Análisis biomecánico de la sentadilla libre en el levantamiento de potencia en Quito

El análisis de la técnica deportiva desde el punto de vista biomecánico posibilita controlar los supuestos que conforman la técnica deportiva específica para su futuro perfeccionamiento, esto es esencial en la toma de decisiones como parte del proceso de dirección deportiva, sobre todo en deportes poco estudiados como es el powerlifting. En tal sentido, se determinó como objetivo de la investigación analizar biomecánicamente la técnica de sentadilla libre en el levantamiento de potencia por géneros. La investigación fue de tipo descriptiva-correlacional. Se estudiaron a 42 levantadores con rango etario entre 17-28 años, clasificados en dos grupos independientes según el género. Se estudió la técnica de la sentadilla libre en cuatro variables de análisis. No se evidenciaron diferencias significativas en ninguna de las variables analizadas. Se incluyó el ángulo de la rodilla (p=0.845), el pico de velocidad máxima (p=0.095) y la trayectoria del movimiento en su eje X (p=0.979) y su eje Y (p=0.845). No se evidenciaron diferencias entre los rangos etarios de los géneros estudiados (p=0.237). La técnica de sentadilla libre analizada, en su comparación por géneros, no evidenció diferencias significativas, aspecto que permitió deducir un nivel técnico similar entre los géneros estudiados. Se concluyó que, si es correcta la ejecución motriz específica en el deporte estudiado, el componente técnico del entrenamiento deportivo en powerlifting se cumple satisfactoriamente e independientemente del género entrenado.

SÍNTESE A análise da técnica esportiva do ponto de vista biomecânico permite controlar as suposições que compõem a técnica esportiva específica para seu futuro aperfeiçoamento, isto é essencial na tomada de decisões como parte do processo de gestão esportiva, especialmente em esportes pouco estudados, como o powerlifting. Neste sentido, o objetivo da pesquisa era analisar biomecanicamente a técnica de agachamento livre no powerlifting por gênero. A pesquisa foi descritivo-correlacional. Foram estudados 42 elevadores com idades entre 17-28 anos, classificados em dois grupos independentes de acordo com o gênero. A técnica do agachamento livre foi estudada em quatro variáveis de análise. Não foram encontradas diferenças significativas em nenhuma das variáveis analisadas. Foram incluídos o ângulo do joelho (p=0,845), a velocidade máxima de pico (p=0,095) e a trajetória do movimento em seu eixo X (p=0,979) e eixo Y (p=0,845). Não foram evidentes diferenças entre as faixas etárias dos gêneros estudados (p=0,237). A técnica de agachamento livre analisada, em sua comparação por gênero, não mostrou diferenças significativas, um aspecto que nos permitiu deduzir um nível técnico semelhante entre os gêneros estudados. Concluiu-se que, se a execução motora específica no esporte estudado estiver correta, o componente técnico do treinamento esportivo em powerlifting é cumprido satisfatoriamente e independentemente do gênero treinado.

The analysis of the sports technique from the biomechanical point of view makes it possible to control the assumptions that make up the specific sports technique for its future improvement, this is essential in decision-making as part of the sports management process, especially in sports little studied as It's powerlifting. In this sense, the research objective was to biomechanically analyze the free squat technique in power lifting by gender. The research was descriptive-correlational. Forty-two lifters with an age range between 17-28 years were studied, classified into two independent groups according to gender. The free squat technique was studied in four analysis variables. No significant differences were found in any of the variables analyzed. The knee angle (p=0.845), the maximum speed peak (p=0.095) and the trajectory of the movement in its X axis (p=0.979) and its Y axis (p=0.845) were included. No differences were found between the age ranges of the genders studied (p=0.237). The analyzed free squat technique, in its comparison by gender, did not show significant differences, an aspect that allowed us to deduce a similar technical level between the genders studied. It was concluded that, if the specific motor execution in the sport studied is correct, the technical component of sports training in powerlifting is satisfactorily fulfilled and regardless of the gender trained.

Effects of horse-riding squat exercise plus Governor Vessel-regulating Tuina therapy on static balance function in patients with stroke / 针灸推拿医学（英文版）

Objective:To observe the effect of horse-riding squat exercise plus Governor Vessel-regulating Tuina(Chinese therapeutic massage)therapy on static balance function in patients with stroke.Methods:A total of 176 stroke patients were enrolled as the study subjects and divided into four groups by the random number table method,namely horse-riding squat+Tuina group,horse-riding squat group,Tuina group,and control group,with 44 cases in each group.The control group was treated with rehabilitation balance training.The horse-riding squat+Tuina group,horse-riding squat group,and Tuina group were treated with additional horse-riding squat exercise plus Tuina,horse-riding squat exercise,and Tuina treatment,respectively.Four weeks of treatment was regarded as one treatment course.After 1 treatment course,the balance function of the four groups was compared.Results:After treatment,the ellipse area of motion and the length of motion in all four groups were reduced,and the intra-group differences were all statistically significant(P＜0.05).The difference in the ellipse area of motion before and after treatment in the horse-riding squat+Tuina group and the horse-riding squat group was larger than that in the control group,and the differences were statistically significant(P＜0.05).The difference in the ellipse area of motion before and after treatment in the horse-riding squat+Tuina group was larger than that in the Tuina group,and the difference was statistically significant(P＜0.05).The difference in the length of motion before and after treatment in the horse-riding squat+Tuina group,the horse-riding squat group,and the Tuina group was greater than that in the control group,and the differences were statistically significant(P＜0.05).There was no statistically significant difference in the pairwise comparison between the horse-riding squat+Tuina group,the horse-riding squat group,and the Tuina group(P＞0.05).Conclusion:Horse-riding squat exercise plus Governor Vessel-regulating Tuina therapy can effectively improve the static balance function in patients with stroke.Training the affected lower limb weight-bearing exercise,adjusting the center of gravity distribution,and promoting the mutual balance and coordination between muscle groups may be the mechanism of improving the static balance function.

