Changes in segmental mass and inertia during pregnancy: A musculoskeletal model of the pregnant woman

Spinal joint moment prediction following simulated breast surgery using a female whole-body musculoskeletal model

This study aimed to use a musculoskeletal model to predict changes in spinal moments following simulated breast surgery. A female full body musculoskeletal model with a fully articulated thoracolumbar spine and independent moveable breast segments was customised for this study. Key findings suggest that the simulated removal of breast tissue (750 g to 1501 g) can reduce the magnitude of lumbar spine extensor moments by >0.05 Nm/kg during walking and jogging. A customised female whole-body musculoskeletal model is capable of providing a first approximation of changes in spinal loading following simulated breast surgery.

The association of back pain with physical inactivity and hypothyroidism in pregnant women

BACKGROUND

During pregnancy, structural and functional changes usually occur in the body, which has various consequences, including lower back pain (LBP) and hypothyroidism. One of the risk factors for these problems is physical inactivity.

OBJECTIVE

This study aimed to investigate the association of back pain and physical inactivity, weight gain, and hypothyroidism in pregnant women.

METHODS

In this cohort study, 420 pregnant women (26.333 ± 5.820 years old) were included. At first, participants answered this question: "Do you have any plans for pregnancy in the next month?" If the answer was yes, further evaluations were performed. The physical activity and pain intensity were measured by the International Physical Activity Questionnaire Short Form (IPAQ-S) and Visual Analogue Scale. Serum TSH was measured by automated chemiluminescence and commercial kits. Measurements were conducted before, the first, second, and third trimester of pregnancy.

RESULTS

Women reporting LBP were less engaged in physical activities and weight gained in the second and third trimesters of pregnancy was significantly higher than pregnant women without LBP (p< 0.05). TSH level and weight gained in pregnant women with low physical activity level was significantly higher than pregnant women with moderate and high physical activity (p< 0.05) (without significant difference in TSH and BMI). The physical inactivity (before: OR: 1.11 95% CI: 0.89 to 1.22; first trimester: OR: 1.09 95% CI: 1.02 to 1.59; second trimester: OR: 0.92 95% CI: 0.87 to 1.31; third trimester: OR: 1.12 95% CI: 1.02 to 1.39), TSH (OR: 0.85 95% CI: 0.57 to 1.29), and weight gain (second trimester: OR: 0.87 95% CI: 0.92 to 1.59; third trimester: OR: 1.44 95% CI: 1.02 to 1.98; p< 0.05) did predict increased pain intensity.

CONCLUSION

Using health-oriented approaches to increase physical activity and normalize thyroid function and weight gain during pregnancy can have beneficial effects on LBP.

Are physical fitness, a history of childbirth and injury history related to knee valgus in female Canadian Armed Forces members during a bodyweight overhead squat movement?

OBJECTIVES

A history of childbirth is associated with musculoskeletal injury (MSKi) in female members of the Canadian Armed Forces (CAF). While previous injury and pregnancy impact knee kinematics, it is unclear if a history of childbirth is associated with medial knee displacement (MKD) in an overhead squat movement screen. The aim of this study is to examine the relationship between MKD and (1) MSKi and (2) parity status in female CAF members.

METHODS

24 nulliparous and 21 parous female participants employed by the CAF completed a comprehensive physical fitness assessment of muscular flexibility, power, strength, endurance, aerobic capacity and a bodyweight overhead squat movement screen (recorded using two-dimensional video, and hip-knee-ankle angle measured using Kinovea software). Interactions between MKD, parity status and MSKi history were assessed by one-way analysis of variance and two-way analysis of covariance (ANCOVA) (adjusted for age).

RESULTS

An interaction between parity status and acute injury of the lower extremity was observed (F=4.379, p=0.043, η2 =0.099) in MKD of the right knee. The two-way ANCOVA examining acute injury of the lumbopelvic hip complex (lower back, pelvis, hip) yielded an interaction between acute injury to the lumbopelvic hip complex and parity status (F=4.601, p=0.038, η2=0.103) in MKD asymmetry.

