Changes in Gait with Anteriorly Added Mass: A Pregnancy Simulation Study

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.

Case Studies in Physiology: Adaptation of Loading-Bearing Tendons during Pregnancy

Pregnancy is characterized by hormone changes that could alter musculoskeletal (MSK) properties and temporarily increase soft tissue injury risk. Whilst the prevalence of MSK injuries in pregnancy has not yet proven itself to be a widespread problem, indirect evidence indicates an uptake in the prevalence of strength training and vigorous-intensity activity during pregnancy, which may result in increased MSK injury incidence. Combining this evidence with the association between sex hormones and MSK injury risk, we recognize the potential importance of this research area and believe the (prospective) examination of connective tissue properties in relation to hormonal changes in pregnancy are appropriate. Given the dearth of information on MSK adaptations to pregnancy, we present a variety of morphological, mechanical and functional tendon data from two consecutive pregnancies in one woman as a means of highlighting this under-researched topic. This data may be representative of the general pregnant population, or it may be highly individualized - more research is required for a better understanding of MSK adaptation and injury risk during and after pregnancy.

Characterization of knee dysfunction and related risk factors during pregnancy

BACKGROUND

Knee pain can be a common complaint during pregnancy; however, the severity of symptoms and their associated risk factors have not been described.

QUESTIONS/PURPOSES

The aim of this study was to characterize knee-related dysfunction and describe risk factors in a general obstetric population.

PATIENTS AND METHODS

Patients in obstetric clinics completed the International Knee Documentation Committee (IKDC) questionnaire to assess their knee function, as well as the Pregnancy Physical Activity Questionnaire (PPAQ), a validated tool to assess physical activity. Age, weeks gestation, height, weight, and history of knee problems prior to pregnancy were analyzed to identify independent associations with IKDC score and determine predictors of knee dysfunction.

RESULTS

310 patients were included in this study, of which 68, 111 and 131 were in their first, second and trimesters, respectively. Mean age of the total study group was 30.3 ± 5.5 years. Knee function decreased with each trimester, from a mean IKDC score of 88.9 ± 13.0 in the first trimester, 84.5 ± 16.8 in the second, and 82.0 ± 20.0 in the third, with corresponding decreases in activity levels of 258.5 ± 141.7, 254.0 ± 141.5, and 246.1 ± 156.6 MET-h/wk. Of the total study group, 26.1% had IKDC scores <75, including 13.2%, 25.2%, and 33.6% in the first, second and third trimesters. Risk factors for knee dysfunction included high activity levels of PPAQ ≥ 500 MET-h/wk (OR 2.8), history of knee problems (OR 2.7), age <25 years (OR 2.6), and BMI ≥ 30 kg/m² (OR 1.9).

CONCLUSION

In our cohort, 26.1% of pregnant women reported severe knee dysfunction, and this was associated with high levels of activity, younger age, greater BMI, and history of knee problems. These findings may have implications for women who wish to maintain training and fitness during pregnancy. Future studies are recommended to assess the need for intervention, as well as to identify optimal methods to prevent and address symptoms in this population.

LEVEL OF EVIDENCE

IV, Case Series.

Short Physical Performance Battery (SPPB) score as a discriminator of dynapenic abdominal obesity among community-dwelling older adults

The aim of this study is to verify the utility of using physical performance to discriminate the presence of dynapenic abdominal obesity (DAO) in older adults. This cross-sectional study was conducted with 382 community-dwelling older adults. DAO was identified when dynapenia (cut-off points of <26 kilogram-force [kgf] for men and <16 kgf for women) was detected together with abdominal obesity (waist circumference >102 cm for men and >88 cm for women). Physical performance was assessed with the Short Physical Performance Battery (SPPB). SPPB scores and DAO were inversely associated even after adjustment (OR: 0.69; 95%CI: 0.58-0.83). Cut-off points of ≤9 for SPPB scores were the most efficient for discriminating the presence of DAO in both men (AUC= 0.836; 95%CI: 0.76-0.89; sensitivity: 90.91% and specificity: 60.33%) and women (AUC= 0.677; 95%CI: 0.62-0.73; sensitivity: 73.33% and specificity: 40.91%). Physical performance assessed with SPPB can discriminate DAO and be useful for the timely identification and management of this condition in older adults.