Diferencias biomecánicas del gesto técnico de la media sentadilla libre en físico-culturistas profesionales y amateur / Diferenças biomecânicas do gesto técnico do meio-francho livre em musculturistas profissionais e iniciantes / Biomechanical differences of the technical gesture of the free half squat in professional and amateur bodybuilders

RESUMEN El perfeccionamiento de la técnica deportiva tiene como premisa comparar los valores del movimiento motriz, esta debe ser caracterizada para corregir errores detectados como parte del proceso de dirección del entrenamiento deportivo. Se pone énfasis en los deportes eminentemente técnicos, como es el caso del entrenamiento del fisiculturismo. En tal sentido, la presente investigación tuvo como objetivo analizar la técnica de la media sentadilla en fisiculturistas profesionales y amateurs como método empírico (medición específica del deporte). La investigación es descriptiva-explicativa de orden correlacional. Se correlacionan seis variables de interés (X1: ángulo de la articulación del hombro; X2: ángulo de la articulación de la cadera; X3: Velocidad máxima alcanzada; X4: aceleración máxima alcanzada; X5: centro de gravedad en X; X6: centro de gravedad en Y). Las medias establecen diferencias entre grupos independientes, tanto en la variable X1 (Grupo 1: ≈66°; grupo 2: H"70°; p=0.247), la X2 (grupo 1: ≈73°; grupo 2: ≈86°; p=0.002), La X3 (grupo 1:≈1.03m/s; grupo 2: ≈1.36m/s; p=0.017), la X4 (grupo 1: ≈2.93m/s2; grupo 2: ≈4.78m/s2; p=0.011), la X5 (grupo 1: ≈0.43m; grupo 2: ≈0.65m; p=0.000), y la X6 (grupo 1: ≈0.61m; grupo 2: ≈0.83m; p=0.000). El grupo 1 posee una técnica más efectiva, mientras que los amateurs poseen menor eficiencia en el movimiento biomecánico dada su inexperiencia, se muestran valores altos en velocidad y aceleración, se incluyen ángulos de movimiento como el de cadera.

RESUMO A melhoria da técnica desportiva baseia-se na premissa de comparar os valores do movimento motor, que deve ser caracterizada a fim de corrigir erros detectados como parte do processo de gestão do treino desportivo. A tónica é colocada no desporto eminentemente técnico, como é o caso do treino de musculação. Neste sentido, o objectivo desta investigação era analisar a técnica de meio agachamento em musculturistas profissionais e iniciantes como um método empírico (medição específica do desporto). A investigação é descritiva-explicativa da ordem correlativa. Seis variáveis de interesse estão correlacionadas (X1: ângulo da articulação do ombro; X2: ângulo da articulação da anca; X3: velocidade máxima alcançada; X4: aceleração máxima alcançada; X5: centro de gravidade em X; X6: centro de gravidade em Y). Os meios estabelecem diferenças entre grupos independentes, tanto na variável X1 (Grupo 1: ≈66°; grupo 2: ≈70°; p=0,247), a X2 (grupo 1: ≈73°; grupo 2: ≈86°; p=0,002), a X3 (grupo 1: ≈1. 03m/s; grupo 2: ≈1.36m/s; p=0.017), o X4 (grupo 1: ≈2.93m/s2; grupo 2: ≈4.78m/s2; p=0.011), o X5 (grupo 1: ≈0.43m; grupo 2: ≈0.65m; p=0.000), e o X6 (grupo 1: ≈0.61m; grupo 2: ≈0.83m; p=0.000). O grupo 1 tem uma técnica mais eficaz, enquanto os iniciantes têm uma eficiência de movimento biomecânico mais baixa devido à sua inexperiência, eles mostram menos eficiência no movimento biomecânico. Dada a sua inexperiência, são mostrados valores elevados em velocidade e aceleração, e são incluídos ângulos de movimento como o ângulo da anca.

ABSTRACT The improvement of the sports technique is premised on comparing the values of the motor movement, this must be characterized to correct errors detected as part of the sports training management process. Emphasis is placed on highly technical sports, such as bodybuilding training. In this sense, the present research aimed to analyze the half-squat technique in professional and amateur bodybuilders as an empirical method (sport-specific measurement). The research is descriptive-explanatory of correlational order. Six variables of interest are correlated (X1: shoulder joint angle; X2: hip joint angle; X3: maximum speed reached; X4: maximum acceleration reached; X5: center of gravity in X; X6: center of gravity in Y). The means establish differences between independent groups, both in variable X1 (group 1: ≈66°; group 2: ≈70°; p=0.247 ), X2 (group 1: ≈73°; group 2: ≈86°; p=0.002 ), X3 (group 1: ≈1.03m/s; group 2:≈1.36m/s; p=0.017 ), X4 (group 1: ≈2.93m/s2; group 2: ≈4.78m/s2; p=0.011 ), X5 (group 1: ≈0.43m; group 2:≈0.65m; p=0.000 ), and X6 (group 1: ≈0.61m; group 2: ≈0.83m; p =0.000 ). Group 1 has a more effective technique, while the amateurs have less efficiency in biomechanical movement due to their inexperience, high values are shown in speed and acceleration, movement angles such as hip angles are included.