DISCUSSION

Parous participants with acute injury to the lower extremity had larger MKD than parous without this injury type. Parous participants without acute injury to the lumbopelvic hip complex had greater MKD asymmetry than nulliparous without this injury type. Our findings suggest that researchers and clinicians should consider parity status in conjunction with MSKi history when assessing knee kinematics in female military members.

Voice Quality of Life and Musculoskeletal Symptoms of Pregnant Women

INTRODUCTION

Quality of life in terms of voice and musculoskeletal symptoms can be affected, especially at the end of pregnancy when major physical changes occur.

OBJECTIVE

To analyze the results of vocal self-assessment and musculoskeletal symptoms of pregnant women in the second and third trimester.

METHODS

Forty-nine pregnant women in the second and third trimester aged between 18 and 40years were examined using the Nordic Musculoskeletal Questionnaire and the Voice-Related Quality of Life Questionnaire. The data were statistically analyzed using the R environment (R Core Team, 2019) with parametric (Student's t, chi-square, and Wald) and nonparametric (Mann-Whitney and Wilcoxon) tests, taking into account a nominal significance level of 5%.

RESULTS

Voice-related quality of life: mean total score and socio-emotional domain significantly within the normal values; physical domain significantly below the normal value; larger number of pregnant women significantly below the normal value in the physical domain. Nordic Musculoskeletal Questionnaire: most of the examined aspects showed a significant negative response; there was a positive significance for the presence of pain and tingling in the lower back; pregnant women with musculoskeletal complaints and impairments showed a significant decrease in the three domains of voice-related quality of life, mainly in the physical domain.

CONCLUSION

Pregnant women showed a deterioration in the physical domain of voice-related quality of life and the presence of pain and tingling in the lower back. Pregnant women who had discomfort and musculoskeletal impairments also showed a deterioration in voice-related quality of life, mainly in the physical domain.

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.

On the estimation of hip joint centre location with incomplete bone ossification for foetus-specific neuromusculoskeletal modeling

Childbirth is a complex physiological process in which a foetal neuromusculoskeletal model is of great importance to develop realistic delivery simulations and associated complication analyses. However, the estimation of hip joint centre (HJC) in foetuses remains a challenging issue. Thus, this paper aims to propose and evaluate a new approach to locate the HJC in foetuses. Hip CT-scans from 25 children (F = 11, age = 5.5 ± 2.6 years, height = 117 ± 21 cm, mass = 26 kg ± 9.5 kg) were used to propose and evaluate the novel acetabulum sphere fitting process to locate the HJC. This new approach using the acetabulum surface was applied to a population of 57 post-mortem foetal CT scans to locate the HJC as well as to determine associated regression equations using multiple linear regression. As results, the average distance between the HJC located using acetabulum sphere fitting and femoral head sphere fitting in children was 1.5 ± 0.7 mm. The average prediction error using our developed foetal HJC regression equations was 3.0 ± 1.5 mm, even though the equation for the x coordinate had a poor value of R2 (R2 for the x coordinate = 0.488). The present study suggests that the use of the acetabulum sphere fitting approach is a valid and accurate method to locate the HJC in children, and then can be extrapolated to get an estimation of the HJC in foetuses with incomplete bone ossification. Therefore, the present paper can be used as a guideline for foetus specific neuromusculoskeletal modelling.

