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The Effect of Stance Width on the Electromyographical Activity of Eight Superficial Thigh Muscles During Back Squat With Different Bar Loads
Abstract
Many strength trainers believe that varying the stance width during the back squat can target specific muscles of the thigh. The aim of the present work was to test this theory measuring the activation of 8 thigh muscles while performing back squats at 3 stance widths and with 3 different bar loads. Six experienced lifters performed 3 sets of 10 repetitions of squats, each one with a different stance width, using 3 resistances: no load, 30% of 1-repetition maximum (1RM), and 70% 1RM. Sets were separated by 6 minutes of rest. Electromyographic (EMG) surface electrodes were placed on the vastus medialis, vastus lateralis, rectus femoris, semitendinosus, biceps femoris, gluteus maximus, gluteus medium, and adductor maior. Analysis of variance and Scheffè post hoc tests indicated a significant difference in EMG activity only for the gluteus maximus; in particular, there was a higher electrical activity of this muscle when back squats were performed at the maximum stance widths at 0 and 70% 1RM. There were no significant differences concerning the EMG activity of the other analyzed muscles. These findings suggest that a large width is necessary for a greater activation of the gluteus maximus during back squats.
... The effect of squat load has previously been investigated only in strength-trained participants. Paoli et al. (2009) found that increasing load from 0% (no external load) to 70% of 1RM has no effect on the electromyographic (EMG) activity of vastus lateralis, vastus medialis, rectus femoris, gluteus maximus, gluteus medius, biceps femoris, semitendinosus or adductor magnus. McCaw and Melrose (1999), in contrast, showed that increasing load from 60% to 75% of 1RM increases the activity of vastus lateralis, vastus medialis, rectus femoris and adductor longus but not the activity of gluteus maximus or biceps femoris. ...
... In response to this cue, participants selfselected a stance width of 1.5 ± 0.2 x inter-ASIS distance. As stance width can influence muscle activity (Paoli et al., 2009), participants were required to use an identical stance width for each of the four squat conditions. ...
... It is also the first time that the effect of load on gluteus maximus, vastus lateralis and biceps femoris activity has been investigated in non-strength trained participants. Previous analyses of gluteus maximus, vastus lateralis and biceps femoris activity in strength-trained participants are conflicting; both a significant effect and no effect of load have been reported (McCaw & Melrose, 1999;Paoli et al., 2009;Van den Tillaar et al., 2019;Yavuz & Erdag, 2017). This inconsistency may be explained by the non-linear relationship between load and muscle activity reported by Van den Tillaar et al. (2019). ...
Les Mills BODYPUMP TM is a resistance training group exercise class with a low load, high repetition format. Squat training in BODYPUMP TM has two key variables: depth and load. The study aim was to determine the effect of these parameters on the mean and peak EMG amplitude of vastus lateralis, gluteus maximus, biceps femoris and lateral gastrocnemius. Ten female BODYPUMP TM participants (age 41 ± 9 years, height 161.9 ± 3.8 cm, mass 67.7 ± 7.0 kg) performed 1 × 7 squats under four conditions, representing every combination of two depths (90° knee angle and 125° knee angle) and two loads (23% bodyweight and 38% bodyweight). The main effect of depth was significant for mean and peak activity of vastus lateralis and gluteus maximus, and peak activity of biceps femoris and lateral gastrocnemius. The main effect of load was significant for mean and peak activity of gluteus maximus and lateral gastrocnemius. There was no depth * load interaction. These data can be used to inform BODYPUMP TM programme design and amplify the training effect of participation in group exercise classes.
... Alternatively, the squatting depth may lead to parallel or full squat, where the descending phase ends when the thighs are parallel to the ground or below this line, respectively [7]. Furthermore, the feet stance may be regular or wide, leading in the latter case to a so-called sumo-squat, where the direction of the feet can be parallel or rotated externally [11]. Obviously, all these independent parameters can be miscellaneously used to create many combinations of squatting techniques and exercises. ...
... Additionally, quadriceps activation was overall greater in full vs. partial squat [14]. Interestingly, no difference in muscle activation was found comparing BS vs. FS performed with 70% 1-RM by healthy men [10], while larger stance specifically activates medial thigh muscles in experienced lifters [15], although no difference was found in gluteal muscles activation [11]. ...
... Additionally, FS vs. BS was previously investigated, but no gluteal muscle was examined [10]. Lastly, the effect of stance does not seem to play a key role in gluteus maximus activation, which contrasts with the greater activation reported at greater stance [11,15]. Again, it is possible that the present bodybuilders population may have cancelled such a difference, since they were able to recruit the gluteus maximus more than just experienced lifters irrespectively of the stance. ...
The present study investigated the activation of gluteal, thigh, and lower back muscles in different squat variations. Ten male competitive bodybuilders perform back-squat at full (full-BS) or parallel (parallel-BS) depth, using large feet-stance (sumo-BS), and enhancing the feet external rotation (external-rotated-sumo-BS) and front-squat (FS) at 80% 1-RM. The normalized surface electromyographic root-mean-square (sEMG RMS) amplitude of gluteus maximus, gluteus medius, rectus femoris, vastus lateralis, vastus medialis, adductor longus, longissimus, and iliocostalis was recorded during both the ascending and descending phase of each exercise. During the descending phase, greater sEMG RMS amplitude of gluteus maximus and gluteus medius was found in FS vs. all other exercises (p < 0.05). Additionally, FS elicited iliocostalis more than all other exercises. During the ascending phase, both sumo-BS and external-rotated-sumo-BS showed greater vastus lateralis and adductor longus activation compared to all other exercises (p < 0.05). Moreover, rectus femoris activation was greater in FS compared to full-BS (p < 0.05). No between-exercise difference was found in vastus medialis and longissimus showed no between-exercise difference. FS needs more backward stabilization during the descending phase. Larger feet-stance increases thigh muscles activity, possibly because of their longer length. These findings show how bodybuilders uniquely recruit muscles when performing different squat variations.
... This technical modification was included in the analysis of the high-bar (Escamilla et al., 2001;Paoli et al., 2009) and the low-bar (McCaw & Melrose, 1999) squat. The main effect of having a wider stance was a higher activation on the gluteus (McCaw & Melrose, 1999;Paoli et al., 2009). ...
... This technical modification was included in the analysis of the high-bar (Escamilla et al., 2001;Paoli et al., 2009) and the low-bar (McCaw & Melrose, 1999) squat. The main effect of having a wider stance was a higher activation on the gluteus (McCaw & Melrose, 1999;Paoli et al., 2009). Variations on the stance width did not produce an effect on the activation of the quadriceps, hamstring, and gastrocnemius (Escamilla et al., 2001). ...
... Attending to the squat biomechanics, the gluteus act as a powerful hip extensor and also as a knee and hip stabilizer. Gluteus activation mainly depends on the force arm length which is conditioned by different technique factors such as the depth, the stance width (McCaw & Melrose, 1999;Paoli et al., 2009;Schoenfeld, 2010). Concerning the calves, low activation levels have been observed in comparison to the thigh muscles. ...
The squat is one of the most commonly used resistance exercises for performance and health due to its biomechanical and neuromuscular similarities to a wide range of athletic and everyday activities. There is a large number of squat variations (based on the descent depth, width of the stance, bar placement) with significant biomechanical and neuromuscular differences between them. The aim of this study was to systematically review the scientific literature to gather data on the muscular activation of the lower limb during different variants of the squat exercise. High-bar squat (full range of motion, to parallel and partial range of motion), low-bar squat, front squat, overhead squat and guided squat on Smith machine were included in the analysis. 30 articles met the inclusion criteria and were reviewed. Quality of the included studies was analysed with the PEDro scale. Main findings were that in the squat exercise activation of the knee-extensors is predominant. However, different activation patterns were observed with different distances between the feet, different depths, hips rotation or flexion, intensities. For instance, low-bar squat involves a greater hip hinge and thus, provokes major activation on the hip-extensors than other squat variations. It is worth highlighting that similar activation patterns were observed between the front squat and the high-bar squat. The variation with least activation was the guided squat. The evidence presented in this study may help the strength and conditioning professionals and practitioners with the exercise selection depending on the muscular targets and the individual characteristics of the athlete. Keywords: Electromyographic activity; Resistance exercise; Quadriceps; Gluteus; Hamstrings; Calves.
... Numerous studies have been conducted to investigate the effect of exercise variations on the pattern of muscle activation. For example, evidence has been provided on variations based on the position of hands (28), body, or limbs (15,22,27). Other researchers have documented changes in electromyographic (EMG) when verbal instructions are given on how to perform an exercise (5,6,29). ...
... Each variation of the HT exercise exhibits a different pattern of muscle activation. The results obtained are consistent with those reported in previous studies, where motor patterns were found to differ according to the exercise (1,9,24) or variation performed (10,15,18,20,27). ...
... In the RHT, the distance between the feet also increased. In a previous study, Paoli et al. (27) observed that when stance width is increased in back squat (1.5 and 2 times the great trochanter distance), the electrical activity of the gluteus maximus without added load or with loads of 70% RM increased. These results are in agreement with those reported by Mccaw and Melrose (22), who documented an increase in the activity of the gluteus maximus when subjects completed parallel squat at 75% of 1RM using 140% of shoulder width, compared with muscle activity at 75% of the subject's shoulder width. ...
Collazo García, CL, Rueda, J, Suárez Luginick, B, Navarro, E. Differences in the electromyographic activity of lower-body muscles in hip thrust variations. J Strength Cond Res XX(X): 000-000, 2018-Coaches often use variations of an exercise to train a specific muscle. The purpose of this study was to analyze motor patterns in 4 variations of one of the most popular strength training exercises for the lower body: the barbell hip thrust. Seven experienced personal trainers performed a series of 8 repetitions of each variation with a load of 40% one repetition maximum. Subjects rested 3' between series. Electromyographic (EMG) muscle activity was measured in the rectus femoris, vastus medialis; vastus lateralis; gluteus maximus; gluteus medius; biceps femoris; and semitendinosus. Variations of the hip thrust exercise were performed by changing the position of the feet (feet were moving away from the body) and the direction of force exerted by subjects (intentional force aimed at hip's external rotation and knee's flexion). Repeated-measures analysis of variance revealed significant differences in EMG in all muscles except for the gluteus medius, where no differences were observed among variations. The results obtained suggest that hip thrust variations have different motor patterns, which can be exploited to adapt an exercise to the individual needs of each athlete.
... The squat has neuromuscular as well as biomechanical similarities to jumping and running and is therefore a commonly used exercise to increase muscle strength among athletes across a range of sports (1). Depending on the athletes' goals, the squat can be performed using several alternative techniques, e.g., squatting with the barbell lower down on the back increases hip flexion and reduces knee flexion (2), whereas gluteus maximus activation has been shown to increase when using a wider foot placement (3) and when squatting deeper (>90 • knee flexion) (4). Squats can also be performed using different kinds of equipment, such as different footwear (5), unstable surfaces (6), chain-loaded variable resistance (7) or with a Smith machine. ...
