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Accurate measurement of knee kinematics during functional activities suffers mainly from soft tissue artifact (STA): the combination of local surface deformations and rigid movement of markers relative to the underlying bone (also called rigid STA movement: RSTAM). This study proposes to assess RSTAM on the thigh, shank, and knee joint and to observe possible features between subjects. Nineteen subjects with knee arthroplasty were asked to walk on a treadmill while a biplane fluoroscopic system (X-rays) and a stereophotogrammetric system (skin markers) recorded their knee movement. The RSTAM was defined as the rigid movement of the cluster of skin markers relative to the prosthesis. The results showed that RSTAM amplitude represents approximately 80–100% of the STA. The vertical axis of the anatomical frame of the femur was influenced the most by RSTAM. Combined with tibial error, internal/external rotation angle and distraction–compression were the knee kinematics parameters most affected by RSTAM during the gait cycle, with average rms values of 3.8° and 11.1 mm. This study highlighted higher RSTAM during the swing phase particularly in the thigh segment and suggests new features for RSTAM such as the particular shape of some RSTAM waveforms and the absence of RSTAM in certain kinematics during the gait phases. The comparison of coefficient of multiple correlations showed some similarities of RSTAM between subjects, while some correlations were found with gait speed and BMI. These new insights could potentially allow the development of new methods of compensation to avoid STA. [ABSTRACT FROM PUBLISHER]

This study introduces a novel approach for automatic temporal phase detection and inter-arm coordination estimation in front-crawl swimming using inertial measurement units (IMUs). We examined the validity of our method by comparison against a video-based system. Three waterproofed IMUs (composed of 3D accelerometer, 3D gyroscope) were placed on both forearms and the sacrum of the swimmer. We used two underwater video cameras in side and frontal views as our reference system. Two independent operators performed the video analysis. To test our methodology, seven well-trained swimmers performed three 300 m trials in a 50 m indoor pool. Each trial was in a different coordination mode quantified by the index of coordination. We detected different phases of the arm stroke by employing orientation estimation techniques and a new adaptive change detection algorithm on inertial signals. The difference of 0.2 ± 3.9% between our estimation and video-based system in assessment of the index of coordination was comparable to experienced operators’ difference (1.1 ± 3.6%). The 95% limits of agreement of the difference between the two systems in estimation of the temporal phases were always less than 7.9% of the cycle duration. The inertial system offers an automatic easy-to-use system with timely feedback for the study of swimming. [ABSTRACT FROM PUBLISHER]

Highlights: [•] Continuous relative phase (CRP) of shank-thigh and thigh-sacrum pairs. [•] 87 jumps were recorded from 33 athletes with an inertial measurement system. [•] Inter-segment coordination during take-off extension is related to performance. [•] The thighs lead more the shanks during a longer time for the best athletes. [•] A more symmetric movement between thighs and sacrum was obtained for the best athletes. [ABSTRACT FROM AUTHOR]

Abstract: In clinical settings, functional evaluation of shoulder movement is primarily based on what the patient thinks he/she is able to do rather than what he/she is actually performing. We proposed a new approach for shoulder assessment based on inertial sensors to monitor arm movement in the daily routine. The detection of movement of the humerus relative to the trunk was first validated in a laboratory setting (sensitivity>95%, specificity>97%). Then, 41 control subjects and 21 patients suffering from a rotator cuff tear were evaluated (before and after surgery) using clinical questionnaires and a one-day measurement of arm movement. The quantity of movement was estimated with the movement frequency and its symmetry index (SI Fr ). The quality of movement was assessed using the Kolmogorov–Smirnov distance (KS) between the cumulative distribution of the arm velocity for controls and the same distribution for each patient. SI Fr presented differences between patients and controls at 3 month follow-up (p <0.05) while KS showed differences also after 6 months (p <0.01). SI Fr illustrated a change in dominance due to the disorder whereas KS, which appeared independent of the dominance and occupation, showed a change in movement velocity. Both parameters were correlated to clinical scores (R 2 reaching 0.5). This approach provides clinicians with new objective parameters for evaluating the functional ability of the shoulder in daily conditions, which could be useful for outcome assessment after surgery. [Copyright &y& Elsevier]

Abstract: Time periods composing stance phase of gait can be clinically meaningful parameters to reveal differences between normal and pathological gait. This study aimed, first, to describe a novel method for detecting stance and inner-stance temporal events based on foot-worn inertial sensors; second, to extract and validate relevant metrics from those events; and third, to investigate their suitability as clinical outcome for gait evaluations. 42 subjects including healthy subjects and patients before and after surgical treatments for ankle osteoarthritis performed 50-m walking trials while wearing foot-worn inertial sensors and pressure insoles as a reference system. Several hypotheses were evaluated to detect heel-strike, toe-strike, heel-off, and toe-off based on kinematic features. Detected events were compared with the reference system on 3193 gait cycles and showed good accuracy and precision. Absolute and relative stance periods, namely loading response, foot-flat, and push-off were then estimated, validated, and compared statistically between populations. Besides significant differences observed in stance duration, the analysis revealed differing tendencies with notably a shorter foot-flat in healthy subjects. The result indicated which features in inertial sensors’ signals should be preferred for detecting precisely and accurately temporal events against a reference standard. The system is suitable for clinical evaluations and provides temporal analysis of gait beyond the common swing/stance decomposition, through a quantitative estimation of inner-stance phases such as foot-flat. [Copyright &y& Elsevier]

