Effect Of Body Position Research Articles

Effects of Different Body Position on Measuring Blood Pressure Among Healthy Individuals

Effects of Different Body Position on Measuring Blood Pressure Among Healthy Individuals

Effect of Body Position on Intraocular Pressure (IOP), Intracranial Pressure (ICP), and Translaminar Pressure (TLP) Via Continuous Wireless Telemetry in Nonhuman Primates (NHPs).

PurposeRecent retrospective clinical studies and animal experiments have suggested that cerebrospinal fluid pressure (CSFP) is important in glaucoma, acting through the translaminar pressure (TLP = IOP − CSFP), which directly affects the optic nerve head. In this study, IOP and intracranial pressure (ICP; a surrogate of CSFP) were measured at various body positions to quantify the determinants of TLP.MethodsWe have developed an implantable wireless pressure telemetry system based on a small piezoelectric sensor with low temporal drift. Telemetry transducers were placed in the anterior chamber to measure IOP and in the brain parenchyma at eye height to measure ICP. IOP was calibrated against anterior cannulation manometry, and ICP/CSFP was calibrated against an intraparenchymal Codman ICP Express microsensor. We measured IOP, ICP, and TLP = IOP − ICP continuously at 200 Hz in three male nonhuman primates (NHPs) in three trials; pressures were then averaged for 30 seconds per body position. Relative change of IOP, ICP, and TLP from the supine (baseline) position to the seated, standing, and inverted positions were quantified.ResultsTLP changed significantly and instantaneously from the supine to seated (+14 mm Hg), supine to standing (+13 mm Hg) and supine to inverted (−12 mm Hg) positions (P < 0.05). There was no significant TLP change for supine to prone. ICP showed greater relative change than IOP.ConclusionsTLP change due to body position change is driven more by ICP/CSFP than IOP. IOP, ICP, and TLP variability, coupled with telemetry, should allow us to test the hypotheses that IOP, ICP, or TLP fluctuations contribute independently to glaucoma onset or progression.

Scanner type and scan body position effects on the complete‐arch digital implant scan accuracy

Scanner type and scan body position effects on the complete‐arch digital implant scan accuracy

Effect of priming exercise and body position on pulmonary oxygen uptake and muscle deoxygenation kinetics during cycle exercise.

We hypothesized that the performance of prior heavy exercise would speed pulmonary oxygen uptake (V̇o2) kinetics (i.e., as described by the time constant, [Formula: see text]) and reduce the amplitude of muscle deoxygenation (deoxy[heme]) kinetics in the supine (S) but not upright (U) body position. Seventeen healthy men completed heavy-intensity constant-work rate exercise tests in S and U consisting of two bouts of 6-min cycling separated by 6-min cycling at 20 W. Pulmonary V̇o2 was measured breath by breath; total and deoxy[heme] were determined via time-resolved near-infrared spectroscopy (NIRS) at three muscle sites. Priming exercise reduced [Formula: see text] in S (bout 1: 36 ± 10 vs. bout 2: 28 ± 10 s, P < 0.05) but not U (bout 1: 27 ± 8 s vs. bout 2: 25 ± 7 s, P > 0.05). Deoxy[heme] amplitude was increased after priming in S (bout 1: 25-28 μM vs. bout 2: 30-35 μM, P < 0.05) and U (bout 1: 13-18 μM vs. bout 2: 17-25 μM, P > 0.05), whereas baseline total[heme] was enhanced in S (bout 1: 110-179 μM vs. bout 2: 121-193 μM, P < 0.05) and U (bout 1: 123-186 μM vs. bout 2: 137-197 μM, P < 0.05). Priming exercise increased total[heme] in both S and U, likely indicating enhanced diffusive O2 delivery. However, the observation that after priming the amplitude of the deoxy[heme] response was increased in S suggests that the reduction in [Formula: see text] subsequent to priming was related to a combination of both enhanced intracellular O2 utilization and increased O2 delivery.NEW & NOTEWORTHY Here we show that oxygen uptake (V̇o2) kinetics are slower in the supine compared with upright body position, an effect that is associated with an increased amplitude of skeletal muscle deoxygenation in the supine position. After priming in the supine position, the amplitude of muscle deoxygenation remained markedly elevated above that observed during upright exercise. Hence, the priming effect cannot be solely attributed to enhanced O2 delivery, and enhancements to intracellular O2 utilization must also be contributory.

