Reproducibility of a Triaxial Seismic Accelerometer (DynaPort)

Physical activity and exercise in chronic kidney disease: consensus statements from the Physical Exercise Working Group of the Italian Society of Nephrology

The Italian Society of Nephrology has tasked its Working Group on Physical Exercise with developing a consensus statement document on physical activity and exercise in patients with chronic kidney disease (CKD). This paper consists of 16 points that were discussed, and approved using the mini-Delphi method by 15 members of the working group. Each statement is based on a comprehensive review of the literature, clinical experience, and expert opinions. Overall, the statements affirm that regular physical activity and exercise training offer numerous benefits to CKD patients, including improved physical function, enhanced cardiometabolic and neuromuscular function, cognitive benefits, and an overall improvement in quality of life. Furthermore, exercise may provide nephroprotection and reduce mortality. These advantages are observed across all CKD stages, whether on conservative therapy or kidney replacement therapy (hemodialysis or peritoneal dialysis), and in kidney transplant recipients. Moreover, when physical activity and exercise training are implemented with appropriate precautions, they are safe in CKD patients. Gradual physical activity and customized exercise programs should be tailored to the patient's exercise tolerance, potentially enhancing compliance. Clinicians are encouraged to use a series of questionnaires and tests to assess the patient's level of physical activity and performance. However, exercise and physical activity are poorly implemented in clinical practice due to many barriers related to patients and healthcare staff. Overcoming these barriers requires the proactive role of the nephrologists, who should actively incorporate exercise training and promote physical activity within routine care plans. Adopting a multidisciplinary team approach, which includes nephrologists, nurses, exercise professionals, and dietitians, is crucial for providing comprehensive rehabilitation for CKD patients. Integrating new technologies and remote check ups could further enhance the effectiveness of these interventions.

Wearable Sensors to Monitor Physical Activity in Heart Failure Clinical Trials: State-of-the-Art Review

BACKGROUND

Estimation of the effects that drugs or other interventions have on patients' symptoms and functions is crucial in heart failure trials. Traditional symptoms and functions clinical outcome assessments have important limitations. Actigraphy may help to overcome these limitations due to its objective nature and the potential for continuous recording of data. However, actigraphy is not currently accepted as clinically relevant by key stakeholders.

METHODS AND RESULTS

In this state-of-the-art study, the key aspects to consider when implementing actigraphy in heart failure trials are discussed. They include which actigraphy-derived measures should be considered, how to build endpoints using them, how to measure and analyze them, and how to handle the patients' and sites' logistics of integrating devices into trials. A comprehensive recommendation based on the current evidence is provided.

CONCLUSION

Actigraphy is technically feasible in clinical trials involving heart failure, but successful implementation and use to demonstrate clinically important differences in physical functioning with drug or other interventions require careful consideration of many design choices.

Gait smoothness during high-demand motor walking tasks in older adults with mild cognitive impairment

Early signs of Mild Cognitive Impairment (MCI)-related gait deficits may be detected through the performance of complex walking tasks that require high gait control. Gait smoothness is a robust metric of overall body stability during walking. This study aimed to explore gait smoothness during complex walking tasks in older adults with and without MCI. Participants were 18 older adults with MCI (mean age = 67.89 ± 4.64 years) and 18 cognitively intact controls (mean age = 67.72 ± 4.63 years). Gait assessment was conducted under four complex walking tasks: walking a narrow path, walking around an obstacle, horizontal head turns while walking, and vertical head turns while walking. The index of harmonicity (IH), representing gait smoothness associated with overall body stability, was measured in anteroposterior, mediolateral, and vertical directions. A multivariate analysis was employed to compare the differences in IH between groups for each complex walking task. The MCI group demonstrated a reduction of IH in the mediolateral direction during the horizontal head turns than the control group (MCI group = 0.64 ± 0.16, Control group = 0.74 ± 0.12, p = 0.04). No significant differences between groups were found for the IH in other directions or walking conditions. These preliminary findings indicate that older adults with MCI have a decline in step regularity in the mediolateral direction during walking with horizontal head turns. Assessment of the smoothness of walking during head turns may be a useful approach to identifying subtle gait alterations in older adults with MCI, which may facilitate timely gait intervention.

Evaluation of gait recovery after total knee arthroplasty using wearable inertial sensors: A systematic review

PURPOSE

This study aimed to conduct a systematic review of the recent research output to present more evidence of the current clinical applications of wearable sensors to determine the change and the recovery in gait function pre- and post-total knee arthroplasty (TKA).

METHODS

A systematic search of the PubMed, ScienceDirect, and Scopus databases was conducted in October 2022. Inclusion criteria consisted of applying acceleration wearable sensors for pre- and post-arthroplasty assessment of the gait cycle. Studies reporting gait analysis using wearable sensors in patients with knee osteoarthritis at any time after total or partial knee arthroplasty (KA) were also included. Each included study was assessed using the Joanna Briggs Institute Critical Appraisal Tool for Quasi-Experimental studies.

RESULTS

Twelve articles were finally considered. The extracted data included essential characteristics of participants, KA studies and their characteristics, sensor technology characteristics and the clinical protocols, gait parameter changes, and various clinical outcome scores at different follow up times after KA. Postoperative examinations were performed from 5 days to 1 year after KA. Clinical outcome scores and gait variables for all patient groups, with or without postoperative rehabilitation, showed various recovery profiles. A variety of wireless sensor devices for gait analysis were recorded. Also, different types of KA were found in the studies.

CONCLUSIONS

The study's findings showed that acceleration-based gait analysis has notable clinical use in monitoring patients after KA. This application provides objective information on the functional outcome beyond the use of clinical outcome scores. More extensive prospective studies are required to investigate gait function further with the help of wearable sensors in patients with knee osteoarthritis.

Validity study of a triaxial accelerometer for measuring energy expenditure in stroke inpatients of a physical medicine and rehabilitation center

PURPOSE

Establish the validity of a triaxial accelerometer (Dynaport®) for evaluating the energy expenditure of patients with stroke sequelae at a rehabilitation hospital.

METHODS

This is a cross-sectional study with 24 stroke inpatients of a rehabilitation hospital. The participants were assessed on energy expenditure by an ergospirometer system and the triaxial accelerometer simultaneously during a walk test. The data collected by both devices were compared by intraclass correlation coefficient (ICC) and Bland-Altman limits of agreement.

RESULTS

An almost perfect agreement (ICC = 0,94) in the energy expenditure measured by the accelerometer compared to the results of the ergospirometer system was found during the exercise test. The Bland-Altman analysis has shown suitable limits of agreement. Post hoc analyses with the maximum volume of oxygen and the total energy expenditure measured by the ergospirometer system evidenced significant correlation with the energy expenditure measurements by the accelerometer.

CONCLUSION

Our results evidence that the triaxial accelerometer Dynaport® and its built-in software are valid for estimating the energy expenditure of stroke sequelae during a walk exercise.

Free-Living Standing Activity as Assessed by Seismic Accelerometers and Cognitive Function in Community-Dwelling Older Adults: The MIND Trial

BACKGROUND

Few older adults are able to achieve recommended levels of moderate-vigorous physical activity despite known cognitive benefits. Alternatively, less intense activities such as standing can be easily integrated into daily life. No existing study has examined the impact of free-living standing activity during daily life as measured by a device on cognition in older adults. Our purpose was to examine the association between free-living standing activity and cognitive function in cognitively healthy older adults.

METHOD

Participants were 98 adults aged 65 years or older from the ongoing MIND trial (NCT02817074) without diagnoses or symptoms of mild cognitive impairment or dementia. Linear regression analyses tested cross-sectional associations between standing activity (duration and intensity from the MoveMonitor+ accelerometer/gyroscope) and cognition (4 cognitive domains constructed from 12 cognitive performance tests).

