Squat reinforced concrete(RC)shear walls are essential structural elements in low-rise buildings,valued for their high strength and stiffness.However,research on their seismic behavior remains limited,as most studies ...Squat reinforced concrete(RC)shear walls are essential structural elements in low-rise buildings,valued for their high strength and stiffness.However,research on their seismic behavior remains limited,as most studies focus on tall,slender walls,which exhibit distinct failure mechanisms and deformation characteristics.This study addresses this gap by conducting an extensive review of existing research on the seismic performance of squat RC shear walls.Experimental studies,analytical models,and numerical simulations are examined to provide insights into key factors affecting wall behavior during seismic events,including material properties,wall geometry,reinforcement detailing,and loading conditions.The review aims to support safer design practices by identifying current knowledge gaps and offering guidance on areas needing further investigation.The findings are expected to aid researchers and practitioners in refining seismic design codes,ultimately contributing to the development of more resilient squat RC shear walls for earthquake-prone regions.This research underscores the importance of improving structural resilience to enhance the safety and durability of buildings.展开更多
Aim: To investigate impact of antenatal squatting activities on labour outcomes. Methods: All eligible primigravida women, with singleton cephalic fetuses, who presented to ward 18 of Colombo South Teaching Hospital, ...Aim: To investigate impact of antenatal squatting activities on labour outcomes. Methods: All eligible primigravida women, with singleton cephalic fetuses, who presented to ward 18 of Colombo South Teaching Hospital, Sri Lanka, during the period 1st of February to 28th of May 2017 were invited into the study. Those who were already in active stage of labor (at least more than two moderate contractions per 10 minutes) on admission were excluded. Demographic data such as age, ethnicity, religion, educational level, occupation, latrine type in use, and booking Body mass index (BMI) were collected via an interviewer administered questionnaire. Data related to labor (modified Bishop score at onset of active labor, labor augmentation, pain relief, labor duration, mode of delivery, episiotomy or tears) and neonatal outcome (birth weight, APGAR score at 1, 5, 10 minutes) were collected from delivery notes. A pre tested interviewer administered questionnaire was used to obtain data regarding routine squatting activities during the previous 6 months. Pain visual analogue scale was used on day after delivery to assess the degree of labour pain. Duration of each squatting activity per day and number of days engaged with the activity per week;were used to calculate total squatting hours per week. In the absence of an accepted threshold for adequate squatting, we employed the sample mean as an operational data-driven threshold to define “more” against “less” squatting activities. Women who did not have squatting activities were considered as the controls. We used chi-square and Fisher’s exact tests to compare characteristics and outcomes between those engaging in more and less levels of squatting activity. We fitted a series of logistic regression models with each dichotomized outcome as the dependent variable, more/less squatting activity as the main independent variable of interest, and age, gestation period, BMI and patient’s occupation as covariates. The resulting adjusted odds ratios (AOR) and their 95% confidence intervals (CI) and statistical significance (p < 0.05) were used to draw conclusions of adjusted associations. Results: We recruited 430 women into this study. Overall, 68% of the women were of 20 - 30 years old, 47% had normal body mass index and 65% were housewives. The most frequent squatting activities were for urination/defecation and clothes washing (146 and 62 minutes/week, respectively). Mean total time was 246 minutes per week, of which more than 147 women (34%) achieved above this level of squatting activities. Those with more squatting activities had a greater modified Bishop Score ≥ 6/10 (92% vs 82%;p < 0.01);labor duration of <6 hours (82% vs 56%;p < 0.01), less likely for labour augmentation (39% vs 51%;p < 0.01) and pain relief (53% vs 65%;p = 0.013). Similar results were obtained after adjustments for maternal age, BMI, gestational age and occupation. However, there were no significant differences in the mode of delivery (normal vaginal vs instrumental vs caesarean), episiotomy rate, birth weight and neonatal Apgar scores. Conclusion: Squatting activities of more than 246 minutes per week may improve labor outcome. Women should be encouraged to increase squatting exercises or incorporate more habitual squatting activities antenatally.展开更多
