The influence of smartphone use on spinal posture – A laboratory study

BackgroundSmartphones have become increasingly more popular and complicated tasks can be performed with these devices. However, the increasing use is associated with shoulder and neck pain, as well as with psychological addiction.Research questionDo different smartphone tasks lead to changes in spinal posture and pelvic position? Is there a relationship between smartphone addiction and changes in posture?MethodsA cross-sectional study including 50 participants was performed. Test subjects completed the Smartphone Addiction Scale and the SF-36 health questionnaire. Subjects spinal posture and pelvic position during different smartphone tasks were measured through a surface topography system. The different tasks were: standing in an upright position, simulating a phone call, texting with one or two hands during standing or while walking on a treadmill. Paired T-tests and ANOVA tests were performed to evaluate differences. The Kendall rank test was used to investigate the association between clinical scores and changes in spinal posture.ResultsAll smartphone tasks lead to a significant increase in thoracic kyphosis and trunk inclination during standing and while walking. A significant increased lumbar lordosis was also found. Texting with one or two hands correlated with increased surface rotation. No associations between smartphone addiction and changes of the spinal posture were reported.SignificanceThis represents the first surface topography study that investigated the influence of different smartphone tasks on the spinal posture and pelvic position during standing and while walking. With the results of this study we demonstrated that smartphone use leads to significant changes of sagittal and frontal spine parameters. Further research should focus on the evaluation of possible detrimental effects of long-term smartphone use on the spinal posture and on the development of preventive measures.     

Mobile phone use is detrimental for gait stability in young adults

BackgroundHuman walking is a highly automated motor task, however if the individual’s attention is divided, gait can be negatively affected. Although the effect of divided attention has been usually tested with standardised cognitive tasks, the common task of walking while talking on the phone may represent an ecological dual task scenario.Research questionWhat is the effect of divided attention on locomotion when using a mobile phone?MethodsThirty-seven healthy participants were asked to walk while performing different cognitive tasks: counting and spelling backwards, talking on the phone (handset by the ear and hands-free), and texting. As a control, extra postural conditions were tested: holding the phone by the ear (without talking) and carrying the phone as in the texting task. These tasks were compared with normal walking (no other cognitive or postural task). Twenty participants also performed the same tasks with the addition of an obstacle halfway through the walkway. Gait performance was measured using non-invasive inertial sensors. Step time and mediolateral acceleration range were calculated.ResultsStep time increased when counting (mean ± standard error 0.63 ± 0.02 s, p < 0.001), spelling backwards (0.67 ± 0.03 s, p < 0.001) and texting (0.61 ± 0.02 s, p = 0.005) compared to normal walking (0.56 ± 0.02 s). Compared to normal walking (8.03 ± 0.58 m/s²), mediolateral acceleration decreased when counting (6.43 ± 0.39 m/s², p < 0.001), spelling backwards (6.67 ± 0.44 m/s², p < 0.001), when talking on the phone while holding the phone (7.28 ± 0.48 m/s², p = 0.003), or hands-free (7.28 ± 0.40 m/s², p = 0.004), or texting (6.71 ± 0.50 m/s², p < 0.001). Introducing an obstacle confirmed these results.SignificanceThis study shows that even in young and healthy individuals, gait is affected by divided attention. Furthermore, the results show that common and ecological cognitive tasks, such as phone use, could induce measurable worsening of gait performance. Individuals should be careful when walking and performing other tasks that could distract them, by dividing their attention.     

Smartphone accelerometry to assess postural control in individuals with multiple sclerosis

BackgroundFalls are a major health concern for people with Multiple Sclerosis (pwMS), and impaired postural control is an important predictor of falls. Lab-based technology to measure posture is precise but expensive, and clinical tests may not capture underlying impairments. An alternative solution is to leverage smartphone accelerometry as it is affordable, ubiquitous, and portable.Research question: Can smartphone accelerometry measure postural control compared to a force plate and research grade accelerometer in pwMS, and can smartphone accelerometry discriminate between assisted device and non-assisted device users?Methods27 pwMS (12 assisted device users, 15 non-assisted device users) stood on a force plate while holding a smartphone with an attached research grade accelerometer against their chest. Participants performed two, 30 s trials of: eyes open, eyes closed, semi-tandem, tandem, and single leg. Acceleration and center of pressure were extracted, and Root Mean Square (RMS) and 95 % confidence ellipse were calculated. Spearman’s correlations were performed, and receiving operating characteristic (ROC) curves and the Area Under the Curve (AUC) were calculated.ResultsThere were moderate to high correlations between the smartphone and accelerometer for RMS (ρ = 0.85 – 1.0; p = 0.001 – <0.001) and 95 % area ellipse (ρ = 0.92 – 0.99; p = <0.001). There were weak to moderate correlations between the smartphone and force plate for RMS (ρ = 0.38 – 0.92; p = 0.06 – <0.001) and 95 % area ellipse (ρ = 0.69 – 0.90 p = 0.002 – <0.001). To discriminate between assisted device usage, ROC curves for smartphone outputs were constructed, the AUC was high and statistically significant (p < 0.001 – 0.02).SignificanceThere is potential to leverage smartphone accelerometery to measure postural control in pwMS. These finding provide preliminary results to support the development of a mobile health application to measure fall risk for pwMS.     