RESULTS

Participants were on average 69.7 years old (SD = 3.7), 69.4% women, and 73.5% had a college degree or higher. Higher mean intensity of standing activity was significantly associated with higher levels of perceptual speed when adjusting for age, gender, and education level. Each log unit increase in standing activity intensity was associated with 0.72 units higher of perceptual speed (p = .023). When we additionally adjusted for cognitive activities and moderate-vigorous physical activity, and then also for body mass index, depressive symptoms, prescription medication use, and device wear time, the positive association remained.

CONCLUSIONS

These findings should be further explored in longitudinal analyses and interventions for cognition that incorporate small changes to free-living activity in addition to promoting moderate-vigorous physical activity.

Free-Living Physical Activity and Sedentary Behaviour in Autoimmune Myasthenia Gravis: A Cross-Sectional Study

BACKGROUND

Muscle weakness and fatigability, the prominent symptoms of autoimmune myasthenia gravis (MG), negatively impact daily function and quality of life (QoL). It is currently unclear as to what extent symptoms limit activity and whether physical activity (PA) behaviours are associated with reduced QoL.

OBJECTIVES

This study aimed to describe habitual PA patterns and explore relationships between PA metrics, clinical MG characteristics, and health-related QoL (HRQoL).

METHODS

PA data from a tri-axial trunk accelerometer worn for seven days, was collected from females with generalized, stable MG and compared to control subjects. MG-specific evaluations, the six-minute walk test and knee extension strength were assessed in individuals with MG (IwMG). Mann-Whitney tests were used to study between-group differences. Spearman rank correlation coefficient was performed to explore relationships between variables.

RESULTS

Thirty-three IwMG (mean (SD) age 45 (11) years) and 66 control subjects were included. IwMG perform less vigorous-intensity PA than control subjects (p = 0.001), spend more time sedentary (p = 0.02) and engage in less and shorter durations of moderate-vigorous-intensity PA (MVPA). For IwMG, habitual PA correlated positively with 6 min walking distance (rho = 0.387, p = 0.029) and negatively with body mass index (rho = -0.407, p = 0.019). We did not find any association between PA or sedentary behaviour and; HRQoL, symptom severity nor lower limb strength.

CONCLUSIONS

Individuals with stable MG perform less PA, at lower intensities, and are more inactive than control individuals. Further research is warranted to understand factors influencing PA patterns in MG and whether interventions could be successful in increasing PA quantity and intensity in IwMG.

Relationship of the sacral slope with early gait derangements in robust older women

BACKGROUND

Trunk pelvic dissociation is fundamental to the compensatory mechanism for muscle weakness during body bending. We carried out an early investigation of gait changes in a sample of community-dwelling women ≥60 years without gait complaints. The primary objective was to correlate spine and pelvic angles with performance tests and accelerometry parameters. The secondary objective was to correlate performance tests with accelerometry.

METHODS

In this cross-sectional study, 54 community-dwelling women ≥60 years were subjected to Falls Efficacy Scale-International (FES-I), performance tests (Berg Balance Scale, Timed Up and Go, and Gait analysis), and radiographic analysis of sagittal alignment (Thoracic and Lumbar Cobb, Pelvic Incidence, Sacral Slope, and Pelvic Tilt angles). Gait speed was assessed in a 10-m comfortable walk, and accelerometry parameters were obtained in a 30-m walk distance.

RESULTS

The sample, aged 72 ± 6 years, exhibited moderate correlation between Sacral Slope and Step Length (+ 0.615). Sacral Slope weakly correlated with FES-I (- 0.339), Berg Balance Scale (+ 0.367), and with further accelerometry data in the AP plane: RMS, (+ 0.439) and Stride Regularity (+ 0.475), p < 0.05, all. Lumbar Cobb weakly correlated with the following accelerometry data in the AP plane: Step Length (+ 0.405), RMS, (+ 0.392), and Stride Regularity (+ 0.345), p < 0.05, all. Additionally, Stride Regularity in AP moderately correlated with FES-I (0,561, p < 0.05), among other weak correlations between performance tests and accelerometry data in AP.

CONCLUSIONS

Early alterations in Sacral Slope and gait abnormalities in the AP plane may provide understanding of the early gait changes in robust older women.

Muscle Oxidative Capacity Is Reduced in Both Upper and Lower Limbs in COPD

INTRODUCTION

Skeletal muscle atrophy, weakness, mitochondrial loss, and dysfunction are characteristics of chronic obstructive pulmonary disease (COPD). It remains unclear whether muscle dysfunction occurs in both upper and lower limbs, because findings are inconsistent in the few studies where upper and lower limb muscle performance properties were compared within an individual. This study determined whether muscle oxidative capacity is low in upper and lower limbs of COPD patients compared with controls.

METHODS

Oxidative capacity of the forearm and medial gastrocnemius was measured using near-infrared spectroscopy to determine the muscle O2 consumption recovery rate constant (k, min) in 20 COPD (Global Initiative for Chronic Obstructive Lung Disease (GOLD) 2/3/4, n = 7/7/6) and 20 smokers with normal spirometry (CON). Muscle k is linearly proportional to oxidative capacity. Steps per day and vector magnitude units per minute (VMU·min) were assessed using triaxial accelerometry. Differences between group and limb were assessed by two-way ANOVA.

RESULTS

There was a significant main effect of group (F = 11.2, ηp = 0.13, P = 0.001): k was lower in both upper and lower limb muscles in COPD (1.01 ± 0.17 and 1.05 ± 0.24 min) compared with CON (1.29 ± 0.49 and 1.54 ± 0.60 min). There was no effect on k of limb (F = 1.8, ηp = 0.02, P = 0.18) or group-limb interaction (P = 0.35). (VMU·min) was significantly lower in COPD (-38%; P = 0.042). Steps per day did not differ between COPD (4738 ± 3194) and CON (6372 ± 2107; P = 0.286), although the difference exceeded a clinically important threshold (>600-1100 steps per day).

CONCLUSIONS

Compared with CON, muscle oxidative capacity was lower in COPD in both upper (-20%) and lower (-30%) limbs. These data suggest that mitochondrial loss in COPD is not isolated to locomotor muscles.

Cognitive impairment and sedentary behavior predict health-related attrition in a prospective longitudinal Parkinson's disease study

INTRODUCTION

In Parkinson's disease (PD), the high burden of motor and non-motor symptoms, such as cognitive impairment or falls, is associated with rapid disease progression and mortality. This is often reflected by an increased drop-out rate of PD patients in longitudinal studies. Active physical behavior can impact the disease course beneficially and has an overall positive effect on health. Contrarily, sedentary behavior is associated with cognitive impairment in PD. The aim of this study was to investigate whether sedentary physical behavior assessed in the home environment and cognitive impairment can predict health-related study attrition due to sickness and death in PD.

METHODS

Data of 45 PD patients, longitudinally assessed, were analyzed. Of those, 20 patients completed six yearly visits, 16 dropped out due to sickness or death, and nine for other reasons. All patients wore a mobile device to assess physical behavior and completed cognitive testing.

RESULTS

Logistic regression revealed global cognition was the primary predictor for health-related drop-out in varying models (p ≤ .04). In the survival analysis, cognitive impairment (p = .005) and longer sedentary mean bout length (p = .02) were associated with drop-out due to sickness and death. The occurrence of health-related study drop-out or death was highest in patients with both impaired cognition and longer sedentary bouts.

CONCLUSIONS

Cognition was the primary predictor for study drop-out due to sickness and death. However, it seems that sedentary behavior might have a potential negative influence on PD patients' health, especially those with cognitive impairment.