... Comparing muscle activity between squats of different movement paths requires standardization of potentially confounding variables that may influence the outcomes of interest. For example, gluteus maximus activation increases when the external load is higher (3), with a wider foot placement (3,14) and with a depth of ≥90 • knee flexion (4). Gluteus medius also seems to reach higher degrees of activation with a wider foot placement (15 • hip abduction) (15). ...
Introduction
Traditional recordings of muscle activation often involve time-consuming application of surface electrodes affixed to the skin in laboratory environments. The development of textile electromyography (EMG) electrodes now allows fast and unobtrusive assessment of muscle activation in ecologically valid environments. In this study, textile EMG shorts were used to assess whether performing squats with the barbell resting freely on the shoulders or using a Smith machine for a fixed barbell movement path is preferable for maximizing lower limb muscle activation.
Methods
Sixteen athletes performed free and fixed barbell squats in a gym with external loads equivalent to their body mass. Quadriceps, hamstrings and gluteus maximus activation was measured bilaterally with textile EMG electrodes embedded in shorts.
Results
Mean quadriceps activation was greater for the free compared with the fixed movement path for the right (mean difference [MD] 14μV, p = 0.04, η p ² = 0.28) and left leg (MD 15μV, p = 0.01, η p ² = 0.39) over the entire squat and specifically during the first half of the eccentric phase for the left leg (MD 7μV, p = 0.04, d = 0.56), second half of the eccentric phase for both legs (right leg MD 21μV, p = 0.05, d = 0.54; left leg MD 23μV, p = 0.04, d = 0.52) and the first half of the concentric phase for both legs (right leg MD 24μV, p = 0.04, d = 0.56; left leg MD 15μV, p = 0.01, d = 0.72). Greater hamstrings activation for the free path was seen for the second half of the eccentric phase (left leg MD 4μV, p = 0.03, d = 0.58) and first half of the concentric phase (right leg MD 5μV, p = 0.02, d = 0.72). No significant differences were found for gluteus maximus.
Discussion
Textile EMG electrodes embedded in shorts revealed that to maximize thigh muscle activity during loaded squats, a free barbell movement path is preferable to a fixed barbell movement path.
... McCaw's study tested changes in muscle activity according to the load exerted during squats and reported that the muscle activity increased with increasing load [23]. In addition, Paoli et al. (2009) studied the changes in muscle activity according to squat motions for loads of 0%, 30%, and 70% in professional lifters, and found that muscle activity increased with an increase in load [37], consistent with our study findings and McCaw's results. In particular, the comparison between 50% and 70% in this study showed that the activities of all muscles were significantly increased. ...
... McCaw's study tested changes in muscle activity according to the load exerted during squats and reported that the muscle activity increased with increasing load [23]. In addition, Paoli et al. (2009) studied the changes in muscle activity according to squat motions for loads of 0%, 30%, and 70% in professional lifters, and found that muscle activity increased with an increase in load [37], consistent with our study findings and McCaw's results. In particular, the comparison between 50% and 70% in this study showed that the activities of all muscles were significantly increased. ...
This study aimed to investigate the effect of the load and bar position on trunk and lower extremity muscle activity during squat exercise. High bar back squats (HBBS) and low bar back squats (LBBS) were performed in random order at 50%, 60%, and 70% loads of one repetition maximum by 28 experienced healthy adult men who had been performing squats for at least one year. Before the experiment, the maximal voluntary contraction of the vastus medialis, vastus lateralis, rectus femoris, biceps femoris, rectus abdominis, transverse abdominis, external oblique, and erector spinae muscles was measured by means of surface electromyography. In addition, eccentric and concentric exercises were performed for 3 s each to measure the muscle activity. There was a significant difference in muscle activity according to the load for all muscles in the eccentric and concentric phases (p < 0.05), indicating that muscle activity increased as the load increased. In addition, in the comparison between HBBS and LBBS, significant differences were shown in all lower extremity muscles and all trunk muscles except for the external oblique in the concentric phase according to the bar position (p < 0.05). HBBS showed a higher muscle activity of the lower extremity in the eccentric and concentric phases than in LBBS, while LBBS showed a higher muscle activity of the trunk muscle in the eccentric and concentric phases than in HBBS (p < 0.05). HBBS requires more force in the lower extremity than LBBS and is particularly advantageous in strengthening the muscular strength of the quadriceps. In contrast, LBBS requires more muscle activity in the trunk than HBBS and is more effective in carrying heavier loads because of the advantage of body stability. This study suggests that rehabilitation experts apply the bar position and load as important variables affecting the intensity and method of training for target muscle strengthening of the lower extremities and trunk.
... Their findings show that the hamstring and gastrocnemius muscle activation was significantly greater in the wide squat compared to the narrow position. Similarly, Paoli et al. [9] examined the influence of the squat width on the lower extremity muscular activation, and their results indicate that the gluteus maximus activation was significantly greater in the wide squat condition. Sogabe et al. [10] explored the power production measured at the barbell using stance widths of 50, 100, 150 and 200% shoulder distance. ...
... When also taking into account the observations from both experiments relating them to the joint energy production, this study indicates that the NARROW condition appears to arbitrate a knee-dominant squat strategy that targets the anterior chain musculature, whereas the WIDE condition produced a hip-dominant strategy [16] and targets the posterior chain musculature more effectively. This observation concurs with the electromyographic investigations of Escamilla et al. [7], McCaw & Melrose [8] and Paoli et al. [9], who found that wide-stance squat positions recruited the posterior chain musculature to a significantly greater extent. Furthermore, our observations in relation to the joint dominance are also supported by the examination of the joint moments by Lahti et al. [11], who showed that the hip-to-knee joint extension moment ratio was significantly greater when adopting a wide stance. ...
This two-experiment study aimed to explore habitual and manipulated stance widths on squat biomechanics. In experiment one, 70 lifters completed back squats at 70%, 1 repetition maximum (1RM), and were split into groups (NARROW < 1.06 * greater trochanter width (GTW), MID 1.06–1.18 * GTW and WIDE > 1.37 * GTW) according to their self-selected stance width. In experiment two, 20 lifters performed squats at 70%, 1RM, in three conditions (NARROW, MID and WIDE, 1.0, 1.25 and 1.5 * GTW). The three-dimensional kinematics were measured using a motion capture system, ground reaction forces (GRF) using a force platform, and the muscle forces using musculoskeletal modelling. In experiment two, the peak power was significantly greater in the NARROW condition, whereas both experiments showed the medial GRF impulse was significantly greater in the WIDE stance. Experiment two showed the NARROW condition significantly increased the quadriceps forces, whereas both experiments showed that the WIDE stance width significantly enhanced the posterior-chain muscle forces. The NARROW condition may improve the high mechanical power movement performance and promote the quadriceps muscle development. Greater stance widths may improve sprint and rapid change-of-direction performance and promote posterior-chain muscle hypertrophy. Whilst it appears that there is not an optimal stance width, these observations can be utilized by strength and conditioning practitioners seeking to maximize training adaptations.
... The barbell back squat is one of the most frequently adopted resistance exercises for development purposes in athletic disciplines that necessitate high levels of strength and power [1]. Because of its ability to recruit the quadriceps, hamstrings, tibialis anterior, gastrocnemius, soleus and lumbar muscles [2], and its function as a closed kinetic chain exercise, it is also commonly utilised in rehabilitation settings [3]. ...
... Their observations showed that the hip was in a significantly more flexed position and the knee extensor and ankle plantarflexor moments were significantly greater in the wide and medium conditions compared to narrow. Paoli et al. [2] showed that gluteus maximus activation was significantly greater in the wide squat condition. Lahti et al. [9] examined wide (1.5× greater trochanter width) and narrow (1.0 greater trochanter width) barbell back squats. ...
This two-experiment study aimed to examine the effects of different habitual foot placement angles and also the effects of manipulating the foot placement angle on the kinetics, three-dimensional kinematics and muscle forces of the squat. In experiment 1, seventy lifters completed squats at 70% of their one repetition maximum using a self-preferred placement angle. They were separated based on their habitual foot angle into three groups HIGH, MEDIUM and LOW. In experiment 2, twenty lifters performed squats using the same relative mass in four different foot placement angle conditions (0°, 21°, 42° and control). Three-dimensional kinematics were measured using an eight-camera motion analysis system, ground reaction forces (GRF) using a force platform, and muscle forces using musculoskeletal modelling techniques. In experiment 1, the impulse of the medial GRF, in the descent and ascent phases, was significantly greater in the HIGH group compared to LOW, and in experiment 2 statistically greater in the 42° compared to the 21°, 0° and control conditions. Experiment 2 showed that the control condition statistically increased quadriceps muscle forces in relation to 0°, whereas the 0° condition significantly enhanced gluteus maximus, gastrocnemius and soleus forces compared to control. In experiment 1, patellofemoral joint stress was significantly greater in the HIGH group compared to LOW, and in experiment 2, patellar and patellofemoral loading were statistically greater in the control compared to the 42°, 21°, 0° and control conditions. Owing to the greater medial GRF’s, increased foot placement angles may improve physical preparedness for sprint performance and rapid changes of direction. Reducing the foot angle may attenuate the biomechanical mechanisms linked to the aetiology of knee pathologies and to promote gluteus maximus, gastrocnemius and soleus muscular development. As such, though there does not appear to be an optimal foot placement angle, the observations from this study can be utilised by both strength and conditioning and sports therapy practitioners seeking to maximise training and rehabilitative adaptations.
... Previous research has provided evidence that variations in body and limb positioning can affect muscle activation (Escamilla et al., 2002;McCaw & Melrose, 1995;Paoli et al., 2009). In addition, previous research has examined the biomechanical differences between the BHT and BGB among trained male participants (Korta & Peña, 2018). ...
... To date, no previous BHT study has utilised the 5-RM. Moreover, this load was selected to normalise each exercise's load to each exercise by taking into consideration the possibility of effects on muscular activity due to the presence of biomechanical and limb position variations (Escamilla et al., 2002;Korta & Peña, 2018;McCaw & Melrose, 1995;Paoli et al., 2009). Unlike previous BHT studies, foot position was standardised to the shoulder width of each subject, as noted in previous research (Contreras et al., 2011) to further standardised exercise set-up. ...
Hip extensor muscles are critical to sport performance as events requiring sprinting and forceful landings are highly dependent on these muscles. Despite biomechanical differences between the barbell hip thrust (BHT) and the barbell glute bridge (BGB), both are biomechanically efficient ways to load this musculature for training purposes. Research investigating the differences in muscular activity between the BHT and BGB has yet been conducted. The aim of this study was to investigate, through surface electromyography, if one exercise is more optimal than the other in producing greater muscle activation for specific hip extensor muscles. Ten male participants completed a two-part study protocol. Results revealed the BHT elicited significantly greater muscle activity within the vastus lateralis for peak and mean outcomes; however, the BGB elicited significantly greater muscle activity in the upper and lower gluteus maximus for peak and mean outcomes and mean outcome in the gluteus medius. Current findings suggest, the BGB is, at minimum, a superior substitute for the BHT for eliciting a larger magnitude of activity in the gluteus maximus. Future studies between the two exercises are warranted to discern which produces greater hypertrophy and whether adaption of the BHT or BGB transfers more optimally to sport performance.
