Agreement of Two Physical Behaviour Monitors for Characterising Posture and Stepping in Children Aged 6-12 Years

All new physical behaviour measurement devices should be assessed for compatibility with previous devices. Agreement was assessed between the activPAL4TM and activPAL3TM physical behavior monitors within a laboratory and a multi-day free-living context. Healthy children aged 6-12 years performed standardised (sitting, standing, stepping) (12 min) and non-standardised (6 min) activities in a laboratory and a multi-day (median 3 days) free-living assessment whilst wearing both monitors. Agreement was assessed using Bland-Altman plots, sensitivity, and the positive predictive value (PPV). There were 15 children (7M/8F, 8.4 ± 1.8 years old) recruited. For the laboratory-based standardised activities, sitting time, stepping time, and fast walking/jogging step count were all within ±5% agreement. However, the activPAL4TM standing time was lower (-6.4%) and normal speed walking step count higher (+7.8%) than those of the activPAL3TM. For non-standardised activities, a higher step count was recorded by the activPAL4TM (+4.9%). The standardised activity sensitivity and PPV were all >90%, but the non-standardised activity values were lower. For free-living agreement, the standing time was lower (-7.6%) and step count higher (all steps + 2.2%, steps with cadence >100 step/min + 6.6%) for the activPAL4TM than the activPAL3TM. This study highlights differences in outcomes as determined by the activPAL4TM and activPAL3TM, which should be considered when comparing outcomes between studies.

Full-Day Physical Activity and Sedentary Behaviour Levels of Typically Developing Children and Adolescents in the Middle East: A Systematic Review

Physical activity (PA) and sedentary behaviour (SB) are important components of physical behaviour associated with long-term health outcomes. Environmental and cultural factors may influence physical behaviour. To explore full day PA and SB in children and adolescents (2-18 years old) in the Middle East, a systematic literature review was performed including 183 journal articles. A wide range of PA and SB outcomes were reported, in some cases making synthesis of results difficult. As a consequence, results were generally reported narratively (MVPA time, total PA, SB time). Meta-regression of daily step count revealed females took 4600 fewer steps than males, with 3000 fewer steps on weekdays than weekends, and overweight individuals taking 2800 fewer steps/day. Steps decreased with age. Meta-regression for TV viewing time demonstrated an increase by 0.04 h per year of age. Even though environmental and cultural conditions may be different, PA and SB of children and adolescents in the Middle East were largely comparable to those of Europeans and North Americans. The wide range of data collection instruments used (both self-report questionnaire and body-worn devices) and heterogeneity of data made synthesis of reported data across studies very difficult, suggesting a need for greater standardisation of data collection methods.

Validity and Reliability of the activPAL4TM for Measurement of Body Postures and Stepping Activity in 6-12-Year-Old Children

A link between inappropriate physical behaviour patterns (low physical activity and high sedentary behaviour) and poor health outcomes has been observed. To provide evidence to quantify this link, it is important to have valid and reliable assessment tools. This study aimed to assess the validity and reliability of the activPAL4^TM monitor for distinguishing postures and measuring stepping activity of 6-12-year-old children. Thirteen children (8.5 ± 1.8 years) engaged in pre-determined standardised (12 min) and non-standardised (6 min) activities. Agreement, specificity and positive predictive value were assessed between the activPAL4^TM and direct observation (DO) (nearest 0.1 s). Between-activPAL4^TM (inter-device) and between-observer (inter-rater) reliability were determined. Detection of sitting and stepping time and forward purposeful step count were all within 5% of DO. Standing time was slightly overestimated (+10%) and fast walking/jogging steps underestimated (-20%). For non-standardised activities, activPAL4^TM step count matched most closely to combined backward and forward purposeful steps; however, agreement varied widely. The activPAL4^TM demonstrated high levels of reliability (ICC(1, 1) > 0.976), which were higher in some instances than could be achieved through direct observation (ICC(2, 1) > 0.851 for non-standardised activities). Overall, the activPAL4^TM recorded standardised activities well. However, further work is required to establish the exact nature of steps counted by the activPAL4^TM.