Utility of the iPhone 4 Gyroscope Application in the Measurement of Wrist Motion

BACKGROUND

Measurement of wrist range of motion (ROM) is important to all aspects of treatment and rehabilitation of upper extremity conditions. Recently, gyroscopes have been used to measure ROM and may be more precise than manual evaluations. The purpose of this study was to evaluate the use of the iPhone gyroscope application and compare it with use of a goniometer, specifically evaluating its accuracy and ease of use.

METHODS

A cross-sectional study evaluated adult Caucasian participants, with no evidence of wrist pathology. Wrist ROM measurements in 306 wrists using the 2 methods were compared. Demographic information was collected including age, sex, and occupation. Analysis included mixed models and Bland-Altman plots.

RESULTS

Wrist motion was similar between the 2 methods. Technical difficulties were encountered with gyroscope use. Age was an independent predictor of ROM.

CONCLUSIONS

Correct measurement of ROM is critical to guide, compare, and evaluate treatment and rehabilitation of the upper extremity. Inaccurate measurements could mislead the surgeon and harm patient adherence with therapy or surgeon instruction. An application used by the patient could improve adherence but needs to be reliable and easy to use. Evaluation is necessary before utilization of such an application. This study supports revision of the application on the iPhone to improve ease of use.

Effects of intradialytic resistance training on physical activity in daily life, muscle strength, physical capacity and quality of life in hemodialysis patients: a randomized clinical trial

Purpose: We evaluated the effects of supervised intradialytic resistance training on physical activity in daily life (PADL), muscle strength, physical capacity and quality of life (QoL) in hemodialysis patients.Methods: Twenty-four hemodialysis patients were randomly assigned to either a 12-weeks moderate-intensity resistance training or a control period. An accelerometer evaluated PADL for seven consecutive days, measuring the time spent in different activities and positions of daily routine and the number of steps taken. Muscle strength, physical capacity and QoL were evaluated.Results: After 12 weeks of training, we did not find significant difference (post-pre values) in walking time (-1.2 ± 18.3 vs. -9.2 ± 13.1 min/day); standing time (-10.2 ± 28.6 vs. 3.2 ± 20.1 min/day); sitting time (20.8 ± 58.9 vs. -30.0 ± 53.0 min/day); lying down time (-9.3 ± 57.9 vs. 34.6 ± 54.0 min/day); number of steps taken [-147 (1834) vs. -454 (2066)] and muscle strength in training and control group, respectively. There was a significant increase in the six-minute walking test distance (48.8 ± 35.9 vs. 6.9 ± 45.9 m, p < 0.05) and some domains of QoL in the training compared to the control group.Conclusions: PADL was not modified after 12 weeks of intradialytic resistance training in hemodialysis patients. However, the exercise program was able to increase the physical capacity and some domains of QoL.Implications for rehabilitationPhysical activity in daily life was not modified after 12 weeks of intradialytic resistance training in hemodialysis patients.The exercise program was able to increase the physical capacity, efficacy of dialysis and some domains of quality of life in hemodialysis patients.The protocol used in this study was safe since no complications were observed during and after resistance training.These results should be interpreted with caution because we applied a moderate resistance training in both lower limbs and in the contralateral arteriovenous fistula upper limb, using perceived exertion by Borg scale to exercise prescription. Moreover, the safety protocol evaluation was not conducted.

Verification of a Motion Sensor for Evaluating Physical Activity in COPD Patients

Background

Objective evaluation of the physical activity (PA) in patients with chronic obstructive pulmonary disease (COPD) is important. We validated a triaxial accelerometer, Active Style Pro HJA-750C® (HJA), and evaluated the necessary conditions for obtaining reproducible data.

Methods

The PA measured by HJA was compared with that measured by two already validated accelerometers in 11 patients with COPD (age: 76.6 ± 6.9, FEV1% predicted: 57.6 ± 18.6). Then, the influence of weather and holidays on the PA and the required number of days to obtain repeatability were examined in 21 patients with COPD (age: 73.0 ± 8.0, FEV1% predicted: 58.7 ± 19.0).

Results

The PA values measured by HJA and those by DynaPort Move Monitor® (DMM) or Actimarker® (AM) were significantly correlated at all intensities (p=0.024 at ≥4.0 METs by DMM and p < 0.0001 at the rest) except at ≥4.0 METs by AM, though the values measured by HJA were higher than those by AM which was reported to underestimate PA. The durations of PA on rainy days were significantly shorter than those on nonrainy days, but those on holidays were not different from those on weekdays. The values of ICC for 3, 4, or 5 days were higher than 0.8 at all intensities. The PA measured by HJA was correlated with the dyspnea scale FVC and age and tended to correlate with FEV1.

Conclusions

The HJA was validated for evaluating the PA in patients with COPD. This trial is registered with UMIN000016363.

The benefits and tolerance of exercise in myasthenia gravis (MGEX): study protocol for a randomised controlled trial

BACKGROUND

Research exploring the effects of physical exercise in auto-immune myasthenia gravis (MG) is scarce. The few existing studies present methodological shortcomings limiting the conclusions and generalisability of results. It is hypothesised that exercise could have positive physical, psychological as well as immunomodulatory effects and may be a beneficial addition to current pharmacological management of this chronic disease. The aim of this study is to evaluate the benefits on perceived quality of life (QOL) and physical fitness of a home-based physical exercise program compared to usual care, for patients with stabilised, generalised auto-immune MG.

METHODS

MGEX is a multi-centre, interventional, randomised, single-blind, two-arm parallel group, controlled trial. Forty-two patients will be recruited, aged 18-70 years. Following a three-month observation period, patients will be randomised into a control or experimental group. The experimental group will undertake a 40-min home-based physical exercise program using a rowing machine, three times a week for three months, as an add-on to usual care. The control group will receive usual care with no additional treatment. All patients will be followed up for a further three months. The primary outcome is the mean change in MGQOL-15-F score between three and six months (i.e. pre-intervention and immediately post-intervention periods). The MGQOL-15-F is an MG-specific patient-reported QOL questionnaire. Secondary outcomes include the evaluation of deficits and functional limitations via MG-specific clinical scores (Myasthenia Muscle Score and MG-Activities of Daily Living scale), muscle force and fatigue, respiratory function, free-living physical activity as well as evaluations of anxiety, depression, self-esteem and overall QOL with the WHO-QOL BREF questionnaire. Exercise workload will be assessed as well as multiple safety measures (ECG, biological markers, medication type and dosage and any disease exacerbation or crisis).

DISCUSSION

This is the largest randomised controlled trial to date evaluating the benefits and tolerance of physical exercise in this patient population. The comprehensive evaluations using standardised outcome measures should provide much awaited information for both patients and the scientific community. This study is ongoing.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT02066519 . Registered on 13 January 2014.

The association between objectively measured physical activity and morning symptoms in COPD

PURPOSE

The morning is the most bothersome period for COPD patients. Morning symptom severities in different Global Initiative for Chronic Obstructive Lung Disease (GOLD) stages are not well studied. Furthermore, factors that are associated with morning symptoms, especially the associations with objectively measured physical activity, are also not well described.

MATERIALS AND METHODS

The aim of this cross-sectional observational study was to assess morning symptom severity in GOLD A, B, C and D patients, according to the definitions of the GOLD 2015 statement. Morning symptoms were assessed with the PRO-Morning COPD Symptoms Questionnaire. Differences in morning symptom severity between different COPD stages were assessed with a one-way analysis of variance followed by post hoc analyses. The association between dyspnea severity (assessed with the modified Medical Research Council scale), health status, airflow limitation, lung hyperinflation, anxiety and depression, inflammatory parameters, exacerbations, objectively measured physical activity parameters retrieved from accelerometry and morning symptom severity was evaluated using linear regression analysis.