... En cuanto al tema de la medición de la EMG en la SLB, diversos estudios han analizado de qué manera la actividad muscular puede ser influenciada por efecto de variables tales como: i) modificaciones en su rango de movimiento (ROM) en donde mayores ángulos de flexión en la rodilla no necesariamente tienden a representar mayor actividad muscular cuando la 1RM es equiparada para cada variante (Contreras et al., 2016;Da Silva et al., 2017), ii) bajo distintas aperturas en la base de apoyo en donde contrario a la creencia popular, se reconoce que la anchura de apoyo de los pies no tiende a afectar la actividad muscular del cuádriceps, sin embargo, una mayor apertura puede a aumentar la actividad de músculos secundarios como lo son el aductor largo y el glúteo mayor (Dave Clark et al., 2012;Paoli et al., 2009); iii) modificando el tipo de resistencia con el uso con cargas inestables o bandas elásticas, las cuales no tiende a producir cambios significativos en los músculos del tren inferior, salvo en los músculos estabilizadores del tronco (Lawrence & Carlson, 2015;Saeterbakken et al., 2016); iv) bajo el efecto de diferentes cargas de trabajo en base al %1RM, en donde se identifica que la actividad de los músculos tiende a aumentar conforme al aumento de cargas; v) en donde la velocidad de ascenso parece solo afectar a músculos primarios y secundarios del muslo sin efecto aparente en aquellos de función estabilizadora (D. Clark et al., 2016;Van den Tillaar et al., 2019); y vi) cuando se valoraron diferencias entre sexos, la SLB no supone cambios de actividad eléctrica de músculos primarios entre hombres y mujeres, sin embargo, los hombres tienden ligeramente a una mayor actividad de músculos secundarios como los son el bíceps femoral (BF) y el gastrocnemio (Ga) (Gulick et al., 2015;Mehls et al., 2020). ...
... Yavuz et al., 2015), lo cual ayuda a responder la primera pregunta planteada de ¿cuál es el músculo con mayor activación? Esto puede ser razonable debido a dos factores, primero a que la SLB contempla una apertura del apoyo de los pies similar a la anchura de hombros y una alineación de rodilla con la punta de los pies, propiciando una rotación externa del fémur, lo cual podría facilitar la activación del VM, aunque también es importante reconocer que en estudios previos no se ha encontrado evidencia de que la amplitud de apoyo afecte el reclutamiento de los músculos del cuádriceps (McCaw & Melrose, 1999;Paoli et al., 2009). En segundo, se ha reconocido con anterioridad, que el RF al ser un músculo flexor de la cadera y extensor de la rodilla, tiende a acortarse en su inserción y alargarse en su origen durante la fase de subida de la sentadilla, lo cual podría limitar su óptimo reclutamiento muscular (Schoenfeld, 2010). ...
Resumen. Objetivo: Realizar una revisión sistemática de literatura que evalúa la activación muscular por electromiografía (EMG) en sentadilla libre con barra (SLB), así como cambios producidos por factores cinéticos y cinemáticos. Métodos: Se utilizaron los lineamientos de la declaración PRISMA y de calidad metodológica de la declaración STROBE. Se incluyeron artículos originales encontrados en bases de datos Scopus, PubMed, Scielo y Cochrane Central Register of Controlled Trials (CENTRAL). Se encontraron 1889 artículos de los cuales debido a los criterios: sujetos con experiencia previa en entrenamiento resistido que midieran la ejecución de la SLB y utilización de EMG. Finalmente se utilizaron 18 artículos para el análisis. Resultados: La evidencia posiciona al cuádriceps femoral y el vasto medial como el grupo muscular y el músculo con mayor participación en la SLB. La actividad muscular en la SLB puede ser afectada por la carga de trabajo, la velocidad de ejecución, el tipo de resistencia y el rango de movimiento. Existe una tendencia a mayor compromiso muscular en la medida que aumenta la carga o la velocidad de ascenso, sin embargo, el aumento de la carga tiende a afectar de forma negativa a la velocidad. Conclusiones: Las cargas submáximas parecen generar activaciones musculares similares al 1RM, con el aliciente de menor riesgo de lesión que las cargas máximas. Mayores estudios con criterios metodológicos unificados son requeridos para identificar el punto óptimo de activación muscular en base a la carga de trabajo. Palabras clave: Entrenamiento deportivo, fuerza muscular, ejercicio físico, biomecánica, contracción muscular, 1RM. Abstract. Purpose: To conduct a systematic review of studies that evaluate electromyography muscle activation in the free barbell back squat (BS), and the changes produced by the effect of kinetic and kinematic factors. Methods: This study was conducted according to The PRISMA declaration and the STROBE guidelines to assess the methodological quality. Databases included were Scopus, PubMed, Scielo y Cochrane Central Register of Controlled Trials (CENTRAL). A total of 1889 original articles were selected using the inclusion criteria as follows: subjects previously experienced in resistance training including EMG assesment during the execution of the BS. The final selection consisted of 18 articles. Results: The evidence suggest to the quadriceps femoris and vastus medialis as the muscle group and the muscle with the greatest participation in BS. Muscle activity in BS can be affected by load, speed of execution, resistance type, and range of motion. There is a relationship between high muscle activity and increased load or velocity in the lift back up phase, however, increased load tends to negatively affect velocity in squat performance. Conclusions: Submaximal loads seem to produce similar muscle activation to the 1RM, with the incentive of a lower risk of injury compared to the maximum loads. More studies with unified methodological criteria are required to identify the optimal muscle activation based on the load.
... The squat exercise is frequently employed by both healthy and rehabilitating athletes. This closed-kinetic chain task is popular for reducing tibial-femoral shear forces in anterior cruciate ligament (ACL) rehabilitation [1], patella-femoral tracking dysfunctions (PFTD), and total knee replacement therapy [2]. However, it is not always applicable or advantageous to use a traditional back squat. ...
... The athlete donned the speci ic belt for the device and placed his feet shoulder width apart (on either side of the cylinder, lever or cable depending upon the device) to standardize positioning [1,10] and placed arms in front of the chest; ...
... The squat exercise is frequently employed by both healthy and rehabilitating athletes. This closed-kinetic chain task is popular for reducing tibial-femoral shear forces in anterior cruciate ligament (ACL) rehabilitation [1], patella-femoral tracking dysfunctions (PFTD), and total knee replacement therapy [2]. However, it is not always applicable or advantageous to use a traditional back squat. ...
... The athlete donned the speci ic belt for the device and placed his feet shoulder width apart (on either side of the cylinder, lever or cable depending upon the device) to standardize positioning [1,10] and placed arms in front of the chest; ...
... Na prática, observa-se que existe uma crença de que a ativação dos vastos será modificada com a alteração da distância entre os pés. Entretanto, os estudos científicos não indicam alteração na ativação dos vastos com afastamento ou aproximação dos pés (16,21,22) . Assim, abduzir o quadril (afastar os pés) ou aduzir o quadril (aproximar os pés) não afetará significativamente a ativação dos vastos. ...
... Assim, abduzir o quadril (afastar os pés) ou aduzir o quadril (aproximar os pés) não afetará significativamente a ativação dos vastos. Entretanto, realizar o agachamento com maior distância entre os pés (ligeiramente maior que a largura do quadril) poderá ser mais efetivo, uma vez que aumenta a ativação do glúteo máximo e dos adutores de quadril (16,22) . Na sequência, o Quadro 1 apresenta parâmetros de avaliação da técnica do agachamento, que foram adaptados do estudo de O'connor et al. (23) . ...
... The squat has a very important place in all type of competitive sports and recreational exercises. It is regarded the "most important" exercise in strength training by coaches and sport scientists [3] or "king" [4] of strengthening exercises for the lower body [5][6][7][8][9][10][11]. During the squat, the force is expressed through the length of the leg while the feet are fixed to the ground [5,12]. ...
... Gluteus maximus, hamstrings, quadriceps and gastrocnemius are the mainly active muscles during squat [6,13,14]. Ankle, knee and hip joints musculature are active with the contribution of the abdominals and spinal erectors [8,14]. ...
The importance of Electromyography (EMG) signals analysis with advanced methodologies is increasing in biomedics, clinical diagnosis and biomechanics and it becomes a required practice for many scientists from both health and engineering fields. The squat is a very important exercise for improving athletic performance and for prevention and rehabilitation of injuries. It has many different variations which are supposedly focusing on different muscles. We aimed to compare vastus medialis, rectus femoris, vastus lateralis, gluteus maximus, semitendinosus, biceps femoris and erector spinae EMG activities during popular squat variations while the participants (14 healthy males, 23.7 ± 2.7 years-old) were performing 6 repetitions of front squat, back squat, hack squat, sumo squat and zercher squat with 60% of the 1 repetition maximum loading. Muscle EMG activities during different variations were compared by using Repeated measures ANOVA. The highest rectus femoris, vastus lateralis and vastus medialis EMG activities were observed during front squat with a significant difference with Zercher squat. EMG activities of Erector spinae and semitendinosus during Hack squat were significantly lower than all other squat variations (p < 0.05). These findings may suggest that front squat may be chosen to focus on quadriceps muscles while Hack squat may be a good choice for better knee and spinal stabilization.
... No entanto, alguns estudos importantes utilizando o método de eletromiografia (EMG) têm contrariado estas hipotéticas e desejadas respostas quanto a recrutamento dos músculos específicos ao longo da execução dos movimentos nestes ou outros tipos de variações do exercício. Como exemplo o estudo de Paoli et al. 9 no qual por meio da EMG avaliaram a atividade de 8 músculos da coxa (vasto medial, vasto lateral, reto femoral, semitendinoso, bíceps femoral, glúteo máximo, glúteo médio e maior adutor) durante a realização do agachamento em diferentes posições dos membros inferiores, em que levantadores experientes realizaram séries de repetições de agachamento, com diferentes posicionamentos dos membros e distintas cargas. Os resultados não encontraram diferenças significativas entre a musculatura do quadríceps, adutor ou isquiotibiais, mas apenas um pequeno aumento da ativação dos glúteos quando se aumenta o afastamento dos pés. ...
... Também se observa que o livre juntamente com agachamento sumô foi muito mais citado entre as mulheres. Pode-se inferir que o exercício sumô tenha ganhado popularidade entre as mulheres, haja vista que exista a ideia de que o mesmo venha prover maior solicitação dos músculos adutores da coxa, ou ainda da região glútea, o que no caso já pode ser suportado por alguma evidência científica, no estudo de Paoli et al. 9 . ...
Resumo Objetivo: Descrever sobre quais são os tipos mais frequentes do exercício de agachamento. Métodos: Amostra que contou com 150 estudantes de três instituições de ensino superior, por meio de aplicação de um questionário estruturado. Resultados: Os resultados demonstraram que o agachamento do tipo livre (barra) foi significativamente mais citado (p < 0,05) em relação aos demais, sendo também identificado que além deste, no mínimo mais outro tipo é bastante utilizado, com destaque para o agachamento do tipo sumô pelas mulheres. Conclusão: A diversidade de muitas variações adotadas para o treinamento de agachamento, sob o propósito de que possa ser mais desenvolvida esteticamente determinada região muscular, não condiz com os achados da literatura, o que aponta para uma necessidade de maior intervenção por parte dos profissionais ou futuros profissionais da área de educação física, no sentido de orientar e direcionar prescrição de exercícios com pesos. Palavras-chave: exercício, treinamento, educação física. Abstract Objective: To describe about what are the most frequent types the squat exercise. Methods: A sample that included 150 students from three institutions of higher education, through the application of a structured questionnaire. Results: The results showed that the squat free type (bar) was significantly more cited (p <0.05) than the other, and also identified that in addition to this, at least most other type is widely used, especially the squat type sumo women. Conclusion: The diversity of many variations adopted for the squat training under the purpose that can be further developed aesthetically particular muscular region does not match the literature findings, which points to a need for greater intervention by professionals or future professionals physical education area, to guide and direct prescription of exercises with weights.