Assessment of locomotion through simple tests such as timed up and go (TUG) or walking trials can provide valuable information for the evaluation of treatment and the early diagnosis of people with Parkinson's disease (PD). Common methods used in clinics are either based on complex motion laboratory settings or simple timing outcomes using stop watches. The goal of this paper is to present an innovative technology based on wearable sensors on-shoe and processing algorithm, which provides outcome measures characterizing PD motor symptoms during TUG and gait tests. Our results on ten PD patients and ten age-matched elderly subjects indicate an accuracy ± precision of 2.8 ± 2.4 cm/s and 1.3 ± 3.0 cm for stride velocity and stride length estimation compared to optical motion capture, with the advantage of being practical to use in home or clinics without any discomfort for the subject. In addition, the use of novel spatio-temporal parameters, including turning, swing width, path length, and their intercycle variability, was also validated and showed interesting tendencies for discriminating patients in ON and OFF states and control subjects. [ABSTRACT FROM PUBLISHER]

Three-dimensional analysis of the entire sequence in ski jumping is recommended when studying the kinematics or evaluating performance. Camera-based systems which allow three-dimensional kinematics measurement are complex to set-up and require extensive post-processing, usually limiting ski jumping analyses to small numbers of jumps. In this study, a simple method using a wearable inertial sensors-based system is described to measure the orientation of the lower-body segments (sacrum, thighs, shanks) and skis during the entire jump sequence. This new method combines the fusion of inertial signals and biomechanical constraints of ski jumping. Its performance was evaluated in terms of validity and sensitivity to different performances based on 22 athletes monitored during daily training. The validity of the method was assessed by comparing the inclination of the ski and the slope at landing point and reported an error of -0.2 ± 4.8°. The validity was also assessed by comparison of characteristic angles obtained with the proposed system and reference values in the literature; the differences were smaller than 61 for 75% of the angles and smaller than 151 for 90% of the angles. The sensitivity to different performances was evaluated by comparing the angles between two groups of athletes with different jump lengths and by assessing the association between angles and jump lengths. The differences of technique observed between athletes and the associations with jumps length agreed with the literature. In conclusion, these results suggest that this system is a promising tool for a generalization of three-dimensional kinematics analysis in ski jumping. [ABSTRACT FROM AUTHOR]

Gait analysis methods to estimate spatiotemporal measures, based on two, three or four gyroscopes attached on lower limbs have been discussed in the literature. The most common approach to reduce the number of sensing units is to simplify the underlying biomechanical gait model. In this study, we propose a novel method based on prediction of movements of thighs from movements of shanks. Datasets from three previous studies were used. Data from the first study (ten healthy subjects and ten with Parkinson’s disease) were used to develop and calibrate a system with only two gyroscopes attached on shanks. Data from two other studies (36 subjects with hip replacement, seven subjects with coxarthrosis, and eight control subjects) were used for comparison with the other methods and for assessment of error compared to a motion capture system. Results show that the error of estimation of stride length compared to motion capture with the system with four gyroscopes and our new method based on two gyroscopes was close ( -\0.8 \pm \6.6 versus \3.8 \pm \6.6 cm). An alternative with three sensing units did not show better results (error: -\0.2 \pm \8.4 cm). Finally, a fourth that also used two units but with a simpler gait model had the highest bias compared to the reference (error: -\25.6 \pm \7.6 cm). We concluded that it is feasible to estimate movements of thighs from movements of shanks to reduce number of needed sensing units from 4 to 2 in context of ambulatory gait analysis. [ABSTRACT FROM PUBLISHER]

Abstract: Objective: Motor changes in major depression (MD) may represent potential markers of treatment response. Physiological rhythms (heart rate/gait cycle/hand movements) have been recently shown to be neither random nor regular but to display a fractal temporal organisation, possibly reflecting a unique central “internal clock” control. Sleep and mood circadian rhythm modifications observed in MD also suggest a role for this “internal clock”. We set out to examine the fractal pattern of motor activity in MD. Methods: Ten depressed patients (46±20 years) and ten age- and gender-matched healthy controls (48±21 years) underwent a 6-h ambulatory monitoring of spontaneous hand activity with a validated wireless device. Fractal scaling exponent (α) was analysed. An α value close to 1 means the pattern is fractal. Results: Healthy controls displayed a fractal pattern of spontaneous motor hand activity (α: 1.0±0.1), whereas depressed patients showed an alteration of that pattern (α:1.2±0.15, p<0.01), towards a smoother organisation. Conclusion: The alteration of fractal pattern of hand activity by depression further supports the role of a central internal clock in the temporal organisation of movements. This novel way of studying motor changes in depression might have an important role in the detection of endophenotypes and potential predictors of treatment response. [Copyright &y& Elsevier]