RESULTS

Eighty patients were included (aged 65.6±8.7 years, forced expiratory volume in 1 second [FEV₁] % predicted 55.1±16.9). Mean (±SD) morning symptom score was 19.7 (±11.7). Morning symptom severity was significantly different between COPD stages: mean (±SD) score in GOLD A was 9.7 (±7.2), in GOLD B 19.8 (±10.7), in GOLD C 8.6 (±9.3) and in GOLD D 23.8 (±11.2) (p<0.001). Lower health status, more symptoms, increased anxiety and depression, less physical activity (all p<0.001) and lower FEV₁ (p=0.03) were associated with an increased morning symptom severity.

CONCLUSION

Patients with overall more symptomatic COPD have significant higher morning symptom scores. Morning symptom severity was associated with important clinical outcomes: lower health status, more symptoms, increased anxiety and depression, fewer steps a day, less time in moderate and vigorous physical activity with bouts of at least 10 minutes and lower FEV₁. The data suggest that morning symptoms should be carefully assessed in addition to assessment by general COPD-specific questionnaires, especially in those with more symptomatic COPD. More research is needed on potential therapies to improve morning symptoms; this study shows potential targets for intervention.

Tablet-Based Application for Objective Measurement of Motor Fluctuations in Parkinson Disease

BACKGROUND

The motor subscale of the Movement Disorder Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS-III) has limited applicability for the assessment of motor fluctuations in the home setting.

METHODS

To assess whether a self-administered, tablet-based application can reliably quantify differences in motor performance using two-target finger tapping and forearm pronation-supination tasks in the ON (maximal dopaminergic medication efficacy) and OFF (reemergence of parkinsonian deficits) medication states, we recruited 11 Parkinson disease (PD) patients (age, 60.6 ± 9.0 years; disease duration, 12.8 ± 4.1 years) and 11 healthy age-matched controls (age, 62.5 ± 10.5 years). The total number of taps, tap interval, tap duration, and tap accuracy were algorithmically calculated by the application, using the more affected side in patients and the dominant hand in healthy controls.

RESULTS

Compared to the OFF state, PD patients showed a higher number of taps (84.2 ± 20.3 vs. 54.9 ± 26.9 taps; p = 0.0036) and a shorter tap interval (375.3 ± 97.2 vs. 708.2 ± 412.8 ms; p = 0.0146) but poorer tap accuracy (2,008.4 ± 995.7 vs. 1,111.8 ± 901.3 pixels; p = 0.0055) for the two-target task in the ON state, unaffected by the magnitude of coexistent dyskinesia. Overall, test-retest reliability was high (r >0.75) and the discriminatory ability between OFF and ON states was good (0.60 ≤ AUC ≤ 0.82). The correlations between tapping data and MDS-UPDRS-III scores were only moderate (-0.55 to 0.55).

CONCLUSIONS

A self-administered, tablet-based application can reliably distinguish between OFF and ON states in fluctuating PD patients and may be sensitive to additional motor phenomena, such as accuracy, not captured by the MDS-UPDRS-III.

Reeducation of vergence dynamics improves postural control

INTRODUCTION

The purpose was to investigate the effect of vergence reeducation on postural control, in subjects with isolated vergence disorders.

MATERIAL AND METHODS

We studied the dynamics of vergence in 19 subjects (20-44 years old) using video-oculography (Eye See Cam). On the basis of orthoptic and symptomatology assessments, ten of the subjects were diagnosed for vergence disorders then vergence eye movements were reeducated with the REMOBI method (US8851669, 5 weekly sessions lasting for 35min). Postural control was measured before and after reeducation, postural recording was done in upright stance (Dynaport), with both eyes closed or open and looking a visual target located at 2m distance.

RESULTS

After reeducation with REMOBI, the visual symptomatology faded away and the stereoacuity improved at least for some subjects; the vergence latency decreased significantly and the vergence accuracy increased significantly. In terms of posture, the Mean Power Frequency (MPF) of the body sway decreased significantly in both eyes open and eyes closed conditions. Considering all subjects together (i.e. healthy subjects and subjects with vergence disorders before the reeducation), the antero-posterior body sway (Root Mean Square A/P) was positively correlated with the visual symptomatology: the higher the visual symptomatology, the higher was the body sway.

CONCLUSION

The results bring evidence for synergy between the quality of vergence and the quality of postural control. They open a new research line that bridges the gap between neuroscience, ophthalmology-orthoptics and posturology.

The Instrumented Sit-to-Stand Test (iSTS) Has Greater Clinical Relevance than the Manually Recorded Sit-to-Stand Test in Older Adults

BACKGROUND

The ability to rise from sitting to standing is critical to an individual's quality of life, as it is a prerequisite for functional independence. The purpose of the current study was to examine the hypothesis that test durations as assessed with the instrumented repeated Sit-To-Stand (STS) show stronger associations with health status, functional status and daily physical activity of older adults than manually recorded test durations.

METHODS

In 63 older participants (mean age 83 ±6.9 years, 51 female), health status was assessed using the European Quality of Life questionnaire and functional status was assessed using the physical function index of the of the RAND-36. Physical performance was measured using a wearable sensor-based STS test. From this test, durations, sub-durations and kinematics of the STS movements were estimated and analysed. In addition, physical activity was measured for one week using an activity monitor and episodes of lying, sitting, standing and locomotion were identified. Associations between STS parameters with health status, functional status and daily physical activity were assessed.

RESULTS

The manually recorded STS times were not significantly associated with health status (p = 0.457) and functional status (p = 0.055), whereas the instrumented STS times were (both p = 0.009). The manually recorded STS durations showed a significant association to daily physical activity for mean sitting durations (p = 0.042), but not for mean standing durations (p = 0.230) and mean number of locomotion periods (p = 0.218). Furthermore, durations of the dynamic sit-to-stand phase of the instrumented STS showed more significant associations with health status, functional status and daily physical activity (all p = 0.001) than the static phases standing and sitting (p = 0.043-0.422).

CONCLUSIONS

As hypothesized, instrumented STS durations were more strongly associated with participant health status, functional status and physical activity than manually recorded STS durations in older adults. Furthermore, instrumented STS allowed assessment of the dynamic phases of the test, which were likely more informative than the static sitting and standing phases.

Evaluation of suitability of a micro-processing unit of motion analysis for upper limb tracking

The aim of this study is to assess the suitability of a micro-processing unit of motion analysis (MPUMA), for monitoring, reproducing, and tracking upper limb movements. The MPUMA is based on an inertial measurement unit, a 16-bit digital signal controller and a customized algorithm. To validate the performance of the system, simultaneous recordings of the angular trajectory were performed with a video-based motion analysis system. A test of the flexo-extension of the shoulder joint during the active elevation in a complete range of 120º of the upper limb was carried out in 10 healthy volunteers. Additional tests were carried out to assess MPUMA performance during upper limb tracking. The first, a 3D motion reconstruction of three movements of the shoulder joint (flexo-extension, abduction-adduction, horizontal internal-external rotation), and the second, an upper limb tracking online during the execution of three movements of the shoulder joint followed by a continuous random movement without any restrictions by using a virtual model and a mechatronic device of the shoulder joint. Experimental results demonstrated that the MPUMA measured joint angles that are close to those from a motion-capture system with orientation RMS errors less than 3º.

Physical Performance and Physical Activity in Older Adults: Associated but Separate Domains of Physical Function in Old Age

BACKGROUND

Physical function is a crucial factor in the prevention and treatment of health conditions in older adults and is usually measured objectively with physical performance tests and/or physical activity monitoring.

