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Wearable activity sensors typically count movement quantity, such as the number of steps taken or the number of upper extremity (UE) counts achieved. However, for some applications, such as neurologic rehabilitation, it may be of interest to quantify the quality of the movement experience (QOME), defined, for example, as how diverse or how complex movement epochs are. We previously found that individuals with UE impairment after stroke exhibited differences in their distributions of forearm postures across the day and that these differences could be quantified with kurtosis-an established statistical measure of the peakedness of distributions. In this paper, we describe further progress toward the goal of providing real-time feedback to try to help people learn to modulate their movement diversity. We first asked the following: to what extent do different movement activities induce different values of kurtosis? We recruited seven unimpaired individuals and evaluated a set of 12 therapeutic activities for their forearm postural diversity using kurtosis. We found that the different activities produced a wide range of kurtosis values, with conventional rehabilitation therapy exercises creating the most spread-out distribution and cup stacking the most peaked. Thus, asking people to attempt different activities can vary movement diversity, as measured with kurtosis. Next, since kurtosis is a computationally expensive calculation, we derived a novel recursive algorithm that enables the real-time calculation of kurtosis. We show that the algorithm reduces computation time by a factor of 200 compared to an optimized kurtosis calculation available in SciPy, across window sizes. Finally, we embedded the kurtosis algorithm on a commercial smartwatch and validated its accuracy using a robotic simulator that wore the smartwatch, emulating movement activities with known kurtosis. This work verifies that different movement tasks produce different values of kurtosis and provides a validated algorithm for the real-time calculation of kurtosis on a smartwatch. These are needed steps toward testing QOME-focused, wearable rehabilitation.

Previous work assessing the effect of additive noise on the postural control system has found a positive effect of additive white noise on postural dynamics. This study covers two separate experiments that were run sequentially to better understand how the structure of the additive noise signal affects postural dynamics, while also furthering our knowledge of how the intensity of auditory stimulation of noise may elicit this phenomenon. Across the two experiments, we introduced three auditory noise stimulations of varying structure (white, pink, and brown noise). Experiment 1 presented the stimuli at 35 dB while Experiment 2 was presented at 75 dB. Our findings demonstrate a decrease in variability of the postural control system regardless of the structure of the noise signal presented, but only for high intensity auditory stimulation.

Upper extremity (UE) impairment is common after stroke resulting in reduced arm use in daily life. A few studies have examined the use of wearable feedback of the quantity of arm movement to promote recovery, but with limited success. We posit that it may be more effective to encourage an increase in beneficial patterns of movement practice - i.e. the overall quality of the movement experience - rather than simply the overall amount of movement. As a first step toward testing this idea, here we sought to identify statistical features of the distributions of daily arm movements that become more prominent as arm impairment decreases, based on data obtained from a wrist IMU worn by 22 chronic stroke participants during their day. We identified several measures that increased as UE Fugl-Meyer (UEFM) score increased: the fraction of movements achieved at a higher speed, forearm postural diversity (quantified by kurtosis of the tilt-angle), and forearm postural complexity (quantified by sample entropy of tilt angle). Dividing participants into severe, moderate, and mild impairment groups, we found that forearm postural diversity and complexity were best able to distinguish the groups (Cohens D =1.1, and 0.99, respectively) and were also the best subset of predictors for UEFM score. Based on these findings coupled with theories of motor learning that emphasize the importance of variety and challenge in practice, we suggest that using these measures of diversity and complexity in wearable rehabilitation could provide a basis to test whether the quality of the daily movement experience is therapeutic.

Behavioral flexibility-the ability to tailor motor actions to changing body-environment relations-is critical for functional movement. Navigating the everyday environment requires the ability to generate a wide repertoire of actions, select the appropriate action for the current situation, and implement it quickly and accurately. We used a new, adjustable barrier paradigm to assess flexibility of motor actions in 20 17-month-old (eight girls, 12 boys) and 14 13-month-old (seven girls, eight boys) walking infants and a comparative sample of 14 adults (eight women, six men). Most participants were White, non-Hispanic, and middle class. Participants navigated under barriers normalized to their standing height (overhead, eye, chest, hip, and knee heights). Decreases in barrier height required lower postures for passage. Every participant altered their initial walking posture according to barrier height for every trial, and all but two 13-month-olds found solutions for passage. Compared to infants, adults displayed a wider variety of strategies (squat-walking, half-kneeling, etc.), found more appropriate solutions based on barrier height (ducked at eye height and low crawled at knee height), and implemented their solutions more quickly (within 4 s) and accurately (without bumping their heads against the barrier). Infants frequently crawled even when the barrier height did not warrant a low posture, displayed multiple postural shifts prior to passage and thus took longer to go, and often bumped their heads. Infants' improvements were related to age and walking experience. Thus, development of flexibility likely involves the contributions of multiple domains-motor, perception, and cognition-that facilitate strategy selection and implementation. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

BackgroundMany American workers spend over 7 hours a day at work in primarily sedentary office work. Physical activity is a key aspect of optimizing health and preventing disease; yet, 80% of American adults do not meet the recommended guidelines for physical activity. In this systematic review, the relationship between physical work environment and physical activity among office workers was explored.MethodsOf the 321 studies screened, 26 studies met the eligibility criteria and were included for evaluation in this systematic review.ResultsOf the 26 studies, four were cross-sectional studies, 14 were quasi-experimental studies, and eight were randomized control trials. Physical activity during the workday was measured using self-report surveys and electromechanical devices such as accelerometers. Physical work environments examined by the studies included different types of desks (n = 16), office arrangements (n = 5), and building design (n = 5). In nine studies, office environments and building work environments designed to promote activity using active design principles such as stairs and flexible workspaces were associated with increased physical activity. Sit-stand desks reduced overall sitting time, but had a minimal effect on physical activity.Conclusion/application to practiceOffices and buildings designed for activity had the largest impact on physical activity among office workers. To increase physical activity in office workers, focus should be placed on opportunities to increase incidental movement that can increase physical activity throughout the workday. Occupational health nurses should advocate workspace designs that can increase physical activity in workers.

