Upright balance control strategies during pregnancy

Evaluating Desk-Assisted Standing Techniques for Simulated Pregnant Conditions: An Experimental Study Using a Maternity-Simulation Jacket

Lower back pain, a common issue among pregnant women, often complicates daily activities like standing up from a chair. Therefore, research into the standing motion of pregnant women is important, and many research studies have already been conducted. However, many of these studies were conducted in highly controlled environments, overlooking everyday scenarios such as using a desk for support when standing up, and their effects have not been adequately tested. To address this gap, we measured multimodal signals for a sit-to-stand (STS) movement with hand assistance and verified the changes using a t-test. To avoid imposing strain on pregnant women, we used 10 non-diseased young adults who wore jackets designed to simulate pregnancy conditions, thus allowing for more comprehensive and rigorous experimentation. We attached surface electromyography (sEMG) sensors to the erector spinae muscles of participants and measured changes in muscle activity, skeletal positioning, and center of pressure both before and after wearing a Maternity-Simulation Jacket. Our analysis showed that the jacket successfully mimicked key aspects of the movement patterns typical in pregnant women. These results highlight the possibility of developing practical strategies that more accurately mirror the real-life scenarios met by pregnant women, enriching the current research on their STS movement.

Sensory integration and segmental control of posture during pregnancy

BACKGROUND

Approximately 25% of pregnant people fall, yet the underlying mechanisms of this increased fall-risk remain unclear. Prior studies examining pregnancy and balance have utilized center of pressure analyses and reported mixed results. The purpose of this study was to examine sensory and segmental contributions to postural control throughout pregnancy using accelerometer-based measures of sway.

METHODS

Thirty pregnant people (first trimester: n = 10, second trimester: n = 10, third trimester: n = 10) and 10 healthy, nonpregnant control people stood quietly for one minute in four conditions: eyes open on a firm surface, eyes closed on a firm surface, eyes open on a foam pad, and eyes closed on foam. Postural sway was quantified using the root mean square accelerations in the anterior-posterior and medial-lateral directions from an inertial sensor at the lumbar region. Sensory sway ratios, segmental coherence and co-phase, were calculated to assess sensory contributions and segmental control, respectively.

FINDINGS

Pregnant people did not display greater sway compared to healthy, nonpregnant controls. There were no group differences in vestibular, visual, or somatosensory sway ratios, and no significant differences in balance control strategies between pregnant and nonpregnant participants across sensory conditions.

INTERPRETATION

The small effects observed here contrast prior studies and suggest larger, definitive studies are needed to assess the effect of pregnancy on postural control. This study serves as a preliminary exploration of pregnant sensory and segmental postural control and highlights the need for future to hone the role of balance in fall risk during pregnancy.

Comparison of static postural sway characteristics between pregnant and non-pregnant women

The present study aimed to compare the postural sway between pregnant and non-pregnant women during eight different sensory conditions including those in which vision, proprioception, and base of support are compromised. Forty primigravidae at the 32nd week of pregnancy and forty non-pregnant women who were matched for age and anthropometric measurements participated in this cross-sectional comparison study. Static posturography equipment was used to record the anteroposterior sway velocity, mediolateral sway velocity, and velocity moment during normal stance and when vision, proprioception, and base of support were compromised. Pregnant women (mean age: 25.4) demonstrated a larger median velocity moment and mean anteroposterior sway velocity compared to non-pregnant women (mean age:24.4) across all tested sensory conditions (p < 0.05). Although mediolateral sway velocity did not show any statistically significant difference, the ANCOVA results suggested that there was a statistically significant difference in mediolateral sway velocity in Eyes open feet apart condition on the firm surface [F (1,77, p = 0.030, η_p² = 0.121] and Eyes closed feet apart condition on the firm surface [F (1,77, p = 0.015, η_p² = 0.15] between pregnant and non-pregnant women. There was a larger velocity moment and anteroposterior postural sway velocity in pregnant women in their third trimester compared to non-pregnant women when exposed to different sensory conditions. Title: Comparison of static postural sway characteristics between pregnant and non-pregnant women.