OBJECTIVE

To examine whether 1) physical performance (PP) and physical activity (PA) constitute separate domains of physical function; 2) differentiation of PA classes is more informative than overall PA.

DESIGN

Cross-sectional study to explore the relationships within and among PP and PA measures.

METHODS

In 49 older participants (83 ± 7 years; M ± SD), performance-based tests were conducted and PA was measured for one week. Activity monitor data were reduced in terms of duration, periods, and mean duration of periods of lying, sitting, standing and locomotion. The relation between and within PP scores and PA outcomes were analysed using rank order correlation and factor analysis.

RESULTS

Factor structure after varimax rotation revealed two orthogonal factors explaining 78% of the variance in the data: one comprising all PA variables and one comprising all PP variables. PP scores correlated moderately with PA in daily life. Differentiation of activity types and quantification of their duration, intensity and frequency of occurrence provided stronger associations with PP, as compared to a single measure of acceleration expressing overall PA.

LIMITATIONS

For independent validation, the conclusions about the validity of the presented conceptual framework and its clinical implications need to be confirmed in other studies.

CONCLUSIONS

PP and PA represent associated but separate domains of physical function, suggesting that an improvement of PP does not automatically imply an increase of PA, i.e. a change to a more active lifestyle. Differentiation of activity classes in the analysis of PA provides more insights into PA and its association with PP than using a single overall measure of acceleration.

The impact of an external breast prosthesis on the gait parameters of women after mastectomy

BACKGROUND

An integral part of the recovery process after mastectomy involves the consideration of restorative options, including external prosthesis use; however, only few studies regarding the influence of breast prostheses on functional status have been done.

OBJECTIVE

This study aimed to determine whether wearing an external breast prosthesis affects gait in women after a mastectomy.

METHODS

Spatiotemporal gait parameters were collected in 40 women, postmastectomy, aged 37 to 70 years, divided into age subgroups of 37 to 54 years and 55 to 70 years, and in 38 healthy controls, women aged 38 to 69 years. Gait parameters were assessed with and without the breast prosthesis, including walking velocity, cadence, step length, step time, and left-right step time asymmetry.

RESULTS

Significant differences were found in the gait parameters of the younger age group with and without a prosthesis. No significant differences were found in the women of the older group with and without the prosthesis.

CONCLUSION

Gait parameters of the younger age group were closer to those of the healthy control group when they were wearing an external prosthesis, as compared with when they were not. This suggests a positive influence of breast prosthesis use on the functional status of women after mastectomy.

IMPLICATIONS FOR PRACTICE

Clinical practitioners should be aware of the study results suggesting a positive influence of breast prosthesis use on gait parameters after mastectomy surgery, which could improve the patient's functional status after surgery; however, further research is still needed on factors affecting changes in gait with a larger study population.

Physical Activity in Hemodialysis Patients Measured by Triaxial Accelerometer

Different factors can contribute to a sedentary lifestyle among hemodialysis (HD) patients, including the period they spend on dialysis. The aim of this study was to evaluate characteristics of physical activities in daily life in this population by using an accurate triaxial accelerometer and to correlate these characteristics with physiological variables. Nineteen HD patients were evaluated using the DynaPort accelerometer and compared to nineteen control individuals, regarding the time spent in different activities and positions of daily life and the number of steps taken. HD patients were more sedentary than control individuals, spending less time walking or standing and spending more time lying down. The sedentary behavior was more pronounced on dialysis days. According to the number of steps taken per day, 47.4% of hemodialysis patients were classified as sedentary against 10.5% in control group. Hemoglobin level, lower extremity muscle strength, and physical functioning of SF-36 questionnaire correlated significantly with the walking time and active time. Looking accurately at the patterns of activity in daily life, HDs patients are more sedentary, especially on dialysis days. These patients should be motivated to enhance the physical activity.

Measuring Eccentric Strength of the Shoulder External Rotators Using a Handheld Dynamometer: Reliability and Validity

CONTEXT

Shoulder strength assessment plays an important role in the clinical examination of the shoulder region. Eccentric strength measurements are of special importance in guiding the clinician in injury prevention or return-to-play decisions after injury.

OBJECTIVE

To examine the absolute and relative reliability and validity of a standardized eccentric strength-measurement protocol for the glenohumeral external rotators.

DESIGN

Descriptive laboratory study.

SETTING

Testing environment at the Department of Rehabilitation Sciences and Physiotherapy of Ghent University, Belgium.

PATIENTS OR OTHER PARTICIPANTS

Twenty-five healthy participants (9 men and 16 women) without any history of shoulder pain were tested by 2 independent assessors using a handheld dynamometer (HHD) and underwent an isokinetic testing procedure.

INTERVENTION(S)

The clinical protocol used an HHD, a DynaPort accelerometer to measure acceleration and angular velocity of testing 30°/s over 90° of range of motion, and a Biodex dynamometer to measure isokinetic activity.

MAIN OUTCOME MEASURE(S)

Three eccentric strength measurements: (1) tester 1 with the HHD, (2) tester 2 with the HHD, and (3) Biodex isokinetic strength measurement.

RESULTS

The intratester reliability was excellent (0.879 and 0.858), whereas the intertester reliability was good, with an intraclass correlation coefficient between testers of 0.714. Pearson product moment correlation coefficients of 0.78 and 0.70 were noted between the HHD and the isokinetic data, showing good validity of this new procedure.

CONCLUSIONS

Standardized eccentric rotator cuff strength can be tested and measured in the clinical setting with good-to-excellent reliability and validity using an HHD.

Clinical evaluation of a mobile sensor-based gait analysis method for outcome measurement after knee arthroplasty

Clinical scores and motion-capturing gait analysis are today's gold standard for outcome measurement after knee arthroplasty, although they are criticized for bias and their ability to reflect patients' actual quality of life has been questioned. In this context, mobile gait analysis systems have been introduced to overcome some of these limitations. This study used a previously developed mobile gait analysis system comprising three inertial sensor units to evaluate daily activities and sports. The sensors were taped to the lumbosacral junction and the thigh and shank of the affected limb. The annotated raw data was evaluated using our validated proprietary software. Six patients undergoing knee arthroplasty were examined the day before and 12 months after surgery. All patients reported a satisfactory outcome, although four patients still had limitations in their desired activities. In this context, feasible running speed demonstrated a good correlation with reported impairments in sports-related activities. Notably, knee flexion angle while descending stairs and the ability to stop abruptly when running exhibited good correlation with the clinical stability and proprioception of the knee. Moreover, fatigue effects were displayed in some patients. The introduced system appears to be suitable for outcome measurement after knee arthroplasty and has the potential to overcome some of the limitations of stationary gait labs while gathering additional meaningful parameters regarding the force limits of the knee.

Autocalibration of accelerometer data for free-living physical activity assessment using local gravity and temperature: an evaluation on four continents

Wearable acceleration sensors are increasingly used for the assessment of free-living physical activity. Acceleration sensor calibration is a potential source of error. This study aims to describe and evaluate an autocalibration method to minimize calibration error using segments within the free-living records (no extra experiments needed). The autocalibration method entailed the extraction of nonmovement periods in the data, for which the measured vector magnitude should ideally be the gravitational acceleration (1 g); this property was used to derive calibration correction factors using an iterative closest-point fitting process. The reduction in calibration error was evaluated in data from four cohorts: UK (n = 921), Kuwait (n = 120), Cameroon (n = 311), and Brazil (n = 200). Our method significantly reduced calibration error in all cohorts (P < 0.01), ranging from 16.6 to 3.0 mg in the Kuwaiti cohort to 76.7 to 8.0 mg error in the Brazil cohort. Utilizing temperature sensor data resulted in a small nonsignificant additional improvement (P > 0.05). Temperature correction coefficients were highest for the z-axis, e.g., 19.6-mg offset per 5°C. Further, application of the autocalibration method had a significant impact on typical metrics used for describing human physical activity, e.g., in Brazil average wrist acceleration was 0.2 to 51% lower than uncalibrated values depending on metric selection (P < 0.01). The autocalibration method as presented helps reduce the calibration error in wearable acceleration sensor data and improves comparability of physical activity measures across study locations. Temperature ultization seems essential when temperature deviates substantially from the average temperature in the record but not for multiday summary measures.