Effect of Bridge Position Swallow on Esophageal Motility in Healthy Individuals Using High-Resolution Manometry

Recently, there has been clinical interest in the effect of different body positions on esophageal motility. This study aimed to identify the effect of three different body positions on esophageal motility using high-resolution manometry. Thirteen healthy adults swallowed 5 mL of water in the upright, supine, and bridge positions. For the bridge position, each subject raised their waist against gravity, placed a cushion under their back, and bent their knees. The proximal contractile integral (PCI) and distal contractile integral (DCI), integrated relaxation pressure (IRP), distal latency (DL), peristaltic breaks (PBs), intrabolus pressure (IBP), and expiratory and inspiratory esophagoesophageal junction (EGJ) pressure were measured. In the bridge position, PCI, DCI, IRP, and expiratory and inspiratory EGJ pressure were significantly higher than those in the upright position (bridge PCI vs. upright PCI [p = 0.001], bridge DCI vs. upright DCI [p < 0.001], bridge IRP vs. upright IRP [p = 0.018], bridge EGJ pressure vs. upright EGJ pressure [expiratory: p = 0.001] [inspiratory: p < 0.001]). PBs were significantly shorter and DL was significantly longer in the bridge position compared to upright (bridge PBs vs. upright PBs [p = 0.001], bridge DL vs. upright DL [p = 0.001]). IBP was significantly higher in the bridge position compared to supine (bridge IBP vs. supine IBP [p = 0.01]). These results demonstrated changes in esophageal motility according to changes in position while swallowing, where esophageal contractions became stronger against gravity. Further study is required to examine the effectiveness of swallowing in the bridge position.

Positional Therapy and Regional Pulmonary Ventilation.

Prone ventilation redistributes lung inflation along the gravitational axis; however, localized, nongravitational effects of body position are less well characterized. The authors hypothesize that positional inflation improvements follow both gravitational and nongravitational distributions. This study is a nonoverlapping reanalysis of previously published large animal data. Five intubated, mechanically ventilated pigs were imaged before and after lung injury by tracheal injection of hydrochloric acid (2 ml/kg). Computed tomography scans were performed at 5 and 10 cm H2O positive end-expiratory pressure (PEEP) in both prone and supine positions. All paired prone-supine images were digitally aligned to each other. Each unit of lung tissue was assigned to three clusters (K-means) according to positional changes of its density and dimensions. The regional cluster distribution was analyzed. Units of tissue displaying lung recruitment were mapped. We characterized three tissue clusters on computed tomography: deflation (increased tissue density and contraction), limited response (stable density and volume), and reinflation (decreased density and expansion). The respective clusters occupied (mean ± SD including all studied conditions) 29.3 ± 12.9%, 47.6 ± 11.4%, and 23.1 ± 8.3% of total lung mass, with similar distributions before and after lung injury. Reinflation was slightly greater at higher PEEP after injury. Larger proportions of the reinflation cluster were contained in the dorsal versus ventral (86.4 ± 8.5% vs. 13.6 ± 8.5%, P < 0.001) and in the caudal versus cranial (63.4 ± 11.2% vs. 36.6 ± 11.2%, P < 0.001) regions of the lung. After injury, prone positioning recruited 64.5 ± 36.7 g of tissue (11.4 ± 6.7% of total lung mass) at lower PEEP, and 49.9 ± 12.9 g (8.9 ± 2.8% of total mass) at higher PEEP; more than 59.0% of this recruitment was caudal. During mechanical ventilation, lung reinflation and recruitment by the prone positioning were primarily localized in the dorso-caudal lung. The local effects of positioning in this lung region may determine its clinical efficacy.

Normative reference values for esophageal high-resolution manometry in healthy adults: A systematic review.