Long-term effects of mTBIs includes a higher dependency on visual inputs to control vertical posture

This study investigated the hypothesis that individuals living with long-term effects of mild traumatic brain injury (mTBI) develop an increased dependency on visual inputs to control upright posture. To test this hypothesis, we quantified visuo-postural dependency indices (VPDIs) calculated for multiple postural behavioral markers extracted from the body's center of pressure coordinates signals. These signals were recorded during the execution of a quiet bipedal stance under Vision and No-Vision experimental conditions. VPDIs were calculated as the normalized pair-wise subtraction of recordings obtained under Vision and No-Vision. A total of one hundred and twenty-nine volunteers were organized into two groups: mTBI group (n = 50) and neurotypical control group (n = 79). Consistent with our hypothesis, the results reveal that balance behavior of participants with mTBI deteriorate more abruptly in the absence of visual inputs when compared to neurotypical controls. These impairments might increase the likelihood of recurrent injuries and falls when time-constrained reactions are needed in daily activities, sports practice, or military operations. Additionally, the methodology used in this study shows to be potentially useful to aid future investigations of neural circuitry impaired by mTBI. It also provides indices of recovery for future clinical trials testing mTBI-related clinical interventions.

Center of pressure characteristics differ during single leg stance throughout pregnancy and compared to nulligravida individuals

BACKGROUND

Falls are common during pregnancy and present potential for injury to the pregnant individual and the baby.

RESEARCH QUESTION

Do center of pressure characteristics during single leg stance differ between participants during and after pregnancy and nulligravida participants in the presence and absence of visual input?

METHODS

Nineteen pregnant participants completed testing during the second trimester, the third trimester, and 4-6 months post-partum. Matched, nulligravida females completed testing once. All participants performed single leg stance on a force platform on each limb for up to 20 s with eyes open and with eyes closed. Center of pressure characteristics were compared between pregnant and nulligravida females using three separate 2 × 2 mixed way ANOVAs, one for each pregnancy time point (second trimester, third trimester, and post-partum) with Bonferroni correction.

RESULTS

Pregnant females demonstrated smaller single leg stance time with eyes closed during the third trimester. During the second and third trimester, pregnant participants demonstrated smaller sway and sway velocity across eyes open and eyes closed conditions. During the third trimester and post-partum, pregnant participants demonstrated greater median frequency of the center of pressure data. Pregnant participants also demonstrated smaller sample entropy in the anteroposterior direction during the second and third trimesters and in the mediolateral direction during the second trimester.

SIGNIFICANCE

The decreased total sway and sway velocity observed during pregnancy may reflect rigidity or a protective strategy during single limb stance. Additionally, center of pressure data were less smooth and more repetitive during pregnancy indicating robust differences in postural control strategies and potentially increased fall risk. Because single limb stance is a component of many activities of daily living, the single limb stance task may have clinical utility for testing or training balance in this population with a goal of decreasing falls.

Motor control of the spine in pregnancy-related lumbopelvic pain: A systematic review

BACKGROUND

Some studies observed differences in motor control of the spine between women with pregnancy-related lumbopelvic pain and matched controls. Understanding alterations in spine motor control may help optimizing treatment in this population. The objective is to determine if there are differences in motor control of the spine in pregnant and post-partum women with and without pregnancy-related lumbopelvic pain.

METHODS

Five databases were searched: MEDLINE, Embase, CINAHL, Web of Science and Evidence-Based Medicine Reviews (last search: February 4th 2021). Observational studies that compared motor control of the lumbopelvic spine (in terms of muscle activation [e.g. using EMG or ultrasound imaging] or kinematics) between women with pregnancy-related lumbopelvic pain and matched controls were included. Risk of bias was assessed with a modified version of STROBE statement for cross-sectional studies. No meta-analysis was performed.