Physical activity monitoring in patients with peripheral arterial disease: validation of an activity monitor

OBJECTIVES

The daily life physical activity (PA) of patients with peripheral arterial disease (PAD) may be severely hampered by intermittent claudication (IC). From a therapeutic, as well as research, point of view, it may be more relevant to determine improvement in PA as an outcome measure in IC. The aim of this study was to validate daily activities using a novel type of tri-axial accelerometer (Dynaport MoveMonitor) in patients with IC.

METHODS

Patients with IC were studied during a hospital visit. Standard activities (locomotion, lying, sitting, standing, shuffling, number of steps and "not worn" detection) were video recorded and compared with activities scored by the MoveMonitor. Inter-rater reliability (expressed in intraclass correlation coefficients [ICC]), sensitivity, specificity, and positive predictive values (PPV) were calculated for each activity.

RESULTS

Twenty-eight hours of video observation were analysed (n = 21). Our video annotation method (the gold standard method) appeared to be accurate for most postures (ICC > 0.97), except for shuffling (ICC = 0.38). The MoveMonitor showed a high sensitivity (>86%), specificity (>91%), and PPV (>88%) for locomotion, lying, sitting, and "not worn" detection. Moderate accuracy was found for standing (46%), while shuffling appeared to be undetectable (18%). A strong correlation was found between video recordings and the MoveMonitor with regard to the calculation of the "number of steps" (ICC = 0.90).

CONCLUSIONS

The MoveMonitor provides accurate information on a diverse set of postures, daily activities, and number of steps in IC patients. However, the detection of low amplitude movements, such as shuffling and "sitting to standing" transfers, is a matter of concern. This tool is useful in assessing the role of PA as a novel, clinically relevant outcome parameter in IC.

A wearable inertial measurement unit for long-term monitoring in the dependency care area

Human movement analysis is a field of wide interest since it enables the assessment of a large variety of variables related to quality of life. Human movement can be accurately evaluated through Inertial Measurement Units (IMU), which are wearable and comfortable devices with long battery life. The IMU's movement signals might be, on the one hand, stored in a digital support, in which an analysis is performed a posteriori. On the other hand, the signal analysis might take place in the same IMU at the same time as the signal acquisition through online classifiers. The new sensor system presented in this paper is designed for both collecting movement signals and analyzing them in real-time. This system is a flexible platform useful for collecting data via a triaxial accelerometer, a gyroscope and a magnetometer, with the possibility to incorporate other information sources in real-time. A μSD card can store all inertial data and a Bluetooth module is able to send information to other external devices and receive data from other sources. The system presented is being used in the real-time detection and analysis of Parkinson's disease symptoms, in gait analysis, and in a fall detection system.

Automated approach for quantifying the repeated sit-to-stand using one body fixed sensor in young and older adults

Much is known about the sit-to-stand (STS) and its biomechanics. Currently, however, there is little opportunity for instrumented quantification of the STS as part of screening or diagnosis in clinical practice. The objectives of the present study were to describe the feasibility of using an automated approach for quantifying the STS using one sensor location and to start testing the discriminative validity of this approach by comparing older and younger adults. 15 older subjects recruited from a residential care home and 16 young adults performed 5 repeated sit-to-stand and stand-to-sit movements. They were instrumented with a small and lightweight measurement system (DynaPort(®)) containing 1 triaxial seismic accelerometer and 3 uniaxial gyroscopes fixed in a belt around the waist. Durations of the (sub-)phases of the STS were analyzed and maximum angular velocities were determined. All successful STS cycles were automatically detected without any errors. The STS duration in the older adults was significantly longer and more variable in all phases (i.e., sit-to-stand, standing, stand-to-sit and sitting) compared to the young adults. Older adults also exhibited lower trunk flexion angular velocity. The results of this first fully automated analysis of instrumented repeated STS movements demonstrate that several STS parameters can be identified that provide a basis for a more precise, quantitative study of STS performance in clinical practice.

Estimating energy expenditure from raw accelerometry in three types of locomotion

PURPOSE

Accuracy of estimating activity-related energy expenditure (AEE) from raw body acceleration may improve by using prediction equations that are specific for the type of activity. The current study aims to improve published equations by deriving an equation for overground walking and to evaluate whether overground cycling and stair walking require specific prediction equations.

METHODS

Participants (91 male/95 female, 8-81 yr old) were equipped with a triaxial accelerometer (DynaPort MiniMod; McRoberts BV, The Hague, The Netherlands) on their lower back. Total energy expenditure (TEE) was measured using a mobile oxygen analyzer (MetaMax 3b; Cortex Biophysik, Leipzig, Germany). Resting energy expenditure (REE) was measured for 30 min, following which a physical activity course was completed involving walking on level ground at slow (8 min), normal (8 min), and fast speed (3 min), stair walking (3 min), and cycling (8 min). AEE was calculated as TEE - REE, expressed in both absolute (kJ·min) and relative (J·min·kg) units. Mixed linear regression analysis was used for developing regression equations for walking, stair walking, and cycling.

RESULTS

Acceleration contributed 76% and 93% (P < 0.001) to explained variance in walking AEE for absolute and relative AEE models, respectively. Age and gender improved estimation accuracy by <1%. Applying a conservative walking equation, AEE (J·min·kg) = -40.19 + 816.11 acceleration (g) (root-mean-square error = 34.00 J·min·kg), to cycling and stair walking resulted in mean bias (95% limits of agreement) of -253 (-449, 46) and -276 (-442, 109) J·min·kg, respectively (approximately 50% bias). Acceleration added 35% and 42% to explained variance in relative AEE (J·min·kg) during cycling and stair walking, respectively; this fraction was approximately 20% for absolute AEE (kJ·min) in both activities.

CONCLUSION

AEE during walking can be predicted across a wide age range using raw acceleration, but activity-specific equations are needed for cycling and stair walking.

Objective assessment, repeatability, and agreement of shoulder ROM with a 3D gyroscope

BACKGROUND

Assessment of shoulder mobility is essential for diagnosis and clinical follow-up of shoulder diseases. Only a few highly sophisticated instruments for objective measurements of shoulder mobility are available. The recently introduced DynaPort MiniMod TriGyro ShoulderTest-System (DP) was validated earlier in laboratory trials. We aimed to assess the precision (repeatability) and agreement of this instrument in human subjects, as compared to the conventional goniometer.

METHODS

The DP is a small, light-weight, three-dimensional gyroscope that can be fixed on the distal upper arm, recording shoulder abduction, flexion, and rotation. Twenty-one subjects (42 shoulders) were included for analysis. Two subsequent assessments of the same subject with a 30-minute delay in testing of each shoulder were performed with the DP in two directions (flexion and abduction), and simultaneously correlated with the measurements of a conventional goniometer. All assessments were performed by one observer. Repeatability for each method was determined and compared as the statistical variance between two repeated measurements. Agreement was illustrated by Bland-Altman-Plots with 95% limits of agreement. Statistical analysis was performed with a linear mixed regression model. Variance for repeated measurements by the same method was also estimated and compared with the likelihood-ratio test.