Introduction: This retrospective cohort study aimed to compare the change in upper airway and craniocervical posture after orthodontic treatment between adolescent and adult patients with Class II high-angle malocclusion. Methods: A total of 12 adolescent (mean ± standard deviation age = 13.0 ± 2.0 years) and 12 adult patients with Class II high-angle malocclusion (mean ± standard deviation age = 23.7 ± 6.4 years) were selected in this study. The lateral cephalograms and cone beam computed tomography images of adolescent and adult patients were taken before and after treatment, which can be employed to evaluate the variables of craniofacial morphology, upper airway, and craniocervical posture through paired t tests, respectively. An independent sample t test was performed to observe the differences between two groups after orthodontic intervention. For adults and adolescents, the correlation between craniofacial morphology, upper airway, and craniocervical posture was determined through Pearson correlation analysis. Results: In all subjects, the improvements in vertical and sagittal facial morphology after treatment were observed. Anterior and inferior movements of the hyoid bone, an increase of upper airway dimension, posterior tipping of the head and a reduction of cervical inclination in the lower and middle segments post-treatment were identified in adolescence (P < 0.05). Adults displayed anterior movements of the hyoid bone, whereas no significant difference was observed in upper airway dimension and craniocervical posture (P < 0.05). Notable differences were identified in the change of hyoid position and airway volume between two groups (P > 0.05). Mandibular plane inclination, growth pattern, occlusal plane inclination, and chin position were all significantly correlated with craniocervical posture in adolescent patients. Besides, the mandibular growth pattern and chin position in adult patients were significantly correlated with craniocervical posture (P < 0.05). Conclusions: Orthodontic treatment is capable of enhancing the facial profile of patients with skeletal class II high-angle while improving their upper airway morphology and craniocervical posture, where adolescents and adults differ substantially in that the former exhibit a more favorable alteration in the airway-craniocervical functional environment. [ABSTRACT FROM AUTHOR]

Recent work suggests human physiology is not well adapted to prolonged periods of inactivity, with time spent sitting increasing cardiovascular disease and mortality risk. Health risks from sitting are generally linked with reduced levels of muscle contractions in chair-sitting postures and associated reductions in muscle metabolism. These inactivity-associated health risks are somewhat paradoxical, since evolutionary pressures tend to favor energy-minimizing strategies, including rest. Here, we examined inactivity in a hunter-gatherer population (the Hadza of Tanzania) to understand how sedentary behaviors occur in a nonindustrial economic context more typical of humans' evolutionary history. We tested the hypothesis that nonambulatory rest in hunter-gatherers involves increased muscle activity that is different from chair-sitting sedentary postures used in industrialized populations. Using a combination of objectively measured inactivity from thigh-worn accelerometers, observational data, and electromygraphic data, we show that hunter-gatherers have high levels of total nonambulatory time (mean ± SD = 9.90 ± 2.36 h/d), similar to those found in industrialized populations. However, nonambulatory time in Hadza adults often occurs in postures like squatting, and we show that these "active rest" postures require higher levels of lower limb muscle activity than chair sitting. Based on our results, we introduce the Inactivity Mismatch Hypothesis and propose that human physiology is likely adapted to more consistently active muscles derived from both physical activity and from nonambulatory postures with higher levels of muscle contraction. Interventions built on this model may help reduce the negative health impacts of inactivity in industrialized populations.

Kinetic and dynamic motion analysis provides quantitative, functional assessments of human ability that are unobtainable through static imaging methods or subjective surveys. While biomechanics facilities are equipped to perform this measurement and analysis, the clinical translation of these methods is limited by the specialized skills and equipment needed. This paper presents and validates a method for estimating dynamic effects such as joint torques and body momenta using a single depth camera. An allometrically scaled, sagittal plane dynamic model is used to estimate the joint torques at the ankles, knees, hips, and low back, as well as the torso momenta, and shear and normal loads at the L5-S1 disk. These dynamic metrics are applied to the sit-to-stand motion and validated against a gold-standard biomechanical system consisting of full-body active motion-capture and force-sensing systems. The metrics obtained from the proposed method were found to have excellent concordance with peak metrics that are consistent with prior biomechanical studies. This suggests the feasibility of using this system for rapid clinical assessment, with applications in diagnostics, longitudinal tracking, and quantifying patient recovery.

ObjectiveTo examine the relationship between prospectively assessed maternal sleep position and subsequent adverse pregnancy outcomes.MethodsThis was a secondary analysis of a prospective observational multicenter cohort study of nulliparous women with singleton gestations who were enrolled between October 2010 and May 2014. Participants had three study visits that were not part of clinical care. They prospectively completed in-depth sleep questionnaires between 6 0/7 and 13 6/7 weeks of gestation and 22 0/7 and 29 6/7 weeks of gestation, the first and third study visits. A subset of women also underwent level 3 home sleep tests using the Embletta Gold device. The primary outcome was a composite of adverse pregnancy outcomes such as stillbirth, a small-for-gestational-age newborn, and gestational hypertensive disorders.ResultsA total of 8,706 (of 10,038) women had data from at least one sleep questionnaire and for pregnancy outcomes, and they comprised the population for this analysis. The primary outcome occurred in 1,903 pregnancies (22%). There was no association between reported non-left lateral or supine sleep during the last week of the first visit (adjusted odds ratio [aOR] 1.00 [95% CI 0.89-1.14]) or third visit (aOR 0.99 [95% CI 0.89-1.11] and the composite or any individual outcome, except for an apparent protective effect for stillbirth at the third visit (aOR 0.27 (95% CI 0.09-0.75). Women with objectively measured supine sleep position for at least 50% of the time were no more likely than those in the supine position 50% or less of the time to have the composite adverse outcome.ConclusionsGoing to sleep in the supine or right lateral position, as self-reported before the development of pregnancy outcome and objectively assessed through 30 weeks of gestation, was not associated with an increased risk of stillbirth, a small-for-gestational-age newborn, or gestational hypertensive disorders.