Cognitive and visual demands,but not gross motor demand,of concurrent smartphone use affect laboratory and free-living gait among young and older adults

BackgroundAs smartphones are an integral part of daily activities, understanding the underlying mechanism associated with concurrent cell phone use while walking may help reduce the risks of injury.Research questionThis study examined the effect of cognitive, visual, and gross motor demands while using a phone during gait among young and older adults in the laboratory and free-living environments.MethodsTwelve young and twelve older adults walked along a 10-m walkway under five conditions: single-task walking (Walk), walking and bi-manually holding a phone (Walk-Hold), walking while looking at a phone held in front of the participants (Walk-Look), walking while answering questions (Walk-Answer), and walking while texting (Walk-Text). All conditions were performed in laboratory and free-living environments. Gait velocity, step time, step length, and cadence were obtained using a smartphone with a built-in accelerometer attached to the body. The dual-task cost (DTC) was also assessed. A three-way ANOVA was utilized for all parameters.ResultsWhile no three-way interactions were found for any parameter, group × condition interactions were significant for gait velocity, step time, step length, cadence and their corresponding DTC. Decreased gait velocity, step length and cadence, with increased step time was demonstrated during Walk-Look, Walk-Answer, and Walk-Text, compared to Walk and Walk-Hold. While older adults markedly changed their gait during Walk-Answer and Walk-Text, these changes were less pronounced among young adults.SignificanceVisual and cognitive demand while concurrently using a phone influenced gait, especially among the elderly. Environment did not accentuate gait alterations during concurrent phone use. Therefore, smartphone technology should be developed to detect dual-task walking and temporarily modify functionality to reduce risk of injury from divided attention.     

Smartphone virtual reality to increase clinical balance assessment responsiveness

ObjectiveTo determine if a low cost smartphone based, clinically applicable virtual reality (VR) modification to the standard Balance Error Scoring System (BESS) can challenge postural stability beyond the traditional BESS.DesignCross-sectional study.SettingUniversity research laboratory.Participants28 adults (mean age 23.36 ± 2.38 years, mean height 1.74 m ± 0.13, mean weight 77.95 kg ± 16.63).Main outcome measuresBESS postural control errors and center of pressure (CoP) velocity were recorded during the BESS test and a VR modified BESS (VR-BESS). The VR-BESS used a headset and phone to display a rollercoaster ride to induce a visual and vestibular challenge to postural stability.ResultsThe VR-BESS significantly increased total errors (20.93 vs. 11.42, p < 0.05) and CoP velocity summed across all stances and surfaces (52.96 cm/s vs. 37.73 cm/s, p < 0.05) beyond the traditional BESS.ConclusionThe VR-BESS provides a standardized, and effective way to increase postural stability challenge in the clinical setting. The VR-BESS can use any smartphone technology to induce postural stability deficits that may otherwise normalize with traditional testing. Thus, providing a unique relatively inexpensive and simple to operate clinical assessment tool and∖or training stimulus.     

Can arm movements improve postural stability during challenging standing balance tasks?

