Skeletal muscle energetics during submaximal contractions are linked to metabolic performance during ambulatory exercise: A pilot study in male adults.

Skeletal muscle's capacity for oxidative energy production can be measured in vivo by phosphocreatine (PCr) recovery following maximal contractions inside a magnetic resonance scanner. However, muscle energetic characteristics during submaximal contractions of similar intensity as used in free-living activities may be more relevant to the energetic support of ambulatory tasks during daily life. We measured vastus lateralis muscle oxidative capacity, acidification, submaximal oxidative energy production, and acetylcarnitine accumulation in response to an incremental contraction protocol (6%-15% maximal torque).

Returning Individualized Wearable Sensor Results to Older Adult Research Participants: A Pilot Study.

Background: Wearable sensors that monitor physical behaviors are increasingly adopted in clinical research. Older adult research participants have expressed interest in tracking and receiving feedback on their physical behaviors. Simultaneously, researchers and clinical trial sponsors are interested in returning results to participants, but the question of how to return individual study results derived from research-grade wearable sensors remains unanswered.

Wearable microfluidic biosensors with haptic feedback for continuous monitoring of hydration biomarkers in workers.

Real-time monitoring of hydration biomarkers in tandem with biophysical markers can offer valuable physiological insights about heat stress and related thermoregulatory response. These metrics have been challenging to achieve with wearable sensors. Here we present a closed-loop electrochemical/biophysical wearable sensing device and algorithms that directly measure whole-body sweat loss, sweating rate, sodium concentration, and sodium loss with electrode arrays embedded in a microfluidic channel.

Muscle Torque-Velocity Relationships and Fatigue With Reduced Knee Joint Range of Motion in Young and Older Adults.

The purpose of this study was to evaluate the influence of knee joint range of motion (RoM) on the torque-velocity relationship and fatigue in the knee extensor muscles of 7 young (median = 26 y) and 7 older (68 y) adults. Each leg was assigned a RoM (35° or 75°) over which to perform a torque-velocity protocol (maximal isokinetic contractions, 60-300°·s-1) and a fatigue protocol (120 maximal contractions at 120°·s-1, 0.5 Hz).

Changes to balance dynamics following a high-intensity run are associated with future injury occurrence in recreational runners.

Fatigue is associated with increased injury risk along with changes in balance control and task performance. Musculoskeletal injury rates in runners are high and often result from an inability to adapt to the demands of exercise and a breakdown in the interaction among different biological systems. This study aimed to investigate whether changes in balance dynamics during a single-leg squat task following a high-intensity run could distinguish groups of recreational runners who did and did not sustain a running-related injury within 6 months.

A Transparent Method for Step Detection using an Acceleration Threshold.

Step-based metrics provide simple measures of ambulatory activity, yet device software either includes undisclosed proprietary step detection algorithms or simply do not compute step-based metrics. We aimed to develop and validate a simple algorithm to accurately detect steps across various ambulatory and non-ambulatory activities. Seventy-five adults (21-39 years) completed seven simulated activities of daily living (e.

Sleep Measurement Using Wrist-Worn Accelerometer Data Compared with Polysomnography.

This study determined if using alternative sleep onset (SO) definitions impacted accelerometer-derived sleep estimates compared with polysomnography (PSG). Nineteen participants (48%F) completed a 48 h visit in a home simulation laboratory. Sleep characteristics were calculated from the second night by PSG and a wrist-worn ActiGraph GT3X+ (AG).

Establishing a Global Standard for Wearable Devices in Sport and Exercise Medicine: Perspectives from Academic and Industry Stakeholders.

Millions of consumer sport and fitness wearables (CSFWs) are used worldwide, and millions of datapoints are generated by each device. Moreover, these numbers are rapidly growing, and they contain a heterogeneity of devices, data types, and contexts for data collection. Companies and consumers would benefit from guiding standards on device quality and data formats.

Changes in coordination and variability during running as a function of head stability demands.