Cutaneous tactile sensitivity before and after tail loss and regeneration in the leopard gecko (Eublepharis macularius)

Amongst tetrapods, mechanoreceptors on the feet establish a sense of body placement and help to facilitate posture and biomechanics. Mechanoreceptors are necessary for stabilizing the body while navigating through changing terrains or responding to a sudden change in body mass and orientation. Lizards such as the leopard gecko (Eublepharis macularius) employ autotomy – a voluntary detachment of a portion of the tail – to escape predation. Tail autotomy represents a natural form of significant (and localized) mass loss. Semmes–Weinstein monofilaments were used to investigate the effect of tail autotomy (and subsequent tail regeneration) on tactile sensitivity of each appendage of the leopard gecko. Prior to autotomy, we identified site-specific differences in tactile sensitivity across the ventral surfaces of the hindlimbs, forelimbs and tail. Repeated monofilament testing of both control (tail-intact) and tail-loss geckos had a significant sensitization effect (i.e. decrease in tactile threshold, maintained over time) in all regions of interest except the palmar surfaces of the forelimbs in post-autotomy geckos, compared with baseline testing. Although the regenerated tail is not an exact replica of the original, tactile sensitivity is shown to be effectively restored at this site. Re-establishment of tactile sensitivity on the ventral surface of the regenerate tail points towards a (continued) role in predator detection.

Impact of parity on biomechanical risk factors for knee OA initiation

BACKGROUND

Women are twice as likely as men to develop knee osteoarthritis (OA), and with it experience greater losses of physical function and disability. A change in the mechanical environment of the joint is a key initiating factor for knee OA. Differences in morphology, joint injury risk, and hormonal shifts in mid-life are often considered factors which increase OA risk for women. Pregnancy, a time of significant hormonal, morphological, and biomechanical change, has received comparably less attention. If morphological and biomechanical changes persist postpartum, this could increase OA risk for parous (childbearing) women.

RESEARCH QUESTION

Are lower limb gait mechanics different between healthy nulliparous (non-childbearing) and parous (childbearing) women?

METHODS

Twenty-eight self-reported not pregnant female participants (14 parous, 14 nulliparous) were recruited for the study. Nulliparous participants had never given birth to a child. Parous participants had given birth to at least one full-term infant (37-42 weeks) without complications between one to five years before data collection. Motion capture of participants' preferred, fast, and set (1.4 m/s) walking speeds was conducted. Repeated measures ANOVA were performed to test for significant group differences in joint kinematics and kinetics.

RESULTS

There was a significant main effect of group indicating a larger knee flexion angle at toe off (p = 0.0002), smaller knee extension moment at heel strike (p = 0.0006), smaller first peak knee flexion moment (p = 0.040), and smaller peak hip adduction moment for the parous group compared to the nulliparous group (p = 0.003). Static Q-angle did not differ between groups.

SIGNIFICANCE

Alteration in mechanics from the habitual loading pattern are thought to increase risk of OA. Smaller knee moments in post-partum women could alter the mechanical stimulus to cartilage, and should be investigated in conjunction with cartilage health measures to determine the link with OA initiation.

The Association of Obesity With Quadriceps Activation During Sit-to-Stand

OBJECTIVE

Obesity reduces voluntary recruitment of quadriceps during single-joint exercises, but the effects of obesity on quadriceps femoris muscle activation during dynamic daily living tasks, such as sit-to-stand (STS), are largely unknown. The purpose of this study was to determine how obesity affects quadriceps muscle recruitment during STS.

METHODS

In this cross-sectional study, 10 women who were lean and 17 women who were obese completed STS from a chair with arms crossed over the chest. Three-dimensional motion analysis was used to define 3 distinct phases (I-III) of the STS cycle. The electromyographic (EMG) activity of the vastus medialis, vastus lateralis, and semitendinosus was measured.

RESULTS

STS duration was greater (3.02 [SD = 0.75] seconds vs 1.67 [SD = 0.28] seconds) and peak trunk flexion angle was lower (28.9 degrees [SD = 10.4 degrees] vs 35.8 degrees [SD = 10.1 degrees]) in the women who were obese than in the women who were lean. The mean EMG activity of the knee extensors increased from phase I to phase II in both groups; however, the mean EMG activities of both the vastus medialis (32.1% [SD = 16.6%] vs 47.3% [SD = 19.6%] maximal voluntary isometric contraction) and the vastus lateralis (31.8% [SD = 19.4%] vs 47.5% [SD = 19.6%] maximal voluntary isometric contraction) were significantly lower during phase II in the women who were obese. The mean EMG activity of the semitendinosus increased throughout STS but was not significantly different between the 2 groups. Coactivation of the semitendinosus and knee extensors tended to be greater in the women who were obese but failed to reach statistical significance.

CONCLUSIONS

Knee extensor EMG amplitude was reduced in women who were obese during STS, despite reduced trunk flexion.

IMPACT

Reduced knee extensor recruitment during STS in obesity may redistribute forces needed to complete this task to other joints. Functional movement training may help improve knee extensor recruitment during STS in people who are obese.