... Although, these are presented as group effects and co-contractions at one joint can possibly be compensated for at other, adjacent joints by placing agonists and/or synergistic musculature in a more optimal position in terms of force-length relationships. A similar quadriceps EMG amplitude found in previous studies comparing NARROW and WIDE barbell back squat positions [22][23][24] can possibly also be associated with a more medially directed resultant force vector, potentially increasing the sagittal plane moment arm at the knee. In addition to the limitations surrounding NJM analysis, differences in quadriceps utilization between squatting widths should not be inferred solely based on EMG results 26 . ...
... maximus EMG amplitude found in the wide squat in previous studies comparing squatting widths 22,24 . Therefore, in WIDE, the hip-to-knee extension NJM ratio measured in the sagittal plane might provide a realistic idea of the NJM relationship between the hip and knee, since the decreased knee extension NJM is, to some extent, "cancelled out" by in the increased knee adduction NJM. ...
Different stance widths are commonly utilized when completing the barbell back squat during athletic general preparedness training. Width manipulation is thought to influence sagittal plane stimuli to the hip and knee extensors, the primary extensor musculature in the squat. However, how width manipulation affects frontal plane stimuli is less understood. Knowledge of hip and knee net joint moments (NJM) could improve exercise selection when aiming to improve sport‐specific performance and prevent injuries. Fourteen adult amateur rugby athletes were recruited for this study. After a familiarization period, participants performed wide‐ (WIDE, 1.5x greater trochanter width) and narrow‐stance (NARROW, 1x greater trochanter width) barbell back squats to femur parallel depth, using relative loads of 70 and 85% of one‐repetition maximum. Sagittal and frontal plane hip and knee kinetics and kinematics were compared between widths. A Bonferroni‐corrected alpha of 0.01 was employed as the threshold for statistical significance. Knee flexion angle was statistically greater in NARROW than WIDE (p < 0.0001, d = 2.56–2.86); no statistical differences were observed for hip flexion angle between conditions (p = 0.049‐0.109, d = 0.33–0.38). Hip‐to‐knee extension NJM ratios and knee adduction NJMs were statistically greater in WIDE than NARROW (p < 0.007, d = 0.51–1.41). At femur parallel, stance width manipulation in the barbell back squat may provide substantial differences in biomechanical stimulus in both the sagittal and the frontal plane. In certain contexts, these differences may have clinically relevant longitudinal implications, from both a performance and injury prevention standpoint, which are discussed.
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... Similarly, while each participant's stance width was the same for both testing days, it was not controlled across participants. Gluteus maximus activity has been shown to increase with increasing stance width 20,21 , which could influence the hip moment values. However, these two studies used extreme stance widths not representative of normal squatting technique and that were not used in the current study. ...
... Previous studies that studied changes in muscle activity according to squat posture reported that changes in posture did not affect the muscle activity of the lower extremity, including VM and VL. 46,47 However, previous studies that examined the effect of knee angle and ankle angle on VM, VL activity, and VM:VL reported conflicting results. 48,49 Such different results are assumed to be due to differences in intervention methods. ...
Various sensory feedback methods are considered important for motor learning, but the effect of each sensory feedback method on effective squat learning still needs to be clarified. This study aimed to investigate the effect of sensory feedback types on the acquisition and retention of a squat. A double‐blinded, randomized controlled trial was carried out. Thirty‐healthy people were recruited and randomly assigned to the visual feedback group (VFG = 10), tactile feedback group (TFG = 10), and control group (CG = 10). VFG received visual feedback through video data of the participant performing squats, and TFG received tactile feedback through manual contact with a physical therapist. Both groups received feedback on the movements that needed correction after each set was completed. CG maintained rest without receiving any feedback. The retro‐reflexive marker, force plate, and electromyography were used to measure body angle, foot center of pressure (COP), and muscle activity. All assessments were measured to confirm a squat acquisition. VFG and TFG showed significant differences in neutral knee position (NKP), trunk forward lean (TFL), anterior knee displacement (AKD), and anteroposterior (AP) foot COP (p < 0.050). In addition, the acquisition was retained until 3 days later for NKP and a week later for TFL, AKD, and AP foot COP in VFG (p < 0.050), while the acquisition was not retained in TFG (p > 0.050). There was no statistically significant change in CG (p > 0.050). This study demonstrated that visual feedback positively affects the acquisition and retention of squats. Therefore, we recommend the use of visual feedback for squat acquisition and retention in exercise novices.
... For all linear parameters, the wide squat was the exercise in which the values were the highest. Both Comfort [4] and Paoli, Marcolinand Petrone [32] highlighted that the width base of support during squat alter muscle recruitment patterns increasing the activity of the adductor longus. This different activity could be the explanation, that WS squat has the highest values of linear and also nonlinear measures. ...
Purpose: The symmetry of feet loading and adequate postural control are crucial aspects of proper squat performance. The study aimed to evaluate the effect of various stance widths during squat on postural control and symmetry of feet loading. Methods: Thirty healthy individuals participated in this study. Each participant performed one type of squat with a narrow stance (NS), hip stance (HS) and wide stance (WS). Results: A significantly higher value of CoP path length, the velocity of sways and Area95 were obtained for the WS squat compared to NS and HS. In addition, the wide feet setting significantly affected not only the feet loading symmetry but also the strategy (high LyE), the amount of irregularities (high SampEn) and the CoP time-series roughness complexity (high FD). It has been shown that as the base of support grew, the asymmetry index grew. Conclusions: The wide squat is less stable, requiring more complex postural control behavior and more flexibility. Performing this squat significantly shifts the pressure to the dominant limb.
... Even with standardized squat depth criteria, target distance, and medicine ball mass for this exercise (3), it is virtually impossible for athletes to squat the same depth or shoot the medicine ball to the same target spot on each repetition. Either might lead to differences in the amount of work being performed on each repetition, and an athlete's height and stance width only further complicate this by altering squat range of motion (34) and shot distance to target. Overall, however, using traditional methods for quantifying resistance training intensities and workloads within the context of a CF workout will always be problematic. ...
The design of high-intensity functional training (HIFT; e. g., CrossFit ® ) workouts and targeted physiological trait(s) vary on any given training day, week, or cycle. Daily workouts are typically comprised of different modality and exercise combinations that are prescribed across a wide range of intensities and durations. The only consistent aspect appears to be the common instruction to maximize effort and workout density by either completing “as many repetitions as possible” within a time limit (e.g., AMRAP, Tabata) or a list of exercises as quickly as possible. However, because effort can vary within and across workouts, the impact on an athlete's physiology may also vary daily. Programming that fails to account for this variation or consider how targeted physiological systems interrelate may lead to overuse, maladaptation, or injury. Athletes may proactively monitor for negative training responses, but any observed response must be tied to a quantifiable workload before meaningful changes (to programming) are possible. Though traditional methods exist for quantifying the resistance training loads, gymnastic movements, and cardiorespiratory modalities (e.g., cycling running) that might appear in a typical HIFT workout, those methods are not uniform, and their meaning will vary based on a specific exercise's placement within a HIFT workout. To objectively quantify HIFT workloads, the calculation must overcome differences in measurement standards used for each modality, be able to account for a component's placement within the workout and be useful regardless of how a workout is commonly scored (e.g., repetitions completed vs. time-to-completion) so that comparisons between workouts are possible. This review paper discusses necessary considerations for quantifying various HIFT workout components and structures, and then details the advantages and shortcomings of different methods used in practice and the scientific literature. Methods typically used in practice range from being excessively tedious and not conducive for making comparisons within or across workouts, to being overly simplistic, based on faulty assumptions, and inaccurate. Meanwhile, only a few HIFT-related studies have attempted to report relevant workloads and have predominantly relied on converting component and workout performance into a rate (i.e., repetitions per minute or second). Repetition completion rate may be easily and accurately tracked and allows for intra- and inter-workout comparisons. Athletes, coaches, and sports scientists are encouraged to adopt this method and potentially pair it with technology (e.g., linear position transducers) to quantify HIFT workloads. Consistent adoption of such methods would enable more precise programming alterations, and it would allow fair comparisons to be made between existing and future research.
... The motion-based task was a desirable platform for this research about augmented visual feedback because it is a multi-joint movement with a single modulation variable, squat depth. Squat technique, such as squat depth, highly influences muscle activations [146]- [148] and can be regulated through visual feedback [72], [149], [150]. Concurrent visual feedback can display squat depth [71], reduce hip and knee internal rotation [72], and increase movement symmetry during sit-to-stand [70]. ...
Neurological traumas can impair motor function and compromise the ability to perform activities of daily living. Physical rehabilitation can aid in motor recovery, but these practices are frustrating due to their rigorous and repetitive nature. Emerging rehabilitation technologies utilize computerized interfaces, such as virtual reality to increase participant engagement and better train muscle-level control. These interfaces can readily provide enhanced augmented sensory feedback, especially at visual levels, to accelerate motor outcomes. Still, there remains a lack of understanding in optimizing the deployment of augmented sensory feedback for clinical motor rehabilitation. In this research, I investigated how specific features of augmented visual feedback can improve motor performance during rehabilitation training. The two primary features of interest were complexity and intermittency, which vary the amount and frequency of visual guidance provided, respectively. A key supplementary feature of augmented visual feedback is the level of body representation to leverage visual embodiment, which was also examined. I evaluated unique combinations of these features to improve functional performance of two different motor rehabilitation exercises, representing either a motion- or force-based task. For a two-legged squat exercise (motion-based), augmented visual feedback that was relatively complex with more body-discernible guidance cues produced the best performance during and after training. The dynamic embodiment may have facilitated the ability to effectively synthesize more feedback information during a synergistic, multi-segment movement. Alternatively, training with simple feedback demonstrated a greater potential for motor learning of a task utilizing isometric muscle control (force-based). Complex feedback may have been interpreted as superfluous to this task, given the shifted emphasis to force control without dynamic embodiment. Thus, the additional cues may have hindered both learning and user experience, reflected in reduced performance and significant physical and cognitive stress changes. For training of either experimental task, intermittently providing visual feedback about real-time performance errors (i.e., concurrent bandwidth feedback) suggested a greater potential for motor learning. In conclusion, systematic variation of specific features in augmented feedback can significantly improve motor performance. Thus, optimizing computerized interfaces for motor rehabilitation requires a greater understanding of how sensory feedback affects the user for a given functional task.
... Alternatively, in accordance with previous studies, the lack of EMG changes may have been due to a reduced EMG sensitivity to small differences in loads. [18][19][20] ...