The purpose of this study was to identify changes in segment/joint coordination and coordination variability in running with increasing head stability requirements. Fifteen strides from twelve recreational runners while running on a treadmill at their preferred speed were collected. Head stability demands were manipulated through real-time visual feedback that required head-gaze orientation to be contained within boxes of different sizes, ranging from 21 to 3 degrees of visual angle in 3-degree decrements.

Establishing a Global Standard for Wearable Devices in Sport and Fitness: Perspectives from the New England Chapter of the American College of Sports Medicine Members.

The recent explosion of wearable technology and the associated concerns prompted the International Federation of Sports Medicine (FIMS) to create a quality assurance standard for wearable devices, which provides commissioned testing of marketing claims and endorsement of commercial wearables that test favorably. An open forum as announced in the conference advertising was held at the Annual Meeting of the New England Regional Chapter of the American College of Sports Medicine (NEACSM) November 7 to 8, 2019, in Providence, Rhode Island, USA for attending NEACSM members to voice their input on the process. Herein, we report the proceedings.

Walking cadence (steps/min) and intensity in 21-40 year olds: CADENCE-adults.

Background: Previous studies have reported that walking cadence (steps/min) is associated with absolutely-defined intensity (metabolic equivalents; METs), such that cadence-based thresholds could serve as reasonable proxy values for ambulatory intensities.

Purpose: To establish definitive heuristic (i.e.

Association between stride time fractality and gait adaptability during unperturbed and asymmetric walking.

Human locomotion is an inherently complex activity that requires the coordination and control of neurophysiological and biomechanical degrees of freedom across various spatiotemporal scales. Locomotor patterns must constantly be altered in the face of changing environmental or task demands, such as heterogeneous terrains or obstacles. Variability in stride times occurring at short time scales (e.

Comparisons of Segment Coordination: An Investigation of Vector Coding.

The development of a methodology to assess movement coordination has provided gait researchers a tool to assess movement organization. A challenge in analyzing movement coordination using vector coding lies within the inherent circularity of data garnered from this technique. Therefore, the purpose of this investigation was to determine if accurate group comparisons can be made with varying techniques of vector coding analyses.

Adaptive changes in running kinematics as a function of head stability demands and their effect on shock transmission.

This study aimed to identify adaptive changes in running kinematics and impact shock transmission as a function of head stability requirements. Fifteen strides from twelve recreational runners were collected during preferred speed treadmill running. Head stability demands were manipulated through real-time visual feedback that required head-gaze orientation to maintain within boxes of different sizes, ranging from 21° to 3° of visual angle with 3° decrements.

Step-Based Physical Activity Metrics and Cardiometabolic Risk: NHANES 2005-2006.

Purpose: This study aimed to catalog the relationships between step-based accelerometer metrics indicative of physical activity volume (steps per day, adjusted to a pedometer scale), intensity (mean steps per minute from the highest, not necessarily consecutive, minutes in a day; peak 30-min cadence), and sedentary behavior (percent time at zero cadence relative to wear time; %TZC) and cardiometabolic risk factors.

Methods: We analyzed data from 3388 participants, 20+ yr old, in the 2005-2006 National Health and Nutrition Examination Survey with ≥1 valid day of accelerometer data and at least some data on weight, body mass index, waist circumference, systolic and diastolic blood pressure, glucose, insulin, HDL cholesterol, triglycerides, and/or glycohemoglobin. Linear trends were evaluated for cardiometabolic variables, adjusted for age and race, across quintiles of steps per day, peak 30-min cadence, and %TZC.

Additional helmet and pack loading reduce situational awareness during the establishment of marksmanship posture.

The pickup of visual information is critical for controlling movement and maintaining situational awareness in dangerous situations. Altered coordination while wearing protective equipment may impact the likelihood of injury or death. This investigation examined the consequences of load magnitude and distribution on situational awareness, segmental coordination and head gaze in several protective equipment ensembles.

Allometrically Scaled Children's Clinical and Free-Living Ambulatory Behavior.

Purpose: This study aimed to compare clinical and free-living walking cadence in school-age children and to examine how the allometric scaling of leg length variability affects objective ambulatory activity assessment.