LAY SUMMARY

People with obesity often have low quadriceps muscle strength and impaired mobility during daily activities. This study shows that women who are obese have lower voluntary recruitment of quadriceps when rising from a chair than women who are lean do, which could increase workload on hip or ankle muscles during this important daily task. Quadriceps strengthening exercises might improve the ability to rise from sitting to standing.

Mechanisms of Gait Adaptation in Overweight Pregnant Women

BACKGROUND

Pregnancy is a period when a woman's body undergoes changes. The purpose of this study was to analyze the mechanisms of gait adaptation in overweight pregnant women regarding spatiotemporal gait parameters, ground reaction forces, and plantar pressure distribution.

METHODS

The tests were performed in 29 normal-weight pregnant women and 26 pregnant women who were overweight before pregnancy. The measurements included spatiotemporal gait parameters, in-shoe plantar pressure distribution, and ground reaction forces during gestation.

RESULTS

The results indicate that both normal-weight and overweight pregnant women make use of the same spatiotemporal gait parameters to increase body stability and safety of movement during pregnancy. The double-step duration in the third trimester of pregnancy was higher in normal-weight and overweight pregnant women compared with in the first trimester (P < .05). A significant change in pressure amplitude was found under all anatomical parts of the foot in the third trimester (P < .05). The results also suggest a higher increase in the maximum amplitude of force in overweight pregnant women in the third trimester compared with the normal-weight group.

CONCLUSIONS

This study suggests that both normal-weight and overweight pregnant women use different mechanisms of gait adaptation during pregnancy. In practice, understanding the biomechanical changes in women's gait can protect the musculoskeletal system during gestation.

Effort-Based Decision-Making and Gross Motor Performance: Are They Linked?

The purpose of this study was to investigate the relationship between effort-based decision making and gross motor performance. Effort-based decision making was measured using a modified version of the Effort Expenditure for Rewards Task (EEfRT), in which participants pressed a button on a keyboard to fill a bar on a screen for monetary reward. Participants received monetary rewards that were commensurate with the level of effort that they were willing to expend. Gross motor performance was measured with a walking task, in which participants matched their steps to the beat of an audio metronome; they walked to metronome beats that were slower and also faster than their normal walking pace. We hypothesized that increased effort during the effort-based decision making task would be paired with an increase in steps taken per minute during the gross motor task. However, the results of this study indicated a lack of a statistically significant relationship between the effort-based decision making task and the gross motor task. Planning rather than decision-making may have been the cognitive construct that governed our gross motor task. These findings can be beneficial when thinking about potential interventions for populations who experience deficits in motor performance and cognition as well as for understanding the relationship between both cognitive and motor performance in healthy adults.

Adolescent Awkwardness: Alterations in Temporal Control Characteristics of Posture with Maturation and the Relation to Movement Exploration

A phenomenon called adolescent awkwardness is believed to alter motor control, but underlying mechanisms remain largely unclear. Since adolescents undergo neurological and anthropometrical changes during this developmental phase, we hypothesized that adolescents control their movements less tightly and use a different coordinative structure compared to adults. Moreover, we tested if emerging differences were driven by body height alterations between age groups. Using 39 reflective markers, postural movements during tandem stance with eyes open and eyes closed of 12 adolescents (height 168.1 ± 8.8 cm) and 14 adults were measured, in which 9 adults were smaller or equal than 180 cm (177.9 ± 3.0 cm) and 5 taller or equal than 190 cm (192.0 ± 2.5 cm). A principal component analysis (PCA) was used to extract the first nine principal movement components (PMk). The contribution of each PMk to the overall balancing movement was determined according to their relative variance share (rVARk) and tightness of motor control was examined using the number of times that the acceleration of each PMk changed direction (Nk). Results in rVARk did not show significant differences in coordinative structure between adolescents and adults, but Nk revealed that adolescents seem to control their movements less tightly in higher-order PMk, arguably due to slower processing times and missing automatization of postural control or potential increases in exploration. Body height was found to not cause motor control differences between age groups.

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

BACKGROUND

One in four pregnant women falls at least once during her pregnancy. During pregnancy, the body undergoes tremendous vascular, hormonal, physiological, and psychological changes to accommodate the growing fetus. The pregnancy-induced mass gain of 10 to 25 kg is not evenly distributed and results in a large change in mass distribution and shift in segmental centers of mass. To accurately understand how the change in mass distribution leads to an increase in fall events, a musculoskeletal model of the pregnant body is necessary. Generic musculoskeletal models cannot accurately represent the morphology of pregnant women and the study of postural stability of pregnant women is limited by the lack of adapted musculoskeletal models.

RESEARCH QUESTION

Could a model reflecting the change in segmental inertia during pregnancy explain the pregnancy-related risk of falling?

