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Pflugers Archiv : European Journal of... Jun 2024Autonomic control of heart rate is well known in adult subjects, but limited data are available on the development of the heart rate control during childhood and...
Autonomic control of heart rate is well known in adult subjects, but limited data are available on the development of the heart rate control during childhood and adolescence. Continuous 12-lead electrocardiograms were recorded in 1045 healthy children and adolescents (550 females) aged 4 to 19 years during postural manoeuvres involving repeated 10-min supine, unsupported sitting, and unsupported standing positions. In each position, heart rate was measured, and heart rate variability indices were evaluated (SDNN, RMSSD, and high (HF) and low (LF) frequency components were obtained). Quasi-normalized HF frequency components were defined as qnHF = HF/(HF + LF). These measurements were, among others, related to age using linear regressions. In supine position, heart rate decreases per year of age were significant in both sexes but lower in females than in males. In standing position, these decreases per year of age were substantially lowered. RMSSD and qnHF indices were independent of age in supine position but significantly decreased with age in sitting and standing positions. Correspondingly, LF/HF proportions showed steep increases with age in sitting and standing positions but not in the supine position. The study suggests that baseline supine parasympathetic influence shows little developmental changes during childhood and adolescence but that in young children, sympathetic branch is less responsive to vagal influence. While vagal influences modulate cardiac periods in young and older children equally, they are less able to suppress the sympathetic influence in younger children.
PubMed: 38937370
DOI: 10.1007/s00424-024-02979-0 -
PloS One 2024Although sloped surfaces are common in daily living, most studies of body balance are carried out on flat surfaces, and few data are available for sloping angles below...
INTRODUCTION
Although sloped surfaces are common in daily living, most studies of body balance are carried out on flat surfaces, and few data are available for sloping angles below 14°.
OBJECTIVES
The purpose of this study was to explore the effect of forward and backward sloping surfaces at 7° and 15° on postural equilibrium and the activity of flexor/extensor ankle muscles.
METHODS
Fifteen healthy subjects (8 males and 7 females) (27.67 ± 3.9 years) underwent a posturographic examination associated with a surface electromyogram (EMG) of tibialis anterior (TA), soleus (Sol) and gastrocnemius medialis (GasM) under five conditions of support inclination: 0° (H0), backward inclination at 7° and 15° (DF7 and DF15), forward inclination at 7° and 15° (PF7 and PF15).
RESULTS
Results showed that the center of pressure (CP) was shifted according to the surface slope, with a forward move in PF7 (p <0.001) and PF15 (p <0.001) and a backward move in DF7 (p <0.01) and in DF15 (p <0.001). The mean displacement of the CP along the anterior-posterior axis (Xm) was increased in DF15 (p <0.01) relative to the H0 condition but reduced in PF7 (p <0.01). The normalized EMG revealed higher values when the muscles were in a shortened position (PF7 for Sol, p <0.05; PF15 for GasM, p <0.01; DF15 for TA, p<0.01) and lower values of GasM and Sol when lengthened (DF15, p <0.05).
CONCLUSION
Our findings indicate that standing on a backward sloped surface impairs body balance, while low-angle forward sloped surfaces might improve postural stability. Muscular activity variations of the ankle flexors/extensors, which are stretched or shortened, also seem to be related to the length-tension relationship of skeletal muscles.
Topics: Humans; Male; Female; Adult; Muscle, Skeletal; Postural Balance; Electromyography; Ankle; Young Adult; Ankle Joint
PubMed: 38935639
DOI: 10.1371/journal.pone.0305840 -
Sensors (Basel, Switzerland) Jun 2024The remote monitoring of vital signs via wearable devices holds significant potential for alleviating the strain on hospital resources and elder-care facilities. Among...
The remote monitoring of vital signs via wearable devices holds significant potential for alleviating the strain on hospital resources and elder-care facilities. Among the various techniques available, photoplethysmography stands out as particularly promising for assessing vital signs such as heart rate, respiratory rate, oxygen saturation, and blood pressure. Despite the efficacy of this method, many commercially available wearables, bearing Conformité Européenne marks and the approval of the Food and Drug Administration, are often integrated within proprietary, closed data ecosystems and are very expensive. In an effort to democratize access to affordable wearable devices, our research endeavored to develop an open-source photoplethysmographic sensor utilizing off-the-shelf hardware and open-source software components. The primary aim of this investigation was to ascertain whether the combination of off-the-shelf hardware components and open-source software yielded vital-sign measurements (specifically heart rate and respiratory rate) comparable to those obtained from more expensive, commercially endorsed medical devices. Conducted as a prospective, single-center study, the research involved the assessment of fifteen participants for three minutes in four distinct positions, supine, seated, standing, and walking in place. The sensor consisted of four PulseSensors measuring photoplethysmographic signals with green light in reflection mode. Subsequent signal processing utilized various open-source Python packages. The heart rate assessment involved the comparison of three distinct methodologies, while the respiratory rate analysis entailed the evaluation of fifteen different algorithmic combinations. For one-minute average heart rates' determination, the Neurokit process pipeline achieved the best results in a seated position with a Spearman's coefficient of 0.9 and a mean difference of 0.59 BPM. For the respiratory rate, the combined utilization of Neurokit and Charlton algorithms yielded the most favorable outcomes with a Spearman's coefficient of 0.82 and a mean difference of 1.90 BrPM. This research found that off-the-shelf components are able to produce comparable results for heart and respiratory rates to those of commercial and approved medical wearables.