Tripping is considered a major cause of fall in older people. Therefore, foot clearance (i.e., height of the foot above ground during swing phase) could be a key factor to better understand the complex relationship between gait and falls. This paper presents a new method to estimate clearance using a foot-worn and wireless inertial sensor system. The method relies on the computation of foot orientation and trajectory from sensors signal data fusion, combined with the temporal detection of toe-off and heel-strike events. Based on a kinematic model that automatically estimates sensor position relative to the foot, heel and toe trajectories are estimated. 2-D and 3-D models are presented with different solving approaches, and validated against an optical motion capture system on 12 healthy adults performing short walking trials at self-selected, slow, and fast speed. Parameters corresponding to local minimum and maximum of heel and toe clearance were extracted and showed accuracy ± precision of 4.1 ± 2.3 cm for maximal heel clearance and 1.3 ± 0.9 cm for minimal toe clearance compared to the reference. The system is lightweight, wireless, easy to wear and to use, and provide a new and useful tool for routine clinical assessment of gait outside a dedicated laboratory. [ABSTRACT FROM PUBLISHER]

Monitoring the performance is a crucial task for elite sports during both training and competition. Velocity is the key parameter of performance in swimming, but swimming performance evaluation remains immature due to the complexities of measurements in water. The purpose of this study is to use a single inertial measurement unit (IMU) to estimate front crawl velocity. Thirty swimmers, equipped with an IMU on the sacrum, each performed four different velocity trials of 25 m in ascending order. A tethered speedometer was used as the velocity measurement reference. Deployment of biomechanical constraints of front crawl locomotion and change detection framework on acceleration signal paved the way for a drift-free integration of forward acceleration using IMU to estimate the swimmers velocity. A difference of 0.6 ± 5.4 cm·s-1 on mean cycle velocity and an RMS difference of 11.3 cm·s-1 in instantaneous velocity estimation were observed between IMU and the reference. The most important contribution of the study is a new practical tool for objective evaluation of swimming performance. A single body-worn IMU provides timely feedback for coaches and sport scientists without any complicated setup or restraining the swimmer's natural technique. [ABSTRACT FROM AUTHOR]

Usually the measurement of multi-segment foot and ankle complex kinematics is done with stationary motion capture devices which are limited to use in a gait laboratory. This study aimed to propose and validate a wearable system to measure the foot and ankle complex joint angles during gait in daily conditions, and then to investigate its suitability for clinical evaluations. The foot and ankle complex consisted of four segments (shank, hindfoot, forefoot, and toes), with an inertial measurement unit (3D gyroscopes and 3D accelerometers) attached to each segment. The angles between the foul" segments were calculated in the sagittal, coronal, and transverse planes using a new algorithm combining strap-down integration and detection of low-acceleration instants. To validate the joint angles measured by the wearable system, three subjects walked on a treadmill for five minutes at three different speeds. A camera-based stationary system that used a cluster of markers on each segment was used as a reference. To test the suitability of the system for clinical evaluation, the joint angle ranges were compared between a group of 10 healthy subjects and a group of 12 patients with ankle osteoarthritis, during two 50-m walking trials where the wearable system was attached to each subject. On average, over all joints and walking speeds, the RMS differences and correlation coefficients between the angular curves obtained using the wearable system and the stationary system were 1 deg and 0.93, respectively. Moreover, this system was able to detect significant alteration of foot and ankle function between the group of patients with ankle osteoarthritis and the group of healthy subjects. In conclusion, this wearable system was accurate and suitable for clinical evaluation when used to measure the multi-segment foot and ankle complex kinematics during long-distance walks in daily life conditions. [ABSTRACT FROM AUTHOR]

Despite extensive preventive efforts, falls continue to be a major source of morbidity and mortality among elderly. Real-time detection of falls and their urgent communication to a telecare center may enable rapid medical assistance, thus increasing the sense of security of the elderly and reducing some of the negative consequences of falls. Many different approaches have been explored to automatically detect a fall using inertial sensors. Although previously published algorithms report high sensitivity (SE) and high specificity (SP), they have usually been tested on simulated falls performed by healthy volunteers. We recently collected acceleration data during a number of real-world falls among a patient population with a high-fall-risk as part of the SensAction-AAL European project. The aim of the present study is to benchmark the performance of thirteen published fall-detection algorithms when they are applied to the database of 29 real-world falls. To the best of our knowledge, this is the first systematic comparison of fall detection algorithms tested on real-world falls. We found that the SP average of the thirteen algorithms, was (mean±std) 83.0%±30.3% (maximum value = 98%). The SE was considerably lower (SE = 57.0%±27.3%, maximum value = 82.8%), much lower than the values obtained on simulated falls. The number of false alarms generated by the algorithms during 1-day monitoring of three representative fallers ranged from 3 to 85. The factors that affect the performance of the published algorithms, when they are applied to the real-world falls, are also discussed. These findings indicate the importance of testing fall-detection algorithms in real-life conditions in order to produce more effective automated alarm systems with higher acceptance. Further, the present results support the idea that a large, shared real-world fall database could, potentially, provide an enhanced understanding of the fall process and the information needed to design and evaluate a high-performance fall detector. [ABSTRACT FROM AUTHOR]