Establishing normative values of high-resolution esophageal manometry is necessary for accurate interpretation and comparison of measurements. In this systematic review, we aimed to summarize normal values for different esophageal high-resolution manometry systems. Moreover, we assessed the effect of body position, bolus consistency, and provocative maneuvers on these normative thresholds. We searched Medline, Embase, and the Cochrane Library from January 1st, 2006, to January 20th, 2020, for studies that reported normative data of high-resolution manometry in healthy volunteers. We assessed methodological quality of the included studies and planned a descriptive analysis. We analyzed data from 54 articles describing normative thresholds in high-resolution manometry using solid-state or water-perfused systems. Forty-six studies performed the manometry study in the supine position with liquid swallows, whereas sixteen studies described normative values in the upright position. Twelve studies assessed normative values for different bolus consistencies, and nine studies evaluated different provocative maneuvers. There is a considerable variety of normative values for esophageal high-resolution manometry depending on the equipment used and the protocols performed to obtain measurements. This should be taken into account when evaluating measurements in clinical practice and when comparing results of published research studies.

The effect of body position on maternal cardiovascular function during sleep and wakefulness in late pregnancy

Introduction An association between the increased risk of late stillbirth and the maternal supine sleeping position has been recently established. The risk of stillbirth following supine sleep has been suspected to occur as a result of aortocaval compression by the gravid uterus. A number of studies conducted during wakefulness have reported compromised cardiovascular function during supine rest, as demonstrated by reductions in cardiac output, blood pressure and utero-placental blood flow. It remains unclear whether similar effects are also present during sleep, due to the presence of key sleep-specific changes in cardiovascular function. Objective To investigate the changes in maternal cardiovascular function between the supine and left-lateral positions during wakefulness and non-rapid eye movement (NREM) sleep in late pregnancy. Methods Twenty-nine women with a singleton pregnancy between 24.7 and 36.7 weeks’ gestation participated in a single overnight sleep study. Physiological measures (blood pressure, heart rate, heart rate variability – HRV, and pulse arrival time – PAT) were measured and recorded throughout the night using standard polysomnography equipment and the Portapres Model-2 device. As the present study evaluated cardiovascular changes during natural rest and sleep in pregnancy, participants were not given explicit instructions on which position to adopt. Body position was continuously recorded using a position monitor and verified with video recording. Results No changes in systolic, diastolic or mean arterial blood pressure were observed between the left-lateral and supine positions during wakefulness or sleep. However, heart rate was significantly higher in the supine position compared to the left during wakefulness (p= .03), with a similar trend present during sleep (p= .11). A significantly shorter PAT was measured in the supine position (compared to the left) during wakefulness (p= .01) and sleep (p= .01). No change in HRV measures was observed between the left and supine positions in either state. Conclusion Blood pressure did not appear to differ significantly between the left-lateral and supine positions during wakefulness and sleep. The lack of blood pressure differences may reflect elevated sympathetic activity during rest and sleep in the supine position (compared to the left), suggesting that some degree of compensation for aortocaval compression may still be possible during sleep.

Dominance or prestige: A review of the effects of power poses and other body postures

AbstractResearch on the effects of body positions has attracted enormous attention in recent years but has been plagued by failed replication attempts. Today, there is some confusion about which effects can be considered reliable. One problem that may have contributed to this confusion is the fact that most previous studies have not clearly distinguished between different types of body positions. We apply the dominance‐prestige framework to distinguish between two types of body positions. On the basis of this reasoning, we argue that research on so‐called power poses in fact has analyzed expansiveness as an indicator of dominance, whereas research on postures has focused on the straightness of the spine, which may be seen as a display of prestige. We review the literature and conclude that there is no clear evidence that short‐term interventions involving body positions affect physiology or behavior. Still, there are effects on actors' self‐perceptions. Repeatedly, studies on power poses have found effects on feelings of power and self‐evaluations, and studies on postures have found effects on emotional experience. However, there is hardly any research that has directly compared the two types of interventions.