Relationship between body composition, multiple repeated sprint ability and vertical jump performance in elite badminton players / Relación entre la composición corporal, la capacidad de realizar múltiples sprints repetidos y el rendimiento del salto vertical en jugadores de bádminton de élite

SUMMARY: The purpose of this study was to assess the correlation between the body composition, multiple repeated sprint ability (MRSAB) test, and vertical jump performance. Fifteen voluntary elite Turkish badminton players participated in the study. The MRSAB test consisted of 2 repetitions of 4 movements (4x3m) separated by 30 seconds of passive recovery. The best time (BT), meantime (MT), total time (TT), and fatigue index (FI) were measured. Body composition was evaluated through dual-energy X-ray absorptiometry (DEXA). Squat jump (SJ) test for explosive power and countermovement jump (CMJ) test for elastic power were used. The main findings were that there was a significant correlation between MRSAB MT and TT with lean body mass, lean arm mass, and trunk lean mass (kg) of male badminton players. However, no significant correlation was observed among MRSAB MT, BT, and TT with another total/regional body composition of female badminton players (p>0.05). Moreover, the results of male badminton players showed that there was a significant negative correlation between FI and percentage ofbody fat (%BF), percentage of leg fat (%LF), percentage of trunk fat (%TF), and trunk mass. In addition, there was a significant negative correlation between FI with %BF, body fat mass kg, percentage of arm fat (%AF), arm fat mass, and %LF of female badminton players. It was also found in the study that there was a significant correlation between SJ and %LF; CMJ and %BF, body fat mass kg, %AF, %LF and leg fat mass kg. However, no significant correlation was observed among CMJ and SJ with other total/regional body compositions of male badminton players (p>0,05). Finally, changes in body composition are important issues for the physical performance level of badminton players as regional excess body fat may cause deterioration, especially in repeated-sprint ability and jumping performance.

RESUMEN: El propósito de este estudio fue evaluar la correlación entre la composición corporal, la prueba de capacidad de sprint repetido (MRSAB) y el rendimiento del salto vertical. Quince jugadores voluntarios de bádminton turcos de élite participaron en el estudio. El test MRSAB consistió en 2 repeticiones de 4 movimientos (4x3m) separados por 30 segundos de recuperación pasiva. Se midieron el mejor tiempo (BT), el tiempo medio (MT), el tiempo total (TT) y el índice de fatiga (FI). La composición corporal se evaluó mediante absorciometría de rayos X de energía dual (DEXA). Se utilizó la prueba de salto desde la sentadilla (SJ) para la potencia explosiva y la prueba de salto con contramovimiento (CMJ) para la potencia elástica. Los principales hallazgos fueron una correlación significativa entre MRSAB MT y TT con la masa corporal magra, la masa magra del brazo y la masa magra del tronco (kg) de los jugadores de bádminton hombres. Sin embargo, no se observó una correlación significativa entre MRSAB MT, BT y TT con otra composición corporal total/regional de jugadoras de bádminton (p>0,05). Además, los resultados de los jugadores hombres de bádminton mostraron que había una correlación negativa significativa entre FI y el porcentaje de grasa corporal (% BF), porcentaje de grasa en las piernas (% LF), porcentaje de grasa en el tronco (% TF) y masa del tronco. Además, hubo una correlación negativa significativa entre FI con %GC, masa de grasa corporal en kg, porcentaje de grasa en el brazo (%AF), masa de grasa en el brazo y %LF de las jugadoras de bádminton. También se descubrió en el estudio que había una correlación significativa entre SJ y %LF; CMJ y %BF, masa grasa corporal kg, %AF, %LF y masa grasa de piernas kg. Sin embargo, no se observó una correlación significativa entre CMJ y SJ con otras composiciones corporales totales/regionales de los hombres jugadores de bádminton (p>0,05). Finalmente, los cambios en la composición corporal son cuestiones importantes para el nivel de rendimiento físico de los jugadores de bádminton, debido a que el exceso de grasa corporal regional, puede causar un deterioro, especialmente en la capacidad de repetir sprints y en el rendimiento de los saltos.

Protocol-optimizing study of combining Tuina and horse-riding squat exercise for knee osteoarthritis / 针灸推拿医学（英文版）