There are actually no sufficient data for lifting technique assessment.A laboratory study was undertaken to determine the effect of 3 regular lifting techniques on erector muscle activation,cardiovascular strain and s...There are actually no sufficient data for lifting technique assessment.A laboratory study was undertaken to determine the effect of 3 regular lifting techniques on erector muscle activation,cardiovascular strain and subjective response.Thirty student volunteers participated in the study,and were required to lift a weight with different techniques.Stoop-,squat-,semi-squat-lifting resulted in 3,2 and 1 time of the highest percentage of the maximum voluntary electrical activation(MVE%) respectively.In the same order,the lowest median frequency(MF) existed 1,1 and 2 times.Muscle fatigue was 4 times in squat,36 in semi-squat and 43 in stoop lifting.Heart rate was the highest in squat and lowest in stoop respectively,with a middle level in semi-squat lifting.It may be recommended to adopt mainly the semi-squat technique for daily lifting works.For heavy lifting,it should use the squat technique.Stoop lifting may also be used alternatively but for light things.展开更多
BACKGROUND Total knee arthroplasty(TKA)has been shown to improve quality of life and reduce pain.High-flexion activities such as squatting,kneeling,and floor transfers are mainly listed as demanding tasks.Among them,s...BACKGROUND Total knee arthroplasty(TKA)has been shown to improve quality of life and reduce pain.High-flexion activities such as squatting,kneeling,and floor transfers are mainly listed as demanding tasks.Among them,squatting is an important position.AIM To provide a new squat position classification and evaluate the different squatting positions of a series of patients after primary TKA.METHODS From May 2018 to October 2019,we retrospectively reviewed 154 video recordings of the squatting-related motions of patients after TKA.Among the included patients,119 were women and 35 were men.Their mean age at the index surgery was 61.4 years(range,30 to 77).RESULTS The median follow-up was 12 mo(range,6 to 156 mo).We classified those squatting-related motions into three major variations according to squatting depth:Half squat,parallel squat,and deep squat.The angles of hip flexion,knee flexion,and ankle dorsiflexion were measured in the screenshots captured from the videos at the moment of squatting nadir.A total of 26 patients were classified as half squats,75 as parallel squats,and 53 as deep squats.The angles of hip flexion,knee flexion,and ankle dorsiflexion all differed significantly among the three squatting positions(P<0.001).In the parallel squat group,the mean knee flexion angle(°)was 116.5(SD,8.1;range,97 to 137).In the deep squat group,the mean knee flexion angle(°)was 132.5(SD,9.3;range,116 to 158).CONCLUSION Among the three squatting positions,deep squat showed the highest hip,knee,and ankle flexion angles,followed by the parallel squat.With the improvement of squatting ability,the patient's postoperative satisfaction rate was also significantly enhanced.However,the different squatting abilities of the patients cannot be effectively distinguished from the scoring results(P>0.05).Our squatting position classification offers a pragmatic approach to evaluating patients’squatting ability after TKA.展开更多
While the quadriceps muscles of human body are quite important to the daily ac-tivities of knee joints,the determination of quadriceps forces poses significant challenges since it cannot be measured in vivo.Here,a nov...While the quadriceps muscles of human body are quite important to the daily ac-tivities of knee joints,the determination of quadriceps forces poses significant challenges since it cannot be measured in vivo.Here,a novel approach is presented to obtain the forces in squat through the combination of motion photography,force transducers measuring,multi-rigid-body theory and finite element analysis.Firstly,the geometrical and angular data of human for squat process were obtained through the analysis of photographed pictures for human squat with cam-era.At the same time,force transducers were used to measure the reaction forces from feet and to determine the center of gravity for identical squat process.Next,based on the multi-rigid-body dynamics,a mathematical model for human right leg and foot was established in order to determine the quadriceps torques under different squat angles.Then,so as to determine the quadriceps forces along with varied squat angles,a simplified three-dimensional finite element model was built,including tibia,fibula,patella,patella ligament and quadriceps tendon.Finally,the contact pressure of knee joint was analyzed for the squat with the established model of knee joint involving the obtained quadriceps forces from finite element analysis.And it showed that in the 0-90 degree squat process,the peak value of contact pressure of articular cartilages and menisci is increased with the increased squat angle.This study can be referenced for further un-derstanding of the biomechanical behaviors of knee,contact pressure effects of daily activities on knee,and is significantly instructive for sports rehabilitation.展开更多