The study of joint kinematics and dynamics has broad clinical applications, including the identification of pathological motions or compensation strategies and the analysis of dynamic stability. High-end motion capture systems, however, are expensive and require dedicated camera spaces with lengthy setup and data processing commitments. Depth cameras, such as the Microsoft Kinect, provide an inexpensive, marker-free alternative at the sacrifice of joint-position accuracy. In this work, we present a fast framework for adding biomechanical constraints to the joint estimates provided by a depth camera system. We also present a new model for the lower lumbar joint angle. We validate key joint position, angle, and velocity measurements against a gold standard active motion-capture system on ten healthy subjects performing sit to stand (STS). Our method showed significant improvement in mean absolute error and intraclass correlation coefficients for the recovered joint angles and position-based metrics. These improvements suggest that depth cameras can provide an accurate and clinically viable method of rapidly assessing the kinematics and kinetics of the STS action, providing data for further analysis using biomechanical or machine learning methods.

BackgroundHabitual postural patterns are associated with musculoskeletal pain, and improving a maladaptive posture requires postural awareness in order to lead to clinical improvements. This study aimed to develop and evaluate the psychometric properties of an innovative postural awareness scale.MethodsA 12-item Postural Awareness Scale (PAS) was developed and administered to 512 chronic pain patients (50.3 ± 11.4 years, 91.6% female, 37.1% spinal/shoulder pain) to assess its factor structure and reliability. To determine convergent validity, measures of body awareness, body responsiveness, body image, and mindfulness were correlated with the PAS, as were clinical measures of pain intensity, disability, and mental health. Sensitivity to change was assessed in 202 outpatients participating in a 10-week multimodal mind-body program.ResultsFactor analysis revealed two factors (Ease/Familiarity with Postural Awareness and Need for Attention Regulation with Postural Awareness) that explained 50.8% of the variance. Cronbach's alpha for the complete scale was 0.80; Spearman-Brown coefficient of split-half reliability was 0.67; and intra-class correlation was ICC2,1 = 0.75 (95% confidence interval = 0.71, 0.78). Significant positive correlations were found for body awareness (r = 0.23), body responsiveness (r = 0.41), body image (r = 0.22-0.32), and mindfulness (r = 0.38); negative correlations for pain intensity (r = - 0.14), disability (r = - 0.12), depression (r = - 0.23), and stress (r = - 0.29). Postural awareness scores increased with a mind-body program (p

Electrical neuromodulation of spinal networks improves the control of movement of the paralyzed limbs after spinal cord injury (SCI). However, the potential of noninvasive spinal stimulation to facilitate postural trunk control during sitting in humans with SCI has not been investigated. We hypothesized that transcutaneous electrical stimulation of the lumbosacral enlargement can improve trunk posture. Eight participants with non-progressive SCI at C3-T9, American Spinal Injury Association Impairment Scale (AIS) A or C, performed different motor tasks during sitting. Electromyography of the trunk muscles, three-dimensional kinematics, and force plate data were acquired. Spinal stimulation improved trunk control during sitting in all tested individuals. Stimulation resulted in elevated activity of the erector spinae, rectus abdominis, and external obliques, contributing to improved trunk control, more natural anterior pelvic tilt and lordotic curve, and greater multi-directional seated stability. During spinal stimulation, the center of pressure (COP) displacements decreased to 1.36 ± 0.98 mm compared with 4.74 ± 5.41 mm without stimulation (p = 0.0156) in quiet sitting, and the limits of stable displacement increased by 46.92 ± 35.66% (p = 0.0156), 36.92 ± 30.48% (p = 0.0156), 54.67 ± 77.99% (p = 0.0234), and 22.70 ± 26.09% (p = 0.0391) in the forward, backward, right, and left directions, respectively. During self-initiated perturbations, the correlation between anteroposterior arm velocity and the COP displacement decreased from r = 0.5821 (p = 0.0007) without to r = 0.5115 (p = 0.0039) with stimulation, indicating improved trunk stability. These data demonstrate that the spinal networks can be modulated transcutaneously with tonic electrical spinal stimulation to physiological states sufficient to generate a more stable, erect sitting posture after chronic paralysis.

Background The relationship between lumbar spine posture and muscle structure is not well understood. Objectives To investigate the predictive capacity of muscle structure on lumbar spine posture in active-duty Marines. Methods Forty-three Marines were scanned in this cross-sectional study, using an upright magnetic resonance imaging scanner while standing without load and standing, sitting, and prone on elbows with body armor. Cobb, horizontal, and sacral angles were measured. Marines were then scanned while unloaded in supine using a supine magnetic resonance imaging scanner. The imaging protocol consisted of T2 intervertebral disc mapping; high-resolution, anatomical, fat-water separation, and diffusion tensor imaging to quantify disc hydration and muscle volume, fat fraction, and restricted diffusion profiles in the lumbar muscles. A stepwise multiple linear regression model was used to identify physiological measures predictive of lumbar spine posture. Results The multiple regression model demonstrated that fractional anisotropy of the erector spinae was a significant predictor of lumbar posture for 7 of 18 dependent variables measured, and explained 20% to 35% of the variance in each model. Decreased fractional anisotropy of the erector spinae predicted decreased lordosis, lumbosacral extension, and anterior pelvic tilt. Conclusion Fractional anisotropy is inversely related with muscle fiber size, which is associated with the isometric force-generating capacity of a muscle fiber. This suggests that stronger erector spinae muscles predict decreased lordosis, lumbosacral extension, and anterior pelvic tilt in a highly trained population. J Orthop Sports Phys Ther 2018;48(8):613-621. Epub 17 May 2018. doi:10.2519/jospt.2018.7865.