FINDING

Fifteen studies were included. Compared to matched controls, pregnant women with pregnancy-related lumbopelvic pain showed differences in lumbar spine kinematic during walking and lifting, although not consistent between studies. The only consistent results were higher transversus abdominis muscle activation during leg movements in post-partum pregnancy-related lumbopelvic pain. Differences in pelvic floor muscle function was inconsistent.

INTERPRETATION

This systematic review identified multiple differences in motor control in pregnancy-related lumbopelvic pain population, predominantly in dynamic tasks. However, consistent differences in lumbopelvic spine motor control were rare. More studies are necessary to determine if motor control is different in pregnancy-related lumbopelvic pain to better understand alteration in motor control and to optimize the efficacy of rehabilitation treatments.

Changes in static balance during pregnancy and postpartum: A systematic review

BACKGROUND

Because pregnant women show a high risk of falling, some researchers examined their balance during static standing. This systematic review summarized the findings from all studies evaluating static balance in women during pregnancy and postpartum.

RESEARCH QUESTION

Do pregnant and postpartum women show differences in static balance compared to non-pregnant women, and does static balance change during pregnancy and postpartum?

METHODS

Pubmed, Embase, CINAHL, and Web of Science databases were searched systematically from inception until Feb 23, 2022. Studies were eligible for inclusion if they measured COP sway with a force plate during bipedal static standing, and compared COP outcomes between healthy pregnant or postpartum women and non-pregnant women, and/or during different stages of pregnancy and the postpartum period. Methodological quality was assessed overall with a modified version of the Downs and Black checklist, and specifically related to COP measurement by using recommendations of Ruhe et al. (2010). The protocol was registered in PROSPERO (CRD42020166302).

RESULTS

Thirteen studies were included. Because methodological approaches varied greatly between studies, results were summarized descriptively. Studies reported either greater overall and anteroposterior COP sway magnitude, velocity and variability in women from the second half of pregnancy until six months postpartum compared to non-pregnant controls, or no differences in static balance. Changes in static balance throughout pregnancy were generally not found. Finally, there was no clear consensus on the influence of pregnancy on the reliance on visual inputs for balance control, and on whether differences in balance in pregnant and postpartum women reflect poorer balance or positive adaptations to the physical changes experienced during pregnancy.

SIGNIFICANCE

Methodological heterogeneity between studies prevented us from drawing strong conclusions regarding the effect of pregnancy on static balance. Assessing the methodological quality of the studies revealed weaknesses that should be taken into account in future studies.

Assessment of postural sway with a pendant-mounted wearable sensor

BACKGROUND

Body-worn inertial measurement unit (IMU) sensors have been widely used in postural stability and balance studies because of their low cost and convenience. In most of these studies, a single IMU sensor is attached to a waist belt near the body's center of mass. Some populations such as pregnant women, however, may find a waist belt challenging in terms of fit and comfort. For this reason it may be useful to identify an alternative location for placement of an IMU and a more comfortable means for attaching the sensor to the body. Research question Does placing an IMU sensor in a pendant worn around the neck permit discrimination between conditions with varying postural stability?

METHODS

Twenty-six healthy participants performed three standing tasks (double-leg, tandem, and single-leg standing) under eyes-open and eyes-closed vision conditions to preliminarily assess the ability of the pendant sensor to discriminate between balance conditions. Discrimination based upon data from a belt-mounted IMU was assessed in the same trials. Differences in standard deviation of acceleration components, sway area, and jerkiness due to trial condition and sensor were evaluated using analysis of variance followed by post hoc comparisons. These data were also incorporated into receiver-operator characteristic (ROC) curve analysis to assess the effectiveness of each sensor at discriminating between conditions.

RESULTS

Stability was found to vary across conditions, but there was no interaction between stability and sensor location (all p ≥ 0.323). ROC curve analysis showed that sensors in both locations were good discriminators between conditions. Significance Placing an IMU in a pendant may be feasible for studying and monitoring postural instability. This approach may be especially valuable when considering populations for which wearing a belt is uncomfortable.