BackgroundThere is growing evidence that arm movements make a substantial and functionally relevant contribution to dynamic balance. Additional insight of the important role of arm movements may be gained by quantifying the effects of arm restriction on the performance of commonly recommended static balance tasks of increasing difficulty.Research questionThe purpose of the present study was to determine whether restricting/permitting arm movements influences postural sway during tasks of various levels of difficulty.MethodsA total of 20 healthy and physically active adults (females; n = 10; age, 20.7 ± 1.3 years) randomly completed (a) quiet standing postural control tasks of increasing difficulty (bipedal, tandem, unipedal) on a fixed and foam surface, and (b) a dynamic postural control task (Y balance test), under two different verbally conveyed instructions of arm position; (1) restricted arm movement and (2) free arm movement. Centre of pressure outcomes measured during quiet standing served as a measure of static balance performance.ResultsThe results showed that restricting movements of the arms elicited large magnitude (Cohen’s d = 0.97 – 1.28) increases in mediolateral postural sway (P < 0.05) but not anteroposterior (P > 0.05) sway. These effects were only observed during challenging (tandem and unipedal) standing balance tasks. Restricting arm movements elicited a marked reduction in the Y Balance reach distance (all directions, P < 0.001, d = −0.53 to −1.15).SignificanceThe findings from the present study suggest that the contribution of the arms only become relevant when frontal plane balance is challenged. Moreover, the data indicate that arm movements are vital for the control of mediolateral postural sway.     

Step length synergy while crossing obstacles is weaker in patients with Parkinson’s disease

BackgroundImpaired movement stability is a common symptom of Parkinson’s disease (PD) that leads to falls and mishandled objects. Decline in synergistic stabilization of movement in PD patients has been observed in manual and postural tasks. However, locomotor synergies have not been quantified in PD patients.Research questionThe purpose of this work was to quantify the strength of the synergy stabilizing the step length while crossing an obstacle in PD patients. We hypothesized that (1) the distances of the front and rear feet relative to the obstacle would display compensatory across-trial co-variance that stabilizes step length in PD patients and age-matched controls, and (2) the step-length stabilization would be weaker in PD patients.MethodsThirteen PD patients and eleven healthy age-matched controls walked up to and stepped over a 15 cm high obstacle fifteen times.We measured the distances of the rear and front foot toes from the obstacle during the crossing step. We used the uncontrolled manifold method to parse the across-trial variance in toe distances into a component that maintains the step length and a component that changes the step length. These variance components yielded the synergy index that quantified the stability of step length.ResultsStep length was stabilized in PD patients as well as controls. However, the synergy index was 53% lower in the PD patients (p < 0.01). Thus, both our hypotheses were supported.SignificanceThis is the first study reporting impaired locomotor synergies in PD patients. Most PD patients in our sample were early stage (10 out of 13 patients were Hoehn-Yahr ≤ 2). Therefore, this result motivates further studies to establish step-length synergy during adaptive locomotor tasks as a biomarker for early detection of locomotor impairments in PD patients.     

The effect of Tai Chi exercise on postural time-to-contact in manual fitting task among older adults

BackgroundA fall would impact elderly population’s quality of life, which associate with diminished physical and psychological function, and can even be life-threatening. Tai Chi has been used to improve age-related postural instability in locomotion. However, it does not fully explain the mechanism of a lower risk of falling among the Tai Chi population compared to other healthy older adults.Research questionThe maintenance of postural stability is more complicated than minimizing postural movements. Postural time to contact is an important temporal measure of postural stability under fitting tasks, which might further clarify the benefits of long term Tai Chi exercise.MethodsParticipants were required to fit a block (90 × 90 mm) through two different openings (130 × 130 mm and 100 × 100 mm) at two different distances (arm’s length or 130 % of arm’s length). Kistler forceplate and Vicon system were used to collect center of pressure and kinematic data, respectively. Postural time to contact was used to assess instantaneous perturbation for postural system.ResultsTai Chi group exhibited significant longer postural time to contact in quiet standing and shorter postural time to contact in fitting tasks, expecting for close-small condition, compared to the brisk walking and sedentary groups (p < .05). In addition, both large and small opening condition, Tai Chi group showed a shorter postural time to contact than brisk walking and sedentary groups (p < .0001).SignificanceLong term Tai Chi exercise would promote the regulation of posture and decrease the postural constrain to increase the overall stability when performing fitting tasks. Therefore, Tai Chi exercise can be considered as a feasible method to enhance postural control and stability in older adult.     