Antihypertensive drug treatment and susceptibility to SARS-CoV-2 infection in human PSC-derived cardiomyocytes and primary endothelial cells

The pathogenicity of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has been attributed to its ability to enter through the membrane-bound angiotensin-converting enzyme 2 (ACE2) receptor. Therefore, it has been heavily speculated that angiotensin-converting enzyme inhibitor (ACEI) or angiotensin receptor blocker (ARB) therapy may modulate SARS-CoV-2 infection. In this study, exposure of human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs) and human endothelial cells (hECs) to SARS-CoV-2 identified significant differences in protein coding genes involved in immunity, viral response, and cardiomyocyte/endothelial structure. Specifically, transcriptome changes were identified in the tumor necrosis factor (TNF), interferon α/β, and mitogen-activated protein kinase (MAPK) (hPSC-CMs) as well as nuclear factor kappa-B (NF-κB) (hECs) signaling pathways. However, pre-treatment of hPSC-CMs or hECs with two widely prescribed antihypertensive medications, losartan and lisinopril, did not affect the susceptibility of either cell type to SARS-CoV-2 infection. These findings demonstrate the toxic effects of SARS-CoV-2 in hPSC-CMs/hECs and, taken together with newly emerging multicenter trials, suggest that antihypertensive drug treatment alone does not alter SARS-CoV-2 infection.

Quantifying upper limb tremor in people with multiple sclerosis using Fast Fourier Transform based analysis of wrist accelerometer signals

Introduction

Tremor is a disabling symptom of Multiple Sclerosis (MS). The development of objective methods of tremor characterisation to assess intervention efficacy and disease progression is therefore important. The possibility of using a Fast Fourier Transform (FFT) method for tremor detection was explored.

Methods

Acceleration from a wrist-worn device was analysed using FFTs to identify and characterise tremor magnitude and frequency. Processing parameters were explored to provide insight into the optimal algorithm. Participants wore a wrist tri-axial accelerometer during 9 tasks. The FAHN clinical assessment of tremor was used as the reference standard.

Results

Five people with MS and tremor (57.6 ± 15.3 years, 3 F/2M) and ten disease-free controls (42.4 ± 10.9 years, 5 M/5F) took part. Using specific algorithm settings tremor identification was possible (peak frequency 3–15Hz; magnitude greater than 0.06 g; 2 s windows with 50% overlap; using 2 of 3 axes of acceleration), giving sensitivity 0.974 and specificity 0.971 (38 tremor occurrences out of 108 tasks, 1 false positive, 2 false negatives). Tremor had frequency 3.5–13.0 Hz and amplitude 0.07–2.60g.

Conclusions

Upper limb tremor in people with MS can be detected using a FFT approach based on acceleration recorded at the wrist, demonstrating the possibility of using this minimally encumbering technique within clinical practice.

Collaboration during a crisis - the Lighthouse Lab volunteers

As a group of early-career researchers, we recount our experiences of volunteering at one of the national Lighthouse Labs based at the UK Biocentre in Milton Keynes. We worked together as part of a multidisciplinary team to support the large-scale processing of coronavirus disease 2019 (COVID-19) swabs from across the whole of the UK.

A mixed linear modelling characterisation of gender and speed related changes in spatiotemporal and kinematic characteristics of gait across a wide speed range in healthy adults

In exploring the relationship between the kinematics of gait and speed of progression individual variation in patterns and gender differences have not always been adequately taken into account. In the current study mixed linear modelling was used to isolate changes with speed from those associated with individual variation and gender. Three-dimensional motion analysis of 20 participants (10M/10F, 25.7 ± 5.1 years) walking at a wide range of speeds (normalised speeds 0.10-0.55 ∼0.41-2.26 m/s) was recorded (775 walks). Spatiotemporal (speed, cadence, step length, percentage of single and double support) and kinematic characteristics (pelvis through ankle) were determined. Significant between participant differences were highlighted in both intercept and slope of relationships. In addition females exhibiting different peak pelvic tilt and obliquity, hip flexion and internal rotation and ankle dorsiflexion compared to males. Spatiotemporal parameters exhibited non-linear relationships with normalised speed (R²> 0.5). Kinematic features exhibited significant relationships with normalised speed, varying from linear to cubic, from very weak to strong in fit (0.010 > R²> 0.672). Mixed linear modelling highlighted gender dependent, speed related changes in addition to inter-individual variation. Gender and speed are both important determinants of gait patterns, however, individual variations remain.