Effect of Body Position on Cardiorespiratory Stabilization and Comfort in Preterm Infants on Continuous Positive Airway Pressure

PurposeThe purpose of the study is to investigate the effect of four body positions (supine, prone, left lateral, right lateral) on cardiorespiratory stabilization and comfort in preterm infants receiving Nasal Continuous Positive Airway Pressure (NCPAP). Design and methodsIn the study conducted as a randomized crossover design, the sample was composed of 20 preterm infants receiving NCPAP therapy. At each change of position, the baby was allowed to stabilize for 15 min, and heart rate and oxygen saturation values were recorded every 10 min for the next 60 min. The comfort levels of the infants in each position were evaluated at 30th and 60th minutes using the Premature Infant Comfort Scale. ResultsAt the end of the study, it was determined that there was no statistically significant difference between heart rate (p = .83), respiratory rate (p = .90) and oxygen saturation (p = .15) of the infants in terms of their positions. When the mean comfort scores of the preterm infants were compared in terms of position, it was found that there was a difference between the positions (p < .01). According to the scale evaluation, the highest comfort level of the infants was in the prone position, which was followed by right lateral, supine and left lateral positions. Practice implicationsProne position was the most comfortable for preterm infants. However, comfort levels of preterm infants were also high enough in other positions so that no intervention is needed. In order to ensure comfort and cardiorespiratory stabilization, any of the four body positions can be chosen.

The effects of body position on the material properties of soft tissue in the human thigh

Forty percent of patients with a spinal cord injury acquire a pressure ulcer during rehabilitation, and sixty percent of individuals in elderly care facilities have at least one pressure ulcer upon admittance. A commonality between those populations is the increased amount of time they spend in the seated position. The loading on the buttocks and thighs while in the seated position has been cited as a risk factor for pressure ulcer formation, especially for wheelchair users. Finite element models provide a tool with which to evaluate the internal tissue stresses, but they are reliant upon accurate material properties for the soft tissue. Thus the goals of this research were to determine and compare the material properties of the soft tissue in the thigh and buttock regions in the seated, quadruped (a universally accessible position with the knee and hip articulations similar to the seated position), and prone positions. A custom indenter was designed to collect force and deflection data for the buttocks/proximal thigh, middle thigh, and distal thigh regions of twenty able-bodied individuals. The force and deflection data were converted into stress and stretch data, which were used to obtain parameters from an Ogden material model. Our results indicated that the prone position yielded significantly stiffer tissue properties than in the seated and quadruped positions for both males and females, meaning that position should be taken into account when obtaining material properties that are input into finite element models. Realistic material properties of the soft tissue will lead to better understanding of tissue injury risk.

The effect of scanner type and scan body position on the accuracy of complete-arch digital implant scans.

How the accuracy of complete-arch implant scans is affected when different intraoral scanners (IOSs) are used and the effect of scan body position on the accuracy are not well-known. To compare the scan accuracy (trueness and precision) of a recently introduced IOS (Virtuo Vivo) to a commonly used IOS (TRIOS 3) and the scans of a laboratory scanner (LBS; Cares 7 SERIES) in a completely edentulous maxilla with four implants. It was also aimed to evaluate the effect of scan body position on the accuracy. Multi-unit scan bodies were tightened on a poly(methyl methacrylate) edentulous maxillary model with four implants. A master reference model (MRM) stereolithography (STL) file was generated by scanning the model with a high-precision scanner. The model was scanned with three different scanners (n = 10); two different IOSs and a LBS. STL files were superimposed over the MRM. For trueness, scan body position (P = .004) and scanner type (P < .001) had a significant effect on distance deviation and a significant interaction was found (P = .001). For angular deviation, only scanner type had a significant effect (P = .028). For precision, significant difference was found for distance (P = .011) and angular deviations (P = .020) between different scanner types. One scanner type was not superior to others when both trueness and precision were considered. Position of the scan body affected the distance deviation (trueness).

