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Average muscle activity during the front and back squat as a percentage of maximal voluntary isometric contraction (%MVIC). Figure 6. Average muscle activity during the ascending and descending phases of the squat as a percentage of maximal voluntary isometric contraction (%MVIC). *Significant difference between phases (p , 0.05).
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The strength and stability of the knee plays an integral role in athletics and activities of daily living. A better understanding of knee joint biomechanics while performing variations of the squat would be useful in rehabilitation and exercise prescription. We quantified and compared tibiofemoral joint kinetics as well as muscle activity while exe...
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... findings are in accordance with those of several other studies (13,15,23,29). For example, in our study, lower EMG values were found during eccentric (descent) contractions for the rectus femoris compared with concentric (ascent) contractions (Figures 4 and 6). The similarity in EMG activity between bar positions is an intriguing result. ...
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Citations
... 17 As knee°exion angle increases, both tibiofemoral and patellofemoral compression increases. 18 During squatting, the primary hip muscles involved are the gluteus maximus and the hamstrings. 19 Further, hip torques increase in combination with increase in hip°exion. ...
Background: Patellofemoral pain syndrome (PFPS) is a challenging clinical problem affecting adults, adolescents, and physically active populations. PFPS impacts the patient’s trunk kinematics in the frontal plane. Previous studies have found gender-based biomechanical differences in patients with PFPS; however, sagittal trunk kinematics during mini-squats and lumbar proprioception in PFPS have not been studied previously.
Objectives: To investigate sagittal trunk excursion (It is defined as the sagittal trunk flexion angle from the start to the end of the mini squat) during mini-squats as well as lumbar repositioning error between individuals with and without PFPS, and determine gender differences in the outcome variables.
Methods: A sample of 56 participants aged 18–25 years was enrolled; 30 with PFPS (13 males, 17 females) and 26 asymptomatic controls (11 males, 15 females). The sagittal trunk excursion during mini-squats was examined by two-dimensional (2D) photographic analysis using Surgimap software. Active lumbar flexion repositioning error was assessed using an isokinetic dynamometer.
Results: For sagittal trunk excursion, no significant main effect of group was observed ([Formula: see text]). On the other hand, the main effect was significant for gender ([Formula: see text]), as was the interaction effect. Compared to the control group, the PFPS group showed significantly ([Formula: see text]) lower sagittal trunk excursion in females than in males during mini-squats. For active lumbar flexion repositioning error, no evidence was found for significant main or interaction effects ([Formula: see text]).
Conclusion: Females with PFPS exhibit a more erect sagittal trunk posture than males during mini-squats. Trunk posture should be considered during weight-bearing activities in PFPS, and gender-specific assessment protocols should be developed.
... The relative load was 20 RM for all the exercises, with 120 seconds of rest between each set and 180 seconds between each exercise. Following previous procedures, the Barbell Back Squat was performed with the participants standing with their feet aligned and shoulderwidth apart (Gullett, Jonathan et al., 2008). The Barbell Deadlift was performed following previous procedures, and subjects were allowed to use either a pronated or an alternated grip, depending on personal preference (Brennan et al., 2015). ...
This study aimed to determine heart rate accuracy measured by wearable devices during resistance exercises at various intensities. Twenty-nine participants (16 female) aged 19–37 years participated in this cross-sectional study. Participants completed five resistance exercises; Barbell Back Squat, Barbell Deadlift, Dumbbell Curl to Overhead Press, Seated Cable Row, and Burpees. During the exercises, heart rate was concurrently measured using the Polar H10, the Apple Watch Series 6 and the Whoop 3.0. The Apple Watch had high agreement with the Polar H10 during Barbell Back Squats, Barbell Deadlift, and Seated Cable Rows (rho > 0.832) and moderate to low agreement during Dumbbell Curl to Overhead Press and Burpees (rho > 0.364). The Whoop Band 3.0 had high agreement with the Polar H10 during Barbell Back Squats (r > 0.697), moderate agreement during Barbell Deadlift and Dumbbell Curl to Overhead Press (rho > 0.564) and low agreement during Seated Cable Rows and Burpees (rho > 0.383). The results varied across exercises and intensities and indicated the most favourable outcomes for the Apple Watch. In conclusion, our data suggest that the Apple Watch Series 6 is suitable for measuring heart rate during exercise prescription or monitoring resistance exercise performance.