Background: Modern theories define chronic pain as a multidimensional experience - the result of complex interplay between physiological and psychological factors with significant impact on patients' physical, emotional and social functioning. The development of reliable assessment tools capable of capturing the multidimensional impact of chronic pain has challenged the medical community for decades. A number of validated tools are currently used in clinical practice however they all rely on self-reporting and are therefore inherently subjective. In this study we show that a comprehensive analysis of physical activity (PA) under real life conditions may capture behavioral aspects that may reflect physical and emotional functioning. Methodology: PA was monitored during five consecutive days in 60 chronic pain patients and 15 pain-free healthy subjects. To analyze the various aspects of pain-related activity behaviors we defined the concept of PA 'barcoding'. The main idea was to combine different features of PA (type, intensity, duration) to define various PA states. The temporal sequence of different states was visualized as a 'barcode' which indicated that significant information about daily activity can be contained in the amount and variety of PA states, and in the temporal structure of sequence. This information was quantified using complementary measures such as structural complexity metrics (information and sample entropy, Lempel- Ziv complexity), time spent in PA states, and two composite scores, which integrate all measures. The reliability of these measures to characterize chronic pain conditions was assessed by comparing groups of subjects with clinically different pain intensity. Conclusion: The defined measures of PA showed good discriminative features. The results suggest that significant information about pain-related functional limitations is captured by the structural complexity of PA barcodes, which decreases when the intensity of pain increases. We conclude that a comprehensive analysis of daily-life PA can provide an objective appraisal of the intensity of pain. [ABSTRACT FROM AUTHOR]

We propose a new method, based on inertial sensors, to automatically measure at high frequency the durations of the main phases of ski jumping (i.e. take-off release, take-off, and early flight). The kinematics of the ski jumping movement were recorded by four inertial sensors, attached to the thigh and shank of junior athletes, for 40 jumps performed during indoor conditions and 36 jumps in field conditions. An algorithm was designed to detect temporal events from the recorded signals and to estimate the duration of each phase. These durations were evaluated against a reference camera-based motion capture system and by trainers conducting video observations. The precision for the take-off release and take-off durations (indoor <39 ms, outdoor = 27 ms) can be considered technically valid for performance assessment. The errors for early flight duration (indoor = 22 ms, outdoor = 119 ms) were comparable to the trainers' variability and should be interpreted with caution. No significant changes in the error were noted between indoor and outdoor conditions, and individual jumping technique did not influence the error of take-off release and take-off. Therefore, the proposed system can provide valuable information for performance evaluation of ski jumpers during training sessions. [ABSTRACT FROM PUBLISHER]

The aim of this study was to investigate the alteration of the gait pattern in 25 children with Duchenne muscular dystrophy, using body-worn inertial sensors during a long walking distance. Normalized spatiotemporal gait parameters and their variability were extracted from the angular velocity of the shanks; the smoothness of the trunk movement was assessed based on the spectral entropy of the acceleration norm. As compared to healthy children, patients with Duchenne muscular dystrophy showed significantly lower stride velocity and a less smooth trunk movement. When the group of patients was divided into mild and moderate based on the Motor Function Measure, the authors noticed significantly higher values both for cadence and stride velocity, as well as improved trunk smoothness in the mild versus moderate group. The potential of such parameters to distinguish between different disease states opens new perspectives for the objective assessment of efficacy of the new therapies associated with Duchenne muscular dystrophy. [ABSTRACT FROM PUBLISHER]

Although various foot models were proposed for kinematics assessment using skin makers, no objective justification exists for the foot segmentations. This study proposed objective kinematic criteria to define which foot joints are relevant (dominant) in skin markers assessments. Among the studied joints, shank-hindfoot, hindfoot-midfoot and medial-lateral forefoot joints were found to have larger mobility than flexibility of their neighbour bonesets. The amplitude and pattern consistency of these joint angles confirmed their dominancy. Nevertheless, the consistency of the medial-lateral forefoot joint amplitude was lower. These three joints also showed acceptable sensibility to experimental errors which supported their dominancy. This study concluded that to be reliable for assessments using skin markers, the foot and ankle complex could be divided into shank, hindfoot, medial forefoot, lateral forefoot and toes. Kinematics of foot models with more segments must be more cautiously used. [ABSTRACT FROM AUTHOR]

Abstract: This study describes the validation of a new wearable system for assessment of 3D spatial parameters of gait. The new method is based on the detection of temporal parameters, coupled to optimized fusion and de-drifted integration of inertial signals. Composed of two wirelesses inertial modules attached on feet, the system provides stride length, stride velocity, foot clearance, and turning angle parameters at each gait cycle, based on the computation of 3D foot kinematics. Accuracy and precision of the proposed system were compared to an optical motion capture system as reference. Its repeatability across measurements (test-retest reliability) was also evaluated. Measurements were performed in 10 young (mean age 26.1±2.8 years) and 10 elderly volunteers (mean age 71.6±4.6 years) who were asked to perform U-shaped and 8-shaped walking trials, and then a 6-min walking test (6MWT). A total of 974 gait cycles were used to compare gait parameters with the reference system. Mean accuracy±precision was 1.5±6.8cm for stride length, 1.4±5.6cm/s for stride velocity, 1.9±2.0cm for foot clearance, and 1.6±6.1° for turning angle. Difference in gait performance was observed between young and elderly volunteers during the 6MWT particularly in foot clearance. The proposed method allows to analyze various aspects of gait, including turns, gait initiation and termination, or inter-cycle variability. The system is lightweight, easy to wear and use, and suitable for clinical application requiring objective evaluation of gait outside of the lab environment. [Copyright &y& Elsevier]

