Validity of Wearable Activity Monitors for Estimation of Resting Energy Expenditure in Adults

• Wearable accelerometers have become the standard method for assessing physical activity for both individuals and field-based research [1]. These new devices allow consumers to have the ability to estimate total energy expenditure and track it over time. • Resting Energy Expenditure plays a critical role in estimating daily total energy expenditure as it contributes 60-70% of total energy expenditure [2,3]. • Little to no information is available to substantiate the validity of these consumer-based activity monitors under free-living conditions

Inter-limb Coordination in Chronic Stroke Survivors

Stroke is the primary cause of disability among adults and can lead to major physical deficits including impaired gait. Current therapeutic techniques often fail to meaningfully improve mobility, thus increasing the likelihood of subsequent morbidity. Conventional stroke assessments for gait often do not consider inter-limb gait-coordination. Also, current measures do not include an assessment of how such deficits evolve over time, i.e., the temporal structure of inter-limb coordination. Nonlinear measurements allow us to define inter-limb coordination in innovative and effective ways, which can subsequently impact stroke therapy by providing a more comprehensive picture of evolving gait deficits observed in stroke survivors. Cross-sample entropy (cSE) and cross-recurrence quantification analysis (cRQA) are two nonlinear variables that can quantify the regularity and duration of inter-limb coordination, respectively. In this study, inter-limb gait-coordination, in a sample of chronic stroke survivors, was assessed with specific emphasis to their temporal structure and compared to a sample of healthy, age and sex-matched participants. In comparison to healthy controls, we hypothesized the temporal structure of gait coordination would be more regular (i.e. lower cSE values) and that the duration of coordination would be shorter (i.e. lower cRQA values) in chronic stroke survivors. Thirteen chronic stroke survivors and thirteen healthy aged matched controls underwent treadmill-walking trials wearing retro-reflective markers, while having their movements recorded with a motion-capture system. Stroke survivors had significantly more regular gait patterns (

Inter-Limb Coordination in Chronic Stroke Survivors

Background: Stroke is the leading cause of disability in adults. Current rehabilitation practices often fail to correct gait deficits such as gait asymmetry. While gait asymmetry characterizes individual differences between the legs (e.g. step time or step length differences), gait coordination characterizes interactions between the two legs (e.g. durations of similar behavior or repeating patterns). In a healthy system, coordination allows our legs to effectively work together providing a smooth and efficient gait. Defining and understanding the temporal structure of gait patterns in chronic stroke survivors may be the key to creating a successful rehabilitation paradigm. One tool that can help in understanding the temporal structure of variability is cross-recurrence quantification analysis (cRQA) which allows us to quantify the strength of coordination over time (maximum line length) between the two limbs. Purpose: The goal of this project was to determine the temporal structure of inter-limb coordination in chronic stroke survivors. Methods: 12 patients with hemiparesis due to stroke were recruited. Participants walked for as long as they could, and up to 5 minutes at their PWS on a treadmill. cRQA was used to characterize the temporal structure of variability. Participants also completed a battery of clinical tests to determine sensorimotor and cognitive levels. Results & Discussion: As level of asymmetry increases there is a tread towards a decrease in max cRQA line and a lower Fugl-Meyer score. Relating nonlinear variables with clinical measures and then targeting these variables during rehabilitation may provide optimal outcomes for chronic stroke survivors

Perception of Complex Movement in Typically Developing Children and Children With Autism Spectrum Disorder