Recently, it has been demonstrated that hypertrophic training with CLU （cluster） sets produces greater strength and power following a 12-week periodized program. The results suggest possible differences in neuromusc...Recently, it has been demonstrated that hypertrophic training with CLU （cluster） sets produces greater strength and power following a 12-week periodized program. The results suggest possible differences in neuromuscular adaptations. Therefore, we sought to compare the acute effect of TRD （traditional） and CLU set configurations during the parallel back squat on mean power output and integrated EMG （electromyography） activity of the VL （vastus lateralis） and BF （biceps femoris）. Ten males （23 ~ 2.4 years; height 182.9 ~ 6.1 cm; weight 86.2 ~ 4.2 kg; 5 ~ 2 years training） performed the parallel back squat using TRD and CLU with 75% 1RM （one-repetition maximum） in a randomized crossover design. Data was analyzed by a repeated measures--ANOVA （analysis of variance）. A significant effect of set （P = 0.006） was observed in mean power output. Mean power output decreased over each successive set when collapsed for condition. Clusters resulted in greater mean power output during latter repetitions of each set （repetition 4, 6-10; P 〈 0.05）. A significant effect of set （P = 0.049） was observed in VL EMG. VL EMG increased over each successive set when collapsed for condition. TRD training produced significantly greater VL EMG during latter repetitions of each set （repetition 6-8; P 〈 0.05）. An interaction was observed in BF EMG. No significant differences were observed in post-hoc. Thus, cluster sets can be used to achieve greater power output, but greater neuromuscular activity should not be expected relative to traditional training.展开更多
In the present paper, the ground reaction force （GRF） acting on foot in slow squat was determined through a force measuring system, and at the same time, the kinematic data of human squat were obtained by analyzing ...In the present paper, the ground reaction force （GRF） acting on foot in slow squat was determined through a force measuring system, and at the same time, the kinematic data of human squat were obtained by analyzing the photographed image sequences. According to the height and body weight, six healthy volunteers were selected, three men in one group and the other three women in another group, and the fundamental parameters of subjects were recorded, including body weight, height and age, etc. Based on the anatomy characteristics, some markers were placed on the right side of joints. While the subject squatted at slow speed on the force platform, the ground reaction forces on the forefoot and heel for each foot were obtained through calibrated force platform. The analysis results show that the reaction force on heel is greater than that on forefoot, and double feet have nearly constant force. Moreover, from processing and analyzing the synchronously photographed image sequences in squat, the kinematic data of human squat were acquired, including mainly the curves of angle, angular velocity and angular acceleration varied with time for knee, hip and ankle joints in a sagittal plane. The obtained results can offer instructive reference for photographing and analyzing the movements of human bodies, diagnosing some diseases, and establishing in the future appropriate mathematical models for the human motion.展开更多
Rail squats are a form of near surface rolling contact fatigue damage found in rail heads. Currently, the most popular method to detect the rail squats is utilizing ultrasonic techniques to determine their presence an...Rail squats are a form of near surface rolling contact fatigue damage found in rail heads. Currently, the most popular method to detect the rail squats is utilizing ultrasonic techniques to determine their presence and measure their depths. This technique needs to be direct contact between the probe and the rail head, with a coupling fluid in at the interface. Other weaknesses of these ultrasonic techniques include false detections as well as missed detections. Infrared thermography is a relatively new non-destructive inspection technique used for a wide range of applications but is not used for rail squat detection. Lock-in thermography is a non-destructive inspection technique that can be used for the detection of near surface defects. It utilizes an infrared camera to detect the thermal waves and then produces a thermal image, which displays the local thermal wave variation in phase or amplitude. In inhomogeneous materials, the amplitude and phase of the thermal wave carries information related to both the local thermal properties and the nature of the structure being inspected. This comparison is then used to determine the phase angle difference (Δf) between the input and the thermal response of the object. The aim of this paper is to determine whether lock-in thermography can be used to firstly locate squats in rails, and secondly measure their depths. It has demonstrated the feasibility for using such a technique in generating thermal responses that could be adequately utilized for the purpose of defect characterization.展开更多
