Rita Santos-Rocha

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.

Osteogenic index of step exercise depending on choreographic movements, session duration, and stepping rate

Background: Step exercise has been promoted as a low impact physical activity recommended for the improvement of cardiorespiratory and muscular fitness. This recreational activity might also be recommended to improve bone health since mechanical load plays an important role in the normal development of the skeleton. Methods: Our main purpose was to characterised 100 step sessions and to calculated osteogenic index (OI) according to Turner and Robling: OI (one session) = peak ground reaction force(BW)*ln(number of loading cycles+1). Results: Main results (mean±SD) were as follows: OI was 12.0±0.8; peak ground reaction force (GRF) was 1.40±0.10 times body weight (BW); session duration was 38.6±8.3 min; stepping rate was 134.6±4.7 beats per minute (bpm); the movements performed most often were marching, knee hop, side leg, L step, and over the top; and the number of loading cycles was 4194.1±1055.2. OI and GRF increased significantly when stepping rate was higher than 135 bpm. This stepping rate might be used as a reference for higher intensity classes. A frequency of two to three sessions per week of step exercise is recommended. Conclusions: Despite the benefits that have been stated when step classes are structured correctly and adapted to the participants, further research is needed concerning biomechanical load, exercise prescription, and injury prevention.

Biomechanics of Gait during Pregnancy

Introduction. During pregnancy women experience several changes in the bodys physiology, morphology, and hormonal system. These changes may affect the balance and body stability and can cause discomfort and pain. The adaptations of the musculoskeletal system due to morphological changes during pregnancy are not fully understood. Few studies clarify the biomechanical changes of gait that occur during pregnancy and in postpartum period. Purposes. The purpose of this review was to analyze the available evidence on the biomechanical adaptations of gait that occur throughout pregnancy and in postpartum period, specifically with regard to the temporal, spatial, kinematic, and kinetic parameters of gait. Methods. Three databases were searched and 9 studies with a follow-up design were retrieved for analysis. Results. Most studies performed temporal, spatial, and kinematic analysis. Only three studies performed kinetic analysis. Conclusion. The adaptation strategies to the anatomical and physiological changes throughout pregnancy are still unclear, particularly in a longitudinal perspective and regarding kinetic parameters.

Analysis of ground reaction forces in step exercise depending on step pattern and stepping rate.

Santos-Rocha, R, Veloso, A, and Machado, ML. Analysis of ground reaction forces in step exercise depending on step pattern and stepping rate. J Strength Cond Res 23(1): 209-224, 2009-The analysis of ground reaction forces (GRFs) helps one understand the magnitude and pattern of loading experienced by the body while in contact with the ground in locomotor actions. The GRFs reflect a general indicator of mechanical loading on the musculoskeletal system, establishing the “whole-body biomechanical intensity” of physical activity and allowing the comparison between different activities. Our purposes were to analyze the GRFs produced by step exercise particularly-the force profile, average GRF, peak GRF, impulse, and loading rate-on the ascending and descending movements in 18 skilled women, investigating the differences that exist between 4 stepping-rate conditions and between 4 step patterns. Two force platforms were used. These differences were studied using analyses of variance with repeated measures. Our results show that experienced subjects were able to deal with the increase of movement cadence in terms of external load, maintaining the GRF values at the same levels as the ones obtained for quick walking and moderate step running, activities that are considered safe. The results indicate that lower-extremity external loading can be effectively controlled by varying the stepping rate during step classes. With the correct use of this mechanical control, this activity could be included in exercise and rehabilitation programs. The knowledge about the magnitude of loading helps in selecting proper stepping rates and proper movements for inclusion in classes.

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.

Calf-raise senior: a new test for assessment of plantar flexor muscle strength in older adults: protocol, validity, and reliability.

Purpose This study aimed to develop a new field test protocol with a standardized measurement of strength and power in plantar flexor muscles targeted to functionally independent older adults, the calf-raise senior (CRS) test, and also evaluate its reliability and validity. Patients and methods Forty-one subjects aged 65 years and older of both sexes participated in five different cross-sectional studies: 1) pilot (n=12); 2) inter- and intrarater agreement (n=12); 3) construct (n=41); 4) criterion validity (n=33); and 5) test–retest reliability (n=41). Different motion parameters were compared in order to define a specifically designed protocol for seniors. Two raters evaluated each participant twice, and the results of the same individual were compared between raters and participants to assess the interrater and intrarater agreement. The validity and reliability studies involved three testing sessions that lasted 2 weeks, including a battery of functional fitness tests, CRS test in two occasions, accelerometry, and strength assessments in an isokinetic dynamometer. Results The CRS test presented an excellent test–retest reliability (intraclass correlation coefficient [ICC] =0.90, standard error of measurement =2.0) and interrater reliability (ICC =0.93–0.96), as well as a good intrarater agreement (ICC =0.79–0.84). Participants with better results in the CRS test were younger and presented higher levels of physical activity and functional fitness. A significant association between test results and all strength parameters (isometric, r=0.87, r2=0.75; isokinetic, r=0.86, r2=0.74; and rate of force development, r=0.77, r2=0.59) was shown. Conclusion This study was successful in demonstrating that the CRS test can meet the scientific criteria of validity and reliability. The test can be a good indicator of ankle strength in older adults and proved to discriminate significantly between individuals with improved functionality and levels of physical activity.

Peak Ground and Joint Forces in Step-Exercise Depending on Step- Pattern and Stepping-Rate

The assessment of biomechanical loading is quite important for exercise prescription and injury prevention in the scope of Exercise Biomechanics. The study of ground reaction forces, joint forces and joint moments of force at ankle, knee and hip, allows the understanding of the magnitude of external and internal loading experienced by the lower ex- tremity joints and the pattern of force-absorbing adjustments while performing a dynamic activity. The main purposes of this study were to compare the peak values of those forces, during the ascending and the descending phases of four Step- Exercise patterns (basic-step, knee-lift, run-step and knee-hop), performed at varying stepping-rate conditions (125, 130, 135 and 140 beats per minute), in a group of 18 skilled females. The results showed that vertical ground reaction forces and joint forces at ankle varied from: 1.6-1.7 BW (body weight) in basic-step, 1.3-1.6 BW in knee-lift, 1.7-2.1 BW in run- step and, 1.0-1.8 BW in knee-hop; vertical joint forces at knee and hip varied from: 1.5-1.7 BW in basic-step, 1.2-1.5 BW in knee-lift, 1.5-2.0 BW in run-step and, 0.8-1.8 BW in knee-hop. Significant greater values were found in run-step for all parameters. No significant differences were found among conditions of stepping-rate. The anterior-posterior forces varied from 0.2-0.6 BW considering the four movements. Significant greater values were found in the two propulsive move- ments. Also, these forces increased with faster stepping-rates. The joint moments of force varied from 0.1-1.0 Nm/BW considering the four movements. Significant greater values were found: at ankle, in basic-step and run-step; at knee, in run-step and knee-hop (ascending-phase); and at hip, in run-step. No significant differences were found among conditions of stepping-rate, at ankle and at knee (decending-phase). Joint moments increased with faster stepping-rates at knee (as- cending-phase) and at hip. The results suggest that experienced steppers are capable of stepping at different cadences, with generally similar patterns of kinematics and kinetics. We concluded that lower extremity internal loading can be ef- fectively controlled by varying stepping-rate during Step classes.