Objective: To evaluate the efficacy of Tuina (Chinese therapeutic massage) manipulation plus horse-riding squat exercise in treating knee osteoarthritis (KOA) and optimize the combining protocol. Methods: Based on a 2×2 factorial design, 120 eligible KOA patients were randomized into a manipulation group (group A1B2), a manipulation plus horse-riding squat group (group A1B1), a sitting knee-adjustment group (group A2B2 group), and a sitting knee-adjustment plus horse-riding squat group (group A2B1), with 30 cases in each group. The intervention was conducted three times a week, lasting for four weeks. The Western Ontario and McMaster Universities osteoarthritis index (WOMAC) was taken as the major measure for efficacy evaluation (including three component scores, pain, stiffness, and daily function, and total score). Results: The three component scores (pain, stiffness, and daily function) and the total score of WOMAC showed significant differences after the intervention in the four groups (P<0.05). There were significant inter-group differences in the WOMAC stiffness score amongst the four groups after the intervention (P<0.05). In group A1B1, the step length, stride, walking speed, and knee joint flexion angle changed significantly after treatment (P<0.05). After the intervention, the step length changed significantly in group A1B2 (P<0.05), and the walking speed changed significantly in group A2B1 (P<0.05). There were no significant differences in the step length, stride, walking speed, or knee joint flexion angle among the four groups (P>0.05). The extensor peak torque at 180 °/s changed significantly in group A1B2 after treatment (P<0.05). Neither the intra-group nor the inter-group comparisons of the four groups revealed significant differences in the other isokinetic muscle strength parameters (P>0.05). The main effect of manipulation showed significant in affecting the WOMAC pain and total scores (P<0.05). The main effect of horse-riding squat exercise showed significant in affecting the WOMAC pain and stiffness scores (P<0.05). Conclusion: The four treatment protocols all can improve the symptoms of KOA, for instance, relieving pain and stiffness, and enhancing daily function. Group A2B1 produces the most eminent effect in relieving joint stiffness. The main effects of both manipulation and horse-riding squat exercise are significant in reducing pain. Besides, the main effect of horse-riding squat exercise is significant in relieving joint stiffness.

Comparison of the Lower Limb Kinematics and Muscle Activation Between Asian Squat and Western Squat / 医用生物力学

Objective To compare the differences in lower limb joint kinematics and muscle activation between Asian squat (AS) and Western squat (WS). Methods Eleven healthy adults were recruited to complete the biomechanical test of AS and WS. The 3D motion analysis system, force plates and surface electromyography (EMG) were used to collect kinematics, kinetics and muscle activation data of the subjects during two squats, and muscle force of the lower limb was also calculated by OpenSim. Results AS showed pelvis forward flexion, while WS showed pelvis backward extension at the time of peak knee flexion angle. Compared with the AS, a significant smaller hip flexion, larger knee flexion, larger hip abduction and hip rotation angles were found in WS at the time of peak knee flexion angle. Compared with AS, a significant greater peak force of soleus was found in WS during descent and ascent phases of squat. Additionally, a smaller peak force of anterior tibia was found in WS than that in AS during descent and ascent phases of the squat. No significant differences were found in other muscle peak force and the time of peak force between AS and WS. Conclusions The combined tibialis anterior activation and proximal joint flexion might be beneficial to stabilization during AS. The soleus muscle activation was significant in WS with heel lifting. The muscle activation pattern of proximal joint was similar between AS and WS. This study provides theoretical guidance for the design of clinical squat rehabilitation programs or the selection of squat training.

Lactacidemia in two different weight training models / Lactacidemia em dois modelos diferentes de treino de musculação

The knowledge of the physiological aspects in the execution of the training in the bodybuilding is important to improve the training; being the lactate concentration an important marker applied in several types of exercises. Some studies have evaluated lactacidemia and training models but did not use squatting in their protocols. The aim of the study was to analyze blood lactate concentration in free squat exercise training in two training models: strength and resistance.Experimental study with a sample of five men of 24 ± 4.6 years, physically active and practicing for at least one year, with no history of orthopedic and cardiovascular problems. The tests were performed in two days, in the strength session the volunteers performed 12 sets, 6 to 12 maximal repetitions and in the resistance session 12 series, 13 to 20 maximum repetitions. In both tests the interval was 1 minute and 30 seconds between sets and 2 minutes every 4 sets. Blood lactate was collected at rest, during and after the test.No significant differences were found in the lactate concentration during and after the tests in the strength training and the resistance training. However, the lactacidemia variation between the first and last collection presented a significantly higher result in strength training. We conclude that the models of strength and resistance training, in the free squat exercise, do not present significant differences in lactate concentration during and after the tests. The total lactacidemia variation was greater in strength training.

O conhecimento dos aspectos fisiológicos na execução do treino na musculação é importante para aprimorarmos os treinamentos; sendo a concentração de lactato um importante marcador aplicado em diversos tipos de exercícios. Alguns estudos já avaliaram lactacidemia e modelos de treinamento, porém não utilizaram o agachamento em seus protocolos. O objetivo do estudo foi analisar a concentração de lactato sanguíneo no treino do exercício agachamento livre em dois modelos de treinamento: força e resistência. Estudo experimental, com amostra de cinco homens de 24 ± 4.6 anos, fisicamente ativos e praticantes há pelo menos um ano, sem histórico de problemas ortopédicos e cardiovasculares. Os testes foram realizados em dois dias, na sessão de força os voluntários executaram 12 séries, 6 a 12 repetições máximas e na sessão de resistência 12 séries, 13 a 20 repetições máximas. Em ambos os testes o intervalo foi de 1 minuto e 30 segundos entre as séries e de 2 minutos a cada 4 séries. O lactato sanguíneo foi coletado no repouso, durante e no pós-teste. Não foram encontradas diferenças significativas na concentração de lactato durante e após os testes no treino de força e no treino de resistência. No entanto, a variação da lactacidemia entre a primeira e a última coleta apresentou resultado significativamente maior no treino de força. Concluímos que os modelos de treinamento de força e de resistência, no exercício agachamento livre, não apresentam diferenças significativas na concentração de lactato durante e após os testes. Sendo a variação total de lactacidemia maior no treinamento de força.