Background:
Wearable resistance (WR) training is a modality that allows athletes to perform loaded sport-specific movements to develop force and power outputs. The acute responses by which WR works is still relatively unknown, and the effects of WR load and location of the load has not yet been examined.
Objectives:
To investigate the acute neuromuscular and stride characteristic responses to different wearable resistance (WR) loads and placements on the calf muscles during high-speed running.
Methods:
Ten well-trained subjects completed a workout of ten sets of three 10s runs at 18km.h-1 (20s of rest between runs and one min between sets). Five conditions were tested: (1) unloaded control, (2) bilateral 0.75 vs. 1.5% body mass (BM) loading on the distal posterior calf, (3) bilateral proximal vs. distal loading of 1.5% BM positioned posteriorly, (4) bilateral anterior vs. posterior loading of 1.5% BM positioned distally, (5) unilateral loading of 1.5% BM on the distal posterior calf. Data were collected using Electromyography (EMG) and back-mounted GPS-embedded accelerometers. Magnitude of differences of within athlete and between muscle comparisons were calculated using effect sizes (ES) ± 90% confidence limits (CL).
Results:
No substantial differences in accelerometry data were observed between any of the loaded conditions and the control. EMG activity was lower for proximal loading compared to the control for the gluteus maximus (ES±90%CL; -0.72±0.41), vastus lateralis (-0.89±0.47) and vastus medialis (VM) (-0.97±0.46). Anterior loading induced substantially lower EMG activity for the semitendinosus (-0.70±0.48) and VM (-0.64±0.39) muscles compared with the control. EMG activity of the VM (-0.73±0.46) muscle was also substantially lower for posterior loading compared to the control. Unilateral loading induced no substantial differences in EMG activity between the loaded and unloaded legs.
Conclusion:
This preliminary study has provided a rationale for the performance of further investigations into the effects of WR lower limb loading on stride characteristics and EMG activity from a chronic standpoint using a larger population.
... Mechanical models [9], electromyographic techniques [10], magnetic resonance [11], and computed tomography [12] are used to check chronic or acute adaptations of muscles in the LP exercise, to more accurately identify the muscle functions. Several muscles participate in the execution of the exercise LP (quadriceps and gluteus maximus), hamstrings (biceps femoris, semimembranosus, and semitendinosus), triceps sural, among others, with different functions [13]. ...
... 스쿼트는 경기력 향상 및 부상 가능성을 최소화할 수 있는 운동 으로 알려져 있다 [12]. 그러나 불안정한 자세로 스쿼트를 수행하면 허 리의 손상이나 무릎에 과도한 압력을 가해 부상 위험을 높인다는 단 점이 있다 [13][14][15][16]. 이를 보완하기 위해 월스쿼트가 제안되었으며 월스 쿼트는 스쿼트동안 체중을 벽에 지지하여 허리나 무릎이 손상되지 않 도록 하는 장점이 있다 [17]. ...
PURPOSE: The purpose of this study was to compare thigh muscle activities and muscle co-activation when performing squats, wall squats, and Spanish squats on stable and unstable ground.METHODS: Twenty-two healthy male subjects (age: 22.50±2.70 years, height: 178.72±6.04 cm, mass: 76.50±6.80 kg, body mass index: 24.00±2.10 kg/m2, and Godin activity questionnaire: 56.30±24.10) voluntarily participated in the study. All of the participants performed three different squat exercises on the floor and the BOSU ball with an electromyograph attached to each participant’s quadriceps (rectus femoris, RF; vastus lateralis, VL; and vastus medialis, VM) and hamstrings (biceps femoris, BF; semitendinosus, ST; and semimembranosus, SM). Repeated measures of analysis of variance were utilized to compare muscle activity during the three squats exercises by floor type.RESULTS: RF (p<.001, η2=.689), VL (p<.001, η2=.622), and VM (p=.002, η2=.375) showed significant differences between exercises. Spanish squats yielded greater BF activity than did wall squats (p=.018, η2=.269). ST yielded greater muscle activity with the BOSU ball than on the floor (p=.018, η2=.269). Finally, there was a significant ground exercise interaction effect on the co-activation, showing greater muscle co-activation with Spanish squats on the BOSU ball compared to squats, squats on the BOSU ball, and wall squat on the BOSU ball.CONCLUSIONS: The findings of this study indicate that Spanish squats could be an effective exercise option for the facilitation of RF, VL, VM, and BF muscle activation. In particular, performing Spanish squats on an unstable surface could be useful for patients who need to improve their quadriceps muscle activation.
... In each task, the caregivers' stability is maintained through muscle activation while distributing the own body weight evenly before standing up from a seated position as well as lifting the simulated patient (13 kg)/the patient (63 kg). In accordance with literature findings (Yavuz and Erdag, 2017;Aspe and Swinton, 2014;Paoli et al., 2009;Boyden et al., 2000;McCaw and Melrose, 1999), mean muscle activity increases with lifting higher loads in our experimental case study. A more consistent mean activity of the quadriceps and hamstring musculature is indicated, as the load to be lifted gets higher. ...
Manual patient handling is a challenging part of daily care and leads to high mechanical loads as well as to the development of degenerative diseases, e.g. lower back pain. To prevent musculoskeletal overload effects, the use of ergonomic working techniques is essential as well as improving caregivers’ functional ability. However, most of the studies do not consider these aspects and biomechanical evaluations including dynamic electromyography (EMG) are rarely analyzed. In this work, we focus on the quantification of lower limb EMG muscle activation patterns of healthy caregiver students in an experimental setup. The extent of lifting different loads ergonomically is analyzed and similarities/dissimilarities of dynamic EMG data of three lower limb muscles are investigated via cross-correlation calculation. One of the main findings of our investigation is an indication of a more consistent mean activity of the quadriceps and hamstring musculature, as the load
to be lifted increases. Furthermore, we found an intra- as well as an interindividual similarity of EMG muscle activation patterns regarding time and shape of the signals generated during all of the conducted lifting tasks with a predominantly high cross-correlation coefficient for the selected muscles of the lower limb.
... Using the A/D converter of the EMG unit, the load cell data was acquired at a frequency of 1000Hz and filtered with a Butterworth filter set a low pass frequency of 20Hz. The normalized RMS values (%MVIC) were presented as mean values of the concentric phase of the entire 3 sets excluding only the first and last repetition of each set performed during the protocols TRAD, DS and CP (28,36,37). ...
Metabolic stress is a primary mechanism of muscle hypertrophy and is associated with microvascular oxygenation and muscle activation. Considering that drop-set (DS) and crescent pyramid (CP) resistance training systems are recommended to modulate these mechanisms related to muscle hypertrophy, we aimed to investigate if these resistance training systems produce a different microvascular oxygenation status and muscle activation from those observed in traditional resistance training (TRAD). Twelve volunteers had their legs randomized in an intra-subject cross-over design in TRAD (3 sets of 10 repetitions at 75% 1-RM), DS (3 sets of ∼50-75% 1-RM) and CP (3 sets of 6-10 repetitions at 75-85% 1-RM). Vastus medialis microvascular oxygenation and muscle activation were respectively assessed by non-invasive near-infrared spectroscopy and surface electromyography techniques during the resistance training sessions in the leg-extension exercise. Total hemoglobin area under the curve (AUC) (TRAD: -1653.5 ± 2866.5; DS: -3069.2 ± 3429.4; CP: -1196.6 ± 2675.3) and tissue oxygen saturation (TRAD: 19283.1 ± 6698.0; DS: 23995.5 ± 15604.9; CP: 16109.1 ± 8553.1) increased without differences between protocols (p>0.05). Greater decreases in oxygenated hemoglobin AUC and hemoglobin differentiated AUC were respectively found for DS (-4036.8 ± 2698.1; -5004.4 ± 2722.9) compared with TRAD (-1951.8 ± 1720.0; -2250.3 ± 1305.7) and CP (-1814.4 ± 2634.3; 2432.2 ± 2891.4) (p<0.03). Higher increases of hemoglobin deoxygenated AUC were found for DS (1426.7 ± 1320.7) compared with TRAD (316.0 ± 1164.9) only (p=0.04). No differences were demonstrated in electromyographic amplitudes between TRAD (69.0 ± 34.4), DS (61.3 ± 26.7) and CP (60.9 ± 38.8) (p>0.05). Despite DS produced lower microvascular oxygenation levels compared with TRAD and CP, all protocols produced similar muscle activation levels.
... Thus, EMG differences reported by Wretenberg et al. (1996) may not be specifically caused by bar placement per se but possibly by secondary aspects of the techniques used by powerlifters and weightlifters; specifically, powerlifters not only use a low bar position but also a wider stance width, different cues (sitting back vs down), and slightly different depths (Swinton et al., 2012). With that said, previous research on squat stance width has repeatedly found a lack of significant differences in quadriceps muscle activity Paoli et al., 2009); however, some data suggest it may influence glute and adductor EMG (McCaw and Melrose, 1999). Furthermore, Wretenberg et al. (1996) only examined single repetition sets with 65% of 1-RM. ...
The aim of this study was to compare 6-RM muscle activation and kinematics in back squats with low and high barbell placements. Twelve resistance-trained males (23.5 ± 2.6 years, 86.8 ± 21.3 kg, 1.81 ± 0.08 m) with a minimum of 2 years of squatting experience performed a 6-RM using high and low barbell placements while muscle activation of eight muscles and joint kinematics were measured. During high barbell placement squats, lifting time was longer, with lower average velocity than low barbell placement. This was accompanied by a lesser knee flexion angle at the lowest point of the squat, and larger hip flexion angles during high, compared to low barbell squats. Furthermore, peak angular ankle, knee and hip velocities in the descending phase developed differently between conditions. No significant differences in muscle activation were found between conditions. Thus, our data suggests gross muscular adaptations between barbell placements may be similar over time, and therefore, from a muscular development standpoint, both squat styles are valid. Furthermore, unlike the low barbell placement, fatigue may manifest earlier itself in the high barbell squats during 6-RMs as sets progress toward a lifter's maximal capacity, altering kinematics, especially in the last repetition.
... Though squat variations have been extensively studied, the vast majority of attention has been given to leg musculature such as vastus medialis, vastus lateralis, gastrocnemius, soleus, and bicep femoris, as well as trunk musculature such as the rectus abdominis, external oblique and erector spinae. Comparison studies have previously examined these muscles in the free weight barbell squat and smith machine squat (24), FS and back squat (31), back squat on various unstable surfaces (23), high bar and low bar back squat (9), back squat and weighted sled (16), partial and full back squat (8), different stance widths during back squat (21), and back squat vs OHS (2). Still, to date, a dearth of knowledge exists concerning how the FS and OHS differentially impact muscle activity of the scapula and trunk. ...
