Objectively measured arm use in daily life improves during the first 6 months poststroke: a longitudinal observational cohort study.

BACKGROUND: It is unclear how arm use in daily life changes after stroke since studies investigating the change in arm use poststroke are scarce. The aim of this study was to investigate the change in arm use during the first six months poststroke. Secondary aim was to compare arm use changes between arm recovery clusters. METHODS: Arm use was measured during week 3, 12, and 26 poststroke with accelerometers on the wrists and the nonaffected leg. Outcomes were the amount of affected and nonaffected arm use during sitting and standing per day and per sit/stand hour, and the daily ratio between arms. Arm function was measured with the Fugl-Meyer Upper Extremity Scale to identify recovery clusters (poor/moderate/excellent). Generalized estimating equations compared arm use outcomes between time points and between recovery clusters. RESULTS: Thirty-three stroke patients participated. Affected arm use per day increased between week 3 and 12 (30 %; p = 0.04) and it increased per sit/stand hour between week 3-12 (31 %; p < 0.001) and between week 3 and 26 (48 %; p = 0.02). Nonaffected arm use per day decreased between week 3 and 12 (13 %; p < 0.001) and between week 3 and 26 (22 %; p < 0.001) and it decreased per sit/stand hour between week 3 and 26 (18 %; p = 0.003). The daily ratio increased between week 3 and 12 (43 %; p < 0.001) and between week 3 and 26 (95 %; p < 0.001). Changes in arm use did not differ significantly between recovery clusters (p = 0.11-0.62). Affected arm use was higher in the excellent recovery cluster (p < 0.001). CONCLUSIONS: Affected arm use and the ratio between arms increase during the first 26 weeks poststroke especially in patients with excellent arm recovery.

Three distinct physical behavior types in fatigued patients with multiple sclerosis.

BACKGROUND: Multiple sclerosis often leads to fatigue and changes in physical behavior (PB). Changes in PB are often assumed as a consequence of fatigue, but effects of interventions that aim to reduce fatigue by improving PB are not sufficient. Since the heterogeneous nature of MS related symptoms, levels of PB of fatigued patients at the start of interventions might vary substantially. Better understanding of the variability by identification of PB subtypes in fatigued patients may help to develop more effective personalized rehabilitation programs in the future. This study aimed to identify PB subtypes in fatigued patients with multiple sclerosis based on multidimensional PB outcome measures. METHODS: Baseline accelerometer (Actigraph) data, demographics and clinical characteristics of the TREFAMS-ACE participants (n = 212) were used for secondary analysis. All patients were ambulatory and diagnosed with severe fatigue based on a score of ≥35 on the fatigue subscale of the Checklist Individual Strength (CIS20r). Fifteen PB measures were used derived from 7 day measurements with an accelerometer. Principal component analysis was performed to define key outcome measures for PB and two-step cluster analysis was used to identify PB types. RESULTS: Analysis revealed five key outcome measures: percentage sedentary behavior, total time in prolonged moderate-to-vigorous physical activity, number of sedentary bouts, and two types of change scores between day parts (morning, afternoon and evening). Based on these outcomes three valid PB clusters were derived. CONCLUSIONS: Patients with severe MS-related fatigue show three distinct and homogeneous PB subtypes. These PB subtypes, based on a unique set of PB outcome measures, may offer an opportunity to design more individually-tailored interventions in rehabilitation. TRIAL REGISTRATION: Clinical trial registration no ISRCTN 82353628 , ISRCTN 69520623  and  ISRCTN 58583714 .

Physical Behavior Profiles in Chronic Cancer-Related Fatigue.

PURPOSE: Increasing physical activity level is a generally effective intervention goal for patients who suffer from chronic cancer-related fatigue (CCRF). However, patients are unlikely to benefit equally from these interventions, as their behavioral starting points might vary substantially. Therefore, we explored patterns of physical behavior of participants who suffer from CCRF. METHODS: Baseline data of a randomized controlled trial were used for a latent profile analysis on nine accelerometer-derived physical behavior measures, describing levels and patterns of physical activity, moderate-to-vigorous intensity physical activity (MVPA), and sedentary behavior. The relation between participant characteristics and the latent profiles was analyzed. RESULTS: Accelerometer data of 172 participants from the Netherlands was analyzed. Three latent profiles were distinguished that differed most on physical activity level and total time spent in MVPA. Eighty-eight percent of all participants were assigned to a profile with a probability higher than 8. Age and perceiving limitations by comorbid conditions and pain were significant covariates of profile membership. CONCLUSIONS: We distinguished three physical behavior profiles. The differences between the patterns indicate that the heterogeneity of this sample requires patients to have substantially different treatment goals. Further research should test the applicability of these profiles in clinical practice.