Recent developments in EEG recording and signal processing have made it possible to record in an unconstrained, natural movement task, therefore EEG provides a promising approach to understanding the neural mechanisms of upper-limb reaching control. This study specifically addressed how EEG dynamics in the time domain encoded finger movement directions (directional tuning) and posture dependence (movement reference frames) by applying representational similarity analysis. High-density EEG covering the entire scalp was recorded while participants performed eight-directional, center-out reaching movements, thereby allowing us to explore directional selectivity of EEG sources over the brain beyond somatosensory areas. A majority of the source processes exhibited statistically significant directional tuning during peri-movement periods. In addition, directional tuning curves shifted systematically when the shoulder angle was rotated to perform the task within a more laterally positioned workspace, the degree of tuning curve rotation falling between that predicted by models assuming extrinsic and shoulder-based reference frames. We conclude that temporal dynamics of neural mechanisms for motor control can be studied noninvasively in humans using high-density EEG and that directional sensitivity of motor and non-motor processing is not limited within the sensorimotor areas but extends to the whole brain areas.

Background contextProlonged microgravity exposure is associated with localized low back pain and an elevated risk of post-flight disc herniation. Although the mechanisms by which microgravity impairs the spine are unclear, they should be foundational for developing in-flight countermeasures for maintaining astronaut spine health. Because human spine anatomy has adapted to upright posture on Earth, observations of how spaceflight affects the spine should also provide new and potentially important information on spine biomechanics that benefit the general population.PurposeThis study compares quantitative measures of lumbar spine anatomy, health, and biomechanics in astronauts before and after 6 months of microgravity exposure on board the International Space Station (ISS).Study designThis is a prospective longitudinal study.SampleSix astronaut crewmember volunteers from the National Aeronautics and Space Administration (NASA) with 6-month missions aboard the ISS comprised our study sample.Outcome measuresFor multifidus and erector spinae at L3-L4, measures include cross-sectional area (CSA), functional cross-sectional area (FCSA), and FCSA/CSA. Other measures include supine lumbar lordosis (L1-S1), active (standing) and passive (lying) flexion-extension range of motion (FE ROM) for each lumbar disc segment, disc water content from T2-weighted intensity, Pfirrmann grade, vertebral end plate pathology, and subject-reported incidence of chronic low back pain or disc injuries at 1-year follow-up.Methods3T magnetic resonance imaging and dynamic fluoroscopy of the lumbar spine were collected for each subject at two time points: approximately 30 days before launch (pre-flight) and 1 day following 6 months spaceflight on the ISS (post-flight). Outcome measures were compared between time points using paired t tests and regression analyses.ResultsSupine lumbar lordosis decreased (flattened) by an average of 11% (p=.019). Active FE ROM decreased for the middle three lumbar discs (L2-L3: -22.1%, p=.049; L3-L4: -17.3%, p=.016; L4-L5: -30.3%, p=.004). By contrast, no significant passive FE ROM changes in these discs were observed (p>.05). Disc water content did not differ systematically from pre- to post-flight. Multifidus and erector spinae changed variably between subjects, with five of six subjects experiencing an average decrease 20% for FCSA and 8%-9% for CSA in both muscles. For all subjects, changes in multifidus FCSA strongly correlated with changes in lordosis (r2=0.86, p=.008) and active FE ROM at L4-L5 (r2=0.94, p=.007). Additionally, changes in multifidus FCSA/CSA correlated with changes in lordosis (r2=0.69, p=.03). Although multifidus-associated changes in lordosis and ROM were present among all subjects, only those with severe, pre-flight end plate irregularities (two of six subjects) had post-flight lumbar symptoms (including chronic low back pain or disc herniation).ConclusionsWe observed that multifidus atrophy, rather than intervertebral disc swelling, associated strongly with lumbar flattening and increased stiffness. Because these changes have been previously linked with detrimental spine biomechanics and pain in terrestrial populations, when combined with evidence of pre-flight vertebral end plate insufficiency, they may elevate injury risk for astronauts upon return to gravity loading. Our results also have implications for deconditioned spines on Earth. We anticipate that our results will inform new astronaut countermeasures that target the multifidus muscles, and research on the role of muscular stability in relation to chronic low back pain and disc injury.

Technological advances provide opportunities for automating direct observations of physical activity, which allow for continuous monitoring and feedback. This pilot study evaluated the initial validity of computer vision algorithms for ecological assessment of physical activity. The sample comprised 6630 seconds per camera (three cameras in total) of video capturing up to nine participants engaged in sitting, standing, walking, and jogging in an open outdoor space while wearing accelerometers. Computer vision algorithms were developed to assess the number and proportion of people in sedentary, light, moderate, and vigorous activity, and group-based metabolic equivalents of tasks (MET)-minutes. Means and standard deviations (SD) of bias/difference values, and intraclass correlation coefficients (ICC) assessed the criterion validity compared to accelerometry separately for each camera. The number and proportion of participants sedentary and in moderate-to-vigorous physical activity (MVPA) had small biases (within 20% of the criterion mean) and the ICCs were excellent (0.82-0.98). Total MET-minutes were slightly underestimated by 9.3-17.1% and the ICCs were good (0.68-0.79). The standard deviations of the bias estimates were moderate-to-large relative to the means. The computer vision algorithms appeared to have acceptable sample-level validity (i.e., across a sample of time intervals) and are promising for automated ecological assessment of activity in open outdoor settings, but further development and testing is needed before such tools can be used in a diverse range of settings.