RESULTS

Evaluation of abduction showed significantly better repeatability for the DP compared to the conventional goniometer (error variance: DP = 0.89, goniometer = 8.58, p = 0.025). No significant differences were found for flexion (DP = 1.52, goniometer = 5.94, p = 0.09). Agreement assessment was performed for flexion for mean differences of 0.27° with 95% limit of agreement ranging from -7.97° to 8.51°. For abduction, the mean differences were 1.19° with a 95% limit of agreement ranging from -9.07° to 11.46°.

CONCLUSION

In summary, DP demonstrated a high precision even higher than the conventional goniometer. Agreement between both methods is acceptable, with possible deviations of up to greater than 10°. Therefore, static measurements with DP are more precise than conventional goniometer measurements. These results are promising for routine clinical use of the DP.

Test-retest reliability and minimal detectable change of repeated sit-to-stand analysis using one body fixed sensor in geriatric patients

A majority of geriatric patients experience difficulty in performing sit-to-stand (SiSt) transitions. A detailed assessment of SiSt ability is a prerequisite for successful rehabilitation. Body fixed sensors (BFSs) are increasingly used to assess functional performances. As to date there is no system which analyzes clinically relevant phases of SiSt, the aim of this study was to determine the reliability of an automated approach for quantifying durations and angular velocities of trunk flexion and extension during repeated SiSt transitions using one BFS (DynaPort® Hybrid). Forty multimorbid geriatric patients aged 84.1 ± 6.6 years were included. Each patient participated in two test sessions with a 5 min rest period in between. Intra- and interrater reliability was assessed. Intraclass correlation coefficients (ICCs), absolute and relative standard measurement errors (SEMs, SEMs%) and minimal detectable changes (MDCs(95), MDCs(95)%) were calculated. ICCs were good to excellent for all variables in the total sample (0.80-0.94). The intraobserver group (50%) showed a higher number of excellent ICCs (≥.9) compared to the interobserver subgroup (10%). SEM% was low for all variables (6.9-12.7%). MDC(95)% ranged 19.2-34.4% and more variables ≤30% were found in the intra- (80%) compared to the inter-observer group (60%). Study results demonstrate that the BFS system provides a reliable analysis of SiSt phases in geriatric patients, and is a substantial improvement over the stopwatch approach used in clinical practice today.

Protocols for evaluating equivalency of accelerometry-based activity monitors

A wide array of accelerometer-based activity monitors has been developed to facilitate objective monitoring of physical activity behaviors, but it has proven difficult to equate outputs from different monitors. On the surface, commercially available monitors seem to be performing the same basic task-monitoring total body acceleration. However, differences in sensor properties and internal data processing have made it difficult to directly compare output from different monitors. In recent years, many new competing technologies have been released into the market, compounding the challenge of evaluating monitor equivalency and the relative strengths and limitations of different monitors. To advance physical activity assessment and improve our ability to compare results across studies using different monitors, it is important to conduct functional equivalency studies in a standardized and systematic way. This article summarizes issues associated with monitor equivalency and proposes methods for standardization and quality control in future research.

The reliability of MinimaxX accelerometers for measuring physical activity in Australian football

PURPOSE

To assess the reliability of triaxial accelerometers as a measure of physical activity in team sports.

METHODS

Eight accelerometers (MinimaxX 2.0, Catapult, Australia) were attached to a hydraulic universal testing machine (Instron 8501) and oscillated over two protocols (0.5 g and 3.0 g) to assess within- and between device reliability. A static assessment was also conducted. Secondly, 10 players were instrumented with two accelerometers during Australian football matches. The vector magnitude was calculated, expressed as Player load and assessed for reliability using typical error (TE) ± 90% confidence intervals (CI), and expressed as a coefficient of variation (CV%). The smallest worthwhile difference (SWD) in Player load was calculated to determine if the device was capable of detecting differences in physical activity.

RESULTS

Laboratory: Within- (Dynamic: CV 0.91 to 1.05%; Static: CV 1.01%) and between-device (Dynamic: CV 1.02 to 1.04%; Static: CV 1.10%) reliability was acceptable across each test. Field: The between-device reliability of accelerometers during Australian football matches was also acceptable (CV 1.9%). The SWD was 5.88%.

CONCLUSIONS

The reliability of the MinimaxX accelerometer is acceptable both within and between devices under controlled laboratory conditions, and between devices during field testing. MinimaxX accelerometers can be confidently utilized as a reliable tool to measure physical activity in team sports across multiple players and repeated bouts of activity. The noise (CV%) of Player load was lower than the signal (SWD), suggesting that accelerometers can detect changes or differences in physical activity during Australian football.

Comparison between an accelerometer and a three-dimensional motion analysis system for the detection of movement

OBJECTIVE

To examine the reliability and concurrent validity of an accelerometer compared with a three-dimensional (3D) motion analysis system for measuring the motor reaction time of the lower limbs, to validate a simple method for objective clinical assessment of movement onset.

DESIGN

Timing of the onset of knee extension movement in response to an audio signal was measured simultaneously with an accelerometer and a 3D VICON motion analysis system.

PARTICIPANTS

Twelve able-bodied subjects with a mean age of 26 (standard deviation 2.3) years.

RESULTS

Good reliability was found for both instruments, although the intraclass correlation coefficient (ICC) was higher for the accelerometer (ICC₃,₁=0.739; P<0.001). The mean motor reaction time measured by the accelerometer and the VICON system was 205.0 and 196.9 mseconds, respectively. Good agreement was found between the paired measurements (mean ICC=0.774), and the average 95% limits of agreement were -56.4 to 72.5 mseconds.

CONCLUSION

In conclusion, the accelerometer had good reliability for the measurement of movement onset time. Agreement between the measurements from the accelerometer and the VICON system was high. However, the limits of agreement covered a wide range, so absolute timings for movement onset derived from these methods should not be used interchangeably.

Validation of the GENEA Accelerometer

PURPOSE

The study aims were: 1) to assess the technical reliability and validity of the GENEA using a mechanical shaker; 2) to perform a GENEA value calibration to develop thresholds for sedentary and light-, moderate-, and vigorous-intensity physical activity; and 3) to compare the intensity classification of the GENEA with two widely used accelerometers.

METHODS

A total of 47 GENEA accelerometers were attached to a shaker and vertically accelerated, generating 15 conditions of varying acceleration and/or frequency. Reliability was calculated using SD and intrainstrument and interinstrument coefficients of variation, whereas validity was assessed using Pearson correlation with the shaker acceleration as the criterion. Next, 60 adults wore a GENEA on each wrist and on the waist (alongside an ActiGraph and RT3 accelerometer) while completing 10-12 activity tasks. A portable metabolic gas analyzer provided the criterion measure of physical activity. Analyses involved the use of Pearson correlations to establish criterion and concurrent validity and receiver operating characteristic curves to establish intensity cut points.

RESULTS

The GENEA demonstrated excellent technical reliability (CVintra = 1.4%, CVinter = 2.1%) and validity (r = 0.98, P < 0.001) using the mechanical shaker. The GENEA demonstrated excellent criterion validity using VO2 as the criterion (left wrist, r = 0.86; right wrist, r = 0.83; waist, r = 0.87), on par with the waist-worn ActiGraph and RT3. The GENEA demonstrated excellent concurrent validity compared with the ActiGraph (r = 0.92) and the RT3 (r = 0.97). The waist-worn GENEA had the greatest classification accuracy (area under the receiver operating characteristic curve (AUC) = 0.95), followed by the left (AUC = 0.93) and then the right wrist (AUC = 0.90). The accuracy of the waist-worn GENEA was virtually identical with that of the ActiGraph (AUC = 0.94) and RT3 (AUC = 0.95).