Management and experience of postural placement in postoperative mechanical ventilation of newborns

Congenital diaphragmatic hernia (CDH) is a neonatal condition that mainly occurs when the abdominal organs herniate into the thorax, obstructing the development of the lungs. Postoperative neonatal breathing disorder is one of the main causes of neonatal death. This study summarizes the postoperative nursing status of 30 cases of neonatal CDH in our hospital, and explores the effect of body position in mechanical ventilation care following CDH surgery. A total of 30 CHD children admitted in our hospital between June, 2018 and October, 2019 were included. The neonates were divided into preterm infant group (n=15) and full-term infant group (n=15). Each child was immediately transferred to the newborn intensive care unit (NICU) ward after surgery and received the hospital's NCIU special care. Besides routine nursing, each child was placed in a randomly selected primary position (the prone position or supine position). After 30 min, their oxygenation indexes were measured, and then their position (prone position or supine position) was changed. After 30 min, the neonates' oxygenation indicators were measured again. A hospital-made satisfaction questionnaire was used to evaluate the parents' satisfaction with nursing care. Two children died of respiratory failure (one in the preterm group and one in the full-term group), and the rest were in a stable condition after surgery. There was no significant difference between the rates of parent satisfaction in the two groups (preterm infant group: 96.67% verse full-term group: 93.33%, P>0.05). In both groups, the partial pressure of oxygen in arterial blood (PaO2), partial pressure of oxygen in arterial blood/fraction of inspiration O2 (PaO2/FiO2), and partial pressure of oxygen in arterial blood/partial pressure of oxygen in the alveolar gas (PaO2/PAO2) in prone position were significantly higher than those in supine position (P<0.05); the alveolar-arterial oxygen difference (A-aDO2) was significantly lower than that in the supine position (0.05). The prone position can improve the oxygenation index of children after surgery, and improve their respiratory system function. This method is suitable for newborn postoperative NICU care.

Exploring the Relative Effects of Body Position and Spatial Cognition on Presence When Playing Virtual Reality Games

ABSTRACT Previous research has suggested that cognitive functions such as execution, attention, memory, and perception differ when body position changes. However, the influence of body position on these cognitive functions is still not fully understood. In particular, little is known about how physical self-positioning may affect the cognitive process of perceptual responses in a virtual environment (VE). In this regard, we compared three body positions (standing, sitting, and half-sitting) in two types of virtual reality (VR) game with different degrees of freedom in navigation (finite and infinite) to explore the association between body position and the sense of presence in VEs. A two-way ANOVA yielded a main effect for body position, with the sense of presence significantly higher for a standing position than for a half-sitting position. However, there was no main effect for game type, nor was there an interaction between body position and game type. In addition, a one-way ANOVA revealed that, for the game with infinite navigation, participants in a standing position felt stronger presence than those who were sitting or half-sitting, whereas no significant difference was found between the sitting and half-sitting positions. In contrast, there was no statistical difference between the three body positions when playing the game with finite navigation. Taken together, it can be speculated that the cognitive effects of body position on presence are correlated with the degree of freedom in navigation in a VE.

The Effect of Padded Adhesive Dressing and Static Body Position on Sacral Interface Pressure.

Padded adhesive bandages are frequently used in the inpatient setting for sacral pressure injury prevention, but it is unclear whether they truly decrease interface pressure. We hypothesized such devices reduce sacral peak interface pressure in the supine position, which would be further reduced in 30-degree reclined and upright seated positions. Study participants rested with their sacrum on a pressure-sensing mat, in 3 positions, for 30 seconds each: (1) sitting upright; (2) supine; and (3) supine against 30-degree wedge. Measurements were made with and without a padded adhesive bandage overlying the sacrum. Age, sex, and body mass index (BMI) were collected. These variables were entered sequentially, in an a priori order to construct a linear mixed-effects model. Forty healthy adults participated. After controlling for by-subject variation, age, and sex, BMI did not influence peak sacral pressure (P = 0.22), although the effect of body position was significant (P < 0.01). Subsequent addition of padded adhesive dressing was nonsignificant (P = 0.17); sacral peak pressure was similar with a padded adhesive dressing (247.8 ± 147.3 mm Hg) or without (mean ± standard deviation = 229.8 ± 127.7 mm Hg). Lastly, there was no significant interaction between BMI and body position (P = 0.11). Padded adhesive bandages did not reduce interface pressure in any position. Sacral pressure was highest in the supine position and was not specifically affected by BMI. If padded bandages provide clinically significant reduction in pressure injury incidence, it is not simply through the reduction of interface pressure.