Anticipatory postural adjustment during gait initiation in multiple sclerosis patients: A systematic review

BackgroundMultiple sclerosis (MS) causes balance and walking disorders. Gait initiation is the complex transition between standing and walking and is characterized by two distinct phases: the anticipatory postural adjustment (APA) phase followed by the execution of the first step phase.Research aimTo determine alterations in the APA during gait initiation in patients with MS.MethodsA systematic search was conducted in May 2018. The search was carried out by the use of the following databases: PubMed, Web of Science and the Cochrane Library. The following keywords were used: MS, gait initiation, step initiation, and postural adjustment(s). Outcomes of interest were the variables generally used to assess APA, including electromyography, force-plate data, or video-based data, duration of APA, and length of first step. The Ottawa scale was used to assess the quality of the studies.ResultsEight case-control studies were included; one was a transverse study. A total of 215 MS patients and 116 healthy subjects were included with ages ranging from 22 to 76 years old. In MS patients, Expanded Disability Status Scale (EDSS) scores ranged from 0 to 7. APA CoP displacements were smaller in the anteroposterior axis. Four studies evaluated muscle activation during APA. The latencies of all muscles were delayed, and smaller magnitudes of muscle activity during APA were found, even in the early stage of disease. The first step was shorter in MS patients than in healthy patients. No previous study has reported joint movement or trunk inclination during gait initiation.SignificanceThis review illustrates the gap in knowledge of APA alterations in MS patients. APA assessment in the early stage of MS could be an interesting measure to characterize balance, dynamic control and risk of fall for such patients.     

Validation of a smartphone embedded inertial measurement unit for measuring postural stability in older adults

BackgroundIdentifying older adults with increased fall risk due to poor postural control on a large scale is only possible through omnipresent and low cost measuring devices such as the inertial measurement units (IMU) embedded in smartphones. However, the correlation between smartphone measures of postural stability and state-of-the-art force plate measures has never been assessed in a large sample allowing us to take into account age as a covariate.Research questionHow reliably can postural stability be measured with a smartphone embedded IMU in comparison to a force plate?MethodsWe assessed balance in 97 adults aged 50–90 years in four different conditions (eyes open, eyes closed, semi-tandem and dual-task) in the anterio-posterior and medio-lateral directions. We used six different parameters (root mean square and average absolute value of COP displacement, velocity and acceleration) for the force plate and two different parameters (root mean square and average absolute value of COM acceleration) for the smartphone.ResultsTest-retest reliability was smaller for the smartphone than for the force plate (intra class correlation) but both devices could equally well detect differences between conditions (similar Cohen’s d). Parameters from the smartphone and the force plate, with age regressed out, were moderately correlated (robust correlation coefficients of around 0.5).SignificanceThis study comprehensively documents test-retest reliability and effect sizes for stability measures obtained with a force plate and smartphone as well as correlations between force plate and smartphone measures based on a large sample of older adults. Our large sample size allowed us to reliably determine the strength of the correlations between force plate and smartphone measures. The most important practical implication of our results is that more repetitions or longer trials are required when using a smartphone instead of a force plate to assess balance.     

An external focus of attention compared to an internal focus of attention improves anticipatory postural adjustments among people post-stroke

BackgroundPeople after stroke often have postural impairments that can increase their risk of falling. Anticipatory postural adjustments (APAs) are changes in the activity of postural muscles prior to a voluntary movement in order to maintain vertical equilibrium. Previous research suggests that improving APAs leads to better postural control and reduces the risk of falls. Despite the importance of APAs and their impairment among people post-stroke, studies that aim to investigate methods for improving APAs are limited. Consistent evidence supports that an external focus of attention compared to an internal focus of attention, yields superior performance of motor skills that include postural control.Research questionWhat are the effects of adopting different foci of attention on measures of APAs and movement parameters when performing a lower extremity Fitts’ task among people post-stroke?MethodsTwelve individuals post-stroke performed a lower extremity stepping movement (Fitts’ task) while adopting an external focus or an internal focus of attention in a within-subject design. A motion capture system was used to record participants’ movement data. Custom software derived movement time (MT), peak velocity (PV), time to peak velocity (ttPV) and variability at endpoint (SD_T). Electromyography was used to measure muscle activity and determine APAs onset and magnitude. For all dependent variables separate repeated measures ANOVAs were conducted to compare performance between foci of attention.ResultsThe results showed that an external focus of attention yielded significantly better performance on all outcome measures. The improvement in performance was seen in shorter MT, higher PV, shorter ttPV, smaller SD_T, earlier APAs onset and more efficient APAs magnitude.SignificanceThe changes in outcome measures suggest that adopting an external focus of attention during postural tasks could be an effective strategy for improving balance control among people post-stroke.     