International Journal of Exercise Science 13(1): 714-722, 2020. The purpose of this study was to compare the muscle activation of the scapula, leg, and trunk among the front squat (FS), overhead squat (OHS), back extension (BE) and plank (PL). Seven recreationally trained men (age: 28 ± 3.6 years, body mass: 92 ± 26.1 kg, height: 175 ± 5.3 cm, 3-RM front squat test: 125 ± 49.8 kg, 3-RM overhead squat test: 91 ± 15.5 kg) participated in this within-subject crossover design. Two isometric exercises (plank and Biering-Sorenson back extension) were also included for trunk musculature comparisons. Neuromuscular activitation of the vastus lateralis (VL), biceps femoris (BF), thoracic region of erector spinae (ES), middle trapezius (MT), rectus abdominis (RA), external oblique (EO), serratus anterior (SA), and anterior deltoid (AD). The neuromuscular activity of the FS and OHS were analyzed using a 2 X 3 (squat variation X intensity) repeated measures analysis of variance (ANOVA). Effects were further analyzed by Bonferroni corrected paired t-tests. Results showed that AD activity was significantly greater (p < .05) during the FS compared to OHS at 65 and 95% of the 3-RM, while MT activity was significantly greater (p < .05) during the OHS than the FS at 80 and 95% of the 3-RM. ES activity was significantly greater (p< .05) during both the FS and OHS compared to the BE, but PL elicited significantly greater EO and RA activity than both the FS and OHS. These findings reveal that the FS and OHS can help facilitate the activation of muscles supporting the shoulder complex, scapula and lower back.
... Several factors, such as barbell position (front, high/low bar back squat), stance width, and the depth of squat, are the main factors affecting GMax activation during the squat. For example, Paoli et al. (2009) suggested that larger stance widths (1,5 and 2x great trochanter distance) are necessary for greater activation of the GMax during the back squat. Regarding the effect of squat depth on GMax activity, the results are contradicting. ...
The gluteus maximus (GMax) is one of the primary hip extensors. Several exercises have been performed by strength and conditioning practitioners aiming to increase GMax strength and size. This systematic review aimed to describe the GMax activation levels during strength exercises that incorporate hip extension and use of external load. A search of the current literature was performed using PubMed/Medline, SportDiscuss, Scopus, Google Scholar, and Science Direct electronic databases. Sixteen articles met the inclusion criteria and reported muscle activation levels as a percentage of a maximal voluntary isometric contraction (MVIC). The exercises classified as very high level of GMax activation (>60% MVIC) were step-up, lateral step-up, diagonal step-up, cross over step-up, hex bar deadlift, rotational barbell hip thrust, traditional barbell hip thrust, American barbell hip thrust, belt squat, split squat, in-line lunge, traditional lunge, pull barbell hip thrust, modified single-leg squat, conventional deadlift, and band hip thrust. We concluded that several exercises could induce very high levels of GMax activation. The step-up exercise and its variations present the highest levels of GMax activation followed by several loaded exercises and its variations, such as deadlifts, hip thrusts, lunges, and squats. The results of this systematic review may assist practitioners in selecting exercised for strengthening GMax.
... 한국전문물리치료학회지 2019년 26권 4호 20-28 Phys Ther Korea 201926(4):20-28 -21 -Additionally, during the squat, a lumbar flexion of 26.3˚ for men and 12.9˚ for women occurs (McKean et al, 2010). This repetitive flexion can lead to disc herniation and spondylolysis (Matsumoto et al., 2001;Noyes et al, 1984;Paoli et al, 2009;Schoenfeld, 2010;Vakos et al, 1994). Previous studies (Delitto and Rose, 1992;Kasim, 2007) suggested that the lumbar curve should be kept proper lordosis during a squat. ...
... The back squat is perhaps the most frequently utilised resistance training exercise [1]. Because of its ability to recruit the quadriceps, gluteal, hamstrings, tibialis anterior, triceps surae and lumbar muscles [2], it forms the basis of most strength and conditioning regimens [3]. ...
Purpose
The aim of the current investigation was to comparatively examine the effects of knee wraps/sleeves on kinetics, three-dimensional kinematics and muscle forces during the barbell back squat.
Methods
Fifteen male lifters completed squats at 70% of their 1 repetition maximum, in four different conditions (nothing, competition knee wrap, training knee wrap and knee sleeve). Three-dimensional kinematics were measured using an eight-camera motion analysis system, ground reaction forces using a force platform and muscle forces using musculoskeletal modelling techniques. Differences between conditions were examined using one-way repeated measures ANOVA.
Results
The results showed that the integral of the quadriceps (nothing = 58.30, competition = 51.87 and training wrap = 53.33 N/kg s), hamstring (nothing = 39.01, competition = 35.61 and training wrap = 33.97 N/kg s), gluteus maximus (nothing = 24.29, competition = 22.22 and training wrap = 21.03 N/kg s), gastrocnemius (nothing = 7.25, competition = 5.97 and training wrap = 6.39 N/kg s) and soleus muscles (nothing = 15.49, competition = 12.75 and training wrap = 13.64 N/kg s) during the ascent phase was significantly greater in the nothing condition compared to both knee wraps. In addition, whilst knee wraps and knee sleeves significantly improved perceived knee stability, perceived comfort was significantly reduced in the knee wraps and improved in the knee sleeve.
Conclusions
Taking into account the reduced muscle kinetics, knee wraps may diminish lower extremity muscle development. Therefore, knee sleeves may be more efficacious for athletes who regularly utilise the back squat for their training goals, although further longitudinal analyses are required before this can be fully established.
... From the relationship between the moment arm length and joint angle, the gluteus maximus muscle is able to exert higher hip extension torque in a more flexed position of the hip joint (Dostal et al. 1986). Furthermore, McCaw and Melrose (1999) and Paoli et al. (2009) reported that the electromyographic activity of the gluteus maximus muscle increased with wider stances during squat exercises. In the present study, however, this point did not affect the result on changes in the size of the gluteus maximus muscle, since all subjects were instructed that stance width during squat training was almost the same as shoulder width for FST and HST. ...
Purpose
The purpose of this study was to compare the effects of squat training with different depths on lower limb muscle volumes.
Methods
Seventeen males were randomly assigned to a full squat training group (FST, n = 8) or half squat training group (HST, n = 9). They completed 10 weeks (2 days per week) of squat training. The muscle volumes (by magnetic resonance imaging) of the knee extensor, hamstring, adductor, and gluteus maximus muscles and the one repetition maximum (1RM) of full and half squats were measured before and after training.
Results
The relative increase in 1RM of full squat was significantly greater in FST (31.8 ± 14.9%) than in HST (11.3 ± 8.6%) (p = 0.003), whereas there was no difference in the relative increase in 1RM of half squat between FST (24.2 ± 7.1%) and HST (32.0 ± 12.1%) (p = 0.132). The volumes of knee extensor muscles significantly increased by 4.9 ± 2.6% in FST (p < 0.001) and 4.6 ± 3.1% in HST (p = 0.003), whereas that of rectus femoris and hamstring muscles did not change in either group. The volumes of adductor and gluteus maximus muscles significantly increased in FST (6.2 ± 2.6% and 6.7 ± 3.5%) and HST (2.7 ± 3.1% and 2.2 ± 2.6%). In addition, relative increases in adductor (p = 0.026) and gluteus maximus (p = 0.008) muscle volumes were significantly greater in FST than in HST.
Conclusion
The results suggest that full squat training is more effective for developing the lower limb muscles excluding the rectus femoris and hamstring muscles.
... All rights reserved Gullett et al. [8] and Contreras et al. [10] found no sig-23 nificant differences between FS and BS exercises re-24 garding hip and thigh muscle activation. The first study 25 analyzed two sets of three repetitions at 70% of 1 rep-26 etition maximum (1RM), while Contreras et al. [10] 27 found no statistical differences in muscle activity be- to identify how different muscle groups contribute to 42 perform this motion [12]. For instance, some have re-43 ported that the gluteus maximus muscle shows higher 44 activation when squatting with higher degrees of knee 45 flexion [13,14]. ...
... Training two-legged free weight back squats are widely used in many populations, with benefits including the improvement of maximal strength [1], power [2], and hypertrophy [3] of the lower limb. Many studies have investigated the effects of variations of squat depth [4], foot placement [5][6][7], instability [8,9], training status [10], and training intensity [11] during two-legged squats. These training variables vary depending on which specific goal the performers are aiming for [12]. ...
Background: The aim of this study was to investigate the effect of descent velocity during two-legged full back squats upon muscle activation and squat ascent performance. Methods: Eleven healthy resistance-training males (age: 24 ± 6 years, body mass: 89.5 ± 21.5 kg, height: 1.84 ± 0.10 m) performed 4-repetition maximum (4-RM) two-legged full squats with slow, normal, and fast descent phases. Kinematics and muscle activity of ten muscles divided into five regions were measured. Results: The main findings were that maximal and minimal velocity were lower and maximal velocity occurred later in the slow condition, while there was no difference in second peak velocity or ascent displacement when compared with the normal and fast conditions. Furthermore, no differences in muscle activation were found as an effect of the descent velocity. Conclusion: It was concluded that the slow descent velocity had a negative effect upon the ascent phase, because of the lower peak velocity and peak force increasing the chance of failure. The lower velocities were not caused by lower pre-activation of the muscles but were probably a result of potentiation and/or utilization of stored elastic energy and/or the stretch reflex.
... Also, the sumodeadlift, due to its more upright back position may reduce shearing forces on the lower back. 47 Previous research has shown in comparison to a conventional deadlift; the sumo-deadlift activates both the medial and lateral quadriceps (values medial and lateral) and, the anterior tibialis. In contrast, the conventional deadlift showed greater, calve (medial gastrocnemius) and erector spinae activity. ...
The three most fundamental variations of the barbell squat with the bar placed on the shoulders are the high-bar back squat (HBBS), the low-bar back squat (LBBS), and the front squat (FS). There are significant kinematic, kinetic, and biomechanical distinctions between these variations that should be considered in the exercise selection. In comparison to the high-bar variations, the LBBS results in a greater hip joint torque and greater activation of the hip extensor muscles. In contrast, during the FS, the m. quadriceps is utilized more compared to the other two variations due to an increased torque in the knee joint. Regarding the relation between hip and knee joint torques, the HBBS is an intermediate and more balanced exercise variation than the LBBS and the FS. The HBBS is a fundamental exercise in athletic conditioning and a suitable starting point for novices, whereas the LBBS is preferred when the primary objective is to maximize weightlifting performance. The FS is crucial for athletes performing the clean and its derivates since it trains the required body position for a successful catch and might be the biomechanically advantageous variation if the goal is to target the knee extensor muscles. However, the differences in terms of knee extensor demands, muscle activation and kinematics between the HBBS and FS seem to be minimal, as the literature indicates similar results when comparing the FS to the HBBS. As far as analysis methods are concerned, even though 3D movement analysis is regarded as the gold standard for motion capture and analyzing kinematics, 2D models seem to serve as a valid initial guide in order to understand the kinematics and biomechanics of different squat variations.