Lycra splinting garments for adults with intellectual disabilities who fall due to gait or balance issues: a feasibility study

BACKGROUND

Adults with intellectual disabilities (IDs) experience high rates of falls and have high rates of gait or balance issues which contribute to falls. Lycra splinting garments (LSGs) have potential to improve gait or balance, but they have never before been tested with adults with IDs who fall due to gait or balance issues. The aim of this study was to test in adults with IDs, the feasibility of using LSGs to improve movement and function and reduce falls, whilst also exploring usability and likely compliance.

METHOD

A convenience sample of nine adults with IDs wore tailored LSGs over a 6-week assessment period. Laboratory-based foot clearance, balance, and gait measures were collected pre- and post-LSG-wear. Falls charts and questionnaires on usability and likely compliance were also completed.

RESULTS

Seven participants experienced a reduction in falls during their six weeks of LSG wear; most notably in the group of five participants who wore lycra splinting socks, compared with only two in the group of four who wore lycra splinting shorts or leggings only.

CONCLUSION

Lycra splinting socks are likely to bring about positive outcomes for adults with IDs who fall due to gait/balance issues on an individual case by case basis over time, but further research is required to test this hypothesis under randomised controlled trial conditions. Potential benefits of more intrusive LSGs are outweighed by reported problems with usability and compliance.

Spatiotemporal and kinematic characteristics of gait initiation across a wide speed range

BACKGROUND

Gait initiation can be performed at a range of speeds. Those with disability tend to use a slower speed compared to those without disability. In assessing the spatiotemporal and kinematic characteristics of gait initiation it is therefore important to consider the effects of speed on outcomes.

RESEARCH QUESTION

What is the effect of speed of performance on spatiotemporal and kinematic characteristics of gait initiation?

METHODS

Spatiotemporal and kinematic characteristics were measured across a wide range of speeds from very slow to very fast (normalised initiating leg (swing or SW limb) step speed 0.1-0.5) for 20 health adults (10 men/10 women, 22-44 years) using three-dimensional motion analysis of the first two steps of gait.

RESULTS

Mixed linear modelling of 295 walking trials indicated differences between individuals, sexes and strong non-linear relationships between normalised initiating leg step speed and cadence and step lengths (R² > 0.5). Particular characteristics of joint kinematics (maxima and minima for both initiating (SW) and contralateral limb (stance or ST limb)) demonstrated significant non-linear (squared, cubic and power law) changes with speed. Moderate to strong relationships were identified for sagittal plane pelvis, hip and knee kinematics as well as hip adduction (0.3 < R² < 0.7).

SIGNIFICANCE

Gait initiation spatiotemporal and kinematic characteristics were quantified across the maximum range of speeds achievable, providing comprehensive characterisation of changes with speed. Significant, non-linear changes with speed were identified, suggesting different strategies are employed to modify speed at low and high speeds. The highlighted changes with speed illustrate the importance of taking speed into account when comparing outcomes between healthy adults and those with pathology.

Objective identification of upper limb tremor in multiple sclerosis using a wrist-worn motion sensor: Establishing validity and reliability

Introduction

Over 25% of people with multiple sclerosis experience tremor, which may impact on activities of daily living and quality of life. Yet there is no method to objectively measure tremor and effectiveness of interventions on tremor. This study aimed to test validity and reliability of a new objective measurement for upper limb tremor in people with multiple sclerosis.

Method

Twelve participants with multiple sclerosis who self-reported tremor were observed performing standardised tasks. Validity and reliability of a new method to detect tremor from wrist movement was established against occupational therapist observation of tremor (FAHN). Concurrent validity of severity (displacement) of tremor was assessed. Responsiveness to change in tremor characteristics was explored in a sub-set of participants using weighted wrist-cuffs.