Effect of pregnancy on female gait characteristics: a pilot study based on portable gait analyzer and induced acceleration analysis

Introduction: The changes in physical shape and center of mass during pregnancy may increase the risk of falls. However, there were few studies on the effects of maternal muscles on gait characteristics and no studies have attempted to investigate changes in induced acceleration during pregnancy. Further research in this area may help to reveal the causes of gait changes in women during pregnancy and provide ideas for the design of footwear and clothing for pregnant women. The purpose of this study is to compare gait characteristics and induced accelerations between non-pregnant and pregnant women using OpenSim musculoskeletal modeling techniques, and to analyze their impact on pregnancy gait. Methods: Forty healthy participants participated in this study, including 20 healthy non-pregnant and 20 pregnant women (32.25 ± 5.36 weeks). The portable gait analyzer was used to collect participants' conventional gait parameters. The adjusted OpenSim personalized musculoskeletal model analyzed the participants' kinematics, kinetics, and induced acceleration. Independent sample T-test and one-dimensional parameter statistical mapping analysis were used to compare the differences in gait characteristics between pregnant and non-pregnant women. Results: Compared to the control group, pregnancy had a 0.34 m reduction in mean walking speed (p < 0.01), a decrease in mean stride length of 0.19 m (p < 0.01), a decrease in mean stride frequency of 19.06 step/min (p < 0.01), a decrease in mean thigh acceleration of 0.14 m/s² (p < 0.01), a decrease in mean swing work of 0.23 g (p < 0.01), and a decrease in mean leg falling strength of 0.84 g (p < 0.01). Induced acceleration analysis showed that pregnancy muscle-induced acceleration decreased in late pregnancy (p < 0.01), and the contribution of the gastrocnemius muscle to the hip and joint increased (p < 0.01). Discussion: Compared with non-pregnant women, the gait characteristics, movement amplitude, and joint moment of pregnant women changed significantly. This study observed for the first time that the pregnant women relied more on gluteus than quadriceps to extend their knee joints during walking compared with the control group. This change may be due to an adaptive change in body shape and mass during pregnancy.

Distinct Kinematic and Neuromuscular Activation Strategies During Quiet Stance and in Response to Postural Perturbations in Healthy Individuals Fitted With and Without a Lower-Limb Exoskeleton

Many individuals with disabling conditions have difficulty with gait and balance control that may result in a fall. Exoskeletons are becoming an increasingly popular technology to aid in walking. Despite being a significant aid in increasing mobility, little attention has been paid to exoskeleton features to mitigate falls. To develop improved exoskeleton stability, quantitative information regarding how a user reacts to postural challenges while wearing the exoskeleton is needed. Assessing the unique responses of individuals to postural perturbations while wearing an exoskeleton provides critical information necessary to effectively accommodate a variety of individual response patterns. This report provides kinematic and neuromuscular data obtained from seven healthy, college-aged individuals during posterior support surface translations with and without wearing a lower limb exoskeleton. A 2-min, static baseline standing trial was also obtained. Outcome measures included a variety of 0 dimensional (OD) measures such as center of pressure (COP) RMS, peak amplitude, velocities, pathlength, and electromyographic (EMG) RMS, and peak amplitudes. These measures were obtained during epochs associated with the response to the perturbations: baseline, response, and recovery. T-tests were used to explore potential statistical differences between the exoskeleton and no exoskeleton conditions. Time series waveforms (1D) of the COP and EMG data were also analyzed. Statistical parametric mapping (SPM) was used to evaluate the 1D COP and EMG waveforms obtained during the epochs with and without wearing the exoskeleton. The results indicated that during quiet stance, COP velocity was increased while wearing the exoskeleton, but the magnitude of sway was unchanged. The OD COP measures revealed that wearing the exoskeleton significantly reduced the sway magnitude and velocity in response to the perturbations. There were no systematic effects of wearing the exoskeleton on EMG. SPM analysis revealed that there was a range of individual responses; both behaviorally (COP) and among neuromuscular activation patterns (EMG). Using both the OD and 1D measures provided a more comprehensive representation of how wearing the exoskeleton impacts the responses to posterior perturbations. This study supports a growing body of evidence that exoskeletons must be personalized to meet the specific capabilities and needs of each individual end-user.