Squats are frequently performed to strengthen the quadriceps (Quad) and gluteus maximus (GM) in sports and clinical fields. Since the squat itself produces a large knee contact force, clarifying the relationship between the squat techniques and the knee contact force is important. However, the influence of different squat techniques on the medial knee contact force (KCFmed), which would result in knee disease, remains unclear. This study aimed to investigate the influence of various squat techniques on KCFmed during bodyweight squats. Since muscle strengthening by the squat is inevitable, we additionally aimed to explore the effect of a different squat technique on the quadriceps (Quad) and gluteus maximus (GM) forces. Twelve healthy adults performed squats with different stance widths (narrow stance, NS; middle stance, MS; and wide stance, WS) and different toe directions (0° of forefoot abduction – NEUT and 30°forefoot abduction – OUT). The KCFmed, Quad force, and GM force were computed using a musculoskeletal model with marker trajectories and ground reaction forces. The KCFmed in NS was significantly larger than that in MS and WS, and KCFmed in OUT was significantly larger than that in NEUT. The Quad force in OUT was significantly larger than that in the NEUT, and the GM force significantly became larger as the stance width became narrower. These findings suggest that squats in MS and NEUT may be suitable for reducing KCFmed while maintaining the Quad and GM forces.
Background:
Squatting is a core exercise for many purposes. However, there is still controversy surrounding the practice of targeting specific muscle groups when performing the back squat with different stance widths or foot positions. Therefore, this study aimed to assess lower limb muscle activation during different form of back squat when adopting three different foot angles.
Methods:
Eight male active participants (age 24.0±0.8 years, height 1.80±0.63m and mass 85.8±8.7kg) performed maximal isometric squat, back squat with an overload of 80% of 1 repetition maximum, and countermovement jump (CMJ) when adopting three foot rotation angles: parallel (0°); +10° outward (external rotation); +20° outward (external rotation). We calculated the root mean square of the electromyographic signals recorded from eight participant's dominant leg muscles.
Results:
During the descending phase of the back squat, the 20° external foot rotation elicited greater activation of the biceps femoris (+35%; p = 0.027) and gastrocnemius medialis (+70%; p = 0.040) compared to parallel foot. There were no significant differences among the other muscles and exercise conditions.
Conclusions:
The +20° foot position increased BF and GasM muscle activity only during the downward phase of the back squat. Strength coaches should consider the present findings when selecting specific resistance exercises aiming to improve athletes' strength and physical fitness.
BACKGROUND: Squats are considered one of the main exercises for the lower limbs and are used in resistance training under different contexts, including rehabilitation and sports performance. OBJECTIVE: To compare the EMG activity of different muscles in back squat and lunge exercises in trained women. METHODS: Ten healthy women experienced in resistance training performed back squat and lunge exercises on a Smith machine (total work: 70% of 1RM, 1 set, 10 repetitions and 2-s/2-s of execution speed) with an interval of 20-min between exercises. Both exercises were standardized in relation to the trunk inclination and were performed with an erect trunk parallel to the cursor of the guided bar. RESULTS: The EMG activity of the vastus medialis (VM), vastus lateralis (VL), biceps femoris (BF), and gluteus maximus (GM) were analyzed. There were no significant differences in the EMG activity of the VM, VL, and BF muscles between the back squat and lunge exercises (P> 0.05); however, GM activation was greater during the lunge exercise (effect size = 1.15; P= 0.001). CONCLUSIONS: Lunges were more effective in recruiting the GM when compared to back squats. However, both exercises can be recommended when the goal is knee extensor and flexor muscle activity.
Compared to back squat (BSQ), front squat (FSQ) exhibits a smaller anterior trunk tilt to avoid dropping a barbell held in front of the body, which may lead to increase trunk extension and lumbar lordosis. This study aimed to clarify the differences in the lumbar lordosis angle, anterior trunk tilt angle, and muscle activities of the lower limb and trunk between the FSQ and BSQ. Ten healthy men participated in this study. The participants performed parallel and full FSQ and BSQ. The SQ motion was recorded using three-dimensional motion-capture cameras, and divided into four phases. The lumbar lordosis angle, anterior trunk tilt angle, and lower limb and trunk muscles activity were analyzed. Independent t-tests were used to compare the minimum lumbar lordosis angle and maximum anterior trunk tilt angle between the FSQ and BSQ in each SQ depth. Two-way analysis of variances (barbell positions × phases) were used to compare the mean lumbar lordosis angle and each muscle activity in each phase between the FSQ and BSQ in each SQ depth. The lumbar lordosis angle was significantly larger during FSQ than during BSQ at the minimum value and the mean value in each phase, regardless of depths (P < 0.05). There were no significant differences in the maximum anterior trunk tilt angle and muscle activities of the lower limb and trunk between the FSQ and BSQ in both depths (P > 0.05). These results are the basis for proposing an appropriate SQ style using the FSQ and BSQ to prevent low back pain.
Background
Differences in the muscular activity between the high-bar back squat (HBBS) and the low-bar back squat (LBBS) on the same representative group of experienced powerlifters are still scarcely investigated. The main purpose of the study was to compare the normalized bioelectrical activity and maximal angles within single homogeneous group between the HBBS and LBBS for 60% one repetition maximum (1RM), 65% 1RM and 70% 1RM.
Methods
Twelve healthy men (age 24.3 ± 2.8 years, height 178.8 ± 5.6 cm, body mass 88.3 ± 11.5 kg), experienced in powerlifting performed HBBS and LBBS with comparable external loads equal 60% 1RM, 65% 1RM, and 70% 1RM. Electromyography (EMG) signals of muscle groups were synchronously recorded alongside kinematic data (joints angle) by means of a motion capture system.
Results
EMG activity during eccentric phase of squat motion were significantly higher during LBBS than in HBBS for all selected muscles (60% 1RM and 65% 1RM) (p < 0.05). All examined muscles were more activated during concentric phase of the squat cycle (p < 0.05). In the concentric phase, significant differences between the loads were generally not observed between just 5% 1RM change in load level for LBBS.
Conclusions
Our results confirmed significant differences in muscles activation between both squat techniques. Muscle activity during eccentric phase of squat motion were significantly higher during LBBS than HBBS. The differences are crucial for posterior muscle chain during eccentric phase of squat cycle.
This study investigated the effects of visual feedback (VF) complexity on movement performance to potentially optimize the design of VF-based rehabilitation. We evaluated the effects of VF complexity on performance of the two-legged squat during training with concurrent (real-time) VF and short-term retention with no VF. Four VF cases were employed to train spatial positioning of the thigh segment in unique combinations of complexity (simple, complex) and representation of body-discernibility (abstract, representative). Eighteen able-bodied subjects attempted to minimize the error between individual body segment positions and a target trajectory during concurrent VF and short-term retention tests. Complex-representative VF demonstrated greater potential for training with increased performance consistency in both motion and muscle activity patterns.
O objetivo deste estudo foi verificar a magnitude da realização do tríceps na polia no estresse funcional no supino reto. A amostra foi composta por 10 indivíduos, do sexo masculino, com idade de 24,9±3,17 anos, massa corporal de 78,9±11,48 kg e estatura de 1,79±0,05 cm. Os procedimentos consistiram na realização do exercício supino reto. Em outro momento a realização do supino reto imediatamente após a realização do tríceps na polia. Os resultados revelaram que o estresse funcional do tríceps braquial provocado pela execução do tríceps na polia subsequente à execução do supino reto foi de 10.06% na 1ª série (p<0,05), no total de 3 séries. Conclui-se que a execução do exercício de tríceps na polia precedido ao exercício de supino resultou no estresse funcional somente na 1ª série e, que a presença da fadiga do músculo peitoral apresentada nas séries subsequentes não impactou no aspecto funcional do exercício de supino.
The Monopodal Squat, Forward Lunge and Lateral Step-Up exercises are commonly performed with one's own body weight for rehabilitation purposes. However, muscle activity evaluated using surface electromyography has never been analyzed among these three exercises. Therefore, the objectives of the present study were to evaluate the amplitude of the EMG activity of the gluteus medius, gluteus maximus, biceps femoris, vastus lateralis, vastus medialis and rectus femoris muscles in participants performing the Lateral Step-Up, Forward Lunge and Monopodal Squat exercises. A total of 20 physically active participants (10 men and 10 women) performed 5 repetitions at 60% (5 repetition maximum) in each of the evaluated exercises. The EMG amplitude was calculated in percentage of the maximum voluntary contraction. The Monopodal Squat exercise showed a higher EMG activity (p ≤ 0.001) in relation to the Lateral Step-Up and Forward Lunge exercises in all of the evaluated muscles (d > 0.6) except for the rectus femoris. The three exercises showed significantly higher EMG activity in all of the muscles that were evaluated in the concentric phase in relation to the eccentric one. In the three evaluated exercises, vastus lateralis and vastus medialis showed the highest EMG activity, followed by gluteus medius and gluteus maximus. The Monopodal Squat, Forward Lunge and Lateral Step-Up exercises not only are recommended for their rehabilitation purposes but also should be recommended for performance objectives and strength improvement in the lower limbs.
The range of motion (ROM) may affect the external maximal load during back squat (BS) exercise. The correct ROM manipulation can be useful as an exercise load manipulation strategy, changing the volume load during a resistance training session. The aim of this study was to evaluate the acute effects of ROM on relative load, absolute load and the rating of perceived exertion (RPE) during partial and full BS exercise with adjusted loads. Fifteen male individuals (age: 26.5±4.5 years; height: 173±6 cm; body mass: 80.6 ± 8.8 kg; resistance training experience 5±3 years) participated in this study. The experimental procedure was conducted in two sessions. In the first session, brief familiarization and a 10-repetition maximal test (10-RM) was performed for partial (PBS) and full BS exercise (FBS) with 30-min of rest interval. During the second session, all subjects performed 1 set of 10-RM in both conditions (partial and full ROM), and relative load, absolute load, and RPE were evaluated. A paired t-test was used to compare means. The results showed higher values for PBS when compared to FE exercise: relative load (PBS: 1.14±0.24xBW vs. FBS: 0.87±0.24xBW; P<0.001), and absolute load (PBS: 925±249 kg x FBS: 708±232 kg, P<0.001). Similar RPE was observed between conditions (PBS: 8.6±1.3 IEP x FBS: 8.5±1.0 IEP, P=0.855). It was concluded that PBS allowed higher relative load and absolute load during 10RM, without effects on RPE.
The present systematic review aimed to analyze the activation of the muscles involved in the barbell hip thrust (BHT) and its transfer to sports activities that include horizontal displacement. A search of the current literature was performed using the PubMed, SPORTDiscuss, Scopus and Google Scholar databases. The inclusion criteria were: (a) descriptive studies, (b) physically trained participants, (c) analyzed muscle activation using normalized EMG signals or as a percentage of maximal voluntary isometric contraction (MVIC) and (d) acute or chronic transfer of the BHT to horizontal displacement activity. Twelve articles met the inclusion criteria and the following results were found: 1) neuro-muscular activation: hip extensor muscles (gluteus maximus and biceps femoris) demonstrated greater activation in the BHT compared to the squat. The straight bar deadlift exercise demonstrated greater biceps femoris activation than BHT; 2) Regardless of the BHT variation and intensity used, the muscle excitation sequence is gluteus maximus, erector spinae, biceps femoris, semitendinosus, vastus lateralis, gluteus medius, vastus medialis and rectus femoris; 3) acute transfer: four studies demonstrated a significant improvement in sprinting activities after BHT exercise; 4) as for the chronic transfer: two studies demonstrated improvement of the sprint time, while other two studies failed to present such effect. We concluded that: a) the mechanics of BHT favors greater activation of the hip extensor muscles compared to more conventional exercises; b) regardless of the variation of BHT used, the muscle excitation sequence is gluteus maximus, erector spinae, hamstrings, and quadriceps femoris; c) the acute transfer of the post-activation potentiation of the BHT is significant, improving the sprinting time; and d) despite training with BHT submaximal loads can improve sprint times, further investigations are needed.