Low back pain has a 70% higher prevalence in members of the armed forces than in the general population, possibly due to the loads and positions soldiers experience during training and combat. Although the influence of heavy load carriage on standing lumbar spine posture in this population is known, postures in other operationally relevant positions are unknown. Therefore, the purpose of this study was to characterize the effect of simulated military operational positions under relevant loading conditions on global and local lumbar spine postures in active duty male US Marines. Secondary objectives were to evaluate if intervertebral disc degeneration and low back pain affect lumbar spine postures. Magnetic resonance images were acquired on an upright scanner in the following operational positions: Natural standing with no external load, standing with body armor (11.3 kg), sitting with body armor, and prone on elbows with body armor. Custom software was used to measure global lumbar spine posture: Lumbosacral flexion, sacral slope, lordosis, local measures of intervertebral angles, and intervertebral distances. Sitting resulted in decreased lumbar lordosis at all levels of the spine except L1-L2. When subjects were prone on elbows, a significant increase in local lordosis was observed only at L5-S1 compared with all other positions. Marines with disc degeneration (77%) or history of low back pain (72%) had decreased lumbar range of motion and less lumbar extension than healthy Marines. These results indicate that a male Marine's pathology undergoes a stereotypic set of postural changes during functional tasks, which may impair performance. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2145-2153, 2017.

Time spent sitting is associated with negative health outcomes, motivating some individuals to adopt standing desk workstations. This study represents the first investigation of the effects of standing desk use on reading comprehension and creativity. In a counterbalanced, within-subjects design, 96 participants completed reading comprehension and creativity tasks while both sitting and standing. Participants self-reported their mood during the tasks and also responded to measures of expended effort and task difficulty. In addition, participants indicated whether they expected that they would perform better on work-relevant tasks while sitting or standing. Despite participants' beliefs that they would perform worse on most tasks while standing, body position did not affect reading comprehension or creativity performance, nor did it affect perceptions of effort or difficulty. Mood was also unaffected by position, with a few exceptions: Participants exhibited greater task engagement (i.e., interest, enthusiasm, and alertness) and less comfort while standing rather than sitting. In sum, performance and psychological experience as related to task completion were nearly entirely uninfluenced by acute (~30-min) standing desk use.

Military training aims to improve load carriage performance and reduce risk of injuries. Data describing the lumbar spine (LS) postural response to load carriage throughout training are limited. We hypothesised that training would reduce the LS postural response to load. The LS posture of 27 Marines was measured from upright MR images: with and without load (22.6 kg) at the beginning, middle, and end of School of Infantry (SOI) training. Disc degeneration was graded at L5-S1. No changes in posture and disc degeneration were found throughout training. During load carriage the LS became less lordotic and the sacrum more horizontal. Marines with disc degeneration had larger sacral postural perturbations in response to load. Our findings suggest that the postural response to load is defined more by the task needs than by the physical condition of the Marine. Practitioner Summary: The effect of military training on lumbar spine posture is unknown. The lumbar posture of 27 Marines was measured from upright MR images, with and without load throughout infantry training. No changes in posture or IVD degeneration were found across training. Marines with degeneration at the L5-S1 level had larger sacral postural perturbations in response to load.

BackgroundRelations of orthostatic change in blood pressure with brain structure and function have not been studied thoroughly, particularly in younger, healthier individuals. Elucidation of factors that contribute to early changes in brain integrity may lead to development of interventions that delay or prevent cognitive impairment.Methods and resultsIn a sample of the Framingham Heart Study Third Generation (N=2119; 53% women; mean age±SD, 47±8 years), we assessed orthostatic change in mean arterial pressure (MAP), aortic stiffness (carotid-femoral pulse wave velocity), neuropsychological function, and markers of subclinical brain injury on magnetic resonance imaging. Multivariable regression analyses were used to assess relations between orthostatic change in MAP and brain structural and neuropsychological outcomes. Greater orthostatic increase in MAP on standing was related to better Trails B-A performance among participants aged

Study designRepeated measures.ObjectiveThe purpose of this study was to quantify the effect of operationally relevant loads and distributions on lumbar spine (LS) in a group of active-duty Marines.Summary of background dataLow-back pain has been associated with heavy load carriage among military personnel. Although there are data describing the LS posture in response to load, the effect of varying load characteristics on LS posture remains unknown.MethodsMagnetic resonance images of Marines (n = 12) were acquired when standing unloaded and when carrying 22, 33, and 45 kg of load distributed both 50% to 50% and 20% to 80% anteriorly and posteriorly. Images were used to measure LS and pelvic postures. Two-way repeated-measures ANOVA and posthoc tests were used to compare LS posture across load magnitudes and distributions (α = 0.05). This project was founded by the US Army Medical Research Acquisition Activity, Award No. W81XWH-13-2-0043, under Work Unit No. 1310.ResultsNo changes in LS posture were induced when load was evenly distributed. When load was carried in the 20% to 80% distribution lumbosacral flexion increased as a result of sacral anterior rotation and overall reduced lumbar lordosis. This pattern was greater as load was increased between 22 and 33 kg, but did not increase further between 33 and 45 kg. We observed that the inferior LS became uniformly less lordotic, independently of load magnitude. However, the superior LS became progressively more lordotic with increasing load magnitude CONCLUSION.: Postural adaptations were found only when load was carried with a posterior bias, suggesting that load-carriage limits based on postural changes are relevant when loads are nonuniformly distributed. Although the tendency would be to interpret that loads should be carried symmetrically to protect the spine, the relationship between postural changes and injury are not clear. Finally, the operational efficiency of carrying load in this distribution needs to be tested.Level of evidence3.