METHODS

We built a musculoskeletal model of the pregnant women, combining literature anthropomorphic measurements with generic models. We optimized the dimensions of the anthropomorphic model shapes to fit the average measurements of 25 pregnant women. The mass, center of mass, and inertia of each segment are then computed throughout pregnancy. Finally, the stance phase of a gait cycle was modeled using the pregnancy-specific and the generic models. The ankle, knee, hip and lumbar joint moments during gait were compared between the two models.

RESULTS

The built musculoskeletal model of the pregnant woman includes changes in mass and geometry of the thorax, pelvis, thighs, and legs. The model reproduces the change in lumbar curvature during pregnancy. Gait simulation results show a limited impact of pregnancy on the ankle, knee, and hip moment, but a large impact on the lumbar moment.

SIGNIFICANCE

Such a musculoskeletal model will help elucidate the mechanisms leading to falls or low back pain during pregnancy.

Ankle and midtarsal joint quasi-stiffness during walking with added mass

Examination of how the ankle and midtarsal joints modulate stiffness in response to increased force demand will aid understanding of overall limb function and inform the development of bio-inspired assistive and robotic devices. The purpose of this study is to identify how ankle and midtarsal joint quasi-stiffness are affected by added body mass during over-ground walking. Healthy participants walked barefoot over-ground at 1.25 m/s wearing a weighted vest with 0%, 15% and 30% additional body mass. The effect of added mass was investigated on ankle and midtarsal joint range of motion (ROM), peak moment and quasi-stiffness. Joint quasi-stiffness was broken into two phases, dorsiflexion (DF) and plantarflexion (PF), representing approximately linear regions of their moment-angle curve. Added mass significantly increased ankle joint quasi-stiffness in DF (p < 0.001) and PF (p < 0.001), as well as midtarsal joint quasi-stiffness in DF (p < 0.006) and PF (p < 0.001). Notably, the midtarsal joint quasi-stiffness during DF was ~2.5 times higher than that of the ankle joint. The increase in midtarsal quasi-stiffness when walking with added mass could not be explained by the windlass mechanism, as the ROM of the metatarsophalangeal joints was not correlated with midtarsal joint quasi-stiffness (r = -0.142, p = 0.540). The likely source for the quasi-stiffness modulation may be from active foot muscles, however, future research is needed to confirm which anatomical structures (passive or active) contribute to the overall joint quasi-stiffness across locomotor tasks.

Reproductive factors and risk of total knee replacement due to severe knee osteoarthritis in women, the Singapore Chinese Health Study

OBJECTIVES

Knee osteoarthritis (OA) is more common in women, and may be related to reproductive or hormonal factors. We evaluated these factors with the risk of total knee replacement (TKR) for severe knee OA among women.

METHODS

The Singapore Chinese Health Study recruited 63,257 Chinese aged 45-74 years from 1993 to 1998, and among them, 35,298 were women. Information on height, weight, lifestyle factors, number of biological children, ages at menarche and menopause, and use of hormonal therapies was collected through interviews. Incident cases of TKR were identified via linkage with nationwide database.

RESULTS

There were 1,645 women with TKR after mean follow-up of 14.8 years. Higher parity was associated with increased TKR risk in a stepwise manner (P for trend <0.001). Compared to nulliparous women, those with ≥5 children had the highest risk [hazard ratio (HR) 2.01, 95% confidence intervals (CIs) 1.50-2.70]. The effect of parity on TKR risk was significantly stronger among lean women compared to heavier women; HRs (95% CIs) for highest parity was 4.86 (2.22-10.63) for women with body mass index (BMI) <23 kg/m² and 1.57 (1.14-2.14) for those ≥23 kg/m² (P for interaction = 0.001). Earlier age at menarche and use of oral contraceptives were significantly associated with TKR in a stepwise manner (P for trend ≤0.002). Age at menopause and use of hormonal therapy were not associated with TKR risk.

CONCLUSION

Higher parity, earlier age of menarche and use of oral contraceptives were associated with increased risk of TKR for severe knee OA among women.

The Human Pelvis: Variation in Structure and Function During Gait

The shift to habitual bipedalism 4-6 million years ago in the hominin lineage created a morphologically and functionally different human pelvis compared to our closest living relatives, the chimpanzees. Evolutionary changes to the shape of the pelvis were necessary for the transition to habitual bipedalism in humans. These changes in the bony anatomy resulted in an altered role of muscle function, influencing bipedal gait. Additionally, there are normal sex-specific variations in the pelvis as well as abnormal variations in the acetabulum. During gait, the pelvis moves in the three planes to produce smooth and efficient motion. Subtle sex-specific differences in these motions may facilitate economical gait despite differences in pelvic structure. The motions of the pelvis and hip may also be altered in the presence of abnormal acetabular structure, especially with acetabular dysplasia. Anat Rec, 300:633-642, 2017. © 2017 Wiley Periodicals, Inc.