Análise do exercício agachamento com e sem o uso de physioball e banda elástica em diferentes intensidades / Analysis of the squat exercise with and without physioball and elastic band in different intensities

RESUMO O objetivo do presente estudo foi analisar a atividade mioelétrica (EMG), o tempo sob tensão (TST) e a projeção dos joelhos no exercício agachamento sem o uso de implementos (SI) e com o uso de physioball (PH) e banda elástica (BE) em diferentes intensidades de esforço. Dez homens realizaram o exercício nos três protocolos com a intensidade de 50 e 100% de 10 RM. A distância entre joelhos no protocolo controle (51,25cm) foi menor quando comparada com o SI 50% (84,38cm; p < 0,001), com o SI 100% (88,80cm; p < 0,001) e com BE 100% (67,41cm; p = 0,014). A distância entre os joelhos também foi menor para os protocolos PH 100% (53,10cm; p < 0,001) e BE 100% (67,41cm; p < 0,001) comparada ao SI 100% (88,80cm). O Vasto Medial Oblíquo (VMO) apresentou maior ativação nos protocolos SI 50% (p = 0,035) e PH 50% (p = 0,028) quando comparados ao protocolo BE 50%. A realização do agachamento com cargas submáximas parece aumentar e diminuir a ativação do VMO quando realizado com PH e BE, respectivamente.

ABSTRACT The objective of the present study was to analyze the myoelectric activity (EMG), the time under tension (TST) and the knee projection in the squat exercise without the use of implements (SI) and with the use of physioball (PH) and elastic band (EB) at different intensities of effort. Ten men performed the exercise in the three protocols with the intensity of 50 and 100% of 10 RM. The distance between knees in the control protocol (51.25 cm) was lower when compared to SI 50% (84.38 cm, p <0.001), with SI 100% (88.80 cm, p <0.001) and with EB 100% (67.41cm, p = 0.014). The distance between the knees was also lower for the protocols PH 100% (53.10cm, p <0.001) and EB 100% (67.41, p <0.001) compared to the SI 100% (88.80 cm) protocols. The Vasto Medial Oblique (VMO) presented greater activation in the SI 50% protocols (p = 0.035) and PH 50% (p = 0.028) when compared to the EB 50% protocol. The accomplishment of squatting with submaximal loads seems to increase and decrease the activation of VMO when performed with physioball and BE, respectively.

Effect of Visual Feedback Squat Motion on Core Muscles Thickness of Young People with Lower Back Pain

PURPOSE: This study examined the effect of visual feedback squat on the core muscle thickness of young adults experiencing back pain. METHODS: Thirty adult men and women who experienced back pain were assigned randomly to 15 members of the visual feedback squat group (VSG) and 15 of the normal squat group (NSG) to train three times a week for a total of eight weeks. The core muscle thickness was compared prior to the test for four weeks and eight weeks after the test by dividing it into warm-up exercise, main exercise, and 10 minutes finishing exercise. Before, and four weeks and eight weeks later, the thickness of the core muscle was compared using an ultrasonic imaging system. Repeated measured ANOVA was performed to compare the groups, and a Bonferroni test was performed as a post-hoc test to assess the significance of the timing of the measurements in each group according to the periods. An independent t-test was conducted to test the significance between the groups according to the measurement points. RESULTS: A significant change in the main effects of time and interactions of the time difference in muscle thickness of transvers abdominis were observed between the visual feedback squat and control groups according to the measurement point (p0.05). CONCLUSION: These findings suggest that visual feedback squat exercise is expected to have positive effects on the development of transverse abdominis in core muscles.

Effects of Squatting with Different Foot Positions on Muscle Activations in Subjects with Genu Varum

PURPOSE: This study examined the effects of squatting with different foot positions on the muscle activation of the vastus medialis oblique (VMO) and vastus lateralis (VL) muscles in subjects with genu varum. METHODS: Thirty four subjects participated in this study. Surface electromyography was used to measure the muscle activation of the VMO and VL muscles at the knee angles (15°, 60°) at three foot positions (internal rotation, neutral position, external rotation) during squatting. RESULTS: Muscle activation differences at different knee angles and foot positions differed significantly between the VMO and VL muscles in both the varus and normal groups. In addition, there was a significant difference according to the knee angles with the foot in external rotation in the VMO and VL ratio. In the varus group, however, the VMO and VL ratio were significantly different only with the feet in internal rotation. In the muscle activation changes of the knee angle differences in the foot position, there was no significant difference in the varus group, but both the VMO and VL muscles were significant different in the normal group. CONCLUSION: In both groups, regardless of the foot position, muscle activation of the VMO and VL muscles increased with increasing knee flexion angle. In the normal group, when squatting with the feet in external rotation, the VMO and VL muscles activations increased with increasing knee angle. In the varus group, however, the foot position did not affect the VMO or VL muscle activation. This study shows that subjects with genu varum and normal subjects have different VMO and VL muscle activation patterns during squat exercises.

Research progress in biomechanics of deep squat / 医用生物力学

High flexion squat is extremely common in the daily activities of Asian countries and certain occupations.In this paper,different types of deep squats and their motion characteristics were summarized,and recent research progress of squat biomechanics was reviewed.Different research methods on squats such as in vitro experiment,in vivo test and computer simulation were also classified and represented.Biomechanical studies on deep squat of the knee can benefit establishment of reasonable rehabilitation training,prevention of sports risks as well as provide some references for optimization of knee prosthesis design.