Purpose(1) To investigate the reference value of peak-trough difference in circadian rhythm of intraocular pressure (IOP) in habitual position and (2) to compare the IOP parameters among 3 age groups.Materials and methodsHabitual IOP of healthy subjects sampled from the population in the Handan Eye Study was measured every 2 hours in the seated position during light-wake period (7:30 AM, 9:30 AM, 11:30 AM, 1:30 PM, 3:30 PM, 5:30 PM, 7:30 PM, 9:30 PM) and in the supine position during dark-sleep period (11:30 PM, 1:30 AM, 3:30 AM, 5:30 AM). Blood pressure and heart rate were obtained subsequently at each IOP measurement.ResultsTwo hundred six healthy subjects were included in the final analyses (n=20, 30 to 39 y old; n=95, 40 to 49 y old; n=91, 50 to 59 y old). For peak-trough difference (7.2±2.3 mm Hg; 6.8 to 7.5 mm Hg, 95% confidence interval) in habitual position, the reference value was described as median 7.0 mm Hg, 25th percentile 5.5 mm Hg, and 95th percentile 11.5 mm Hg. No significant differences in peak-trough difference, acrophase (cosine-fit analysis derived peak timing) and amplitude (half distance between the cosine-fit maximum and minimum) were found among the 3 age groups. In the cosine model, the nocturnal acrophase (3:49±0.53 AM; 3:42 to 3:55 AM, 95% confidence interval) was detected for the entire group. Furthermore, 106 subjects (52%) had a nocturnal peak pattern, 36 subjects (17%) had a diurnal peak pattern, and 64 subjects (31%) had no evident pattern.ConclusionsIn habitual position, 75% of healthy subjects from a population-based investigation had IOP variation >5.5 mm Hg and 95% subjects had

The inability to maintain balance during varying postural control conditions can lead to falls, a significant cause of mortality and serious injury among older adults. However, our understanding of the underlying dynamical and stochastic processes in human postural control have not been fully explored. To further our understanding of the underlying dynamical processes, we examine a novel conceptual framework for studying human postural control using the center of pressure (COP) velocity autocorrelation function (COP-VAF) and compare its results to Stabilogram Diffusion Analysis (SDA). Eleven healthy young participants were studied under quiet unipedal or bipedal standing conditions with eyes either opened or closed. COP trajectories were analyzed using both the traditional posturographic measure SDA and the proposed COP-VAF. It is shown that the COP-VAF leads to repeatable, physiologically meaningful measures that distinguish postural control differences in unipedal versus bipedal stance trials with and without vision in healthy individuals. More specifically, both a unipedal stance and lack of visual feedback increased initial values of the COP-VAF, magnitude of the first minimum, and diffusion coefficient, particularly in contrast to bipedal stance trials with open eyes. Use of a stochastic postural control model, based on an Ornstein-Uhlenbeck process that accounts for natural weight-shifts, suggests an increase in spring constant and decreased damping coefficient when fitted to experimental data. This work suggests that we can further extend our understanding of the underlying mechanisms behind postural control in quiet stance under varying stance conditions using the COP-VAF and provides a tool for quantifying future neurorehabilitative interventions.

This paper introduces a human posture tracking platform to identify the human postures of sitting, standing or lying down, based on a smartwatch. This work develops such a system as a proof-of-concept study to investigate a smartwatch's ability to be used in future remote health monitoring systems and applications. This work validates the smartwatches' ability to track the posture of users accurately in a laboratory setting while reducing the sampling rate to potentially improve battery life, the first steps in verifying that such a system would work in future clinical settings. The algorithm developed classifies the transitions between three posture states of sitting, standing and lying down, by identifying these transition movements, as well as other movements that might be mistaken for these transitions. The system is trained and developed on a Samsung Galaxy Gear smartwatch, and the algorithm was validated through a leave-one-subject-out cross-validation of 20 subjects. The system can identify the appropriate transitions at only 10 Hz with an F-score of 0.930, indicating its ability to effectively replace smart phones, if needed.

Skeletal muscle deoxygenated hemoglobin and myoglobin concentration ([HHb]), assessed by near-infrared spectroscopy (NIRS), is commonly used as a surrogate of regional O2 extraction (reflecting the O2 delivery-to-consumption ratio, Q̇/V̇o2). However, [HHb] change (Δ[HHb]) is also influenced by capillary-venous heme concentration, and/or small blood vessel volume (reflected in total heme; [THb]). We tested the hypotheses that Δ[HHb] is associated with O2 extraction, and insensitive to [THb], over a wide range of Q̇/V̇o2 elicited by passive head-up tilt (HUT; 10-min, 15° increments, between -10° and 75°). Steady-state common femoral artery blood flow (FBF) was measured by echo-Doppler, and time-resolved NIRS measured [HHb] and [THb] of vastus lateralis (VL) and gastrocnemius (GS) in 13 men. EMG confirmed muscles were inactive. During HUT in VL [HHb] increased linearly (57 ± 10 to 101 ± 16 μM; P < 0.05 above 15°) and was associated (r(2) ∼ 0.80) with the reduction in FBF (618 ± 75 ml/min at 0° to 268 ± 52 ml/min at 75°; P < 0.05 above 30°) and the increase in [THb] (228 ± 30 vs. 252 ± 32 μM; P < 0.05 above 15°). GS response was qualitatively similar to VL. However, there was wide variation within and among individuals, such that the overall limits of agreement between Δ[HHb] and ΔFBF ranged from -35 to +19% across both muscles. Neither knowledge of tissue O2 saturation nor vascular compliance could appropriately account for the Δ[HHb]-ΔFBF dissociation. Thus, under passive tilt, [HHb] is influenced by Q̇/V̇o2, as well as microvascular hematocrit and/or tissue blood vessel volume, complicating its use as a noninvasive surrogate for muscle microvascular O2 extraction.