The Timed Up and Go (TUG) test has been used to assess balance and mobility in Parkinson's Disease (PD). However, it is not known if this test is sensitive to subtle abnormalities present in early stages of the disease, when balance and gait problems are not clinically evident but may be detected with instrumented analysis of movement. We hypothesise that postural transitions and arm swing during gait will be the most sensitive characteristics of the TUG for early PD. In the present study, we instrumented the TUG test (iTUG) using portable inertial sensors, and extended the walking distance from 3 m (traditional TUG) to 7 m. Twelve subjects with early-to-moderate, untreated PD and 12 healthy individuals participated. Our findings show that although the stopwatch measure of TUG duration did not detect any abnormalities in early-to-mid-stage PD, the peak arm swing velocity on the more affected side, average turning velocity, cadence and peak trunk rotation velocity were significantly slower. These iTUG parameters were also correlated with the Unified Parkinson's Disease Rating Motor Scale. Thus, the iTUG test is sensitive to untreated PD and could potentially detect progression of PD and response to symptomatic and disease-modifying treatments. [ABSTRACT FROM AUTHOR]

Abstract: The joint deformity that arises as a result of Charcot neuroarthropathy, leads to gait modification. Ulceration risk associated with the deformity is generally assessed by measuring plantar pressure magnitude (PPM). However, as PPM is partially dependent on gait speed and treatment interventions may impact speed, the use of PPM to validate treatment is not ideal. This study suggests a novel assessment protocol, which is speed independent and can objectively (1) characterize abnormality in dynamic plantar loading in patients with foot Charcot neuroarthropathy and (2) screen improvement in dynamic plantar loading after foot reconstruction surgery. To examine whether the plantar pressure distribution (PPD) measured using EMED platform, was normal, a customized normal distribution curve was created for each trial. Then the original PPD was fitted to the customized normal distribution curve. This technique yields a regression factor (RF), which represents the similarity of the actual pressure distribution with a normal distribution. RF values may range from negative 1 to positive 1 and as the value increases positively so does the similarity between the actual and normalized pressure distributions. We tested this novel score on the plantar pressure pattern of healthy subjects (N =15), Charcot patients pre-operation (N =4) and a Charcot patient post-foot reconstruction (N =1). In healthy subjects, the RF was 0.46±0.1. When subjects increased their gait speed by 29%, PPM was increased by 8% (p <10−5), while RF was not changed (p =0.55), suggesting that RF value is independent of gait speed. In preoperative Charcot patients, the RF<0, however, RF increased post-surgery (RF=0.42), indicating a transition to normal plantar distribution after Charcot reconstruction. [Copyright &y& Elsevier]

A new ambulatory technique for qualitative and quantitative movement analysis of the humerus is presented. 3D gyroscopes attached on the humerus were used to recognize the movement of the arm and to classify it as flexion, abduction and internal/external rotations. The method was first validated in a laboratory setting and then tested on 31 healthy volunteer subjects while carrying the ambulatory system during 8 h of their daily life. For each recording, the periods of sitting, standing and walking during daily activity were detected using an inertial sensor attached on the chest. During each period of daily activity the type of arm movement (flexion, abduction, internal/external rotation) its velocity and frequency (number of movement/hour) were estimated. The results showed that during the whole daily activity and for each activity (i.e. walking, sitting and walking) the frequency of internal/external rotation was significantly higher while the frequency of abduction was the lowest ( P < 0.009). In spite of higher number of flexion, abduction and internal/external rotation in the dominant arm, we have not observed in our population a significant difference with the non-dominant arm, implying that in healthy subjects the arm dominance does not lie considerably on the number of movements. As expected, the frequency of the movement increased from sitting to standing and from standing to walking, while we provide a quantitative value of this change during daily activity. This study provides preliminary evidence that this system is a useful tool for objectively assessing upper-limb activity during daily activity. The results obtained with the healthy population could be used as control data to evaluate arm movement of patients with shoulder diseases during daily activity. [ABSTRACT FROM AUTHOR]

Abstract: Patients with diabetes have been shown to suffer from increased fall risk. However, authors disagree as to whether only diabetic patients with neuropathy, or also those without neuropathy, present gait alterations. Existing studies evaluate gait indoors, i.e. in specialized gait laboratories. This study evaluates gait parameters in diabetic patients under various real life conditions and compares them to those recorded for healthy controls. Methods: We conducted a clinical observation study. Forty-five subjects’ gait was assessed on three different surfaces (tar, grass and stones) with a Physilog® system (BioAGM, CH), consisting of accelerometers and gyroscopes. Temporal and spatial gait parameters as well as stride-to-stride variability of 30 patients with type 2 diabetes, 15 with and 15 without neuropathy were compared to 15 healthy controls. The three groups were comparable for age, height and body weight (p >0.05). Results: Diabetic patients’ gait parameters differed significantly from those of healthy controls. Post hoc analysis revealed a significant difference between healthy individuals and patients with neuropathy, and between healthy individuals and patients without neuropathy. No difference was observed between patients with and without neuropathy. The highest surface effect was found in patients with diabetic neuropathy, followed by patients without neuropathy and healthy controls. Conclusions: Walking in real life conditions revealed gait difficulties in patients with type 2 diabetes before neuropathy was clinically detectable. Clinicians should be aware that diabetic individuals’ gait capacity decreases and fall risk increases at an early stage of the disease. [Copyright &y& Elsevier]