Research progress in biomechanics of deep squat / 医用生物力学

High flexion squat is extremely common in the daily activities of Asian countries and certain occupations. In this paper, different types of deep squats and their motion characteristics were summarized, and recent research progress of squat biomechanics was reviewed. Different research methods on squats such as in vitro experiment, in vivo test and computer simulation were also classified and represented. Biomechanical studies on deep squat of the knee can benefit establishment of reasonable rehabilitation training, prevention of sports risks as well as provide some references for optimization of knee prosthesis design.

Effects of different-states-squatting on surface electromyography of thigh muscles and lumbar multifidus muscle / 实用医学杂志

Objective This work aimed to observe averaged electromyogram(AEMG)changes in surface electromyography(sEMG)of thigh muscles and lumbar multifidus muscles in different states of squat training. Then,to find out which is the most effective for squat training. Methods A total of 46 healthy volunteers were selected and divided into two groups,namely,with and without leaning against the wall.sEMG was used to record vastus lateralis muscle,vastus medialis muscle,biceps femoris muscle,and lumbar multifidus muscles at differ-ent knee flexion angles(30°,45°,60°,and 75°). AEMG was analyzed by repeated-measures analysis of vari-ance. Results Different knee flexion angles exerted significant effects on AEMG of all tested muscles(P <0.001).Whether leaning against the wall to squat had a significant impact on AEMG of biceps femoris muscle,but not on vastus lateralis muscle,vastus medialis muscle and lumbar multifidus muscles. Significant difference was detected in interactions of knee flexion angle,and the same to the factor of with and without leaning against the wall on examined AEMG of the thigh muscle,but not for lumbar multifidus muscles. Multiple comparisons showed,the AEMG level of the tested muscles was significantly increased when the knee flexion angles was 75°. Conclusions With increased knee flexion angle,muscle activation has enheanced for vastus lateralis muscle, vastus medialis muscle,biceps femoris muscle and lumbar multifidus muscles. Squatting without leaning against the wall exerts a more marked influence on activation of biceps femoris muscle,but no activation for vastus lateralis muscle,vastus medialis muscle and lumbar multifidus muscles.

Extension Force Deficiency of the Lower Extremity in Squat Contributing to Increased Fall Risk in the Female Elderly / 中国运动医学杂志

Objectives To explore the relationship between the extension force deficiency of the lower extremity and fall risks among the senior female,so as to reveal the potential factors contributing to fall.Methods Forty community-dwelling senior females aged 65 and older were assigned to the group of fallers or non-fallers according to their reported fall history and measured fall risk index (FRI).Extension force of the lower extremity was measured through 3-consecutive fast squats on a force platform.The time for 3m-time up and going (TUG),as well as static and dynamic balance were also measured.Results Compared to the non-fallers,the fallers showed lower peak extension force per body weight (PEF/BW) of the left leg and larger asymmetry of the peak extension force per body weight between the two legs in squats.Correlation analysis showed that FRI had a strong negative relation with PEF/BW of the left leg and a strong positive relation with extension force asymmetry/body weight.Also time for 3m-TUG was positively related to all the force variables standardized by the body weight,especially for the left leg.However,the analysis failed to find a relationship between the velocity of the center of pressure (COP) sway on static balance and any force variables.In addition,PEF/BW of the left leg decreased and force asymmetry/body weight between the two legs increased with aging.Conclusion Extension force measurement in squat is an effective way to assess the muscle strength deficiency related to the increased fall risk.The extension force of the lower extremity to support the body weight in squat had a strong relation to the function decline in the dynamic balance,which contributes greatly to fall risk.The extensive force asymmetry in squat between the two legs is another important fall risk factor for the senior females.

Intra-Rater Reliability and Minimal Detectable Change of Vertical Ground Reaction Force Measurement during Gait and Half-Squat Tasks on Healthy Male Adults

Background: The understanding of vertical ground reaction force (VGRF) during walking and half-squatting is necessary and commonly utilised during the rehabilitation period. The purpose of this study was to establish measurement reproducibility of VGRF that reports the minimal detectable changes (MDC) during walking and half-squatting activity among healthy male adults. Methods: 14 male adults of average age, 24.88 (5.24) years old, were enlisted in this study. The VGRF was assessed using the force plates which were embedded into a customised walking platform. Participants were required to carry out three trials of gait and half-squat. Each participant completed the two measurements within a day, approximately four hours apart. Results: Measurements of VGRF between sessions presented an excellent VGRF data for walking (ICC Left = 0.88, ICC Right = 0.89). High reliability of VGRF was also noted during the half-squat activity (ICC Left = 0.95, ICC Right = 0.90). The standard errors of measurement (SEM) of VGRF during the walking and half-squat activity are less than 8.35 Nm/kg and 4.67 Nm/kg for the gait and half-squat task respectively. Conclusion: The equipment set-up and measurement procedure used to quantify VGRF during walking and half-squatting among healthy males displayed excellent reliability. Researcher should consider using this method to measure the VGRF during functional performance assessment.

Consciousness of training body part(s) by showing a picture of an exercise to young inexperienced people: A case of squatting exercises / 体力科学

The aim of the present study was to investigate the consciousness among young people (n = 494) of training body part(s) by showing participants a picture of an exercise, through a questionnaire-based survey. Participants were shown a picture of a Back Squat, and were asked which body part(s) they felt was being trained in the picture. Participants who had no experience of doing squatting exercises (NO-SQUAT group, n = 102) and participants who were experienced in terms of doing squatting exercises and weight training under appropriate supervision (INSTRUCTED group, n = 146) were selected for the analysis. On seeing the picture, more than half of the NO-SQUAT group felt that the Back Squat was to train not only their lower body but also another body part(s); among these participants, approximately 70% felt that a Back Squat was appropriate to train their upper torso and arms too. Further, the NO-SQUAT group had made significantly fewer attempts to consciously train their gluteal and knee flexor muscles, and had made significantly more attempts to consciously train their upper torso and arms during the squatting exercises than the INSTRUCTED group had. These results suggest that to do exercises by referring to only a picture may result in the participants not properly understanding how the body part(s) should be trained during exercise. Therefore, to enhance the benefits of training, individuals need to be instructed, under appropriate supervision, on correct technique as well as knowledge about the exercise.