... The squat movement recruits distinct muscle groups that involve the hip, knee, and ankle joints, consisting of one of the most common exercises in strength training (ST) programs [1]. In addition, this exercise is used as a form of rehabilitation because it enables the strengthening of the hip and thigh muscles [2] and presents a movement with a mechanical-functional pattern [3]. ...
... In addition, this exercise is used as a form of rehabilitation because it enables the strengthening of the hip and thigh muscles [2] and presents a movement with a mechanical-functional pattern [3]. In this sense, the understanding of muscle activation may assist in improving training prescription and, consequently, the generated adaptations, contributing to physical performance, quality improvement, and performance of activities of daily living [1]. Adjustments are necessary in training variables regarding the improvement in physical performance, such as the type and order of exercises, execution speed, types of muscle contraction, and range of motion [4]. ...
... Both muscle actions showed differences for the two types of squats, with higher activation in the concentric action. Gullet et al. [1] and Clark, Lambert, and Hunter [29] found similar results. According to Robertson, Wilson, and Pierre [26], GM is less activated at 140 • , as the moment of force of extensor muscles during the descent eccentrically controls hip flexion while allowing this joint to perform flexion. ...
Purpose: To analyze the muscle activation of the rectus femoris (RF), vastus lateralis (VL), gluteus maximus (GM), and biceps femoris (BF) in concentric and eccentric actions in the squat at 90 • and 140 • range of motion. Methods: Thirty-five women (32.9 ± 7.4 years; 64.5 ± 11.5 kg; 1.63 ± 0.1 m; BMI: 24.2 ± 2.9 kg/m 2 ; %fat: 24.9 ± 6.5%) experienced exercise for at least eight weeks. Electrodes were positioned in standardized locations. The signals were acquired by an A/D SAS1000 V8 converter and the electromyographic activity normalized in the percentage of the highest produced value (%RMS). The data were analyzed using repeated measures two-way ANOVA, with effect size (η 2) and differences calculated in percentage points (∆ p.p.). Results: The RF (p = 0.001; ∆ = 5.1 p.p.) and BF activation (p = 0.020; ∆ = 4.0 p.p.) was higher at 90 • in the eccentric action. The RF showed an interaction between the range of motion and %RMS, with a large effect size (F = 37.9; p = 0.001; η 2 = 0.485). The VL activation was higher at 140 • (p = 0.005; ∆ = 3.9 p.p.) in the concentric action and higher at 90 • (p = 0.006; ∆ = 3.7 p.p.) in the eccentric action, with a large effect size significant interaction (F = 21.3; p = 0.001; η 2 = 0.485). The GM activation was higher at 90 • in the concentric (p = 0.020; ∆ = 5.4 p.p.) and eccentric action (p = 0.022; ∆ = 41 p.p.). Conclusions: The biarticular muscles were influenced by the squat range only in the eccentric action of the movement, while the monoarticular muscles were influenced by the squat in both concentric and eccentric muscle action.
... Barbell squatting is a common exercise used to strengthen lower limbs and drive away strength in training and rehabilitation (Chandler and Stone, 1991;Hickson et al., 1994;Thein and Brody, 1998;Gullett et al., 2009;Sato et al., Frontiers in Neurorobotics frontiersin.org . /fnbot. . ...
Background
Barbell squats are commonly used in daily training and rehabilitation. Injuries are not common when the posture is standard, but the wrong posture can lead to injuries. Rearfoot valgus is a common foot abnormality that may increase the risk of injury during sports. The purpose of this study was to compare the biomechanics of lower limbs in normal foot and valgus patients during barbell squat.
Methods
In this study, 10 participants with normal foot shape and 10 participants with rearfoot valgus were enrolled. The joint angle, joint moment, and range of motion of hip, knee, and ankle joints were collected under 0, 30, and 70% one-repetition maximum (RM) load, where discrete data are statistically analyzed using the independent sample t -test, and continuous data are statistically analyzed using one-dimensional parameter statistical mapping.
Results
In barbell squats, the range of motion and the joint moment of the hip, knee, and ankle in the rearfoot valgus participants were significantly larger than those in normal foot participants ( p < 0.05). The participants with rearfoot valgus had a more significant knee valgus angle when squatting to the deepest ( p < 0.05). In addition, with the increase in load, the participants with rearfoot valgus showed greater standardized medial knee contact force ( p < 0.05). In the process of barbell squats, the participants with rearfoot valgus showed no significant difference in the foot valgus angle when compared with the normal foot shape ( p > 0.05).