Characteristics of functional gait among people with and without peripheral neuropathy

It is advantageous from a rehabilitation standpoint to determine physiological factors associated with functional gait. These factors may be fundamentally different in those with peripheral neuropathy (PN) compared to age-matched healthy individuals. The purpose of this investigation was to examine associations between functional gait and measures of leg strength, standing balance, and locomotor kinematics in people with and without PN.MethodsIndividuals with PN and age-matched controls were assessed for functional gait by the 6-min walk and timed up-and-go tests. Leg strength was measured as isokinetic peak torque of the knee extensors. Standing balance was assessed by center-of-pressure sway velocity and area during quiet stance. Locomotor kinematics from treadmill walking were used to compute stride duration variability and local instability (i.e., finite-time Lyapunov exponents), which estimate kinematic divergence caused by small-scale perturbations.ResultsLeg strength and locomotor kinematics – in particular local instability – correlated with functional gait performance in controls. Conversely, reduced functional gait performance in the PN group was primarily mediated by impaired standing balance control.DiscussionLocomotor kinematics predicts functional gait, and the magnitude of variability and local instability should be calculated to fully evaluate locomotor system health. The observation that different factors associated with functional gait between groups speaks to the uniqueness of the PN-related movement disorder. Functional gait-related rehabilitation programs for PN patients should be tailored toward this uniqueness.     

Impaired postural control of axial segments in children with cerebral palsy

BackgroundSensorimotor control of axial segments, which develops during childhood and is not mature until adolescence, is essential for the development of balance control during motor activities. Children with cerebral palsy (CP) have deficits in postural control when standing or walking, including less stabilization of the head and trunk which could affect postural control.Research questionIs dynamic stabilization of axial segments during an unstable sitting task deficient in children with CP compared to typically developing children? Is this deficit correlated with the deficit of postural control during standing?MethodSeventeen children with CP (GMFCS I-II) and 17 typically-developing children from 6 to 12 years old were rated on the Trunk Control Measurement Scale (TCMS). In addition, posturography was evaluated in participants while they maintained their balance in stable sitting, unstable sitting, and quiet standing, under “eyes open” and “eyes closed” conditions. In sitting tasks, the participants had to remain stable while being prevented from using the lower and upper limbs (i.e. to ensure the involvement of axial segments alone).ResultsChildren with CP compared to TD children had significantly larger surface area, mean velocity and RMS values of CoP displacements measured during the unstable sitting task and the standing task, under both “eyes open” and “eyes closed” conditions. No significant group effects were observed during the stable sitting task. The TCMS total score was significantly lower, indicating trunk postural deficit, in the CP group than in the TD group and was significantly correlated with postural variables in the sitting and standing tasks.SignificanceChildren with CP indeed have a specific impairment in the postural control of axial segments. Since the postural control of axial segments is important for standing and walking, its impairment should be taken into account in rehabilitation programs for children with CP.     

Determining the utility of a smartphone-based gait evaluation for possible use in concussion management

ABSTRACT

Objectives: Our was objectives were to (1) assess the validity of a smartphone-based application to obtain spatiotemporal gait variables relative to an established movement monitoring system used previously to evaluate post-concussion gait, and (2) determine the test-retest reliability of gait variables obtained with a smartphone.

Methods: Twenty healthy participants (n = 14 females, mean age = 22.2, SD = 2.1 years) were assessed at two time points, approximately two weeks apart. Two measurement systems (inertial sensor system, smartphone application) acquired and analyzed single-task and dual-task spatio-temporal gait variables simultaneously. Our primary outcome measures were average walking speed (m/s), cadence (steps/min), and stride length (m) measured by the inertial sensor system and smartphone application.

Results: Correlations between the systems were high to very high (Pearson r = 0.77–0.98) at both time points, with the exception of dual-task stride length at time 2 (Pearson r = 0.55). Bland-Altman analysis for average gait speed and cadence indicated the average disagreement between systems was close to zero, suggesting little evidence for systematic bias between acquisition systems. Test-retest consistency measures using the smartphone revealed high to very high reliability for all measurements (ICC = 0.81–0.95).

Conclusions: Our results indicate that sensors within a smartphone are capable of measuring spatio-temporal gait variables similar to a validated three-sensor inertial sensor system in single-task and dual-task conditions, and that data are reliable across a two-week time interval. A smartphone-based application might allow clinicians to objectively evaluate gait in the management of concussion with high ease-of-use and a relatively low financial burden.     