Results

The new method correctly predicted 98.2% of tremor cases identified by the occupational therapist, with high sensitivity (0.988) and specificity (0.976). Calculated displacement of tremor correlated with FAHN tremor severity scores moderately (rs = .452, p = .004). The new measure was responsive to changes in tremor characteristics due to change in weight of wrist-cuffs.

Conclusion

The new method of characterising tremor in those with multiple sclerosis demonstrated excellent validity and reliability in relation to tremor identified by an occupational therapist, and could provide valuable objective insight into the efficacy of interventions.

Agreement of the activPAL3 and activPAL for characterising posture and stepping in adults and children

Characterisation of physical activity and sedentary behaviour under free-living conditions is becoming increasingly important in light of growing evidence for the health implications of these behaviours. The integrity of long-term follow-up and the ability to compare outcomes between studies is critically dependent on the agreement of outcomes from successive generations of monitors. This study evaluated the agreement of the activPAL and second generation activPAL3 devices. Agreement was assessed in both adults (median 27.6y IQR 22.6) (n=20) and young people (median 12.0y IQR 4.1) (n=8) during standardised and daily living (ADL) test activities. During standardised activities; sedentary duration, upright duration, stepping duration and overall number of steps were all detected within small limits of agreement (≤5%). However, the activPAL characterised more steps during jogging than the activPAL3 (adults +8.36%, young people +6.80%). Also during ADL differences arose due to different posture characterisation in young people and lower step detection in the activPAL than the activPAL3 (adults -20.58%, young people -11.43%). Second-by-second posture analysis demonstrated high levels (>90%) of agreement for all activities between monitors. However, sensitivity (68.7%) and positive predictive value (78.8%) for adult stepping demonstrated disagreement between monitor interpretation of movement patterns during ADL. Agreement between monitor outcomes for standardised activities provides confidence that these outcomes can be considered almost equivalent. However, for characterisation of jogging and smaller movements during ADL, it is likely that significant differences between monitor outcomes will arise.

Ethnic Differences in and Childhood Influences on Early Adult Pulse Wave Velocity: The Determinants of Adolescent, Now Young Adult, Social Wellbeing, and Health Longitudinal Study

Supplemental Digital Content is available in the text.

Early determinants of aortic stiffness as pulse wave velocity are poorly understood. We tested how factors measured twice previously in childhood in a multiethnic cohort study, particularly body mass, blood pressure, and objectively assessed physical activity affected aortic stiffness in young adults. Of 6643 London children, aged 11 to 13 years, from 51 schools in samples stratified by 6 ethnic groups with different cardiovascular risk, 4785 (72%) were seen again at aged 14 to 16 years. In 2013, 666 (97% of invited) took part in a young adult (21–23 years) pilot follow-up. With psychosocial and anthropometric measures, aortic stiffness and blood pressure were recorded via an upper arm calibrated Arteriograph device. In a subsample (n=334), physical activity was measured >5 days via the ActivPal. Unadjusted pulse wave velocities in black Caribbean and white UK young men were similar (mean±SD 7.9±0.3 versus 7.6±0.4 m/s) and lower in other groups at similar systolic pressures (120 mm Hg) and body mass (24.6 kg/m²). In fully adjusted regression models, independent of pressure effects, black Caribbean (higher body mass/waists), black African, and Indian young women had lower stiffness (by 0.5–0.8; 95% confidence interval, 0.1–1.1 m/s) than did white British women (6.9±0.2 m/s). Values were separately increased by age, pressure, powerful impacts from waist/height, time spent sedentary, and a reported racism effect (+0.3 m/s). Time walking at >100 steps/min was associated with reduced stiffness (P<0.01). Effects of childhood waist/hip were detected. By young adulthood, increased waist/height ratios, lower physical activity, blood pressure, and psychosocial variables (eg, perceived racism) independently increase arterial stiffness, effects likely to increase with age.

