Background

Chronic obstructive pulmonary disease (COPD) is considered a heterogenic syndrome with systemic effects, including muscle dysfunction. There is evidence of postural control impairments among individuals with COPD, partly related to muscle weakness. However, research is scarce regarding the other underlying systems of postural control, such as the visual, somatosensory and vestibular system. The aim was to compare postural control, as well as the motor and sensory systems, between individuals with and without COPD.

Methods

Twenty-two participants with COPD (mean age 74.0 ±6.2 years) and 34 non-obstructive references (mean age 74.9 ±4.9 years) participated in this cross-sectional study. Postural control was assessed with center of pressure trajectory of postural sway in quiet as well as a limits of stability test, calculating mediolateral and anteroposterior amplitudes for each test. Assessment of function in the motor system included maximum hand grip strength, as well as maximum strength in muscles around the hip, knee and ankle joints. Visual acuity, pressure sensibility, proprioception, vestibular screening, and reaction time were also included. Data was compared between groups, and significant differences in postural control were further analyzed with an orthogonal projection of latent structures regression model.

Results

There was a significantly increased sway amplitude in the mediolateral direction in quiet stance on soft surface with eyes open (p = 0.014) as well as a smaller anteroposterior amplitude in the limits of stability test (p = 0.019) in the COPD group. Regression models revealed that the mediolateral amplitude was related to visual acuity and the burden of tobacco smoking assessed as pack-years. Further, muscle strength associated with anteroposterior amplitude in limits of stability test in the COPD group, and with age and ankle dorsal flexion strength among the referents. Besides for lower ankle plantar flexion strength in the COPD group, there were however no significant differences in muscle strength.

Conclusions

Individuals with COPD had a decreased postural control and several factors were associated with the impairments. The findings imply that the burden of tobacco smoking and reduced visual acuity relate to increased postural sway in quiet stance, and that muscle weakness is related to decreased limits of stability, among individuals with COPD.

Although growing attention has been paid to motivation in explaining active travel to school among young people at the international level, no measures of motivation for active commuting to school (ACS) were found in Sweden. Guided by self-determination theory, this research aimed to adapt the Behavioral Regulation in Active Commuting to and from School (BR-ACS) questionnaire to the Swedish context and test the resulting version’s psychometric properties. The purposive and cross-sectional sample included 273 students (58 % girls, aged 10–12 years) from four Swedish urban schools. Results from confirmatory factor analyses psychometrically supported the six-factor correlated model (intrinsic motivation, integrated regulation, identified regulation, introjected regulation, external regulation, and amotivation) and the hierarchical three-factor model (autonomous, controlled motivation, and amotivation), which were invariant across gender. Latent correlations underpinned a symplex-like pattern. Discriminant and convergent validity and reliability were gathered. Criterion validity evidence was met with positive associations from intrinsic motivation, integrated and identified regulation to ACS, and a negative relationship between amotivation and ACS. The Swedish version of the BR-ACS questionnaire is a valid and reliable measure of children’s motivation toward ACS.

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.

The emergence of COVID-19 has changed the world as we know it, arguably none more so than for older people. In Sweden, the majority of COVID-19-related fatalities have been among people aged ⩾70 years, many of whom were receiving health and social care services. The pandemic has illuminated aspects within the care continuum requiring evaluative research, such as decision-making processes, the structure and organisation of care, and interventions within the complex public-health system. This short communication highlights several key areas for future interdisciplinary and multi-sectorial collaboration to improve health and social care services in Sweden. It also underlines that a valid, reliable and experiential evidence base is the sine qua non for evaluative research and effective public-health systems.

Background:

Hand grip strength is frequently used as a measurement of muscle strength, especially among older adults. Muscle strength is only one of the many components in postural control and it is currently unclear to what extent hand grip strength is associated with postural control. The aim was to analyze the association between hand grip strength and lower limb muscle strength, and postural control among older adults.

Methods:

Forty-five community-dwelling individuals over 70 years of age provided isometric hand grip strength and lower limb strength (including hip extension and abduction, knee flexion and extension, and ankle dorsiflexion and plantarflexion), as well as postural control measurements. In the latter, center of pressure excursions were recorded for quiet stance and limits of stability tests on a force plate. Orthogonal projection of latent structures regression models were used to analyze associations between hand grip strength and lower limb strength as well as postural control, respectively.

Results:

Lower limb strength explained 74.4% of the variance in hand grip strength. All lower limb muscle groups were significantly associated with hand grip strength. In a corresponding model, postural control measured with center of pressure excursions explained 20.7% of the variance in a statistically significant, albeit weak, model.

Conclusions:

These results support that hand grip strength is a valid method to estimate lower limb strength among older adults on a group level. However, strength measurements seem insufficient as a substitute for measuring postural control, and therefore specific balance tests are necessary.

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. 

Self-perceptions of aging (SPA) is associated with various health-related outcomes, including physical performance. No previous study has investigated the potential predictive influence of SPA on physical performance among Swedish community-dwelling older adults. This was a cross-sectional study using a random sample of 153 Swedish community-dwelling individuals aged 70 and older. Multiple logistic regression analysis was performed, using the subscale “Attitude Towards Own Aging” of the Philadelphia Geriatric Center Morale Scale, as a measure of SPA. The Short Physical Performance Battery (SPPB) was dichotomized and used as the outcome variable. SPA was a significant predictor (OR = 1.546, CI = 1.066–2.243) of physical performance, adjusted for age, cognitive function, and life-space mobility. Further analyses revealed significant sex differences, with SPA not being included in the model for the men whilst it was still a significant predictor (OR = 1.689, CI = 1.031–2.765) of physical performance in the group of women. SPA plays a significant role in predicting physical performance among Swedish community-dwelling older adults. To further clarify this relationship and its consequences, future longitudinal research should focus on the relationship between SPA, physical performance, and fall risk.

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.

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.