A ‘Fingerprint’ of locomotor maturation: Motor development descriptors,reference development bands and data-set

BackgroundWhen aiming at studying and monitoring locomotor development in childhood, innovative indexes for the characterization of motor control performance and wearable technologies have highlighted the potential of significant advances. In particular, quantitative assessment of motor performance during natural walking (NW) and tandem walking (TW) has been proposed to highlight manifestations of motor automaticity and complexity, respectively.Research questionThis work aims at providing a quantitative overview of metrics characterizing locomotor maturation in a typically developing population, by analysing NW and TW. The final goal is to propose a novel graphical representation of motor development from childhood to adulthood, providing metrics for quantitative assessment with reference bands and data-set, supporting data interpretation and longitudinal assessment.Methods112 typically developing participants (age groups: 6-, 7-, 8-, 9-, 10-, 15-, and 25 years) walked in NW and in TW at self-selected speed. 3D acceleration and angular velocity of lower trunk and shanks were collected. Temporal parameters, their variability, and nonlinear metrics characterizing human movement (harmonic ratio, short-term Lyapunov exponents, multiscale entropy, and recurrence quantification analysis) were calculated. Effect of age was analysed on the different parameters and a graphical polar plot was defined to represent parameters that showed age effect in at least one of the two tasks.ResultsAge effect was shown on temporal parameters, their variability, multiscale entropy and recurrence quantification analysis. These parameters were selected for monitoring locomotor development and presented on an ad-hoc designed polar plot showing age-group reference bands.SignificanceGraphic results outline locomotor differences with maturation at first glance. The patterns in NW and TW allow to characterize specific aspects of locomotor maturation, to evaluate in which area changes occur and towards which direction, depending on the task. The novel database containing participants’ raw collected data is made available as additional result of the present study.     

The interacting effect of cognitive and motor task demands on performance of gait,balance and cognition in young adults

Mobility limitations and cognitive impairments, each common with aging, reduce levels of physical and mental activity, are prognostic of future adverse health events, and are associated with an increased fall risk. The purpose of this study was to examine whether divided attention during walking at a constant speed would decrease locomotor rhythm, stability, and cognitive performance. Young healthy participants (n = 20) performed a visuo-spatial cognitive task in sitting and while treadmill walking at 2 speeds (0.7 and 1.0 m/s).Treadmill speed had a significant effect on temporal gait variables and ML-COP excursion. Cognitive load did not have a significant effect on average temporal gait variables or COP excursion, but variation of gait variables increased during dual-task walking. ML and AP trunk motion was found to decrease during dual-task walking. There was a significant decrease in cognitive performance (success rate, response time and movement time) while walking, but no effect due to treadmill speed. In conclusion walking speed is an important variable to be controlled in studies that are designed to examine effects of concurrent cognitive tasks on locomotor rhythm, pacing and stability. Divided attention during walking at a constant speed did result in decreased performance of a visuo-spatial cognitive task and an increased variability in locomotor rhythm.     

Relation between physical exertion and postural stability in hemiparetic participants secondary to stroke

IntroductionChronic hemiparetic stroke individuals are at a higher risk of falling. This may be due to balance impairments, cardiovascular deconditioning, and muscle weakness associated with stroke effects. Postural instability associated with fatigue would likely be attained more rapidly for stroke individuals than for healthy individuals.ObjectiveTo determine the effects of physical exertion induced by walking on postural stability in hemiparetic stroke participants.MethodsTwelve hemiparetic participants and 12 control participants walked over-ground for a duration of 6 min and 18 min at their comfortable speed. Postural stability was assessed using centre of pressure related parameters during double-legged stance and tasks before the walk, immediately after the walk, 15 min post-walk, and 30 min post-walk. Measures of physical exertion during walking were also obtained from cardiorespiratory parameters, time-distance parameters, and subjective scales. Variables on postural stability and on physical exertion were analyzed using two-way repeated measures ANOVA and Generalized Estimating Equations.ResultsPhysical exertion measures significantly increased when the duration of walk was increased from 6 min to 18 min in both control and hemiparetic participants. For postural stability measures, increasing the duration of walking led to a significant increase of postural sway in double-legged stance and sit-to-stand for the hemiparetic participants only. This effect on balance of hemiparetic participants was observed immediately after the end of the walk.ConclusionThis study demonstrated that physical exertion can increase postural sway in hemiparetic participants which could possibly lead to an increased risk of falling in these individuals.     

