research. - : Frontiers Media S.A.. - 2673-561X. ; 3
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Tidskriftsartikel (refereegranskat)abstract
- Chronic neck pain is associated with sensorimotor dysfunctions, which may develop symptoms, affect daily activities, and prevent recovery. Feasible, reliable, and valid objective methods for the assessment of sensorimotor functions are important to identify movement impairments and guide interventions. The aim of this study was to investigate the discriminative validity of a clinical cervical movement sense test, using a laser pointer and an automatic video-based scoring system. Individuals with chronic neck pain of idiopathic onset (INP), traumatic onset (TNP), and healthy controls (CON) were tested. Associations between movement sense and neck disability were examined and the repeatability of the test was investigated. A total of 106 participants (26 INP, 28 TNP, and 52 CON) were included in a cross-sectional study. Acuity, Speed, Time, and NormAcuity (i.e., normalized acuity by dividing acuity with movement time) were used as outcome measures. ANOVAs were used for group comparisons and Pearson correlations for associations between movement sense variables and neck disability index (NDI). Notably, 60 of the participants (30 CON, 17 INP, and 13 TNP) performed the test on a second occasion to explore test-retest reliability. Results revealed a reduced NormAcuity for both INP and TNP compared with CON (p < 0.05). The neck pain groups had similar Acuity but longer Time compared with CON. Among TNP, there was a fair positive correlation between Acuity and NDI, while there was a negative correlation between Acuity and NDI among INP. Reliability measures showed good to excellent ICC values between tests, but standard error of measurements (SEM) and minimal detectable change (MDC) scores were high. The results showed that NormAcuity is a valuable measure to identify disturbed cervical movement sense among INP and TNP. While Acuity was similar between the groups, different strategies, such as longer Time, to perform the task among neck patient groups were used. Few differences were identified between the neck pain groups, but altered strategies may exist. Reliability was acceptable, and the test is feasible to perform in the clinic. However, the technical complexity of the automated image analysis is a concern. Future developments will provide more feasible solutions.
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