Impaired respiratory function and associations with health-related quality of life in people with spinal cord injury.

STUDY DESIGN: Follow-up measurement in a multicenter prospective cohort study. OBJECTIVES: To examine the prevalence of impaired respiratory function (pulmonary function and perceived respiratory function), the incidence of respiratory infection and the associations among these parameters in people with spinal cord injury (SCI) 5 years after initial inpatient rehabilitation. Second, we assessed associations between respiratory function and health-related quality of life (HRQOL). SETTING: Eight rehabilitation centers with specialized SCI units in the Netherlands. METHODS: Measurements were performed 5 years after discharge of inpatient rehabilitation. Pulmonary function was determined by forced vital capacity (FVC) and perceived respiratory function by self-reported cough strength and dyspnea. HRQOL was measured using the Sickness Impact Profile 68 and the 36-item Short Form Health Survey. RESULTS: One-hundred forty-seven people with SCI participated. Of this sample, 30.9% had impaired FVC, 35.9% poor or moderate cough strength, 18.4% dyspnea at rest and 29.0% dyspnea during activity. In the year before the measurements, 8.9% had had respiratory infection. FVC was associated with cough strength, but not with dyspnea. All respiratory function parameters were associated with social functioning, whereas other HRQOL domains were associated with dyspnea only. CONCLUSION: Five years after initial inpatient rehabilitation, impaired respiratory function and respiratory infection were common in people with SCI. More severely impaired respiratory function was associated with lower HRQOL. SPONSORSHIP: The Netherlands Organisation for Health Research and Development.

A steep ramp test is valid for estimating maximal power and oxygen uptake during a standard ramp test in type 2 diabetes.

A short maximal steep ramp test (SRT, 25 W/10 s) has been proposed to guide exercise interventions in type 2 diabetes, but requires validation. This study aims to (a) determine the relationship between Wmax and V˙O2peak reached during SRT and the standard ramp test (RT); (b) obtain test-retest reliability; and (c) document electrocardiogram (ECG) abnormalities during SRT. Type 2 diabetes patients (35 men, 26 women) performed a cycle ergometer-based RT (women 1.2; men 1.8 W/6 s) and SRT on separate days. A random subgroup (n = 42) repeated the SRT. ECG, heart rate, and V˙O2 were monitored. Wmax during RT: 193 ± 63 (men) and 106 ± 33 W (women). Wmax during SRT: 193 ± 63 (men) and 188 ± 55 W (women). The relationship between RT and SRT was described by men RT V˙O2peak (mL/min) = 152 + 7.67 × Wmax SRT1 (r: 0.859); women RT V ˙ O 2 p e a k (mL/min) = 603 + 4.75 × Wmax SRT1 (r: 0.771); intraclass correlation coefficients between first (SRT1) and second SRT Wmax (SRT2) were men 0.951 [95% confidence interval (CI) 0.899-0.977] and women 0.908 (95% CI 0.727-0.971). No adverse events were noted during any of the exercise tests. This validation study indicates that the SRT is a low-risk, accurate, and reliable test to estimate maximal aerobic capacity during the RT to design exercise interventions in type 2 diabetes patients.

Stroke patients' motivation for home-based upper extremity rehabilitation with eHealth tools.