Automated gait event detection for a variety of locomotion tasks using a novel gyroscope-based algorithm

BackgroundThe robust identification of initial contact (IC) and toe-off (TO) events is a vital task in mobile sensor-based gait analysis. Shank attached gyroscopes in combination with suitable algorithms for data processing can robustly and accurately complete this task for gait event detection. However, little research has considered gait detection algorithms that are applicable to different locomotion tasks.Research questionDoes a gait event detection algorithm for various locomotion tasks provide comparable estimation accuracies as existing task-specific algorithms?MethodsThirteen males, equipped with a gyroscope attached to the right shank, volunteered to perform nine different locomotion tasks consisting of linear movements and movements with a change of direction. A rule-based algorithm for IC and TO events was developed based on the shank sagittal plane angular velocity. The algorithm was evaluated against events determined by vertical ground reaction force. Absolute mean error (AME), relative absolute mean error (RAME) and Bland–Altman analysis was used to assess its accuracy.ResultsThe average AME and RAME were 11 ± 3 ms and 3.07 ± 1.33 %, respectively, for IC and 29 ± 11 ms and 7.27 ± 2.92 %, respectively, for TO. Alterations of the walking movement, such as turns and types of running, slightly reduced the accuracy of IC and TO detection. In comparison to previous methods, increased or comparable accuracies for both IC and TO detection are shown.SignificanceThe study shows that the proposed algorithm is capable of detecting gait events for a variety of locomotion tasks by means of a single gyroscope located on the shank. In consequence, the algorithm can be applied to activities, which consist of various movements (e.g., soccer). Ultimately, this extends the use of mobile sensor-based gait analysis.     

Impact of strength and balance on Functional Gait Assessment performance in older adults

BackgroundThe Functional Gait Assessment (FGA) evaluates postural stability in gait and predicts fall risk in older adults. Individual tasks within the FGA consider aspects of mobility assumed to require strength and/or balance to complete. Identifying how quantitative measures of strength and balance relate to FGA performance would allow for more targeted interventions based on one’s pattern of performance on different tasks.Research QuestionIs performance on the FGA (total score and individual task scores) related to measures of strength and balance in healthy older adults?MethodsIn a cross-sectional study, healthy older adults (N = 46) were evaluated with the FGA, measures of knee extensor strength, and balance (static stance and weight shifting) (N = 46). Correlational analyses were performed between FGA scores (total and individual) and measures of strength and balance.ResultsTotal FGA performance was positively correlated with knee extensor strength (maximum torque and rate of torque development). Individual FGA tasks of walking backwards (task 9) and stair climbing (task 10) had the highest correlations with strength measures. Total FGA performance was correlated with reduced postural sway in static balance tasks, but not with balance performance on the weight shifting tasks. The individual FGA task that challenged proprioceptive (task 7) inputs for balance was associated with static balance.SignificanceThe total FGA score is related to domains of strength and static balance. The results indicate that the FGA can be influenced by reduced strength and balance. The pattern of performance on individual FGA tasks may indicate whether reduced postural stability in gait is related to deficits in strength or balance domains in this older population.     

Haptic information provided by anchors and the presence of cognitive tasks contribute separately to reducing postural sway in young adults

BackgroundHaptic information provided by the anchors reduces postural sway while standing upright. It is unclear whether this benefit would remain in the presence of cognitive tasks combined with a more challenging postural task.Research questionOur aim was to investigate the effects of the anchors and visual and auditory cognitive tasks on postural control in young adults in a challenging balancing task.MethodsTwenty young adults stood upright on a balance beam with the central portion of each foot placed over the beam and feet at shoulder width without and with the use of the anchors in three cognitive conditions: control, visual Stroop task, and auditory digit-monitoring task. Each anchor consisted of a flexible cable with a light load (125 g) attached at one end of the cable. With the anchors, the participants held the flexible cable in each hand with the light load resting on the ground while keeping tension in the cable.ResultsBoth visual and auditory cognitive tasks reduced the center of pressure (COP) ellipse area, the root mean square of the margin of dynamic stability (based on the extrapolated center of mass, COM) and increased the COM time-to-contact relative to the boundaries of the base of support in the AP direction. The anchors reduced the COP ellipse area.SignificanceThere is a functional integration between postural control and cognitive tasks, such that postural sway was reduced to facilitate the execution of the cognitive tasks. Anchors were effective in reducing postural sway, suggesting that haptic information was able to benefit postural control in a challenging balancing task regardless of the cognitive task.