PurposeThis study investigated the impact of arms/hands and body position on the measurement of breast density using MRI.MethodsNoncontrast-enhanced T1-weighted images were acquired from 32 healthy women. Each subject received four MR scans using different experimental settings, including a high resolution hands-up, a low resolution hands-up, a high resolution hands-down, and finally, another high resolution hands-up after repositioning. The breast segmentation was performed using a fully automatic chest template-based method. The breast volume (BV), fibroglandular tissue volume (FV), and percent density (PD) measured from the four MR scan settings were analyzed.ResultsA high correlation of BV, FV, and PD between any pair of the four MR scans was noted (r > 0.98 for all). Using the generalized estimating equation method, a statistically significant difference in mean BV among four settings was noted (left breast, score test p = 0.0056; right breast, score test p = 0.0016), adjusted for age and body mass index. Despite differences in BV, there were no statistically significant differences in the mean PDs among the four settings (p > 0.10 for left and right breasts). Using Bland-Altman plots, the smallest mean difference/bias and standard deviations for BV, FV, and PD were noted when comparing hands-up high vs low resolution when the breast positions were exactly the same.ConclusionsThe authors' study showed that BV, FV, and PD measurements from MRI of different positions were highly correlated. BV may vary with positions but the measured PD did not differ significantly between positions. The study suggested that the percent density analyzed from MRI studies acquired using different arms/hands and body positions from multiple centers can be combined for analysis.

ObjectiveEvaluate associations between personal and workplace factors and median nerve conduction latency at the wrist.MethodsBaseline data on workplace psychosocial and physical exposures were pooled from four prospective studies of production and service workers (N = 2396). During the follow-up period, electrophysiologic measures of median nerve function were collected at regular intervals.ResultsSignificant adjusted associations were observed between age, body mass index, sex, peak hand force, duration of forceful hand exertions, Threshold Limit Value for Hand Activity Limit, forceful repetition rate, wrist extension, and decision latitude on median nerve latencies.ConclusionsOccupational and nonoccupational factors have adverse effects on median nerve function. Measuring median nerve function eliminates possible reporting bias that may affect symptom-based carpal tunnel syndrome case definitions. These results suggest that previously observed associations between carpal tunnel syndrome and occupational factors are not the result of such reporting bias.

PurposeAlthough the Parks-Bielschowsky three-step test is the cornerstone of cyclovertical strabismus diagnosis, it has not been validated against an external benchmark. We evaluated the test's sensitivity in clinical diagnosis of superior oblique palsy in patients with unequivocal magnetic resonance imaging (MRI) evidence of superior oblique atrophy.MethodsA total of 73 strabismic patients were selected from a prospective MRI study because they exhibited superior oblique atrophy indicative of superior oblique denervation and thus confirmatory of superior oblique palsy. Of these, 50 patients who had no confounding factors were included for detailed study. Ocular motility data were evaluated to determine sensitivity of single and combined clinical findings in diagnosis of superior oblique palsy.ResultsMaximum mean ipsilesional superior oblique cross section was reduced to 9.6 ± 0.6 mm(2) (mean ± standard error) in superior oblique palsy, representing 52% of the 18.5 ± 0.6 mm(2) contralesional superior oblique maximum cross section and 52% of the 18.4 ± 0.4 mm(2) control maximum superior oblique cross section (P < 0.001). Of the 50 patients, 35 (70%) with superior oblique atrophy fulfilled the entire three-step test. In 14 (28%) patients two steps were fulfilled; in 1 patient (2%), only one step. Affected superior oblique cross section was similar in orbits that fulfilled the three-step test (9.8 ± 0.9 mm(2)) and those that did not (9.1 ± 0.7 mm(2); P = 0.58).ConclusionsThe complete three-step test fails to detect 30% of cases of superior oblique atrophy. Often only two of three steps are positive in superior oblique palsy.

ObjectiveThe aim of this study is to examine the feasibility, efficacy, and safety of a group-based yoga therapy intervention for middle-aged and older women with urinary incontinence.MethodsWe conducted a pilot randomized trial of ambulatory women aged 40 years and older with stress, urgency, or mixed-type incontinence. Women were randomized to a 6-week yoga therapy program (n = 10) consisting of twice weekly group classes and once weekly home practice or a wait-list control group (n = 9). All participants also received written pamphlets about standard behavioral self-management strategies for incontinence. Changes in incontinence were assessed with 7-day voiding diaries.ResultsThe mean (SD) age was 61.4 (8.2) years, and the mean baseline frequency of incontinence was 2.5 (1.3) episodes/d. After 6 weeks, the total incontinence frequency decreased by 70% (1.8 [0.9] fewer episodes/d) in the yoga therapy versus 13% (0.3 [1.7] fewer episodes/d) in the control group (P = 0.049). Participants in the yoga therapy group also reported an average of 71% decrease in stress incontinence frequency (0.7 [0.8] fewer episodes/d) compared with a 25% increase in controls (0.2 [1.1] more episodes/d) (P = 0.039). No significant differences in reduction in urgency incontinence were detected between the yoga therapy versus control groups (1.0 [1.0] versus 0.5 [0.5] fewer episodes/d; P = 0.20). All women starting the yoga therapy program completed at least 90% of the group classes and practice sessions. Two participants in each group reported adverse events unrelated to the intervention.ConclusionsFindings provide preliminary evidence to support the feasibility, efficacy, and safety of a group-based yoga therapy intervention to improve urinary incontinence in women.

The analysis of monosynaptic Hoffman's reflex (H-reflex) involves recording the response to electrical stimulation of Ia-afferent fibers from the muscle spindle. The H-reflex can be used as a probe to study spinal neuronal pathways and mechanisms at rest and during movement in humans. The purpose of this study was to analyze the feasibility of the assessment of the H-reflex in people with Down syndrome (DS), and to compare it between adult dancers and non-dancers with and without DS. Twenty-five participants were included and divided into four groups (6 non-dancers and 6 dancers with DS and, 7 non-dancers and 6 dancers without DS). The H-reflex was recorded at the level of the soleus muscle in its central area. We analyzed the H response in three different conditions: decubitus prone, static standing position with open eyes and closed eyes. Non-dancers with DS showed a faster H-reflex latency than both groups without DS (all p <.005). In the present study, we provide evidence of the feasibility of eliciting the H-reflex in adults with DS. Interestingly, the H-reflex was present in decubitus position but not in standing position in most non-dancers with DS and dancers without DS. The data from this study can help to perform future research in adults with DS and the development of full-scale studies to analyze this variable in adults with intellectual disability with and without DS. [ABSTRACT FROM AUTHOR]