A simplified finite element analysis on the squats growth simulation and the effect different contact stresses has been presented. This analysis is based on the element removal study to simulate squat growth in a rail...A simplified finite element analysis on the squats growth simulation and the effect different contact stresses has been presented. This analysis is based on the element removal study to simulate squat growth in a rail track under cyclic loading. The major principal stress (maximum principal stress failure theory) has been used as failure criteria. Evolution strategies are derived from the biological process of evolution, to find squats growth path solution to a complex rail/ wheel contact problem.展开更多
Researchers have proposed various linkage mechanisms to connect knee and ankle joints for above-knee prosthe-ses,but most of them only offer natural walking.However,studies have shown that people assume a squatting po...Researchers have proposed various linkage mechanisms to connect knee and ankle joints for above-knee prosthe-ses,but most of them only offer natural walking.However,studies have shown that people assume a squatting posture during daily activities.This paper introduces a novel mechanism that connects the knee joint with the foot-ankle joint to enable both squatting and walking.The prosthetic knee used is the well-known 3R36,while the energy storing and return(ESAR)prosthetic foot is used for the ankle-foot joint.To coordinate knee and ankle joint movements,a six-bar linkage mechanism structure is proposed.Simulation results demonstrate that the proposed modular transfemoral prosthesis accurately mimics the motion patterns of a natural human leg during walking and squatting.For instance,the prosthesis allows a total knee flexion of more than 140°during squatting.The new prosthesis design also incorporates energy-storing mechanisms to reduce energy expenditure during walking for amputees.展开更多
Background: Patellofemoral pain (PFP) is considered one of the most common dysfunctions of the lower extremities. Faulty lower limb mechanics and increased of knee valgus on loaded tasks are believed to play an import...Background: Patellofemoral pain (PFP) is considered one of the most common dysfunctions of the lower extremities. Faulty lower limb mechanics and increased of knee valgus on loaded tasks are believed to play an important role in the development of PFP. Objective: To figure out if male PFP patients during single leg horizontal hop for distance and squat with greater knee valgus than controls, and if the nature of the task changes the angles of knee valgus. Methods: Twenty males with unilateral PFP formed the patient group and forty-five asymptomatic males formed the control group. Two dimensional (2-D) frontal plane projection angle (FPPA) was used during single leg squatting and horizontal hop for distance tasks. Results: For the single leg squat, the mean of 6.96<span style="white-space:nowrap;">°</span>, 9.80<span style="white-space:nowrap;">°</span>, 15.04<span style="white-space:nowrap;">°</span> was reported in the control, PFP asymptomatic knee, and PFP symptomatic knee, respectively. For the single leg horizontal hop for distance, the mean of 11.63<span style="white-space:nowrap;">°</span>, 13.72<span style="white-space:nowrap;">°</span>, 19.17<span style="white-space:nowrap;">°</span> was reported in the control, PFP asymptomatic knee, and PFP symptomatic knee, respectively. These differences were significant (<em>p </em>< 0.002) for both tasks. Conclusions: Patients with PFP represented with greater knee valgus angle than what was found in either their asymptomatic limb or in the control group.展开更多
Squatting movements are used frequently in the activities of daily living and squatting exercises are used to strengthen abdominal core and lower limb muscles. However, many individuals cannot perform a traditional sq...Squatting movements are used frequently in the activities of daily living and squatting exercises are used to strengthen abdominal core and lower limb muscles. However, many individuals cannot perform a traditional squat. An alternative is to hire a physical trainer or coach for supervision which can be prohibitively expensive. The DB Method<sup><sup><sup>®</sup></sup></sup> machine is unique and affordable. A product satisfaction descriptive survey to owners of The DB Method machine describes increased gluteal, core, pelvic floor and lower body strength, an improvement in gluteal region shape, and an increase in activity and energy level. A surprising result of the survey was that this DB Method also seemed to strengthen the pelvic floor muscles and, in some cases, to lessen urinary incontinence. In this article, the results of this survey are described as the kinetics of this machine relative to the lower limbs and the pelvic floor muscles. A comparison between traditional squats and The DB Method and the benefits of using The DB Method are discussed.展开更多
