Liliana Aguiar

Kinematic Analysis of Gait in the Second and Third Trimesters of Pregnancy

The kinematic analysis of gait during pregnancy provides more information about the anatomical changes and contributes to exercise and rehabilitation prescription. The purposes were to quantify the lower limb kinematics of gait and to compare it between the second and third trimesters of pregnancy and with a control group. A three-dimensional analysis was performed in twenty-two pregnant women and twelve nonpregnant. Repeated Measures and Manova tests were performed for comparisons between trimesters and between pregnant and controls. The walking speed, stride width, right-/left-step time, cycle time and time of support, and flight phases remain unchanged between trimesters and between pregnant and controls. Stride and right-/left-step lengths decreased between trimesters. Double limb support time increased between trimesters, and it increased when compared with controls. Joint kinematics showed a significant decrease of right-hip extension and adduction during stance phase between trimesters and when compared with controls. Also, an increase in left-knee flexion and a decrease in right-ankle plantarflexion were found between trimesters. The results suggested that pregnant women need to maintain greater stability of body and to become more efficient in locomotion. Further data from the beginning of pregnancy anthropometric data may contribute to the analysis.

KINETIC ANALYSIS OF GAIT IN THE SECOND AND THIRD TRIMESTERS OF PREGNANCY

Most of the anatomical changes related to the body of pregnant women occur between the second and third trimesters of pregnancy. The purposes of the study were to quantify the lower limb kinetics of gait and draw a comparison between women in the second and third trimesters of pregnancy, and a nonpregnant group. Subjects and methods: A three-dimensional (3D) kinetic analysis of gait was performed in 24 pregnant and 12 nonpregnant women. Results: Between trimesters of pregnancy, a decrease in the third peak of vertical ground reaction force (GRF) in the third trimester was observed. Most of the changes found between pregnant and nonpregnant women were in the sagittal plane for hip, knee and ankle moments, which report a decrease in mechanical load of the lower limb. In frontal plane a significant decrease in ankle joint moment was found, and in the transverse plane a significant increase in hip moment was found. Joints power decreases for hip and ankle power in sagittal and frontal plane, and increases for hip power in transverse plane. The function of propulsion and mobilization appears to be related to the different changes that occur between the right leg and left. Conclusion: These results suggest that adaptations regarding muscle participation occur first (second trimester), followed by adaptations in muscle power (third trimester). Understanding the biomechanical adaptations during pregnancy may provide more information about mechanical loads, which subsequently will be helpful for prescribing exercise and rehabilitation programs, as well as for the prevention of musculoskeletal injuries.

Comparison between overweight due to pregnancy and due to added weight to simulate body mass distribution in pregnancy.

The assessment of biomechanical loading in the musculoskeletal system of the pregnant women is particularly interesting since they are subject to morphological, physiological and hormonal changes, which may lead to adaptations in gait. The purpose of this study was to analyze the effect of the increased mass in the trunk associated to pregnancy on the lower limb and pelvis, during walking, on temporal-distance parameters, joint range of motion and moments of force, by comparing a pregnant women group to a non-pregnant group, and to this group while carrying a 5 kg additional load located in the abdomen and breasts during walking, to understand which gait adaptations may be more related with the increased trunk mass, or if may be more associated with other factors such as the girth of the thigh. The subjects performed a previous 12 min training adaption to the added load. To calculate ankle, knee and hip joint angles and moments of force, a three-dimensional biomechanical model was developed. The inverse dynamics method was used to estimate net joint moments of force. The increased mass of the anterior trunk associated with second trimester of pregnancy may influence some gait variables such as the left step time, left and right stance times, double limb support time, maximum hip extension, maximum pelvic right obliquity, pelvic obliquity range of motion, maximum transversal left rotation and peak hip flexion moments of force.

BIOMECHANICAL MODEL FOR KINETIC AND KINEMATIC DESCRIPTION OF GAIT DURING SECOND TRIMESTER OF PREGNANCY TO STUDY THE EFFECTS OF BIOMECHANICAL LOAD ON THE MUSCULOSKELETAL SYSTEM

Walking is daily physical activity and a common way of exercise during pregnancy, but morphological changes can modify the gait pattern. Biomechanical models can help in evaluating joint mechanical loads and kinetics and kinematics during gait, and provide patterns. This study aimed to describe the gait pattern during the second trimester of pregnancy and give an orientation for biomechanical modeling for pregnant women. The ankle and hip joints seem to be more overloaded, mainly in the sagittal and frontal planes, respectively. Results show that pregnant women have a similar walking pattern to the normal gait. This model construction was revealed to be appropriate for describing gait during the second trimester of pregnancy.