Topics: Humans; Photoplethysmography; Respiratory Rate; Heart Rate; Software; Male; Signal Processing, Computer-Assisted; Female; Wearable Electronic Devices; Monitoring, Physiologic; Adult; Prospective Studies; Algorithms
PubMed: 38931550
DOI: 10.3390/s24123766 -
International Journal of Environmental... May 2024Children functioning at Gross Motor Function Classification System (GMFCS) levels IV-V cannot maintain an aligned standing position or take steps without support....
Children functioning at Gross Motor Function Classification System (GMFCS) levels IV-V cannot maintain an aligned standing position or take steps without support. Upright positioning and mobility devices have psycho-social significance for these children and their families, enhancing use of vision, communication, functioning and emotional well-being. Standers and supported stepping devices facilitate opportunities for biomechanical loading, potentially helping to build and maintain muscle and bone integrity, and they promote physical development. However, families are often required to choose between these two devices for their young child. This study aims to synthesize evidence for use and benefits of both supported standing and stepping devices through the lens of two contemporary theoretical frameworks to support clinical reasoning and implementation. The F-words for childhood development (functioning, family, fitness, fun, friends, future) and the interdependence-Human Activity Assistive Technology (iHAAT) models were combined to illustrate the complex interactions between the child, family, caregivers, peers and contextual factors when implementing standing and stepping devices with children at GMFCS levels IV and V. Supported standing and stepping devices provide complementary benefits, and both may be necessary starting at 9-15 months. We propose they both be included ON-Time, along with other age-appropriate positioning and mobility devices, to promote more equitable developmental opportunities for children with non-ambulant cerebral palsy.
Topics: Child; Child, Preschool; Humans; Cerebral Palsy; Self-Help Devices; Standing Position
PubMed: 38928915
DOI: 10.3390/ijerph21060669 -
Journal of Orthopaedics and... Jun 2024Lumbar-iliac fixation (LIF) is a common treatment for Tile C1.3 pelvic fractures, but different techniques, including L4-L5/L5 unilateral LIF (L4-L5/L5 ULIF), bilateral...
BACKGROUND
Lumbar-iliac fixation (LIF) is a common treatment for Tile C1.3 pelvic fractures, but different techniques, including L4-L5/L5 unilateral LIF (L4-L5/L5 ULIF), bilateral LIF (BLIF), and L4-L5/L5 triangular osteosynthesis (L4-L5/L5 TOS), still lack biomechanical evaluation. The sacral slope (SS) is key to the vertical shear of the sacrum but has not been investigated for its biomechanical role in lumbar-iliac fixation. The aim of this study is to evaluate the biomechanical effects of different LIF and SS on Tile C1.3 pelvic fracture under two-legged standing load in human cadavers.
METHODS
Eight male fresh-frozen human lumbar-pelvic specimens were used in this study. Compressive force of 500 N was applied to the L4 vertebrae in the two-legged standing position of the pelvis. The Tile C1.3 pelvic fracture was prepared, and the posterior pelvic ring was fixed with L5 ULIF, L4-L5 ULIF, L5 TOS, L4-L5 TOS, and L4-L5 BLIF, respectively. Displacement and rotation of the anterior S1 foramen at 30° and 40° sacral slope (SS) were analyzed.
RESULTS
The displacement of L4-L5/L5 TOS in the left-right and vertical direction, total displacement, and rotation in lateral bending decreased significantly, which is more pronounced at 40° SS. The difference in stability between L4-L5 and L5 ULIF was not significant. BLIF significantly limited left-right displacement. The ULIF vertical displacement at 40° SS was significantly higher than that at 30° SS.
CONCLUSIONS
This study developed an in vitro two-legged standing pelvic model and demonstrated that TOS enhanced pelvic stability in the coronal plane and cephalad-caudal direction, and BLIF enhanced stability in the left-right direction. L4-L5 ULIF did not further improve the immediate stability, whereas TOS is required to increase the vertical stability at greater SS.