Taking into account the squat silos with high grain line and large-volume storage characteristics, to ensure that the stored grain secu rity, we compared phosphine RECIRCULATION FUMIGATION OF PHOSPHINE with the conven...Taking into account the squat silos with high grain line and large-volume storage characteristics, to ensure that the stored grain secu rity, we compared phosphine RECIRCULATION FUMIGATION OF PHOSPHINE with the conventional circulation fumigation method and compared with test data which measured by the analysis and research. Squat Silos taken positions on the circulation phosphine fumigation insecticidal methods, not only to achieve the purpose of the pesticide control, and effectively reduce the cost of fumigation, a decrease of gas in the fight against the occu pational hazards, and have achieved good results.展开更多
文摘Squat reinforced concrete(RC)shear walls are essential structural elements in low-rise buildings,valued for their high strength and stiffness.However,research on their seismic behavior remains limited,as most studies focus on tall,slender walls,which exhibit distinct failure mechanisms and deformation characteristics.This study addresses this gap by conducting an extensive review of existing research on the seismic performance of squat RC shear walls.Experimental studies,analytical models,and numerical simulations are examined to provide insights into key factors affecting wall behavior during seismic events,including material properties,wall geometry,reinforcement detailing,and loading conditions.The review aims to support safer design practices by identifying current knowledge gaps and offering guidance on areas needing further investigation.The findings are expected to aid researchers and practitioners in refining seismic design codes,ultimately contributing to the development of more resilient squat RC shear walls for earthquake-prone regions.This research underscores the importance of improving structural resilience to enhance the safety and durability of buildings.
文摘Aim: To investigate impact of antenatal squatting activities on labour outcomes. Methods: All eligible primigravida women, with singleton cephalic fetuses, who presented to ward 18 of Colombo South Teaching Hospital, Sri Lanka, during the period 1st of February to 28th of May 2017 were invited into the study. Those who were already in active stage of labor (at least more than two moderate contractions per 10 minutes) on admission were excluded. Demographic data such as age, ethnicity, religion, educational level, occupation, latrine type in use, and booking Body mass index (BMI) were collected via an interviewer administered questionnaire. Data related to labor (modified Bishop score at onset of active labor, labor augmentation, pain relief, labor duration, mode of delivery, episiotomy or tears) and neonatal outcome (birth weight, APGAR score at 1, 5, 10 minutes) were collected from delivery notes. A pre tested interviewer administered questionnaire was used to obtain data regarding routine squatting activities during the previous 6 months. Pain visual analogue scale was used on day after delivery to assess the degree of labour pain. Duration of each squatting activity per day and number of days engaged with the activity per week;were used to calculate total squatting hours per week. In the absence of an accepted threshold for adequate squatting, we employed the sample mean as an operational data-driven threshold to define “more” against “less” squatting activities. Women who did not have squatting activities were considered as the controls. We used chi-square and Fisher’s exact tests to compare characteristics and outcomes between those engaging in more and less levels of squatting activity. We fitted a series of logistic regression models with each dichotomized outcome as the dependent variable, more/less squatting activity as the main independent variable of interest, and age, gestation period, BMI and patient’s occupation as covariates. The resulting adjusted odds ratios (AOR) and their 95% confidence intervals (CI) and statistical significance (p < 0.05) were used to draw conclusions of adjusted associations. Results: We recruited 430 women into this study. Overall, 68% of the women were of 20 - 30 years old, 47% had normal body mass index and 65% were housewives. The most frequent squatting activities were for urination/defecation and clothes washing (146 and 62 minutes/week, respectively). Mean total time was 246 minutes per week, of which more than 147 women (34%) achieved above this level of squatting activities. Those with more squatting activities had a greater modified Bishop Score ≥ 6/10 (92% vs 82%;p < 0.01);labor duration of <6 hours (82% vs 56%;p < 0.01), less likely for labour augmentation (39% vs 51%;p < 0.01) and pain relief (53% vs 65%;p = 0.013). Similar results were obtained after adjustments for maternal age, BMI, gestational age and occupation. However, there were no significant differences in the mode of delivery (normal vaginal vs instrumental vs caesarean), episiotomy rate, birth weight and neonatal Apgar scores. Conclusion: Squatting activities of more than 246 minutes per week may improve labor outcome. Women should be encouraged to increase squatting exercises or incorporate more habitual squatting activities antenatally.