Abstract: This study investigates whether the spatio-temporal parameters of gait in the elderly vary as a function of walking distance. The gait pattern of older subjects (n =27) over both short (SWD<10m) and long (LWD>20m) walking was evaluated using an ambulatory device consisting of body-worn sensors (Physilog®). The stride velocity (SV), gait cycle time (GCT), and inter-cycle variability of each parameter (CV) were evaluated for each subject. Analysis was undertaken after evaluating the errors and the test–retest reliability of the Physilog device compared with an electronic walkway system (GaitRite®) over the SWD with different walking speeds. While both systems were highly reliable with respect to the SV and GCT parameters (ICC>0.82), agreement for the gait variability was poor. Interestingly, our data revealed that the measured gait parameters over SWD and LWD were significantly different. LWD trials had a mean increase of 5.2% (p <0.05) in SV, and a mean decrease of 3.7% (p <0.05) in GCT compared with SWD trials. Although variability in both the SV and GCT measured during LWD trials decreased by an average of 1% relative to the SWD case, the drop was not significant. Moreover, reliability for gait variability measures was poor, irrespective of the instrument and despite a moderate improvement for LWD trials. Taken together, our findings indicate that for valid and reliable comparisons, test and retest should be performed under identical distance conditions. Furthermore, our findings suggest that the older subjects may choose different walking strategies for SWD and LWD conditions. [Copyright &y& Elsevier]

Abstract: A new method of evaluation for functional assessment of the shoulder during daily activity is presented. An ambulatory system using inertial sensors attached on the humerus was used to differentiate a dominant from a non-dominant shoulder. The method was tested on 31 healthy volunteers with no shoulder pathology while carrying the system during 8h of their daily life. Shoulder mobility based on the angular velocities and the accelerations of the humerus were calculated and compared every 5s for both sides. Our data showed that the dominant arm of the able bodied participants was more active than the non-dominant arm for standing (+20% for the right handed, +15% for the left handed) and sitting (+24% for the right handed, +32% for the left handed) posture, while for the walking periods the use of the right and left side was almost identical. The proposed method could be used to objectively quantify upper-limb usage during activities of daily living in various shoulder disorders. [Copyright &y& Elsevier]

A new ambulatory method of monitoring physical activities in Parkinson's disease (PD) patients is proposed based on a portable data-logger with three body-fixed inertial sensors. A group of ten PD patients 1 treated with subthalamic nucleus deep brain stimulation (STN-DBS) and ten normal control subjects followed a protocol of typical daily activities and the whole period of the measurement was recorded by video. Walking periods were recognized using two sensors on shanks and lying periods were detected using a sensor on trunk. By calculating kinematics features of the trunk movements during the transitions between sitting and standing postures and using a statistical classifier, sit-to-stand (SiSt) and stand-to-sit (StSi) transitions were detected and separated from other body movements. Finally, a fuzzy classifier used this information to detect periods of sitting and standing. The proposed method showed a high sensitivity and specificity for the detection of basic body postures allocations: sitting, standing, lying, and walking periods, both in PD patients and healthy subjects. We found significant differences in parameters related to SiSt and StSi transitions between PD patients and controls and also between PD patients with and without STN-DBS turned on. We concluded that our method provides a simple, accurate, and effective means to objectively quantify physical activities in both normal and PD patients and may prove useful to assess the level of motor functions in the latter. [ABSTRACT FROM AUTHOR]

This pilot study evaluated variability in physical activities and the correlations between walking, two types of postural transitions, and falls efficacy with an ambulatory activity monitor. An 11-subject convenience sample wore the monitor for 2 consecutive days; in addition, 7 subjects carried the monitor on 1 day of the following week. Demographic characteristics of the sample were age: mean +/- standard deviation [SD] = 87.8 +/- 2.5 yr, body mass index: mean +/- SD = 25.3 +/- 2.1 kg/m², and Mini-Mental State Examination score: mean +/- SD = 27.5 +/- 2.0. Analyzed movements were sit-to-stand (SiSt) and stand-to-sit postural transitions, dynamic activity (walking), and static behavior (sitting, standing, lying). Significant correlations were found for the SiSt transition duration (TD) between days (intraclass correlation coefficient = 0.78). No differences were found between the durations of sitting (p = 0.8), lying (p = 0.72), standing (p = 0.06), and walking (p = 0.6). These parameters showed highly variable correlation coefficients. A significant correlation was observed between falls efficacy and SiSt measures (r = 0.84, p < 0.01, df = 9). We reliably determined the SiSt TD after subjects wore the monitor for 1 day in the home environment. Poor correlations between 2 consecutive measurement days for dynamic and static activity underline the necessity of recording further days to assess physical activity levels in the geriatric population. [ABSTRACT FROM AUTHOR]