Conclusions
The valgus population showed a greater range of joint motion when performing barbell squats and showed genu valgus and greater medial knee contact force, which may increase the risk of musculoskeletal and soft tissue damage such as meniscus wear. In addition, there was no significant difference in the rearfoot valgus angle between people with rearfoot valgus and people with normal foot shape during squatting, so barbell squatting may correct valgus to a certain extent.
... For instance, when executing a squat, a stable knee joint is very important to decelerate the load at the end of the range of motion (Cormie et al., 2011). To achieve this aim, there is significant cocontraction of the hamstrings and quadriceps (Gullett et al., 2009;Slater & Hart, 2017). This intermuscular coordination pattern is different from coordination patterns required for cycling where co-contraction between the quadriceps and the hamstrings is necessary to provide fine control of the direction of force applied to the pedal, rather than stabilising the knee joint (Dorel et al., 2012;Van Ingen Schenau et al., 1992). ...
The aim was to investigate the effects of a gym-based strength training intervention on biomechanics and intermuscular coordination patterns during short-term maximal cycling. Twelve track sprint cyclists performed 3 × 4 s seated sprints at 135 rpm, interspersed with 2 × 4 s seated sprints at 60 rpm on an isokinetic ergometer, repeating the session 11.6 ± 1.4 weeks later following a training programme that included two gym-based strength training sessions per week. Joint moments were calculated via inverse dynamics, using pedal forces and limb kinematics. EMG activity was measured for 9 lower limb muscles. Track cyclists 'leg strength" increased (7.6 ± 11.9 kg, P = 0.050 and ES = 0.26) following the strength training intervention. This was accompanied by a significant increase in crank power over a complete revolution for sprints at 135 rpm (26.5 ± 36.2 W, P = 0.028 and ES = 0.29). The increase in leg strength and average crank power was associated with a change in biceps femoris muscle activity, indicating that the riders successfully adapted their intermuscular coordination patterns to accommodate the changes in personal constraints to increase crank power.
... Prior to the attachment of the surface electrodes, the skin was abraded with a skin abrasive and alcohol was applied to reduce the skin impedance to < 2 kΩ. Surface electrodes (BlueSensor N-00-S, METS Co., Japan) of a diameter of 8-mm, were attached to each muscle belly, which was parallel to the muscle fiber, for the RA, 3 cm lateral to the umbilicus (9) ; for the EO, 15 cm lateral to the umbilicus (9) ; for the IO, 1 cm medial and downward to the anterior superior iliac spine (10) ; for the LES, 3 cm lateral to the L3 spinous process (9) ; for the LMF, 2 cm lateral to the L5 spinous process (11) ; for the GMax, the midpoint of the sacral vertebra and greater trochanter (12) ; for the BF, the midpoint of the ischial tuberosity and the lateral condyle of the femur on the posterior side of the thigh (13) ; for the RF, the midpoint of the anterior inferior iliac spine and the patella on the anterior side of the thigh (13). The inter-electrode distance was 20 mm. ...
This study aimed to clarify the changes in the activity of the trunk and lower limb muscles during 2000-m rowing. Ten male rowers performed a 2000-m race simulation on a rowing ergometer. Electromyography results of the abdominal muscles, back muscles, gluteus maximus (GMax), biceps femoris (BF), and rectus femoris (RF) were recorded. The electromyographic activity during the three strokes after the start (initial stage), at 1000m (middle stage), and before the end (final stage) were analyzed. From the handle position, the rowing motion was divided into five phases (early-drive, middle-drive, late-drive, early-recovery, and late-recovery). The peak activities of the abdominal muscles, back muscles, GMax, and BF in each stroke of the rowing motion were delayed at the middle and final stages compared to the initial stage (P<0.05). The peak activity of the RF was observed in the late-drive phase at the initial stage, whereas a high RF activity was observed in the middle-drive phase at the middle and final stages (P<0.05). Considering the results of the activity of the back muscles and RF, RF muscular endurance enhancement may lead to a decrease in the load on the back muscles and help prevent muscular low back pain in rowers. J. Med. Invest. 69 : 45-50, February, 2022.
... Dynamic movements demonstrate greater muscle activations that are characterized by a higher peak in EMG amplitude than those found in MVIC trials (Ricard et al., 2005;Suydam et al., 2017). A previous EMG analysis also found muscle activation is greatest in lower extremity muscles during the ascending phase of the back squat (Gullett et al., 2009), which is notably the time when lift failure can occur. Although previous EMG research is quite extensive on back squats, there are important methodological factors to consider when culminating the literature on muscle activation patterns during dynamic maneuvers. ...