基金supported in part by a grant from the Chinese Ministry of Science and Technology (No. 2006BAI06B08)
文摘There are actually no sufficient data for lifting technique assessment.A laboratory study was undertaken to determine the effect of 3 regular lifting techniques on erector muscle activation,cardiovascular strain and subjective response.Thirty student volunteers participated in the study,and were required to lift a weight with different techniques.Stoop-,squat-,semi-squat-lifting resulted in 3,2 and 1 time of the highest percentage of the maximum voluntary electrical activation(MVE%) respectively.In the same order,the lowest median frequency(MF) existed 1,1 and 2 times.Muscle fatigue was 4 times in squat,36 in semi-squat and 43 in stoop lifting.Heart rate was the highest in squat and lowest in stoop respectively,with a middle level in semi-squat lifting.It may be recommended to adopt mainly the semi-squat technique for daily lifting works.For heavy lifting,it should use the squat technique.Stoop lifting may also be used alternatively but for light things.
文摘BACKGROUND Total knee arthroplasty(TKA)has been shown to improve quality of life and reduce pain.High-flexion activities such as squatting,kneeling,and floor transfers are mainly listed as demanding tasks.Among them,squatting is an important position.AIM To provide a new squat position classification and evaluate the different squatting positions of a series of patients after primary TKA.METHODS From May 2018 to October 2019,we retrospectively reviewed 154 video recordings of the squatting-related motions of patients after TKA.Among the included patients,119 were women and 35 were men.Their mean age at the index surgery was 61.4 years(range,30 to 77).RESULTS The median follow-up was 12 mo(range,6 to 156 mo).We classified those squatting-related motions into three major variations according to squatting depth:Half squat,parallel squat,and deep squat.The angles of hip flexion,knee flexion,and ankle dorsiflexion were measured in the screenshots captured from the videos at the moment of squatting nadir.A total of 26 patients were classified as half squats,75 as parallel squats,and 53 as deep squats.The angles of hip flexion,knee flexion,and ankle dorsiflexion all differed significantly among the three squatting positions(P<0.001).In the parallel squat group,the mean knee flexion angle(°)was 116.5(SD,8.1;range,97 to 137).In the deep squat group,the mean knee flexion angle(°)was 132.5(SD,9.3;range,116 to 158).CONCLUSION Among the three squatting positions,deep squat showed the highest hip,knee,and ankle flexion angles,followed by the parallel squat.With the improvement of squatting ability,the patient's postoperative satisfaction rate was also significantly enhanced.However,the different squatting abilities of the patients cannot be effectively distinguished from the scoring results(P>0.05).Our squatting position classification offers a pragmatic approach to evaluating patients’squatting ability after TKA.
基金supported by the National Natural Science Foundation of China (Nos. 10702048 and 11102126)Natural Science Foundation of Shanxi (No. 2010021004-1)
文摘While the quadriceps muscles of human body are quite important to the daily ac-tivities of knee joints,the determination of quadriceps forces poses significant challenges since it cannot be measured in vivo.Here,a novel approach is presented to obtain the forces in squat through the combination of motion photography,force transducers measuring,multi-rigid-body theory and finite element analysis.Firstly,the geometrical and angular data of human for squat process were obtained through the analysis of photographed pictures for human squat with cam-era.At the same time,force transducers were used to measure the reaction forces from feet and to determine the center of gravity for identical squat process.Next,based on the multi-rigid-body dynamics,a mathematical model for human right leg and foot was established in order to determine the quadriceps torques under different squat angles.Then,so as to determine the quadriceps forces along with varied squat angles,a simplified three-dimensional finite element model was built,including tibia,fibula,patella,patella ligament and quadriceps tendon.Finally,the contact pressure of knee joint was analyzed for the squat with the established model of knee joint involving the obtained quadriceps forces from finite element analysis.And it showed that in the 0-90 degree squat process,the peak value of contact pressure of articular cartilages and menisci is increased with the increased squat angle.This study can be referenced for further un-derstanding of the biomechanical behaviors of knee,contact pressure effects of daily activities on knee,and is significantly instructive for sports rehabilitation.