Context:
Squats and lunges are common exercises frequently applied in muscle-strengthening and therapeutic exercises. The loading devices are often used to increase the training intensity.
Objective:
To determine the effect of loading devices on muscle activation in squat and lunge and to compare the differences in muscle activation between squat and lunge.
Design:
Cross-sectional cohort.
Participants:
Nineteen healthy, male, recreationally active individuals without a history of lower limb injury.
Interventions:
Each participant performed 10 repetitions of a squat under 5 conditions: unloaded, barbell, dumbbell, loaded vest, and kettlebell, and 10 repetitions of a lunge under 4 conditions: unloaded, barbell, dumbbell, and loaded vest.
Main outcome measures:
The electromyography signals of quadriceps, hamstrings, tibialis anterior, gastrocnemius lateralis and medialis were measured. One-way repeated-measure analysis of variance was used to compare the difference among different loading conditions. Paired t test was used to compare the difference between squat and lunge.
Results:
The muscle activation in the loaded conditions was significantly higher than that in nonloaded conditions in squat and lunge. Compared with the barbell, dumbbell, and loaded vest conditions, the semitendinosus showed significantly higher activation, and the tibialis anterior showed significantly lower activation in kettlebell condition in squat. No significant difference in muscle activation was found among barbell, dumbbell, and kettlebell conditions in lunge. In addition, quadriceps and hamstring activities were significantly higher in lunge than in squat.
Conclusions:
Muscle activation was affected by the loading devices in squat but not affected in lunge. Kettlebell squat could be suggested for targeting in strengthening medial hamstring. Progressive strengthening exercise could be recommended from squat to lunge based on sequential activation level.
This study examined the effect of water immersion on trunk and lower limb kinematics during squat exercises in older aged participants. Twenty-four active older aged adults (71.4 ± 5.4 yrs.) performed squats and split-squats on land and while partially submerged in water. Inertial sensors (100 Hz) were used to record trunk and lower-body kinematics. Water immersion increased the squat depth (squat: P=0.028, d=0.63, split-squat: P=0.005, d=0.83) and reduced the trunk flexion range (squat: P=0.006, d=0.76, split-squat: P<0.001, d=1.35) during both exercises. Additionally, water immersion increased the hip range of motion during the split-squat (P<=0.002, d=0.94). Waveform analyses also indicated differences in the timing of the movements. These results showed that aquatic-based exercise generate a different exercise outcome and appear to provide an alternative option for older aged adults, allowing these tasks to be performed in a manner that is not possible on land.
Resistance exercise intensity is commonly prescribed as a percent of repetition maximum (1RM). However, the relationship between percent 1RM and the number of repetitions allowed remains poorly studied, especially using free weight exercises. The purpose of this study was to determine the maximal number of repetitions that trained (T) and untrained (UT) men can perform during free weight exercises at various percentages of 1RM. Eight T and 8 UT men were tested for 1RM strength. Then, subjects performed 1 set to failure at 60, 80, and 90% of 1RM in the back squat, bench press, and arm curl in a randomized, balanced design. There was a significant (p < 0.05) intensity x exercise interaction. More repetitions were performed during the back squat than the bench press or arm curl at 60%, 1RM for T and UT. At 80 and 90% 1RM. there were significant differences between the back squat and other exercises; however, differences were much less pronounced. No differences in number of repetitions performed at a given exercise intensity were noted between T and UT (except during bench press at 90% 1RM). In conclusion, the number of repetitions performed at a given percent of 1RM is influenced by the amount of muscle mass used during the exercise, as more repetitions can be performed during the back squat than either the bench press or arm curl. Training status of the individual has a minimal impact on the number of repetitions performed at relative exercise intensity.
Altering foot stance is often prescribed as a method of isolating muscles during the parallel squat. The purpose of this study was to compare activity in six muscles crossing the hip and/or knee joints when the parallel squat is performed with different stances and bar loads.
Nine male lifters served as subjects. Within 7 d of determining IRM on the squat with shoulder width stance, surface EMG data were collected (800 Hz) from the rectus femoris, vastus medialis, vastus lateralis, adductor longus, gluteus maximus, and biceps femoris while subjects completed five nonconsecutive reps of the squat using shoulder width, narrow (75% shoulder width), and wide (140% shoulder width) stances with low and high loads (60% and 75% 1RM, respectively). Rep time was controlled. A goniometer on the right knee was used to identify descent and ascent phases. Integrated EMG values were calculated for each muscle during phases of each rep, and the 5-rep means for each subject were used in a repeated measures ANOVA (phase x load x stance, alpha = 0.05).
For rectus femoris, vastus medialis, and vastus lateralis, only the load effect was significant. Adductor longus exhibited a stance by phase interaction and a load effect. Gluteus maximus exhibited a load by stance interaction and a phase effect. Biceps femoris activity was highest during the ascent phase.
The results suggest that stance width does not cause isolation within the quadriceps but does influence muscle activity on the medial thigh and buttocks.
During knee rehabilitation, squats are a commonly used closed kinetic chain exercise. We have been unable to locate data reporting electromyographic (EMG) activity of lower extremity musculature during maximal effort squats and the contribution of gastrocnemius and gluteus maximus muscles. Therefore, the purposes of this study were (a) to quantify EMG activity of selected lower extremity muscles during a maximal isometric squat and during a maximal voluntary isometric contraction (MVIC), and (b) to determine ratios between the vastus medialis oblique (VMO) and vastus lateralis (VL) during maximal isometric squat and MVIC testing. Twenty-three subjects participated in a single testing session. Results are as follows: intraclass correlations for MVIC testing and squat testing ranged from .60 to .80 and .70 to .90, respectively. Percentage MVIC during the squat was as follows: rectus femoris 40 ± 30%, VMO 90 ± 70%, VL 70 ± 40% hamstrings 10 ± 10%, gluteus maximus 20 ± 10%, and gastrocnemius 30 ± 20%. No statistical difference existed in VMO:VL ratios during MVIC or squat testing. We conclude that large variations in muscle recruitment patterns occur between individuals during isometric squats.
The seated knee extension is commonly used with the parallel squat to promote balance between the vastus medialis (VM) and vastus lateralis (VL). No controlled studies have examined the relative contributions of each muscle during these exercises, so this study employed EMG analysis to determine their contributions. Ten experienced lifters performed squats and knee extensions at their 10-RM. Sets were separated by 15 min rest and the order of performance was reversed between sessions, which were 1 week apart. EMG was collected on the VL and VM of the dominant leg during the first and last repetition of each exercise. Since EMG activity differed significantly between the two testing days, each was analyzed separately. No significant differences were found between the root mean square of the amplitude of the EMG for the VL and VM during either exercise. The parallel squat elicited more electrical activity than the knee extension in both muscles, and the downward shift in frequency of the EMG signal was greater for both the VM and VL during the parallel squat. The results question the value of the knee extension as a supplemental exercise in this case.
(C) 1994 National Strength and Conditioning Association
Six experienced lifters performed 3 squats in each of 4 foot positions: -10[degrees] inward, 0[degrees], 10[degrees] outward, and 20[degrees] outward. These were performed at 2 weight conditions: 65 and 75% of 1 repetition maximum. Surface electromyographic activity of the vastus medialis, vastus lateralis, and rectus femoris on the right leg was analyzed in terms of the activity duration and peak levels of activity. Results and analysis of variance indicated that the foot rotation position did not influence the mean peak activity or mean duration of activity of vastus medialis, vastus lateralis, or rectus femoris. The practice of adopting foot rotation to selectively strengthen individual muscles of the quadriceps group was not supported by this study, which involved smaller, more readily adopted, and comfortable levels of foot rotation than did those previously investigated.
(C) 2000 National Strength and Conditioning Association
Many strength trainers believe that varying the foot position during the parallel squat or knee extension can target specific muscles of the quadriceps group. To test this theory, 10 men performed 3 parallel squats at added resistance equal to their body weight and 3 knee extensions at 8- to 10-RM resistance under 3 treatment conditions: toes pointed out, lateral rotation of the tibia (LR); toes straight forward, no rotation of the tibia (N); and inward, medial rotation of the tibia (MR). Lifts were separated by a 5-min rest. Bipolar surface electrodes placed on the bellies of the v. lateralis and v. medialis and on the lateral and medial portions of the rectus femoris revealed no significant differences in electrical activity for any muscle due to changes in foot position during the squat. During the knee extension, however, LR produced a significantly greater mean rmsEMG than the other foot positions across all muscles. Thus for the squat a lifter should choose the most stable and comfortable position. For the knee extension, however, maintaining a laterally rotated position is best.
(C) 1995 National Strength and Conditioning Association
The purpose of this study was to measure the relative contributions of 4 hip and thigh muscles while performing squats at 3 depths. Ten experienced lifters performed randomized trials of squats at partial, parallel, and full depths, using 100-125% of body weight as resistance. Electromyographic (EMG) surface electrodes were placed on the vastus medialis (VMO), the vastus lateralis, (VL), the biceps femoris (BF), and the gluteus maximus (GM). EMG data were quantified by integration and expressed as a percentage of the total electrical activity of the 4 muscles. Analysis of variance (ANOVA) and Tukey post hoc tests indicated a significant difference (p < 0.001*, p = 0.056**) in the relative contribution of the GM during the concentric phases among the partial- (16.9%*), parallel- (28.0%**), and full-depth (35.4%*) squats. There were no significant differences between the relative contributions of the BF, the VMO, and the VL at different squatting depths during this phase. The results suggest that the GM, rather than the BF, the VMO, or the VL, becomes more active in concentric contraction as squat depth increases.
The bench press is one of the most popular weight training exercises. Although most training regimens incorporate multiple repetition sets, there are few data describing how the kinematics of a lift change during a set to failure. To examine these changes, recreational lifters (10 men and 8 women) were recruited. The maximum weight each subject could bench press (1RM) was determined. Subjects then performed as many repetitions as possible at 75% of the 1RM load. Three-dimensional kinematic data were recorded and analyzed for all lifts. Statistical analysis revealed that differences between maximal and submaximal lifts and the kinematics of a submaximal lift change as a subject approaches failure in a set. The time to lift the bar more than doubled from the first to the last repetition, causing a decrease in both mean and peak upward velocity. Furthermore, the peak upward velocity occurred much earlier in the lift phase in these later repetitions. The path the bar followed also changed, with subjects keeping the bar more directly over the shoulder during the lift. In general, most of the kinematic variables analyzed became more similar to those of the maximal lift as the subjects progressed through the set, but there was considerable variation between subjects as to which repetition was most like the maximal lift. This study shows that there are definite changes in the lifting kinematics in recreational lifters during a set to failure and suggests it may be particularly important for coaches and less-skilled lifters to focus on developing the proper bar path, rather than reaching momentary muscular failure, in the early part of a training program.
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