POWERLIFTING: Entendendo a modalidade / POWERLIFTING: Understanding the modality

O objetivo do presente estudo foi entender a modalidade powerlifting associada aos aspectos morfofuncionais que envolvem a modalidade. Para isso, foi realizada uma revisão bibliográfica com busca de artigos que tratavam da modalidade powerlifting associada às respostas morfológicas e neuromusculares. Foram selecionados artigos nacionais e internacionais, retirados das bases de dados: Medline, SciELO, PUBMED, Ebsco e Portal Periódicos Capes entre 2000 a 2013. As palavras-chave utilizadas em português e inglês foram: powerlifting, powerlifting and training, weight training, powerlifting and anthropometrics. Livros texto básicos também foram inseridos para complemento das informações. Os principais achados demonstraram que as variáveis antropométricas (massa corporal, estatura, adiposidade) e disposição corporal (arquitetura) podem influenciar no desempenho do atleta. Assim como as magnitudes de força podem auxiliar no desempenho dos atletas de powerlifting, existe um equilíbrio entre volume e intensidade com o objetivo de desenvolvimento de força com baixas alterações morfológicas. Dessa forma, o presente estudo realizou uma breve revisão da modalidade que pode auxiliar atletas e técnicos no entendimento das melhorias neuromusculares e nas respostas morfológicas relacionadas à modalidade.(AU)

The aim of this study was to understand powerlifting sport associated with morphofunctional aspects involving modality. For this, were a literature review search articles dealing with the powerlifting sport associated morphological and neuromuscular responses was performed. National and international articles drawn from the databases were selected: Medline, SciELO, PubMed, Ebsco and Portal Periodicos Capes between 2000-2013. The keywords used in Portuguese and English were: powerlifting, powerlifting and training, weight training, powerlifting and anthropometrics. Basic textbooks were also inserted to supplement the information. The main findings showed that the anthropometric variables (weight, height, body fat) and body disposal (architecture) can influence the performance of the athlete. As the magnitudes of force can assist the performance of athletes in powerlifting, there is a balance between volume and intensity with the aim of developing strength with low morphological changes. Thus, this study conducted a brief review of the modality that can help athletes and coaches in understanding the neuromuscular improvements and morphological responses related to the modality.(AU)

Ocupações do movimento dos sem-teto e a psicologia do trabalho / Homeless movement's squats and work psychology

O objetivo deste artigo é discutir a importância das atividades coletivas nas ocupações realizadas pelo movimento dos sem-teto e descrever algumas características de sua organização de trabalho, a partir do diálogo entre as referências epistemológicas e teóricas que embasam os estudos da psicologia sobre o trabalho humano e a experiência de um dos autores como apoiador da ocupação. O planejamento, a entrada no imóvel e a sua manutenção são etapas realizadas por um trabalho coletivo. Observa-se a mobilização de uma inteligência astuciosa que permite intervir criativamente na ocupação, lidando com situações imprevistas através de soluções novas. A análise da organização do trabalho permitiu perceber que, embora o ideal de responsabilização coletiva não seja plenamente atingido, essa experiência de organização afirma valores de solidariedade de uma vida em comum, na qual a luta contra a exclusão e a miséria não deriva para saídas totalmente individualistas e marginais.

The aim of this article is to discuss the importance of the collective activities in squats accomplished by the homeless movement and to describe some characteristics of their work organization, from the dialogue between the epistemological and theoretical references that underlie the studies of psychology over human work and the experience of one of the authors as a support of the squat. The planning, the entering the property and its conservation are steps performed by a collective work. It is possible to observe the mobilization of a crafty intelligence that allows the creative intervention in the squat, dealing with unpredictable situations through new solutions. The analysis of the work organization made possible the perception although the ideal of collective accountability isn't fully reached; this organization experience affirms values of solidarity of a common life, where the struggle against exclusion and misery doesn't derive to solutions totally individualistic and marginal.

Análise comparativa da atividade eletromiográfica do reto femoral em isometria na posição inferior do agachamento wall slide, antes e após a aplicação da acupuntura no ponto ST45 / Comparative analisys of electromyographical activity of rectus femoris in lower phase of isometric wall slide squat before and after aplication of acupuncture at ST45

O objetivo deste estudo foi fazer uma análise comparativa da atividade eletromiográfica do reto femoral em isometria na posição inferior do agachamento wall slide, antes e após a estimulação com agulha do ponto ST45. O experimento foi realizado com 10 voluntários, sendo cinco homens e cinco mulheres, com idade entre 20 e 30 anos, estudantes universitários, sem histórico de trauma no joelho ou quadril. Foi coletado o sinal eletromiográfico do reto femoral na posição inferior do agachamento em isometria para cada voluntário. Logo após, foi estimulado o ponto ST45 no sentido da tonificação por 10 minutos, estando o indivíduo sentado, e a agulha sendo girada aos cinco minutos. Em seguida, foi repetido o procedimento de coleta do sinal. Os valores de potencial elétrico, amplitude e ângulo de fase foram analisados. Foram encontradas diferenças significativas (p<0,05) entre o exercício pré e pós acupuntura para cada indivíduo apesar destas variações não terem seguido nenhum padrão. A acupuntura aplicada no ponto mais distal do meridiano agiu na modulação da contração do reto femoral e, provavelmente, na modulação da ação dos músculos sinergistas, alterando a estratégia de movimento adotada por cada voluntário. O fato de não ter havido um padrão nas alterações refletem diferentes estratégias de movimento entre os voluntários. A análise da variável ângulo de fase não foi conclusiva neste estudo, sugerindo que seja um processo estocástico.