Abstract: A new method of scoring systems for the functional assessment of the shoulder is presented. 3D accelerometers and gyroscopes attached on the humerus were used to differentiate a healthy from a painful shoulder. The method was first tested on 10 healthy volunteer subjects with no shoulder pathology. The system was then tested on 10 patients with unilateral shoulder pathology (rotator cuff disease, osteoarthritis) before and after surgery (3, 6 months). In order to evaluate the system, nine tests based on the Simple Shoulder Test (SST) were performed on each shoulder for each patient. Three scores were defined: the P score was based on the angular velocities and accelerations of the humerus; the RAV score was based only on the angular velocities of the humerus; the M score was based on the sum of all moments of the humerus. Our kinematic scores indicated significant differences between baseline and follow-up (p <0.05) and differentiated between patients with varying severity of the same condition. We demonstrated a reliable technique of evaluating shoulder pathology and the results of surgery. [Copyright &y& Elsevier]

An ambulatory system for quantification of tremor and bradykinesia in patients with Parkinson's disease (PD) is presented. To record movements of the upper extremities, a sensing units which included miniature gyroscopes, has been fixed to each of the forearms. An algorithm to detect and quantify tremor and another algorithm to quantify bradykinesia have been proposed and validated. Two clinical studies have been performed. In the first study, 10 PD patients and 10 control subjects participated in a 45-mm protocol of 17 typical daily activities. The algorithm for tremor detection showed an overall sensitivity of 99.5% and a specificity of 94.2% in comparison to a video reference. The estimated tremor amplitude showed a high correlation to the Unified Parkinson's Disease Rating Scale (UPDRS) tremor subscore (e.g., r = 0.87, p < 0.001 for the roll axis). There was a high and significant correlation between the estimated bradykinesia related parameters estimated for the whole period of measurement and respective UPDRS subscore (e.g., r = -0.83, p < 0.001 for the roll axis). In the second study, movements of upper extremities of 11 PD patients were recorded for periods of 3-5 hr. The patients were moving freely during the measurements. The effects of selection of window size used to calculate tremor and bradykinesia related parameters on the correlation between UPDRS and these parameters were studied. By selecting a window similar to the period of the first study, similar correlations were obtained. Moreover, one of the bradykinesia related parameters showed significant correlation (r = -0.74, p < 0.01) to UPDRS with window sizes as short as 5 mm. Our study provides evidence that objective, accurate and simultaneous assessment of tremor and bradykinesia can be achieved in free moving PD patients during their daily activities. [ABSTRACT FROM AUTHOR]

A new method of estimating lower limbs orientations using a combination of accelerometers and gyroscopes is presented. The model is based on estimating the accelerations of ankle and knee joints by placing virtual sensors at the centers of rotation. The proposed technique considers human locomotion and biomechanical constraints, and provides a solution to fusing the data of gyroscopes and accelerometers that yields stable and drift-free estimates of segment orientation. The method was validated by measuring lower limb motions of eight subjects, walking at three different speeds, and comparing the results with a reference motion measurement system. The results are very close to those of the reference system presenting very small errors (Shank: rms = 1.0, Thigh: rms = 1.6°) and excellent correlation coefficients (Shank: r = 0.999, Thigh: r = 0.998). Technically, the proposed ambulatory system is portable, easily mountable, and can be used for long term monitoring without hindrance to natural activities. Finally, a gait analysis tool was designed to visualize the motion data as synthetic skeletons performing the same actions as the subjects. [ABSTRACT FROM AUTHOR]

Abstract: Dual-task related gait changes have been previously reported for healthy older adults, suggesting that gait control requires attention. Compared to balance control, the involvement of attention in the control of the rhythmic stepping mechanism, as reflected by stride time variability, is not well known. In particular, under dual-task, the relative contributions of a second, attention-demanding task and changes in walking speed remain unclear. Thus, the aims of this study were (1) to assess whether walking with a slow-selected speed or walking while performing an attention-demanding task affected stride time variability in a sample of healthy older participants, and (2) to establish whether stride time variability under dual-task conditions is related either to the decrease of walking speed or the simultaneous attention-demanding task, or to both. Forty-five healthy older participants performed four experimental conditions: (1) walking at a normal self-selected speed, (2) walking at a slow self-selected speed, (3) performing a verbal fluency task when sitting on a chair, and (4) performing the verbal fluency task while walking at self-selected walking speed. Gait parameters were recorded across 15 meters, using Physilog®. Results showed a significant dual-task related decrease in mean values of stride velocity, as well as a significant increase in mean values and coefficients of variation of stride time. These dual-task related changes in stride time were explained by the simultaneous performance of the verbal fluency task, the decrease of gait speed and the variability between participants. Although a relationship exists between decreased walking speed and increased stride time variability, the dual-task related increase of stride time variability was also significantly associated with the attention-demanding task, suggesting some attentional control for the rhythmic stepping mechanism of walking in healthy older adults. [Copyright &y& Elsevier]

Abstract: A new method of monitoring physical activity that is able to detect walking upstairs using a miniature gyroscope attached to the shank is presented. Wavelet transformation, in conjunction with a simple kinematics model, was used to detect toe-off, heel-strike and foot-flat, as well cycles corresponding to stair ascent. To evaluate the system, three studies were performed. The method was first tested on 10 healthy young volunteer subjects in a gait laboratory where an ultrasonic motion system was used as a reference system. In the second study, the system was tested on three hospitalized elderly people to classify walking upstairs from walking downstairs and flat walking. In the third study, monitoring was performed on seven patients with peripheral vascular disease for 60min during their daily physical activity. The first study revealed a close relationship between the ambulatory and the reference systems. Compared to the reference system, the ambulatory system had an overall sensitivity and specificity of 98% and 97%, respectively. In the second study, the ambulatory system also showed a very high sensitivity (>94%) in identifying a 50 stairs ascent from walking on the flat and walking downstairs. Finally, compared with visual surveillance, we observed a relatively high accuracy in identifying 196 walking upstairs cycles through daily physical activity in the third study. Our results demonstrated a reliable technique of measuring walking upstairs during physical activity. [Copyright &y& Elsevier]