PURPOSE: eHealth-based exercise therapies were developed to increase stroke patients' adherence to home-based motor rehabilitation. However, these eHealth tools face a rapid decrease in use after a couple of weeks. This study investigates stroke patients' motivation for home-based upper extremity rehabilitation with eHealth tools and their relation with Basic Psychological Needs. MATERIALS AND METHODS: This is a qualitative study using thematic analysis. We conducted semi-structured interviews with stroke patients with upper extremity motor impairments, who were discharged home from a rehabilitation centre, after they interacted with a novel eHealth coach demonstrator in their homes for five consecutive days. RESULTS: We included ten stroke patients. Thematic analysis resulted in eight themes for home-based rehabilitation motivation: Curiosity, Rationale, Choice, Optimal challenge, Reference, Encouragement, Social Support and Trustworthiness. Those themes are embedded into three Basic Psychological Needs: "Autonomy", "Competence", and "Relatedness". CONCLUSION: Eight motivational themes related to the three Basic Psychological Needs describe stroke patients' motivation for home-based upper extremity rehabilitation. We recommend considering those themes when developing a home-based eHealth intervention for stroke patients to increase the alignment of eHealth tools to the patient's needs and reduce motivational decreases in home-based rehabilitation.

Stroke patients show motivational decreases and decreased use of eHealth tools in home-based rehabilitation after a couple of weeks.Eight motivational themes describe home-based rehabilitation motivation in stroke patients: Curiosity, Rationale, Choice, Optimal challenge, Reference, Encouragement, Social Support and Trustworthiness.Those themes are embedded into three Basic Psychological Needs: "Autonomy", "Competence", and "Relatedness".Those themes should be considered when developing a home-based eHealth intervention for stroke patients to increase the alignment of eHealth tools to the patient's needs and reduce motivational decreases in home-based rehabilitation.

Requirements for home-based upper extremity rehabilitation using wearable motion sensors for stroke patients: a user-centred approach.

PURPOSE: Telerehabilitation systems have the potential to enable therapists to monitor and assist stroke patients in achieving high-intensity upper extremity exercise in the home environment. We adopted an iterative user-centred approach, including multiple data sources and meetings with end-users and stakeholders to define the user requirements for home-based upper extremity rehabilitation using wearable motion sensors for subacute stroke patients. METHODS: We performed a requirement analysis consisting of the following steps: 1) context & groundwork; 2) eliciting requirements; 3) modelling & analysis; 4) agreeing requirements. During these steps, a pragmatic literature search, interviews and focus groups with stroke patients, physiotherapists and occupational therapists were performed. The results were systematically analysed and prioritised into "must-haves", "should-haves", and "could-haves". RESULTS: We formulated 33 functional requirements: eighteen must-have requirements related to blended care (2), exercise principles (7), exercise delivery (3), exercise evaluation (4), and usability (2); ten should-haves; and five could-haves. Six movement components, including twelve exercises and five combination exercises, are required. For each exercise, appropriate exercise measures were defined. CONCLUSION: This study provides an overview of functional requirements, required exercises, and required exercise measures for home-based upper extremity rehabilitation using wearable motion sensors for stroke patients, which can be used to develop home-based upper extremity rehabilitation interventions. Moreover, the comprehensive and systematic requirement analysis used in this study can be applied by other researchers and developers when extracting requirements for designing a system or intervention in a medical context.

This study provides an extensive overview of user requirements for home-based upper extremity rehabilitation using wearable motion sensors in stroke patients.These requirements can be used as a basis for developing home-based UE telerehabilitation interventions.Including these requirements may facilitate the clinical implementation of such telerehabilitation systems.The comprehensive and systematic approach used in this sudy can be applied by other researchers and developers when extracting requirements for designing a system or intervention in a medical context.

A more active lifestyle in persons with a recent spinal cord injury benefits physical fitness and health.

STUDY DESIGN: A prospective cohort study. OBJECTIVES: To study the longitudinal relationship between objectively measured everyday physical activity level, and physical fitness and lipid profile in persons with a recent spinal cord injury (SCI). SETTING: A rehabilitation centre in the Netherlands and the participant's home environment. METHODS: Data of 30 persons with a recent SCI were collected at the start of active rehabilitation, 3 months later, at discharge from inpatient rehabilitation, and 1 year after discharge. Physical activity level (duration of dynamic activities as % of 24 h) was measured with an accelerometry-based activity monitor. Regarding physical fitness, peak oxygen uptake (VO(2)peak) and peak power output (POpeak) were determined with a maximal wheelchair exercise test, and upper extremity muscle strength was measured with a handheld dynamometer. Fasting blood samples were taken to determine the lipid profile. RESULTS: An increase in physical activity level was significantly related to an increase in VO(2)peak and POpeak, and an increase in physical activity level favourably affected the lipid profile. A nonsignificant relation was found with muscle strength. CONCLUSION: Everyday physical activity seems to have an important role in the fitness and health of persons with a recent SCI. An increase in physical activity level was associated with an increase in physical fitness and with a lower risk of cardiovascular disease.