Typically developing children prefer to watch locomotion coherent with their own mode of locomotion. The development of motor behavior relies, in part, on being able to incorporate the lessons learned from viewing others’ attempts at similar motor performance. By watching others, we are able to vastly multiply our own experience and knowledge of successful movement strategies. We suggest that the specific aversion to the complex temporo-spatial aspects of others’ movements is related directly to the perception of chaotic motion of the observed individual. Thus, the purpose of the current project was to assess gaze and postural behavior of young children, with and without autism in response to visual stimuli of different temporal complexity. Eight children participated; four have been diagnosed with autism (ASD). Participants attended single collection, which contained measures of eye movements and standing posture (COP) while viewing a point-light stimulus. Motion of the stimulus differed across three conditions, by scaling temporal complexity in terms of approximate entropy; a sine wave, chaos, and brown noise. While not directly supporting our proposed hypothesis, the results do highlight differing responsiveness to motion structure between children with and without ASD The present data suggests that the gaze and postural sway of children with ASD differs from those without. These differences are noticeable in the complexity of temporal variations of each behavior, in response to a stimulus of specific complexity

Relationship Between Posturography and The Gross Motor Portion of The Mullen Scales of Early Learning in Infants

The Mullen Scales of Early Learning (MSEL) is a general developmental measure, up to 68 months of age. MSEL is used to assess cognitive and motor abilities. The MSEL is a subjective and non-quantitative evaluation of gross motor behavior. Recent experimental paradigms may provide an objective method of evaluating gross motor function (e.g. sitting posture). The purpose of this study was to evaluate the relationship of the gross motor portion of the MSEL with sitting posturography. Seven typically developing infants were evaluated at 6 months of age when they could sit independently for 10 seconds. Center of pressure was collected for three trials of 10 sec. Linear and nonlinear measures were used to evaluate sitting postural sway. For statistical analysis we computed simple linear correlations with each of the postural variables and the MSEL motor T scores. The findings showed the RMS (r=0.749) and Range (r=0.966) in the ML direction had a strong negative correlation with the MSEL motor scores. SampEn in the ML direction had a moderate positive correlation with the MSEL motor scores. Infants that had greater MSEL motor scores have lower Range and RMS values in ML direction and infants that had lower MSEL motor scores had greater Range and RMS values in ML direction. In contrast, infants that had greater MSEL scores had greater SampEn values in the ML direction, whereas infants that had lower MSEL scores had lower SampEn values. It is evident that MSEL motor scores seem to capture ML postural behavior better than AP

Spatiotemporal gait variability in children aged 2 to 10 decreases throughout pre-adolescence

Background: Children’s gait is traditionally understood to mature as young as three years old through pre-adolescence. Studies looking at gait biomechanics suggest that gait matures around three years old, while studies investigating gait variability propose a much later maturation. The studies that have examined children’s gait variability did so while the children walked around a track or down hallways that created a discontinuous gait, potentially affecting the measures of variability and the efficacy of the results. Purpose: Therefore, the purpose of our study was to investigate the development of gait dynamics and gait variability in children in a more continuous fashion, in this case, by walking on a treadmill. Methods: To accomplish this, we included four age groups of children, ranging 2–10 years old, walking on a treadmill for at least three minutes while stride time and stride length were collected. Stride time and stride length’s variability was then analyzed using linear (mean, standard deviation, coefficient of variation) and nonlinear (sample entropy, detrended fluctuation analysis) measures across the varying ages of our participants. Results: Interestingly, both the linear and nonlinear variabilities of the stride time and stride length measures decreased as the groups of children got older. Specifically, CV ST (2–3 (9.3 ± 4%), 8–10 (3.6 ± 0.7%), p < 0.05) and CV SL (2–3 (11.4 ± 3%), 8–10 (4.6 ± 1%), p < 0.05) were our strongest linear measures, and DFA α ST (2–3 (0.97 ± 0.12), 8–10 (0.82 ± 0.10), p < 0.05) and DFA α SL (2–3 (0.91 ± 0.04), 8–10 (0.81 ± 0.03), p < 0.05) were our strongest nonlinear measures, particularly between the youngest and oldest groups. This trend of variability decreasing with age suggests that as children’s gait matures, their gait becomes more stable and reliable. Significance: Our study rejects the notion that children’s gait is mature by the age of three, as some would suggest. By analyzing the variability of stride time and stride length, we can see that even later into childhood, children’s gait continues to change and evolve.This research received no external funding