The Influence of a Shoe's Heel-Toe Drop on Gait Parameters during the Third Trimester of Pregnancy

Background: Changes in physical shape and body mass during pregnancy may increase the risk of walking falls. Shoes can protect and enhance the inherent function of the foot, helping to maintain dynamic and static stability. Methods: Sixteen women during the third trimester of pregnancy participated in this study to investigate the effect of negative heel shoes (NHS), positive heel shoes (PHS), and normal shoes (NS) on spatiotemporal parameters, ground reaction force (GRF), and stability. Differences in spatiotemporal parameter, GRF, and center of pressure (COP) between footwear conditions were examined using Statistical Parametric Mapping (SPM) and repeated measures analyses of variance (ANOVA). Results: The walking speed and step length increased with the increase in heel-toe drop. The anterior-posterior (AP)-COP in NHS decreased significantly (p < 0.001). When wearing NHS, peak posterior angles were significantly lower than NS and PHS (p < 0.05). Conclusions: The results show that changing the heel-toe drop can significantly affect the gait pattern of pregnant women. Understanding the gait patterns of pregnant women wearing shoes with different heel-toe drops is very important for reducing the risk of injury and equipment design.

How Does the Lumbopelvic Complex Cope with the Obstetrical Load during Standing? Ergonomic Aspects of Body Posture in Pregnant Women

Pregnancy induces numerous modifications in the musculoskeletal system of the female body. Since one of the essential roles of the lumbopelvic structure is to support mechanical loads in the upright position, this study was designed to simulate the response of this complex to the growing foetus in pregnant women. The authors hypothesized that posture (i.e., lordosis and muscle involvement) under pregnancy conditions might be adjusted to minimize the demands of the obstetrical load. The analysis of the load on the musculoskeletal system during gestation was made based on numerical simulations carried out in the AnyBody Modeling System. The pregnancy-related adjustments such as increased pelvic anteversion and increased lumbar lordosis enhance the reduction of muscle activation (e.g., erector spinae, transversus abdominis or iliopsoas), muscle fatigue and spinal load (reaction force). The results may help develop antenatal exercise programs targeting core strength and pelvic stability.

Simulation of 3D Body Shapes for Pregnant and Postpartum Women

Several studies have reported that pre-pregnant women’s body mass index (BMI) affects women’s weight gain with complications during pregnancy and the postpartum weight retention. It is important to control the BMI before, during and after pregnancy. Our objectives are to develop a technique that can compute and visualize 3D body shapes of women during pregnancy and postpartum in various gestational ages, BMI, and postpartum durations. Body changes data from 98 pregnant and 83 postpartum women were collected, tracked for six months, and analyzed to create 3D model shapes. This study allows users to simulate their 3D body shapes in real-time and online, based on weight, height, and gestational age, using multiple linear regression and morphing techniques. To evaluate the results, precision tests were performed on simulated 3D pregnant and postpartum women’s shapes. Additionally, a satisfaction test on the application was conducted on new 149 mothers. The accuracy of the simulation was tested on 75 pregnant and 74 postpartum volunteers in terms of relationships between statistical calculation, simulated 3D models and actual tape measurement of chest, waist, hip, and inseam. Our results can predict accurately the body proportions of pregnant and postpartum women.

Shoulder and elbow requirements during sagittal reach as a result of changing anthropometry throughout pregnancy

During pregnancy, anthropometric and physiological changes can result in difficulty reaching for and lifting everyday objects. The aims of this study were to determine the changes in sagittal plane anterior reach space (SPARS) and shoulder/elbow strength requirements throughout pregnancy. Seventeen participants were tested through a longitudinal observational cohort study between 16 and 36 weeks gestation in four-week intervals. A 25% decrease in SPARS was observed at the L3-4 torso height. Combined with arm mass increases, shoulder and elbow moment requirements at the minimum and maximum static reach distances significantly increased. However, inverse dynamics analysis determined that mass gains in the arm alone only minimally impact dynamic shoulder moments. Additionally, torso flexion increases throughout pregnancy demonstrates that women are attempting to compensate for decreased SPARS, possibly indicating the additional perceptual importance of reach space in accommodations for pregnant workers.