The aim of this study was to make a comparative analysis of the electromyographical activity of the rectus femoris in the lower position of isometric wall slide squat before and after stimulation with needle point ST45. The experiment was conducted with 10 volunteers, five men and five women, aged between 20 and 30 years old, college students with no history of trauma to the knee or hip. EMG signal was collected in the inferior position during isometric squat in each volunteer, just after was stimulated the point ST45 towards toning for 10 minutes while the subject seated, and the needle is stimulated at five minutes. It was then repeated the procedure of collecting the signal. The values of electric potential, amplitude and phase angle were analyzed. Significant differences (p<0,05) between exercises pre and post acupuncture was found despite these variations did not follow any pattern. Acupuncture applied to the most distal point of the meridian acted in modulating the contraction of the rectus femoris, and probably modulating too the synergistic action of the muscles by changing the movement strategy adopted by each volunteer. The fact that there has not been a pattern in the changes, reflect different movement strategies among the volunteers. The analysis of the variable phase angle in this study was not conclusive suggest it is a stochastic process.

Especificidade da atividade mioelétrica no agachamento excêntrico declinado em 25º e no agachamento padrão com diferentes sobrecargas / Specificity of the myoelectrical activity on the eccentric decline squat at 25º and standard squat with different overloads

OBJETIVO: O objetivo neste estudo foi comparar a atividade mioelétrica entre o agachamento unilateral declinado e o agachamento unilateral em superfície plana, no deslocamento vertical de duas diferentes quantidades de massa. PARTICIPANTES: Um grupo de oito sujeitos treinados recreacionalmente sem sinais e sintomas de lesões nas extremidades inferiores. PROCEDIMENTOS: Em dias separados, os sujeitos realizaram dois tipos distintos de agachamento unilateral na fase descendente, diferenciados em função da direção da base de sustentação, sendo uma horizontal e outra inclinada a 25º. Os dois tipos de agachamento foram realizados com dois valores de carga, com o peso do próprio corpo e com sobrecarga representativa de 15 repetições máximas (15RM). MENSURAÇÕES: As atividades mioelétricas do reto femoral, vasto lateral, posteriores de coxa mediais (semimembranoso e semitendinoso) e gastrocnêmio medial foram mensuradas nas quatro situações de teste. RESULTADOS: O grupamento muscular quadríceps mostrou-se sensível à magnitude do ângulo de inclinação da plataforma, manifestando maior atividade no agachamento declinado, e não apresentou aumentos na ativação muscular como resposta ao aumento da carga. Os músculos mediais posteriores da coxa e o gastrocnêmio medial não se mostraram sensíveis à angulação da plataforma nem ao aumento da sobrecarga. Apesar das taxas de co-contração não serem semelhantes entre as quatro situações testadas, as diferenças entre elas não se mostraram estatisticamente significativas. CONCLUSÃO: Os resultados confirmaram a maior ativação do quadríceps gerada no agachamento declinado em comparação ao agachamento realizado em superfície plana, sugerindo que esse exercício pode constituir uma alternativa para programas de reabilitação da tendinopatia patelar. Apesar de não termos encontrado diferenças estatisticamente significativas em relação à co-contração muscular, os achados sugerem que esse exercício deve ser utilizado com...

OBJECTIVE: The aim of this study was to compare the myoelectrical activity between the single-leg decline squat and the single-leg standard squat, with two different overloads. PARTICIPANTS: A group of eight recreationally trained subjects with no signs or symptoms of injury in the lower limb. PROCEDURES: On different days, the subjects performed two distinct kinds of unilateral eccentric squat, differentiated by the direction of the base of support, being one flat and the other declined at 25º. These two squats were carried out with two different overloads: with no extra overload and with an overload that represented 15 maximum repetitions (RM). OUTCOME MEASURES: The myoelectrical activities of the rectus femoris, vastus lateralis, medial hamstrings and gastrocnemius medialis were measured in the four test conditions (Flat and Decline Squat with and without extra overload). RESULTS: The quadriceps muscles were sensitive to the platform angle, showing greater activity on the decline squat; however, they did not show increase in the activation when overload was added. The medial hamstrings and gastrocnemius medialis were not sensitive to the platform angle or to the overload increase. In spite of the alterations in the muscular co-contraction ratio in several situations, we did not find any statistically significant differences among the four conditions tested. CONCLUSION: The results confirmed the higher activation of quadriceps generated in the decline squat compared to the standard squat, suggesting that this exercise is an interesting choice for rehabilitation management of patellar tendinopathy. Despite the non-significant statistical differences regarding muscular co-contraction, this exercise should be used with caution, since muscle synergism is changed as a function of tested variables, altering the specificity of this exercise in relation to sports activities, mainly in the coordination aspect.