Validity and reliability of the activPAL3 for measuring posture and stepping in adults and young people

Characterisation of free-living physical activity requires the use of validated and reliable monitors. This study reports an evaluation of the validity and reliability of the activPAL3 monitor for the detection of posture and stepping in both adults and young people. Twenty adults (median 27.6y; IQR22.6y) and 8 young people (12.0y; IQR4.1y) performed standardised activities and activities of daily living (ADL) incorporating sedentary, upright and stepping activity. Agreement, specificity and positive predictive value were calculated between activPAL3 outcomes and the gold-standard of video observation. Inter-device reliability was calculated between 4 monitors. Sedentary and upright times for standardised activities were within ±5% of video observation as was step count (excluding jogging) for both adults and young people. Jogging step detection accuracy reduced with increasing cadence >150stepsmin(-1). For ADLs, sensitivity to stepping was very low for adults (40.4%) but higher for young people (76.1%). Inter-device reliability was either good (ICC(1,1)>0.75) or excellent (ICC(1,1)>0.90) for all outcomes. An excellent level of detection of standardised postures was demonstrated by the activPAL3. Postures such as seat-perching, kneeling and crouching were misclassified when compared to video observation. The activPAL3 appeared to accurately detect 'purposeful' stepping during ADL, but detection of smaller stepping movements was poor. Small variations in outcomes between monitors indicated that differences in monitor placement or hardware may affect outcomes. In general, the detection of posture and purposeful stepping with the activPAL3 was excellent indicating that it is a suitable monitor for characterising free-living posture and purposeful stepping activity in healthy adults and young people.

Quantifying the cadence of free-living walking using event-based analysis

PURPOSE

Free-living walking occurs over a wide range of durations and intensities (cadence). Therefore, its characterisation requires a full description of the distribution of duration and cadence of these walking events. The aim was to use event-based analysis to characterise this in a population with intermittent claudication (IC) and a healthy matched control group.

METHODS

Seven-day walking activity was recorded using the activPAL activity monitor in a group of people with IC (n=30) and an age-matched control group (n=30). The cadence, number of steps and duration of individual walking events were calculated and outcomes were derived, and compared (p<0.05), based on thresholds applied.

RESULTS

Both groups had similar number of walking events per day (392±117 vs 415±160). The control group accumulated a greater proportion of their walking at higher cadences and 32% of their steps were taken at a cadence above 100 steps/min, for the IC group this was 20%. Longer walking events had higher cadences and the IC group had fewer of these. As walking events became longer the cadence increased but the inter-event cadence variability decreased. More purposeful walking might occur at a higher cadence, and be performed at a preferred cadence. Individuals with IC had a smaller volume of walking, but these differences occurred almost entirely above a cadence of 90 steps/min.

CONCLUSIONS

This is the first study which has quantified the cadence of continuous periods of free-living walking. The characteristics (duration, number of steps and cadence) of all the individual walking events were used to derive novel outcomes, providing new insights into free-living walking behaviour.

True cadence and step accumulation are not equivalent: the effect of intermittent claudication on free-living cadence

'True cadence' is the rate of stepping during the period of stepping. 'Step accumulation' is the steps within an epoch of time (e.g. 1min). These terms have been used interchangeably in the literature. These outcomes are compared within a population with intermittent claudication (IC). Multiday, 24h stepping activity of those with IC (30) and controls (30) was measured objectively using the activPAL physical activity monitor. 'True cadence' and 'step accumulation' outcomes were calculated. Those with IC took fewer steps/d 6531±2712 than controls 8692±2945 (P=0.003). However, these steps were taken within approximately the same number of minute epochs (IC 301±100min/d; controls 300±70min/d, P=0.894) with only slightly lower true cadence (IC 69 (IQ 66,72) steps/min; controls 72 (IQ 68,76) steps/min, P=0.026), giving substantially lower step accumulation (IC 22 (IQ 19,24) steps/min; controls 30 (IQ 23,34) steps/min) (P<0.001). However, the true cadence of stepping within the blocks of the 1, 5, 20, 30 and 60min with the maximum number of steps accumulated was lower for those with IC than controls (P<0.05). Those with IC took 1300 steps fewer per day above a true cadence of 90 steps/min. True cadence and step accumulation outcomes were radically different for the outcomes examined. 'True cadence' and 'step accumulation' were not equivalent in those with IC or controls. The measurement of true cadence in the population of people with IC provides information about their stepping rate during the time they are stepping. True cadence should be used to correctly describe the rate of stepping as performed.