Topics: Humans; Male; Pelvic Bones; Biomechanical Phenomena; Sacrum; Cadaver; Lumbar Vertebrae; Fractures, Bone; Fracture Fixation, Internal; Ilium; Middle Aged; Aged
PubMed: 38926180
DOI: 10.1186/s10195-024-00776-0 -
Tierarztliche Praxis. Ausgabe G,... Jun 2024In horses, parturition is characterized by the fact that any delays may rapidly result in the death of the foal. Therefore, birth monitoring and the rapid detection of... (Review)
Review
In horses, parturition is characterized by the fact that any delays may rapidly result in the death of the foal. Therefore, birth monitoring and the rapid detection of dystocia are of great importance. For this purpose, the differentiation between behavior associated with physiological parturition and activities related to difficult parturition is important. The aim of this publication is to present the physiological behavior of mares during parturition on the basis of a literature review. The behavior of mares in the opening phase of parturition is highly individual. In general, it is characterized by an increase in movement activity. In this phase of parturition, 13 different behaviors have been described (e. g. lying down and standing up, cessation of feed intake, local sweating, frequent defecation and urination). Mares show a more uniform pattern of behavior in the expulsion phase and the following phase of expulsion of the fetal membranes and placenta. More than 95% of mares give birth in the lateral position. A mare usually remains in recumbency for several minutes following the expulsion of the fetus. Immediately after standing up, the mare begins to intensely interact with the foal. The expulsion of the fetal membranes and the placenta usually takes place in a standing position. From a clinical point of view, it is important to give consideration to the difficulty in recognizing the opening phase of parturition due to the mares' individual behavior patterns.
Topics: Horses; Female; Animals; Parturition; Pregnancy; Behavior, Animal
PubMed: 38925128
DOI: 10.1055/a-2321-4422 -
Gait & Posture Jun 2024In people with lower limb amputation (LLA), the loss of limb structures and peripheral motor and sensory systems result in significant mobility challenges, including...
BACKGROUND
In people with lower limb amputation (LLA), the loss of limb structures and peripheral motor and sensory systems result in significant mobility challenges, including impaired postural stability.
OBJECTIVE
The primary objective of this study was to evaluate the dual-task interference (DTI) on postural control and dual-task interference on cognition during static and dynamic balance in people with LLA and compare the same with controls. The secondary objective of this study was to compare the DTI on postural control and DTI on cognition between LLA of different etiology.
DESIGN
Cross-sectional observational study METHODOLOGY: Fifteen people with unilateral LLA and 15 age and gender-matched controls participated in this study at a tertiary care hospital. The outcome measures used were anterior-posterior stability index (APSI), medial-lateral stability index, and overall stability index (OSI) using Biodex Balance System and a cognitive task parameter, namely correct response rate in serial seven subtraction test. Quantitative variables were compared using a Wilcoxon rank-sum test. Spearman's correlation test was used to establish the correlation between the DTI on cognition and the DTI on postural control.
RESULTS
DTI on postural control during static balance was significantly higher in people with LLA than controls (APSI, OSI). No significant difference was observed in DTI on postural control during dynamic balance. No significant difference was observed in DTI on cognition during static and dynamic balance. A significant negative correlation was observed between DTI on cognition and DTI on postural control (APSI) during static balance people with LLA.
SIGNIFICANCE
In people with unilateral LLA, the addition of a cognitive task results in significant deterioration of sagittal plane postural control during static balance but not during dynamic balance due to the over-allocation of resources to a cognitive task.
PubMed: 38924823
DOI: 10.1016/j.gaitpost.2024.06.013 -
Diabetes, Obesity & Metabolism Jun 2024To investigate how a change in body position with light-intensity physical activity (PA) 'snacks' (LIPAS, alternate sitting and standing, walking or standing...
AIMS
To investigate how a change in body position with light-intensity physical activity (PA) 'snacks' (LIPAS, alternate sitting and standing, walking or standing continuously) compared with uninterrupted prolonged sitting affects glucose metabolism and heart rate variability (HRV) parameters in young adults with overweight and obesity.
MATERIALS AND METHODS
We conducted a four-arm randomized controlled crossover trial. The following conditions were tested during an 8-h simulated workday: uninterrupted prolonged sitting (SIT), alternate sitting and standing (SIT-STAND; 2.5 h total), continuous standing (STAND), and continuous walking (1.0 mph; WALK). The primary outcome was to investigate how a change in body position (alternate sitting and standing, walking or standing continuously) compared with uninterrupted sitting affects mean 8-h glucose metabolism. Secondary outcomes included the effects on 2-h postprandial glucose concentrations, as well as on 8-h/24-h heart rate and HRV parameters, in the respective study arms. Capillary blood samples were drawn from an hyperemised earlobe in the fasted state and once every hour during each trial intervention by puncturing the earlobe with a lancet and collecting 20 μL of blood (Biosen S-Line Lab+; EKF diagnostics, Barleben, Germany). HRV was assessed for 24 h including the 8-h intervention phase, and a home phase by means of a Holter electrocardiogram. All participants received the same standardized non-relativised breakfast and lunch during the four trial visits.