Intensity of daily physical activity - a key component for improving physical capacity after minor stroke?

PURPOSE: Elucidating the complex interactions between physical activity (PA), a multidimensional concept, and physical capacity (PC) may reveal ways to improve rehabilitation interventions. This cross-sectional study aimed to explore which PA dimensions are related to PC in people after minor stroke. MATERIALS AND METHODS: Community dwelling individuals >6 months after minor stroke were evaluated with a 10-Meter-Walking-Test (10MWT), Timed-Up & Go, and the Mini Balance Evaluation System Test. The following PA outcomes were measured with an Activ8 accelerometer: counts per minute during walking (CPMwalking; a measure of intensity), number of active bouts (frequency), mean length of active bouts (distribution), and percentage of waking hours in upright positions (duration). Multivariable linear regression models, adjusted for age, sex and BMI, were used to assess the relationships between PC and PA outcomes. RESULTS: Sixty-nine participants [62.2 ± 9.8 years, 61% male, 20 months post onset (IQR 13.0-53.5)] were included in the analysis. CPMwalking was significantly associated to PC in the 10MWT (std. ß = 0.409, p = 0.002), whereas other associations between PA and PC were not significant. CONCLUSIONS: The PA dimension intensity of walking is significantly associated with PC, and appears to be an important tool for future interventions in rehabilitation after minor stroke.Implications for rehabilitationIt is recommended to express physical activity after minor stroke in multiple dimensions such as intensity, frequency, duration and distribution.In particular, intensity of physical activity measured with accelerometer counts is most closely related to physical capacity.The findings of this study underline the importance of being physically active beyond a certain intensity.In future development of interventions and guidelines that aim to promote daily physical activity, intensity should be taken into account.

Quantifying Quality of Reaching Movements Longitudinally Post-Stroke: A Systematic Review.

BACKGROUND: Disambiguation of behavioral restitution from compensation is important to better understand recovery of upper limb motor control post-stroke and subsequently design better interventions. Measuring quality of movement (QoM) during standardized performance assays and functional tasks using kinematic and kinetic metrics potentially allows for this disambiguation. OBJECTIVES: To identify longitudinal studies that used kinematic and/or kinetic metrics to investigate post-stroke recovery of reaching and assess whether these studies distinguish behavioral restitution from compensation. METHODS: A systematic literature search was conducted using the databases PubMed, Embase, Scopus, and Wiley/Cochrane Library up to July 1st, 2020. Studies were identified if they performed longitudinal kinematic and/or kinetic measurements during reaching, starting within the first 6 months post-stroke. RESULTS: Thirty-two longitudinal studies were identified, which reported a total of forty-six different kinematic metrics. Although the majority investigated improvements in kinetics or kinematics to quantify recovery of QoM, none of these studies explicitly addressed the distinction between behavioral restitution and compensation. One study obtained kinematic metrics for both performance assays and a functional task. CONCLUSIONS: Despite the growing number of kinematic and kinetic studies on post-stroke recovery, longitudinal studies that explicitly seek to delineate between behavioral restitution and compensation are still lacking in the literature. To rectify this situation, future studies should measure kinematics and/or kinetics during performance assays to isolate restitution and during a standardized functional task to determine the contributions of restitution and compensation.

Walking and chair rising performed in the daily life situation before and after total hip arthroplasty.

OBJECTIVE: An earlier study showed that 6 months after total hip arthroplasty (THA) patients' overall daily activity level had not increased, despite significant improvement in their perceived physical functioning. This discrepancy might be because postoperative recovery is not expressed by a more overall active lifestyle, but by the fact that patients could perform the individual activities of daily living (ADL) faster and/or for a longer period of time. The aim of this study was to assess whether patients perform ADL faster and/or for a longer period of time 6 months post-THA compared to baseline. Also examined was whether patients perform activities on the level of healthy matched controls. METHOD: Thirty patients were measured at home with an accelerometry-based Activity Monitor, pre-operatively and 6 months post-THA. Patients were matched with healthy controls on gender and age (±2 years). RESULTS: Compared with baseline, 6 months post-THA the stride frequency and body motility during walking of patients had increased [56.1 (54.3, 57.8)strides/min vs 52.1 (50.3, 54.1)strides/min; P-value<0.0001, and 0.265 (0.245, 0.286)g vs 0.219 (0.197, 0.240)g; P-value<0.0001], and they rose faster from a chair [2.6 (2.5, 2.8)s vs 3.0 (2.8, 3.2)s; P-value<0.0001]. Compared with controls, preoperative all patients had lower values for these parameters. Six months post-THA the stride frequency and body motility during walking were similar to that of controls, but patients rose slower from a chair than controls. CONCLUSION: Six months post-THA patients walked faster and rose from a chair faster compared to baseline. Patients walked as fast as healthy controls but took longer rising from a chair.