Methods: A total of 375 children (154 boys and 221 girls, 9-11 yr old) completed GAITRite-determined slow, normal, and fast walks and wore accelerometers for 1 wk. Dependent variables from clinical assessment included gait speed, cadence, and step length, whereas steps per day, peak 1-min cadence, and peak 60-min cadence were assessed during free living.

Head and Tibial Acceleration as a Function of Stride Frequency and Visual Feedback during Running.

Individuals regulate the transmission of shock to the head during running at different stride frequencies although the consequences of this on head-gaze stability remain unclear. The purpose of this study was to examine if providing individuals with visual feedback of their head-gaze orientation impacts tibial and head accelerations, shock attenuation and head-gaze motion during preferred speed running at different stride frequencies. Fifteen strides from twelve recreational runners running on a treadmill at their preferred speed were collected during five stride frequencies (preferred, ±10% and ±20% of preferred) in two visual task conditions (with and without real-time visual feedback of head-gaze orientation).

Multiscale entropy identifies differences in complexity in postural control in women with multiple sclerosis.

Loss of postural center-of-pressure complexity (COP complexity) has been associated with reduced adaptability that accompanies disease and aging. The aim of this study was to identify if COP complexity is reduced: (1) in those with Multiple Sclerosis (MS) compared to controls; (2) when vision is limited compared to remaining intact; and (3) during more demanding postural conditions compared to quiet standing. Additionally, we explored the relationship between the COP complexity and disease severity, fatigue, cutaneous sensation and central motor drive.

Multiscale entropy: A tool for understanding the complexity of postural control.

Clinical disorders often are characterized by a breakdown in dynamical processes that contribute to the control of upright standing. Disruption to a large number of physiological processes operating at different time scales can lead to alterations in postural center of pressure (CoP) fluctuations. Multiscale entropy (MSE) has been used to identify differences in fluctuations of postural CoP time series between groups with and without known physiological impairments at multiple time scales.

Gait impairments in persons with multiple sclerosis across preferred and fixed walking speeds.

Objectives: To investigate (1) whether previously observed changes in gait parameters in individuals with multiple sclerosis (MS) are the result of slower preferred walking speeds or reflect adaptations independent of gait speed; and (2) the changes in spatiotemporal features of the unstable swing phase of gait in people with MS.

Design: Cross-sectional study assessing changes in gait parameters during preferred, slow (0.6m/s), medium (1.

A statistical approach to the use of control entropy identifies differences in constraints of gait in highly trained versus untrained runners.

Control entropy (CE) is a complexity analysis suitable for dynamic, non-stationary conditions which allows the inference of the control effort of a dynamical system generating the signal. These characteristics make CE a highly relevant time varying quantity relevant to the dynamic physiological responses associated with running. Using High Resolution Accelerometry (HRA) signals we evaluate here constraints of running gait, from two different groups of runners, highly trained collegiate and untrained runners.

Time-to-contact and multiscale entropy identify differences in postural control in adolescent idiopathic scoliosis.

Previous reports on changes in postural control in adolescent idiopathic scoliosis (AIS) compared to healthy controls have been inconsistent. This may suggest center of pressure (COP) sway parameters are not sufficient for determining the ability to maintain quiet upright stance indicating more complex measures may be needed to examine postural control in AIS. The purpose of this investigation was to compare postural control between AIS of different severity levels and healthy controls using time-to-contact (TtC), the complexity index of multiscale entropy (C(r)), and COP sway parameters.

High resolution MEMS accelerometers to estimate VO2 and compare running mechanics between highly trained inter-collegiate and untrained runners.

Background: The purposes of this study were to determine the validity and reliability of high resolution accelerometers (HRA) relative to VO(2) and speed, and compare putative differences in HRA signal between trained (T) and untrained (UT) runners during treadmill locomotion.

Methodology: Runners performed 2 incremental VO(2max) trials while wearing HRA. RMS of high frequency signal from three axes (VT, ML, AP) and the Euclidean resultant (RES) were compared to VO(2) to determine validity and reliability.