Three-Dimensional Kinetic Adaptations of Gait throughout Pregnancy and Postpartum.

Biomechanical adaptations that occur during pregnancy can lead to changes on gait pattern. Nevertheless, these adaptations of gait are still not fully understood. The purpose was to determine the effect of pregnancy on the biomechanical pattern of walking, regarding the kinetic parameters. A three-dimensional analysis was performed in eleven participants. The kinetic parameters in the joints of the lower limb during gait were compared at the end of the first, second, and third trimesters of pregnancy and in the postpartum period, in healthy pregnant women. The main results showed a reduction in the normalized vertical reaction forces, throughout pregnancy, particularly the third peak. Pregnant women showed, during most of the stance phase, medial reaction forces as a motor response to promote the body stability. Bilateral changes were observed in hip joint, with a decrease in the participation of the hip extensors and in the eccentric contraction of hip flexors. In ankle joint a decrease in the participation of ankle plantar flexors was found. In conclusion, the overall results point to biomechanical adjustments that showed a decrease of the mechanical load of women throughout pregnancy, with exception for few unilateral changes of hip joint moments.

GLOBAL OPTIMIZATION METHOD APPLIED TO THE KINEMATICS OF GAIT IN PREGNANT WOMEN

Morphological changes are associated to pregnancy, such as weight gain and increased volume of the trunk. The soft tissue artifact can also increase with these characteristics and affect the real joint kinematics. The main objective of this study was to understand the effect of using three different constraining sets in the lower limb joints, in the amount of soft tissue artifact (STA) of pregnant women, in order to obtain the most appropriated joint set to be used in gait and in this population. The ankle, knee and hip joints were modeled respectively with the following characteristics: (1) Universal–revolute–spherical (URS), (2) spherical–revolute–spherical (SRS) and (3) spherical–spherical–spherical (SSS). The six degrees of freedom (6DOF) model was used as the basis for comparison and considered the one with the highest error associated to the STA. In pregnant women, the URS model seems to affect more the kinematic variables when compared with the 6DOF model. Assuming that the kinematic error associated with pregnant women is increased due to the STA, the URS model may be affecting more the angular kinematics of the knee joint. SSS model seems to be more appropriated to analyze gait in second trimester pregnant women.

Influence of Body Composition on Gait Kinetics throughout Pregnancy and Postpartum Period

Pregnancy leads to several changes in body composition and morphology of women. It is not clear whether the biomechanical changes occurring in this period are due exclusively to body composition and size or to other physiological factors. The purpose was to quantify the morphology and body composition of women throughout pregnancy and in the postpartum period and identify the contribution of these parameters on the lower limb joints kinetic during gait. Eleven women were assessed longitudinally, regarding anthropometric, body composition, and kinetic parameters of gait. Body composition and body dimensions showed a significant increase during pregnancy and a decrease in the postpartum period. In the postpartum period, body composition was similar to the 1st trimester, except for triceps skinfold, total calf area, and body mass index, with higher results than at the beginning of pregnancy. Regression models were developed to predict womens internal loading through anthropometric variables. Four models include variables associated with the amount of fat; four models include variables related to overall body weight; three models include fat-free mass; one model includes the shape of the trunk as a predictor variable. Changes in maternal body composition and morphology largely determine kinetic dynamics of the joints in pregnant women.

THE OVERLOAD INFLUENCE IN ANGULAR KINEMATICS AND JOINT MOMENTS IN LOWER LIMB AND PELVIS DURING GAIT IN SAGITTAL PLANE

One of the many variables that characterize anthropometrically human body is the weight and it is also one way to quantify the load that the body supports statically. Excessive body weight is related to several health problems as cardiovascular, stroke, hypertension and diabetes as well as gait related injuries [Must and Strauss, 1999]. Pregnancy is also an overweight condition, with some specific associated health problems caused by morphological, physiological and hormonal changes [Nicholls and Grieve, 1992]. The main purpose is the comparison of gait pattern, in sagittal plane, regarding three overload conditions (pregnancy, overload and overweight) using a 3D biomechanical model.