Fatigue in neuromuscular disorders: focus on Guillain-Barré syndrome and Pompe disease.

Fatigue accounts for an important part of the burden experienced by patients with neuromuscular disorders. Substantial high prevalence rates of fatigue are reported in a wide range of neuromuscular disorders, such as Guillain-Barré syndrome and Pompe disease. Fatigue can be subdivided into experienced fatigue and physiological fatigue. Physiological fatigue in turn can be of central or peripheral origin. Peripheral fatigue is an important contributor to fatigue in neuromuscular disorders, but in reaction to neuromuscular disease fatigue of central origin can be an important protective mechanism to restrict further damage. In most cases, severity of fatigue seems to be related with disease severity, possibly with the exception of fatigue occurring in a monophasic disorder like Guillain-Barré syndrome. Treatment of fatigue in neuromuscular disease starts with symptomatic treatment of the underlying disease. When symptoms of fatigue persist, non-pharmacological interventions, such as exercise and cognitive behavioral therapy, can be initiated.

Feasibility and short-term effects of Activity Coach+: a physical activity intervention in hard-to-reach people with a physical disability.

PURPOSE: Existing physical activity interventions do not reach a considerable proportion of physically disabled people. This study assessed feasibility and short-term effects of Activity Coach+, a community-based intervention especially targeting this hard-to-reach population. METHODS: Feasibility was determined by reach, dropouts, and compliance with the protocol. Physical activity was measured with the Activ8 accelerometer and the adapted SQUASH questionnaire. Health outcomes were assessed by body composition, blood pressure, hand grip force, 10-metre walk test, 6-minute walk test, and the Berg Balance Scale. The RAND-36, Exercise Self-Efficacy Scale, Fatigue Severity Scale, and IMPACT-S were administered. Measurements were performed at baseline and after 2 and 4 months. Changes over time were analysed by Friedman tests. RESULTS: Twenty-nine participants enrolled during the first 4 months, of whom two dropped out. Intervention components were employed in 86-100% of the participants. Physical activity did not change after the implementation of Activity Coach+. Body mass index (p = 0.006), diastolic blood pressure (p = 0.032), walking ability (p = 0.002), exercise capacity (p = 0.013), balance (p = 0.014), and vitality (p = 0.049) changed over time. CONCLUSIONS: Activity Coach + is feasible in a community setting. Indications for effectivity of Activity Coach + in hard-to-reach people with a physical disability were found.Implications for rehabilitationActivity Coach + was able to reach physically disabled people living in community, a population that is assumed hard-to-reach.Activity Coach + was feasible in a population of persons with a physical disability that was heterogeneous with respect to age and (severity of) disability.The current study provides the first indications for the beneficial health effects of Activity Coach + in hard-to-reach people with a physical disability.

Are pain, functional limitations and quality of life associated with objectively measured physical activity in patients with end-stage osteoarthritis of the hip or knee?