Objective: The aim of this study was to clarify the association of scoliosis and windswept hips with immobility, lying position, and time in lying, in adults with cerebral palsy (CP). Methods: This cross-sectional study included 830 adults (469 males and 361 females) with a diagnosis of CP, 16–73 years, and classified at levels I–V according to the Gross Motor Function Classification System (GMFCS). Subjects' Gross motor function classification system level, presence and severity of scoliosis, hip and knee joint range of movement, lying position, postural ability in lying, and time in lying were used to identify connections between them. Results: Adults who are immobile in the lying position have higher odds of both scoliosis and windswept hips. Spending more than 8 h daily in the same lying position, increased the odds of having scoliosis, while lying solely in a supine position, resulted in higher odds of windswept hips. Conclusions: The "preferred" habitual posture frequently observed in immobile adults with CP, leads to established distortion of their body shape. The results indicate the need for early introduction of appropriate posture control, in immobile individuals with CP, from a young age. The preferred posture, observed in immobile adults with cerebral palsy, leads to a distortion of their body shape. One in four adults with cerebral palsy use only one position when in bed. The results indicate the need for early introduction of appropriate posture control in individuals unable to change position. [ABSTRACT FROM AUTHOR]

Children with autism spectrum disorders (ASDs) often exhibit altered representations of the external world. Consistently, when localizing touch, children with ASDs were less influenced than their peers by changes of the stimulated limb's location in external space [Wada et al., Scientific Reports 2015, 4(1), 5985]. However, given the protracted development of an external‐spatial dominance in tactile processing in typically developing children, this difference might reflect a developmental delay rather than a set suppression of external space in ASDs. Here, adults with ASDs and matched control‐participants completed (a) the tactile temporal order judgment (TOJ) task previously used to test external‐spatial representation of touch in children with ASDs and (b) a tactile‐visual cross‐modal congruency (CC) task which assesses benefits of task‐irrelevant visual stimuli on tactile localization in external space. In both experiments, participants localized tactile stimuli to the fingers of each hand, while holding their hands either crossed or uncrossed. Performance differences between hand postures reflect the influence of external‐spatial codes. In both groups, tactile TOJ‐performance markedly decreased when participants crossed their hands and CC‐effects were especially large if the visual stimulus was presented at the same side of external space as the task‐relevant touch. The absence of group differences was statistically confirmed using Bayesian statistical modeling: adults with ASDs weighted external‐spatial codes comparable to typically developed adults during tactile and visual‐tactile spatio‐temporal tasks. Thus, atypicalities in the spatial coding of touch for children with ASDs appear to reflect a developmental delay rather than a stable characteristic of ASD. Autism Res 2019, 12: 1745–1757. © 2019 International Society for Autism Research, Wiley Periodicals, Inc. Lay Summary: A touched limb's location can be described twofold, with respect to the body (right hand) or the external world (right side). Children and adolescents with autism spectrum disorder (ASD) reportedly rely less than their peers on the external world. Here, adults with and without ASDs completed two tactile localization tasks. Both groups relied to the same degree on external world locations. This opens the possibility that the tendency to relate touch to the external world is typical in individuals with ASDs but emerges with a delay. [ABSTRACT FROM AUTHOR]

IntroductionPleth Variability Index (PVI) is a new algorithm that allows continuous and automatic estimation of respiratory variations in the pulse oximeter waveform amplitude. Our aim was to test its ability to detect changes in preload induced by passive leg raising (PLR) in spontaneously breathing volunteers.MethodsWe conducted a prospective observational study. Twenty-five spontaneously breathing volunteers were enrolled. PVI, heart rate and noninvasive arterial pressure were recorded. Cardiac output was assessed using transthoracic echocardiography. Volunteers were studied in three successive positions: baseline (semirecumbent position); after PLR of 45 degrees with the trunk lowered in the supine position; and back in the semirecubent position.ResultsWe observed significant changes in cardiac output and PVI during changes in body position. In particular, PVI decreased significantly from baseline to PLR (from 21.5 +/- 8.0% to 18.3 +/- 9.4%; P < 0.05) and increased significantly from PLR to the semirecumbent position (from 18.3 +/- 9.4% to 25.4 +/- 10.6 %; P < 0.05). A threshold PVI value above 19% was a weak but significant predictor of response to PLR (sensitivity 82%, specificity 57%, area under the receiver operating characteristic curve 0.734 +/- 0.101).ConclusionPVI can detect haemodynamic changes induced by PLR in spontaneously breathing volunteers. However, we found that PVI was a weak predictor of fluid responsiveness in this setting.

IntroductionReports indicate that brain regulation of oxygenation is inhibited in patients with low baseline oxyhemoglobin concentrations and that brain oxyhemoglobin concentrations are decreased with aging. The purpose of this study was to determine if regulation of brain oxygenation to changes in blood pressure is inhibited by normal aging.MethodsBrain oxyhemoglobin (OHb) and deoxyhemoglobin (HHb) concentrations were determined from the forehead using a frequency domain near infrared spectroscopy in 27 healthy volunteers. Subjects were separated into two groups by age (20-39, n=16; 40-60, n=11). Brain hemoglobin and non-invasive blood pressure were measured in (1) supine, (2) sitting, (3) supine and (4) sitting positions with 10-min equilibration intervals between each determination. Statistical differences were determined by two way repeated measures analysis of variance.ResultsYoung subjects were 28+/-5 years (mean+/-S.D.) and older subjects were 48+/-6 years. In supine position, OHb and HHb were 28.4+/-8.3 and 15.4+/-2.4micromol/L, respectively, in young; 22.4+/-5.7 and 13.4+/-2.9micromol/L, respectively, in older subjects, both P