Load transfer through the radiocarpal joint and the effects of partial wrist arthrodesis on carpal bone behaviour: a finite element study

A finite element model of the wrist was developed to simulate mechanical changes that occur after surgery of the wrist. After partial arthrodesis, the wrist will experience altered force transmission during loading. Three different types of partial arthrodesis were investigated - radiolunate, radioscaphoid, and radioscapholunate - and compared with the healthy untreated wrist. The results showed that the compressive forces on the radiocarpal joint decreased compared with the untreated wrist with both radiolunate and radioscaphoid fusions. The load transmission through the midcarpal joints varied depending on arthrodesis type. The forces in the extrinsic ligaments decreased with the fusion, most noticeably in the dorsal radiotriquetral ligament, but increased in the dorsal scaphotriquetral ligament. From the results of the study it can be concluded that the radioscapholunate fusion shows the most biomechanically similar behaviour out of the three fusion types compared with the healthy wrist. The modelling described in this paper may be a useful approach to pre-operative planning in wrist surgery.

A three-dimensional finite element model of maximal grip loading in the human wrist

The aim of this work was to create an anatomically accurate three-dimensional finite element model of the wrist, applying subject-specific loading and quantifying the internal load transfer through the joint during maximal grip. For three subjects, representing the anatomical variation at the wrist, loading on each digit was measured during a maximal grip strength test with simultaneous motion capture. The internal metacarpophalangeal joint load was calculated using a biomechanical model. High-resolution magnetic resonance scans were acquired to quantify bone geometry. Finite element analysis was performed, with ligaments and tendons added, to calculate the internal load distribution. It was found that for the maximal grip the thumb carried the highest load, an average of 72.2 +/- 20.1 N in the neutral position. Results from the finite element model suggested that the highest regions of stress were located at the radial aspect of the carpus. Most of the load was transmitted through the radius, 87.5 per cent, as opposed to 12.5 per cent through the ulna with the wrist in a neutral position. A fully three-dimensional finite element analysis of the wrist using subject-specific anatomy and loading conditions was performed. The study emphasizes the importance of modelling a large ensemble of subjects in order to capture the spectrum of the load transfer through the wrist due to anatomical variation.

Intra-rater repeatability of the Oxford foot model in healthy children in different stages of the foot roll over process during gait

BACKGROUND

The repeatability of the Oxford foot model has been reported, but possible variations in the repeatability during the foot roll over process have not been examined. The aim of this study was to determine the relative and absolute repeatability of the model for each stage of the foot roll over process during gait and to compare foot kinematic data from this study with that from another centre as a preliminary examination of the model's inter-centre repeatability and validity.

METHOD

Eight healthy children were tested twice at the gait laboratory. Foot kinematics from this study were plotted against those from an earlier repeatability study and repeatability statistics calculated for the three rockers of stance phase and swing phase.

RESULTS

Foot kinematics from this study and an earlier repeatability study produced similar kinematic patterns and joint angle ranges, but there were offsets in the absolute joint angles in the frontal and transverse planes. Relative and absolute repeatability were best in the sagittal plane (flexion/extension) with the poorest repeatability in the transverse plane (rotation and abduction/adduction). There was little difference in repeatability between the three rockers. Typical error of measurement varied between planes and segments from 0.9 degrees for maximum forefoot dorsiflexion in second rocker to 8.6 degrees for maximum hindfoot internal rotation in first rocker.

DISCUSSION

Repeatability varied markedly between planes and segments but was consistent throughout the gait cycle. Further studies are needed to determine the inter-centre repeatability and validity of the model.