OBJECTIVES: Physical activity is promoted in patients with hip or knee osteoarthritis (OA), yet little is known about its relationship with symptoms, functional limitations and Quality of Life (QoL). We investigated if OA-associated pain, functional limitations and QoL are associated with objectively measured physical activity in patients with end-stage hip/knee OA. METHODS: Cross-sectional study including patients scheduled for primary total hip/knee arthroplasty. Patients wore an accelerometer (Activ8) with physical activity assessed over waking hours, and expressed as number of activity daily counts (ADC) per hour, %time spent on physical activity i.e. walking, cycling or running (%PA), and %time spent sedentary (%SB). Pain, functional limitations and joint-specific and general QoL were assessed with the Hip disability/Knee Injury and Osteoarthritis Outcome Score (HOOS/KOOS) and the Short Form (SF)-12. Multivariate linear regression models with the three to Z-scores transformed parameters of physical activity as dependent variables and adjusted for confounding, were conducted. RESULTS: 49 hip and 48 knee OA patients were included. In hip and knee OA patients the mean number of ADC, %PA and %SB were 18.79 ± 7.25 and 21.19 ± 6.16, 14 ± 6.4 and 15 ± 5.0, and 66 ± 10.5 and 68 ± 8.7, respectively. In hip OA, better joint-specific and general QoL were associated with more ADC, (ß 0.028; 95%CI:0.007-0.048, ß0.041; 95%CI:0.010-0.071). Also, better general QoL was associated with the %PA (ß 0.040, 95%CI:0.007-0.073). No other associations were found. CONCLUSION: Whereas QoL was associated with physical activity in hip OA, pain and functional limitations were not related to objectively measured physical activity in patients with end-stage hip or knee OA.

Effect of wearing an activity monitor on the amount of daily manual wheelchair propulsion in persons with spinal cord injury.

STUDY DESIGN: An experimental study. OBJECTIVES: To assess the effect of reactivity related to wearing a multi-sensor activity monitor (AM) on the amount of manual wheelchair propulsion during daily life in wheelchair-bound persons with spinal cord injury (SCI). In addition, to establish the subjectively experienced burden of wearing the AM. SETTING: Rehabilitation centre and home-based study. METHODS: In 10 persons with SCI, during a 7-day period, the daily amount of manual wheelchair propulsion was measured by means of a rotation counter. During this period, an AM was worn for 1 day (AM+ day) by the participants. Experienced burden was measured by a questionnaire based on visual analogue scale scores. RESULTS: The overall median of the number of rotations per minute was 1.38 (range 0.63-1.83). No significant difference was found in the amount of daily manual wheelchair propulsion between AM+ and AM- days (P=0.33, median difference: -0.06 rotations per minute). Experienced burden was not different between subgroups that differed in reactivity. CONCLUSION: The results seem to indicate that wearing the AM of this study does not systematically influence the amount of daily manual wheelchair propulsion. Although low to moderate burden was experienced when wearing the AM, this does not seem to affect the amount of manual wheelchair propulsion.

Validity of the Pedar Mobile system for vertical force measurement during a seven-hour period.

Objective measurement of weight bearing during a long-term period can give insight into the postoperative loading of the lower extremity of orthopedic patients to avoid complications. This study investigated the validity of vertical ground reaction force measurements during a long-term period using the Pedar Mobile insole pressure system, by comparing it with a Kistler force platform. In addition, the validity of a new sensor drift correction algorithm to correct for offset drift in the Pedar signal was evaluated. Ground reaction force data were collected during dynamic and static conditions from five healthy subjects every hour for 7 h. A mean offset drift of 14.6% was found after 7 h. After applying the drift correction algorithm the Pedar system showed a high accuracy for the second peak in the ground reaction force-time curve (1.1 to 3.4% difference, p>0.05) and step duration (-2.0 to 4.4% difference, p>0.05). Less accuracy was found for the first peak in the ground reaction force-time curve (5.2 to 12.0% difference; p<0.05 for the first 3 h, p>0.05 for the last 4 h) and, consequently, in the vertical force impulse (5.5 to 11.0% difference, p>0.05). The Pedar Mobile system appeared to be a valid instrument to measure the vertical force during a long-term period when using the drift correction program described in this study.

Accuracy and repeatability of the Pedar Mobile system in long-term vertical force measurements.