RESULTS
Seventeen individuals (eight women, mean age 23.4 ± 3.3 years, body mass index 29.7 ± 3.8 kg/m, glycated haemoglobin level 34.8 ± 3.1 mmol/mol [5.4 ± 0.3%], body fat 31.8 ± 8.2%) completed all four trial arms. Compared with SIT (89.4 ± 6.8 mg/dL), 8-h mean glucose was lower in all other conditions (p < 0.05) and this was statistically significant compared with WALK (86.3 ± 5.2 mg/dL; p = 0.034). Two-hour postprandial glucose after breakfast was approximately 7% lower for WALK compared with SIT (p = 0.002). Furthermore, significant time × condition effects on HRV parameters favouring light-intensity walking were observed (p < 0.001).
CONCLUSIONS
Replacement and interruption of prolonged sitting with light-intensity walking showed a significant blood glucose-lowering effect and improved HRV during an 8-h work environment in young adults with overweight and obesity.
PubMed: 38923193
DOI: 10.1111/dom.15732 -
Entropy (Basel, Switzerland) Jun 2024Self-organized criticality is a universal theory for dynamical systems that has recently been applied to the cardiovascular system. Precise methodological approaches are...
Self-organized criticality is a universal theory for dynamical systems that has recently been applied to the cardiovascular system. Precise methodological approaches are essential for understanding the dynamics of cardiovascular self-organized criticality. This study examines how the duration and quality of data recording affect the analysis of cardiovascular self-organized criticality, with a focus on the beat-by-beat heart rate variability time series obtained from seven healthy subjects in a standing position. Drawing a Zipf diagram, we evaluated the distribution of cardiovascular events of bradycardia and tachycardia. We identified tipping points for the distribution of both bradycardia and tachycardia events. By varying the recording durations (1, 2, 5, 10, 20, 30, and 40 min) and sampling frequencies (500, 250, and 100 Hz), we investigated their influence on the observed distributions. While shorter recordings can effectively capture cardiovascular events, they may underestimate the variables describing their distribution. Additionally, the tipping point of the Zipf distribution differs between bradycardia and tachycardia events. Comparisons of the distribution of bradycardia and tachycardia events should be conducted using long data recordings. Utilizing devices with lower sampling frequencies may compromise data fidelity. These insights contribute to refining experimental protocols and advancing our understanding of the complex dynamics underlying cardiovascular regulation.
PubMed: 38920505
DOI: 10.3390/e26060496 -
Frontiers in Nutrition 2024Assessment of fat mass has historically employed various methods like Dual-energy X-ray Absorptiometry (DXA), and bioelectrical impedance (BIA), and anthropometry with...
INTRODUCTION
Assessment of fat mass has historically employed various methods like Dual-energy X-ray Absorptiometry (DXA), and bioelectrical impedance (BIA), and anthropometry with its set of formulas. However, doubts persist regarding their validity and interchangeability to evaluate fat mass. This research aimed to determine the validity of anthropometry, and BIA in estimating fat mass Vs DXA, considering the influence of sex and hydration status.
METHODS
A descriptive, cross-sectional study included 265 young adults (161 males and 104 females), assessed through DXA, BIA in a standing position, and anthropometry. A fat mass estimation formula with DXA, a fat mass estimation formula with BIA and 10 fat mass estimation formulas with anthropometry were calculated.
RESULTS
Significant differences were found across DXA, BIA and anthropometry in both kilograms and percentages for the overall sample (<0.001), and when the covariable sex was included (p<0.001), with no significant effect of hydration status (=0.332-0.527). Bonferroni-adjusted analyses revealed significant differences from DXA with anthropometry and BIA in most cases for the overall sample (<0.001), as well as when stratified by sex (<0.001-0.016). Lin's coefficient indicated poor agreement between most of the formulas and methods both in percentage and kilograms of fat mass (CCC=0.135-0.892). In the Bland-Altman analysis, using the DXA fat mass values as a reference, lack of agreement was found in the general sample (<0.001-0.007), except for Carter's formula in kilograms (=0.136) and percentage (=0.929) and Forsyth for percentage (=0.365). When separating the sample by sex, lack of agreement was found in males for all methods when compared with both percentage and kilograms calculated by DXA (<0.001). In the female sample, all methods and formulas showed lack of agreement (<0.001-0.020), except for Evans's in percentage (=0.058).
CONCLUSION
The formulas for fat mass assessment with anthropometry and BIA may not be valid with respect to the values reported with DXA, with the exception of Carter's anthropometry formula for general sample and Evans's anthropometry formula for female sample. BIA could also be an alternative if what is needed is to assess fat mass in women as a group.
PubMed: 38919386
DOI: 10.3389/fnut.2024.1421950