Effects of Different Body Positions and Head Elevation Angles on Regional Cerebral Oxygen Saturation in Premature Infants of China

BackgroundTo investigate the effects of different body positions and head elevation angles on regional cerebral oxygen saturation in premature infants using near-infrared spectroscopy (NIRS). MethodsThis was a prospective study of premature infants hospitalized. The position was changed each feeding cycle (2–3 h), in order: 15° prone, 15° supine, 0° prone, and 0° supine position. Regional cerebral oxygen saturation (rSO2) was measured after each position period using NIRS, over 7 days. FindingsThirty-three premature infants were included in the analysis. Among them, 22 (66.7%) were male, and 11 (33.3%) were female. When placing the premature infants in the prone position, the regional cerebral oxygen saturation (rSO2) values were higher at head elevation 15° compared with 0° (main effect P < 0.001). When placing the premature infants in the supine position, rSO2 was higher at a head elevation of 15° compared with that at 0° (main effect P < 0.001). When placing the premature infants with a head elevation of 15°, rSO2 in the prone position was higher than that of the supine position (main effect P < 0.001). There was no difference between the prone and supine positions when placing the premature infants with the head elevation at 0° (P > 0.05). DiscussionHigher cerebral rSO2 can be achieved when placing premature infants in the prone or supine position, with a 15° head elevation angle. Application to practiceUsing a specific body position and head angle could improve the regional cerebral oxygen saturation of premature infants.

Habitual and ready positions in female table tennis players and their relation to the prevalence of back pain.

BackgroundThe current body of knowledge shows that there is very little research into the occurrence and scale of asymmetry or postural defects in table tennis. It is interesting which regions of the spine are exposed to the greatest changes in the shape of its curvatures and whether the asymmetrical position of the shoulder and pelvic girdles in table tennis players changes when adopting the ready position. Consequently, can overload occur in certain parts of the spine and can the asymmetry deepen as a response of adopting this position? The reply to these questions may be an indication of the need for appropriate compensatory or corrective measures. Therefore, the aim of the study was to evaluate the effect of body position during play on the change in the shape of anterior–posterior spinal curvatures and trunk asymmetry in table tennis players.MethodsTo evaluate body posture the photogrammetric method based on the Moiré phenomenon with equipment by CQ electronic was applied. The study involved 22 female players practicing competitive table tennis (the age of 17 ± 4.5, with the average training experience of 7 ± 4.3 years, body mass of 47.8 ± 15.8, and body height of 161.2 ± 10.4). Each participant completed an author’s own questionnaire on spinal pain. The shape of curvatures in the sagittal and frontal plane was evaluated in the participant in the habitual standing position and in the table tennis ready position. Descriptive statistical analysis was performed and the significance of differences was tested using the Mann–Whitney U test.Results and ConclusionsThis study demonstrated the dominance of kyphotic body posture in table tennis players, which can be caused by many hours of using the ready position during playing. After adopting this position, there are significant differences in the angles of anterior and posterior spinal curvatures compared to the habitual posture. This may be the cause of overloads and pain complaints reported by the study participants. Adopting the ready position is also associated with an increase in asymmetry in the position (rotation) of the pelvis and spinous processes (frontal plane). Therefore, training programs should be extended with exercises that relieve the spine in the vertical line and exercises that improve symmetry of the work of the upper limbs, body trunk muscles and the pelvis.

The effect of body position on intraocular pressure in anesthetized horses.