Portable insole pressure systems can be used to measure the vertical force during long-term (hours) measurements to determine the patient's amount of weight bearing during daily activities in the hospital and at home. Especially for long-term measurements, the amount and duration of loading pressure insoles can have a large influence on the accuracy, as previous studies found a time-dependent behavior after a relatively short period (minutes) of constant loading. Therefore, this study assessed the accuracy and repeatability of a portable capacitive insole system (Pedar, Novel(GmbH)) to measure vertical force during long-term loading. Static loading experiments were performed during which the Pedar insoles were loaded with 5 and 10 N/cm2 for 7 h. Dynamic loading experiments were performed with one Pedar insole which was cyclically loaded with 300, 500 and 1000 N during two sessions of 1200 load cycles. The static and dynamic experiments were repeated 3 days later. Accuracy, due to offset drift, decreased in time during the start of the static experiments (percent error: -1.9% to 0.3% at hour 0; 26.3% to 34% at hour 7). The percent error for the dynamic experiments ranged from -16% to -19%, from -3% to -7% and from -8% to approximately 0% when the insole was loaded with 300, 500 and 1000 N, respectively. The amount of drift ranged from 12 to 62 N for the 500 and 1000 N loads, respectively. The mean day-to-day percentage difference for the static and dynamic experiments ranged from -2.3% to 0.5%, and from -2.9% to 3.0%, respectively. The results indicate that drift correction is necessary for accurate assessment of vertical force by the Pedar Mobile system to determine the amount of weight bearing during long-term measurements.

Analysis and decomposition of accelerometric signals of trunk and thigh obtained during the sit-to-stand movement.

Piezoresistive accelerometer signals are frequently used in movement analysis. However, their use and interpretation are complicated by the fact that the signal is composed of different acceleration components. The aim of the study was to obtain insight into the components of accelerometer signals from the trunk and thigh segments during four different sit-to-stand (STS) movements (self-selected, slow, fast and fullflexion). Nine subjects performed at least six trials of each type of STS movement. Accelerometer signals from the trunk and thigh in the sagittal direction were decomposed using kinematic data obtained from an opto-electronic device. Each acceleration signal was decomposed into gravitational and inertial components, and the inertial component of the trunk was subsequently decomposed into rotational and translational components. The accelerometer signals could be reliably reconstructed: mean normalised root mean square (RMS) trunk: 6.5% (range 3-12%), mean RMS thigh: 3% (range 2-5%). The accelerometric signals were highly characteristic and repeatable. The influence of the inertial component was significant, especially on the timing of the specific event of maximum trunk flexion in the accelerometer signal. The effect of inertia was larger in the trunk signal than in the thigh signal and increased with higher speeds. The study provides insight into the acceleration signal, its components and the influence of the type of STS movement and supports its use in STS movement analysis.

Evaluation of the usability of two types of image display systems, during laparoscopy.

BACKGROUND: This study was performed to assess the optimal display location of a flat-screen monitor for laparoscopy. It was also performed to assess the posture (objective), opinion, and preference (subjective) of subjects using a flat-screen monitor positioned in the optimal display location and a cathode-ray tube monitor on a tower next to the operating table (current situation). METHODS: Twelve surgeons performed cholecystectomies using the two display systems alternately. The postures of the operator and the assistant were assessed by an infrared video analysis system. RESULTS: The posture of the assistant is significantly better when using a flat-screen monitor [more neutral head flexions (p = 0.036) and neutral neck torsions (p = 0.012)]. No significant differences were found for the posture of the operator. The operators and assistants felt more comfortable when using a flat-screen monitor (p = 0.008) and they preferred this display to the use of a monitor on a tower. CONCLUSIONS: The use of flat-screen monitors is better for the physical and psychological comfort of the users, even though the technical performance is inferior in comparison with that of regular monitors.

Ambulatory measurement of upper limb usage and mobility-related activities during normal daily life with an upper limb-activity monitor: a feasibility study.

The aim of this research was to assess the ability of an upper limb-activity monitor (ULAM) to discriminate between upper limb usage and non-usage in healthy and disabled subjects during normal daily life. The ULAM was based on ambulatory accelerometry and consisted of several acceleration sensors connected to a small recorder worn around the waist. While wearing this ULAM, four healthy and four disabled subjects performed an activity protocol representing normal daily life upper limb usage or non-usage. The motility feature (derived from the raw acceleration signals) was used as a measure of the extent of upper limb usage. Agreement scores between ULAM output and videotape recordings (reference method) were calculated. ULAM data that were of special interest for rehabilitation were detected satisfactorily (overall agreement 83.9%). There were no systematic differences in the agreement percentages between healthy and disabled subjects for mobility-related activities (p = 0.345) and the different forms of upper limb usage or non-usage (p= 0.715). The ULAM can be used in future studies in subjects with upper limb disorders to discriminate between upper limb usage and non-usage during performance of mobility-related activities to determine activity limitations.