An ambulatory gait analysis method using body- attached gyroscopes to estimate spatio-temporal parameters of gait has been proposed and validated against a reference system for normal and pathologic gait. Later, ten Parkinson's disease (PD) patients with subthalamic nucleus deep brain stimulation (STN-DBS) implantation participated in gait measurements using our device. They walked one to three times on a 20-m walkway. Patients did the test twice: once STN-DBS was ON and once 180 mm after turning it OFF. A group of ten age-matched normal subjects were also measured as controls. For each gait cycle, spatio-temporal parameters such as stride length (SL), stride velocity (SV), stance (ST), double support (DS), and gait cycle time (GC) were calculated. We found that PD patients had significantly different gait parameters comparing to controls. They had 52% less SV, 60% less SL, and 40% longer GC. Also they had significantly longer ST and DS (11% and 59% more, respectively) than controls. STN-DBS significantly improved gait parameters. During the stim ON period, PD patients had 31% faster SV, 26% longer SL, 6% shorter ST, and 26% shorter DS. GC, however, was not significantly different. Some of the gait parameters had high correlation with Unified Parkinson's Disease Rating Scale (UPDRS) subscores including SL with a significant correlation (r = -0.90) with UPDRS gait subscore. We concluded that our method provides a simple yet effective way of ambulatory gait analysis in PD patients with results confirming those obtained from much more complex and expensive methods used in gait Labs. [ABSTRACT FROM AUTHOR]

This article presents a letter to the editor which discusses the results of gait and balance training in older people.

• Young seniors between 60 and 70 years of age are a rapidly growing population. • Challenging capacity measures are closer linked to mobility performance than basic. • Challenging capacity measures are needed in young seniors. Understanding the association between motor capacity (MC) (what people can do in a standardized environment), mobility performance (MP) (what people actually do in real-life) and falls is important for early detection of and counteracting on functional decline, particularly in the rapidly growing population of young seniors. Therefore, this study aims to 1) explore the association between MC and MP, and between MC and falls, and 2) investigate whether challenging MC measures are better associated with MP and falls than basic MC measures. Basic (habitual gait speed, Timed Up-and-Go) and challenging (fast gait speed, Community Balance & Mobility Scale) MC measures were performed in 169 young seniors (61–70 years). MP was assessed using one-week sensor-monitoring including time being sedentary, light active, and at least moderately active. Falls in the previous six months were reported. Associations and discriminative ability were calculated using correlation, regression and receiver operating curve analysis. Mean age was 66.4 (SD 2.4) years (50.6 % women). Small to moderate associations (r = 0.06−0.31; p <.001–.461) were found between MC, MP and falls. Challenging MC measures showed closer associations with MP and falls (r = 0.10−0.31; p <.001–.461) compared to basic (r = 0.06−0.22; p =.012–.181), remained significant in three out of four regression models explaining 2.5–8.6 % of the variance, and showed highest discriminative ability (area under the curve = 0.59−0.70) in all analyses. Challenging MC measures are closer associated with mobility performance and falls as compared to basic MC measures in young seniors. This indicates the importance of applying challenging motor capacity assessments in young seniors. On the same note, small to moderate associations imply a need for an assessment of both MC and MP in order to capture the best possible MC and the actual daily-life MP in young seniors. [ABSTRACT FROM AUTHOR]

Although many methods have been developed to detect walking by using body-worn inertial sensors, their performances decline when gait patterns become abnormal, as seen in children with cerebral palsy (CP). The aim of this study was to evaluate if fine-tuning an existing walking bouts (WB) detection algorithm by various thresholds, customized at the individual or group level, could improve WB detection in children with CP and typical development (TD). Twenty children (10 CP, 10 TD) wore 4 inertial sensors on their lower limbs during laboratory and out-laboratory assessments. Features extracted from the gyroscope signals recorded in the laboratory were used to tune thresholds of an existing walking detection algorithm for each participant (individual-based personalization: Indiv) or for each group (population-based customization: Pop). Out-of-laboratory recordings were analyzed for WB detection with three versions of the algorithm (i.e., original fixed thresholds and adapted thresholds based on the Indiv and Pop methods), and the results were compared against video reference data. The clinical impact was assessed by quantifying the effect of WB detection error on the estimated walking speed distribution. The two customized Indiv and Pop methods both improved WB detection (higher, sensitivity, accuracy and precision), with the individual-based personalization showing the best results. Comparison of walking speed distribution obtained with the best of the two methods showed a significant difference for 8 out of 20 participants. The personalized Indiv method excluded non-walking activities that were initially wrongly interpreted as extremely slow walking with the initial method using fixed thresholds. Customized methods, particularly individual-based personalization, appear more efficient to detect WB in daily-life settings. [ABSTRACT FROM AUTHOR]