文摘Recently, it has been demonstrated that hypertrophic training with CLU （cluster） sets produces greater strength and power following a 12-week periodized program. The results suggest possible differences in neuromuscular adaptations. Therefore, we sought to compare the acute effect of TRD （traditional） and CLU set configurations during the parallel back squat on mean power output and integrated EMG （electromyography） activity of the VL （vastus lateralis） and BF （biceps femoris）. Ten males （23 ~ 2.4 years; height 182.9 ~ 6.1 cm; weight 86.2 ~ 4.2 kg; 5 ~ 2 years training） performed the parallel back squat using TRD and CLU with 75% 1RM （one-repetition maximum） in a randomized crossover design. Data was analyzed by a repeated measures--ANOVA （analysis of variance）. A significant effect of set （P = 0.006） was observed in mean power output. Mean power output decreased over each successive set when collapsed for condition. Clusters resulted in greater mean power output during latter repetitions of each set （repetition 4, 6-10; P 〈 0.05）. A significant effect of set （P = 0.049） was observed in VL EMG. VL EMG increased over each successive set when collapsed for condition. TRD training produced significantly greater VL EMG during latter repetitions of each set （repetition 6-8; P 〈 0.05）. An interaction was observed in BF EMG. No significant differences were observed in post-hoc. Thus, cluster sets can be used to achieve greater power output, but greater neuromuscular activity should not be expected relative to traditional training.
基金supported by the National Natural Science Foundation of China (10702048 and 11102126)Natural Science Foundation of Shanxi (2010021004-1)
文摘In the present paper, the ground reaction force （GRF） acting on foot in slow squat was determined through a force measuring system, and at the same time, the kinematic data of human squat were obtained by analyzing the photographed image sequences. According to the height and body weight, six healthy volunteers were selected, three men in one group and the other three women in another group, and the fundamental parameters of subjects were recorded, including body weight, height and age, etc. Based on the anatomy characteristics, some markers were placed on the right side of joints. While the subject squatted at slow speed on the force platform, the ground reaction forces on the forefoot and heel for each foot were obtained through calibrated force platform. The analysis results show that the reaction force on heel is greater than that on forefoot, and double feet have nearly constant force. Moreover, from processing and analyzing the synchronously photographed image sequences in squat, the kinematic data of human squat were acquired, including mainly the curves of angle, angular velocity and angular acceleration varied with time for knee, hip and ankle joints in a sagittal plane. The obtained results can offer instructive reference for photographing and analyzing the movements of human bodies, diagnosing some diseases, and establishing in the future appropriate mathematical models for the human motion.
文摘Rail squats are a form of near surface rolling contact fatigue damage found in rail heads. Currently, the most popular method to detect the rail squats is utilizing ultrasonic techniques to determine their presence and measure their depths. This technique needs to be direct contact between the probe and the rail head, with a coupling fluid in at the interface. Other weaknesses of these ultrasonic techniques include false detections as well as missed detections. Infrared thermography is a relatively new non-destructive inspection technique used for a wide range of applications but is not used for rail squat detection. Lock-in thermography is a non-destructive inspection technique that can be used for the detection of near surface defects. It utilizes an infrared camera to detect the thermal waves and then produces a thermal image, which displays the local thermal wave variation in phase or amplitude. In inhomogeneous materials, the amplitude and phase of the thermal wave carries information related to both the local thermal properties and the nature of the structure being inspected. This comparison is then used to determine the phase angle difference (Δf) between the input and the thermal response of the object. The aim of this paper is to determine whether lock-in thermography can be used to firstly locate squats in rails, and secondly measure their depths. It has demonstrated the feasibility for using such a technique in generating thermal responses that could be adequately utilized for the purpose of defect characterization.