CONCLUSION

The GENEA is a reliable and valid measurement tool capable of classifying the intensity of physical activity in adults.

Estimation of daily energy expenditure in pregnant and non-pregnant women using a wrist-worn tri-axial accelerometer

BACKGROUND

Few studies have compared the validity of objective measures of physical activity energy expenditure (PAEE) in pregnant and non-pregnant women. PAEE is commonly estimated with accelerometers attached to the hip or waist, but little is known about the validity and participant acceptability of wrist attachment. The objectives of the current study were to assess the validity of a simple summary measure derived from a wrist-worn accelerometer (GENEA, Unilever Discover, UK) to estimate PAEE in pregnant and non-pregnant women, and to evaluate participant acceptability.

METHODS

Non-pregnant (N = 73) and pregnant (N = 35) Swedish women (aged 20-35 yrs) wore the accelerometer on their wrist for 10 days during which total energy expenditure (TEE) was assessed using doubly-labelled water. PAEE was calculated as 0.9×TEE-REE. British participants (N = 99; aged 22-65 yrs) wore accelerometers on their non-dominant wrist and hip for seven days and were asked to score the acceptability of monitor placement (scored 1 [least] through 10 [most] acceptable).

RESULTS

There was no significant correlation between body weight and PAEE. In non-pregnant women, acceleration explained 24% of the variation in PAEE, which decreased to 19% in leave-one-out cross-validation. In pregnant women, acceleration explained 11% of the variation in PAEE, which was not significant in leave-one-out cross-validation. Median (IQR) acceptability of wrist and hip placement was 9(8-10) and 9(7-10), respectively; there was a within-individual difference of 0.47 (p<.001).

CONCLUSIONS

A simple summary measure derived from a wrist-worn tri-axial accelerometer adds significantly to the prediction of energy expenditure in non-pregnant women and is scored acceptable by participants.

Objective assessment of shoulder mobility with a new 3D gyroscope--a validation study

BACKGROUND

Assessment of shoulder mobility is essential for clinical follow-up of shoulder treatment. Only a few high sophisticated instruments for objective measurements of shoulder mobility are available. The interobserver dependency of conventional goniometer measurements is high. In the 1990s an isokinetic measuring system of BIODEX Inc. was introduced, which is a very complex but valid instrument. Since 2008 a new user-friendly system called DynaPort MiniMod TriGyro ShoulderTest-System (DP) is available. Aim of this study is the validation of this measuring instrument using the BIODEX-System.

METHODS

The BIODEX is a computerized robotic dynamometer used for isokinetic testing and training of athletes. Because of its size the system needs to be installed in a separated room. The DP is a small, light-weighted three-dimensional gyroscope that is fixed on the distal upper patient arm, recording abduction, flexion and rotation. For direct comparison we fixed the DP on the lever arm of the BIODEX. The accuracy of measurement was determined at different positions, angles and distances from the centre of rotation (COR) as well as different velocities in a radius between 0° - 180° in steps of 20°. All measurements were repeated 10 times. As satisfactory accuracy a difference between both systems below 5° was defined. The statistical analysis was performed with a linear regression model.

RESULTS

The evaluation shows very high accuracy of measurements. The maximum average deviation is below 2.1°. For a small range of motion the DP is slightly underestimating comparing the BIODEX, whereas for higher angles increasing positive differences are observed. The distance to the COR as well as the position of the DP on the lever arm have no significant influence. Concerning different motion speeds significant but not relevant influence is detected. Unfortunately device related effects are observed, leading to differences between repeated measurements with any two different devices up to 8° at maximal range of motion (180°).

CONCLUSIONS

In summary the results shows high correlation and good reproducibility of measurements. All deviations are inside the tolerance interval of 5°, if one device is used. An unlikely systematic device effect is detected. These laboratory trials are promising for the validation of this system in humans. The challenge for both systems will be the changing of the COR in the shoulder joint at elevations higher than 90°.

Markedly impaired bilateral coordination of gait in post-stroke patients: Is this deficit distinct from asymmetry? A cohort study

Background

Multiple aspects of gait are typically impaired post-stroke. Asymmetric gait is common as a consequence of unilateral brain lesions. The relationship between the resulting asymmetric gait and impairments in the ability to properly coordinate the reciprocal stepping activation of the legs is not clear. The objective of this exploratory study is to quantify the effects of hemiparesis on two putatively independent aspects of the bilateral coordination of gait to gain insight into mechanisms and their relationship and to assess their potential as clinical markers.

Methods

Twelve ambulatory stroke patients and age-matched healthy adults wore a tri-axial piezo-resistive accelerometer and walked back and forth along a straight path in a hall at a comfortable walking speed during 2 minutes. Gait speed, gait asymmetry (GA), and aspects of the bilateral coordination of gait (BCG) were determined. Bilateral coordination measures included the left-right stepping phase for each stride φ_i, consistency in the phase generation φ_CV, accuracy in the phase generation φ_ABS, and Phase Coordination Index (PCI), a combination of accuracy and consistency of the phase generation.

Results

Group differences (p < 0.001) were observed for gait speed (1.1 ± 0.1 versus 1.7 ± 0.1 m/sec for patients and controls, respectively), GA (26.3 ± 5.6 versus 5.5 ± 1.2, correspondingly) and PCI (19.5 ± 2.3 versus 6.2 ± 1.0, correspondingly). A significant correlation between GA and PCI was seen in the stroke patients (r = 0.94; p < 0.001), but not in the controls.

Conclusions

In ambulatory post-stroke patients, two gait coordination properties, GA and PCI, are markedly impaired. Although these features are not related to each other in healthy controls, they are strongly related in stroke patients, which is a novel finding. A measurement approach based on body-fixed sensors apparently may provide sensitive markers that can be used for clinical assessment and for enhancing rehabilitation targeting in post-stroke patients.

Validation of the Dynaport Minimod during Sleep: A Pilot Study

To measure activity during sleep, polysomnography and actigraphy are often used. The DynaPort MiniMod measures movement intensity and body position day and night. The goal was to examine the validity of the DynaPort MiniMod in assessing physical activity and body posture during sleep. In Study A, 10 healthy participants slept with the DynaPort MiniMod and the Actiwatch for one night. In Study B, 8 participants suspected of having Obstructive Sleep Apnoea Syndrome slept for one night with the DynaPort MiniMod and underwent complete polysomnography as part of the typical care protocol. In Study A, there was a significant moderate correlation ( r = .70) between the movement scores of the Actiwatch and the DynaPort MiniMod. In Study B, a high intraclass correlation ( r = .84) between body posture scores of the DynaPort MiniMod and the polysomnography position sensor was observed. The DynaPort MiniMod is a valid measurement device for physical activity during sleep.

Reliability of the RT3 accelerometer for measurement of physical activity in adolescents

The aim of this study was to assess the reliability of the RT3 accelerometer under conditions of normal physical activity. Sixty healthy individuals (30 boys, 30 girls) aged 10-16 years wore two accelerometers while performing different structured physical activities. The accelerometers were synchronized and data were recorded every minute during nine 15-min sessions of physical activity that varied in intensity from sedentary (watching television, playing video games) to vigorous (running on a treadmill at different speeds). Intra-instrument coefficients of variation (CV) were assessed using the formula CV = standard deviation of the measure x 100/mean of the measure. The intra-instrument coefficient of variation was higher for sedentary (17%) and light activity (16.2%) than moderate (9.3%) and vigorous activity (6.6%). These results confirmed the poor reliability of the RT3 for activity of low magnitude and frequency that was demonstrated in studies using a shaker.