Assessment of knee and ankle proprioception during the third trimester of pregnancy and postpartum period among primiparous women: An observational longitudinal study

BACKGROUND

Pregnant women experience falls, particularly in the third trimester. In this population, physiological changes, as well as ligament laxity, might influence joint proprioception and do not return to normal during the postpartum period. The prevalence of falls during pregnancy and postpartum periods imposes a need to study proprioception in pregnant women and the postpartum period.

MATERIALS AND METHOD

An observational longitudinal study was conducted in June 2018 in outpatient clinic Chinchwad Pune. A total of 36 primiparous women were included in the study by using purposive sampling. The mean and standard deviation of the age was 25.92 (2.59). Proprioception was assessed for the knee joint and the ankle joint during the third trimester of pregnancy and 6^th and 12^th week postpartum. Outcomes included were the Joint Reposition Test for both knee and ankle joints using UTHSCSA Image Tool Software 3.0. Repeated-measure ANOVA was performed for the normally distributed data, and nonparametric test Friedman's test was performed for data that were not distributed normally. The data was statistically analyzed using the SPSS software version 26. The level of significance was set at 0.05, confidence intervals of 95% were used.

RESULT

The result revealed significant (P < 0.05) improvement in both knee and ankle proprioception during the third trimester of pregnancy and postpartum period 6^th and 12^th week.

CONCLUSION

Knee proprioception and ankle proprioception were found to improve significantly during the postpartum period 6^th and 12^th weeks compared to the third trimester of pregnancy but do not return to the prepregnancy state.

Nonlinear Measures to Evaluate Upright Postural Stability: A Systematic Review

Conventional biomechanical analyses of human movement have been generally derived from linear mathematics. While these methods can be useful in many situations, they fail to describe the behavior of the human body systems that are predominately nonlinear. For this reason, nonlinear analyses have become more prevalent in recent literature. These analytical techniques are typically investigated using concepts related to variability, stability, complexity, and adaptability. This review aims to investigate the application of nonlinear metrics to assess postural stability. A systematic review was conducted of papers published from 2009 to 2019. Databases searched were PubMed, Google Scholar, Science-Direct and EBSCO. The main inclusion consisted of: Sample entropy, fractal dimension, Lyapunov exponent used as nonlinear measures, and assessment of the variability of the center of pressure during standing using force plate. Following screening, 43 articles out of the initial 1100 were reviewed including 33 articles on sample entropy, 10 articles on fractal dimension, and 4 papers on the Lyapunov exponent. This systematic study shows the reductions in postural regularity related to aging and the disease or injures in the adaptive capabilities of the movement system and how the predictability changes with different task constraints.

Influence of type 1 diabetes on the postural control of women in the third gestational trimester

BACKGROUND

Diabetes can cause biomechanical alterations that may be responsible for additional changes to those existing in a regular gestational period. The way a maternal body responds when affected by diabetes has not been clearly understood. This study aimed to describe the influence of type 1 diabetes on pregnant women's postural control.

METHODS

Forty pregnant women in their third gestational trimester were allocated in two equal groups - the control group and the type 1 diabetic group. The variables related to postural control and balance were assessed using photogrammetry (head protrusion; cervical lordosis; thoracic kyphosis; lumbar lordosis; pelvic anteversion, knee flexion, tibiotarsal and foot inclination angles were measured), and baropodometry (anteroposterior and mediolateral distance trajectory of the center of pressure, amplitude and average speed of displacement of the center of pressure).

FINDINGS

The results of the type 1 diabetic group showed, in the postural analysis, lower head protrusion and pelvic anteversion angles, while there was higher cervical lordosis, thoracic kyphosis, and lumbar lordosis angles. In the baropodometry, the anteroposterior distance and the amplitude of the center of pressure displacement with eyes open and closed were higher.

INTERPRETATION

The findings suggest that type 1 diabetes mellitus in the third trimester of pregnancy is associated with postural changes, a decrease in the active ankle range of motion and increase in the anteroposterior oscillation of the center of pressure, with negative repercussions for postural control.