To evaluate the effect of four recumbent body positions on intraocular pressure (IOP) in anesthetized normal horses. Ten nonglaucomatous adult horses. Intraocular pressure was measured with a rebound tonometer in both eyes of standing sedated horses (baseline), then under general anesthesia during four randomized recumbent body positions, including Trendelenburg (Tr; 15-degree head down), reverse Trendelenburg (RTr; 15-degree head up), dorsal, and lateral; only the superior eye was measured in lateral positions. The mean of 3 IOP readings was taken at each position, allowing a minimum of 2minutes of acclimatization after each position change before obtaining measurements. Repeated Measures Analysis with Newman-Keuls Multiple Comparison Post hoc was used to compare IOPs in different positions, and linear regression was used to compare IOP with age and weight cofactors. When compared to baseline, the greatest change in IOP occurred in Tr (increase of 25.63±8.12mmHg). When comparing all recumbent positions to baseline, IOP significantly increased in 3 of 4 body positions (P<.001), with no significant difference identified between RTr and baseline. When comparing all body positions to each other, the greatest IOP difference occurred between the Tr and the RTr positions (increase of 26.95±5.41mmHg). Age and weight were not correlated with IOP in any position. Recumbent body position significantly increases IOP in normal eyes of horses under injectable anesthesia.

The effects of different body positions on the accuracy of ultra-short-term heart rate variability indexes

PurposeWith the increasing popularity of ultra-short heart rate variability (HRV) measurements being utilized with mobile devices outside of controlled, research settings, it is important to determine the proper methodology to ensure accuracy. Therefore, the purpose of this study was to examine the validity of ultra-short-term HRV metrics across three different body positions in recreationally active individuals. MethodsTwenty-six subjects (12 males: 24.1 ± 3.6 yrs., 178.6 ± 6.4 cm, 82.9 ± 8.7 kg; 15 females: 21.3 ± 1.2 yrs., 170.7 ± 10.5 cm, 71.6 ± 18.9 kg) participated in 10-min electrocardiogram recordings in the supine, seated, and standing positions. HRV analysis using a variety of time, frequency, and non-linear parameters were performed following traditional recommendations (i.e., last 5 min of each 10-min recording) and ultra-short-term recordings (i.e., 1-min epoch following a 1-min stabilization period). ResultsSlight decreases (e.g., “near perfect” to “very large”) in intraclass correlations (ICC) and increases in the limits of agreement (LOA) were noted for most of the HRV metrics as position changed to sitting and then standing. However, throughout all three positions, the highest ICC values (0.88 to 0.92) and tightest LOA (CE ± 1.96 SD) were displayed in RMSSD. ConclusionsThis study supports the use of RMSSD and SD1 for assessing HRV under ultra-short-term recordings of 1 min regardless of position. However, practitioners should be consistent with the preferred position for measurements and not use them interchangeably to reduce potential errors during long-term monitoring.

The Effect of Body Position on Measures of Arterial Stiffness in Humans

Background: The dynamics ofpulsatile waveforms travelling the central aorta are governed by pressures and arterial compliance. Arterial stiffness, the inverse of compliance, is an independent risk factor for cardiovascular disease and has been suggested as a superior risk index compared to brachial blood pressure (BP). Arterial stiffness is typically measured via carotid-femoral pulse wave velocity (cfPWV) in the supine position; however, different body positions alter orthostatic column height, impacting heart rate and BP. The purpose of this investigation was to examine different body positions and associated measures of cfPWV. Methods: Measures of resting cfPWV were acquired simultaneously with BP during supine, head-up tilt (HUT), head-down tilt (HDT), and Fowler’s position, all at 45 degrees from vertical. Results: Relative to supine, cfPWV was increased 1.1 ± 1.0 and 1.5 ± 1.1 m/s (both p ≤ 0.001) in HUT and Fowler’s positions, respectively. Supine to HDT cfPWV was unaltered (p = 0.1), despite an increase in mean arterial pressure (MAP) (10 ± 9 mm Hg). When cfPWV was normalized to MAP, the same effects persisted (p ≤ 0.001). Conclusion: Increasing orthostatic column height by changing posture independently increases resting cfPWV, concurrent with increases in BP. This data demonstrates the impact of body position on measures of central artery stiffness, which may have clinical relevance.