文摘A simplified finite element analysis on the squats growth simulation and the effect different contact stresses has been presented. This analysis is based on the element removal study to simulate squat growth in a rail track under cyclic loading. The major principal stress (maximum principal stress failure theory) has been used as failure criteria. Evolution strategies are derived from the biological process of evolution, to find squats growth path solution to a complex rail/ wheel contact problem.
文摘Researchers have proposed various linkage mechanisms to connect knee and ankle joints for above-knee prosthe-ses,but most of them only offer natural walking.However,studies have shown that people assume a squatting posture during daily activities.This paper introduces a novel mechanism that connects the knee joint with the foot-ankle joint to enable both squatting and walking.The prosthetic knee used is the well-known 3R36,while the energy storing and return(ESAR)prosthetic foot is used for the ankle-foot joint.To coordinate knee and ankle joint movements,a six-bar linkage mechanism structure is proposed.Simulation results demonstrate that the proposed modular transfemoral prosthesis accurately mimics the motion patterns of a natural human leg during walking and squatting.For instance,the prosthesis allows a total knee flexion of more than 140°during squatting.The new prosthesis design also incorporates energy-storing mechanisms to reduce energy expenditure during walking for amputees.
文摘Background: Patellofemoral pain (PFP) is considered one of the most common dysfunctions of the lower extremities. Faulty lower limb mechanics and increased of knee valgus on loaded tasks are believed to play an important role in the development of PFP. Objective: To figure out if male PFP patients during single leg horizontal hop for distance and squat with greater knee valgus than controls, and if the nature of the task changes the angles of knee valgus. Methods: Twenty males with unilateral PFP formed the patient group and forty-five asymptomatic males formed the control group. Two dimensional (2-D) frontal plane projection angle (FPPA) was used during single leg squatting and horizontal hop for distance tasks. Results: For the single leg squat, the mean of 6.96<span style="white-space:nowrap;">°</span>, 9.80<span style="white-space:nowrap;">°</span>, 15.04<span style="white-space:nowrap;">°</span> was reported in the control, PFP asymptomatic knee, and PFP symptomatic knee, respectively. For the single leg horizontal hop for distance, the mean of 11.63<span style="white-space:nowrap;">°</span>, 13.72<span style="white-space:nowrap;">°</span>, 19.17<span style="white-space:nowrap;">°</span> was reported in the control, PFP asymptomatic knee, and PFP symptomatic knee, respectively. These differences were significant (<em>p </em>< 0.002) for both tasks. Conclusions: Patients with PFP represented with greater knee valgus angle than what was found in either their asymptomatic limb or in the control group.
文摘Squatting movements are used frequently in the activities of daily living and squatting exercises are used to strengthen abdominal core and lower limb muscles. However, many individuals cannot perform a traditional squat. An alternative is to hire a physical trainer or coach for supervision which can be prohibitively expensive. The DB Method<sup><sup><sup>®</sup></sup></sup> machine is unique and affordable. A product satisfaction descriptive survey to owners of The DB Method machine describes increased gluteal, core, pelvic floor and lower body strength, an improvement in gluteal region shape, and an increase in activity and energy level. A surprising result of the survey was that this DB Method also seemed to strengthen the pelvic floor muscles and, in some cases, to lessen urinary incontinence. In this article, the results of this survey are described as the kinetics of this machine relative to the lower limbs and the pelvic floor muscles. A comparison between traditional squats and The DB Method and the benefits of using The DB Method are discussed.
文摘Taking into account the squat silos with high grain line and large-volume storage characteristics, to ensure that the stored grain secu rity, we compared phosphine RECIRCULATION FUMIGATION OF PHOSPHINE with the conventional circulation fumigation method and compared with test data which measured by the analysis and research. Squat Silos taken positions on the circulation phosphine fumigation insecticidal methods, not only to achieve the purpose of the pesticide control, and effectively reduce the cost of fumigation, a decrease of gas in the fight against the occu pational hazards, and have achieved good results.