... EMG waveforms during the concentric phase (from full depth to standing upright; (Maddox et al., 2020)) were used for analyses. The concentric phase was chosen as it required the greatest activations of all recorded muscles, which has also been found in previous literature (Gullett et al., 2009;Yavuz et al., 2015). The muscle activation signals were high-pass filtered at 20 Hz and full-wave rectified (De Luca et al., 2010). ...
Electromyography (EMG) is a popular technique for analyzing muscle activation profiles during athletic maneuvers such as the back squat. Two methods are commonly implemented for normalizing EMG: a maximum voluntary isometric contraction (MVIC) and a dynamic maximum during the task being performed (DMVC). Although recent literature suggests DMVC may be superior, these suggestions haven’t been examined for weighted exercises. This study examined the influence of normalization method on rectus femoris, vastus medialis, and biceps femoris activations during back squats. Muscle activations were collected on twenty-seven participants (13 females, 14 males) performing one-repetition maximum (DMVC) and submaximum (80%) back squats. Data from submaximum squats were normalized to MVICs and DMVC. Data were compared using intra-class correlations over two testing days, variance ratio, and coefficients of variation. Mixed-model ANOVAs were used to elucidate the influence on intra-participant (method) and inter- (sex) subject variability (method). Reliability was “good” or “excellent” for MVIC and “excellent” for DMVC. Inter-subject variability was greater for MVIC compared to DMVC for all muscles. A significant normalization by sex interaction for both peak and mean biceps femoris activation was found. Based on our findings and current literature, normalization to DMVC is the superior method for weighted exercises.
... These complexities can be especially challenging to home users who do not have the benefit of coaching or personal supervision to ensure correct form and safety, and to those with gluteal muscle and quadriceps weakness, lower limb joint and back pain, and balance problems. While many kinetic analyses have been done for traditional, barbell loaded and unilateral squats, the variations in body and weight positions, the depth and velocity of the squat, and the patterns of squatting movements, these analyses can be confusing and comparisons among these complicated [5] [9] [10] [12] [14] [15] [16] [19]- [38]. ...
... Squats can refer to a wide variety of exercises, comprising partial squat [6], half squat [7], parallel squat [8,9], full squat [8,9], and deep squat [7]. Furthermore, there are front [9][10][11], back [10][11][12], and overhead squats [12] with various bar positionings. ...
... Squats can refer to a wide variety of exercises, comprising partial squat [6], half squat [7], parallel squat [8,9], full squat [8,9], and deep squat [7]. Furthermore, there are front [9][10][11], back [10][11][12], and overhead squats [12] with various bar positionings. ...
Isometric bodyweight squats are fundamental exercises in athletic training and rehabilitation. Previously, we measured muscle activity in a normal squat posture (NSP) and a squat posture with the center of foot pressure (COP) intentionally shifted forward as far as possible (forward-shifted posture: FSP), and the muscle activity patterns varied significantly according to the COP location. This study focused on stepwise loading as a training strategy. Ten healthy male participants performed isometric bodyweight squats in a previous study, adopting the NSP and FSP, with three knee flexion angles (30°, 60°, and 90°). The muscle activities of the vastus medialis (VM), semitendinosus, tibialis anterior (TA), and gastrocnemius muscle lateral head were measured using surface electromyogram. This study further explored the relationship between COP shifting and knee flexion angles on electromyogram changes using three-dimensional diagrams. In one-way repeated measures analysis of variance by ranks, knee flexion angles affected the muscle activities of the VM and TA in the NSP and muscle activities of the VM in the FSP. Combining these findings, stepwise loading tasks were created to train individual target muscles. The ten male participants examined all the tasks, and the feasibility was confirmed accordingly.
... These estimates implied similar knee-joint as hip-joint NJM during the flywheel squat exercise, whereas a greater hip-than knee-joint NJM would have been attained, had the NJMs been averaged over the entire ranges of motion (Figure 2). Gullett et al. (2009) reported that the maximum knee-extension NJM was greater during back than front squats, but did not report on hip or ankle NJM. The results of Gullett et al. (2009), and the current use of a harness, distributing the load to the shoulders and the back, suggests that the present flywheel squat resembles a conventional barbell back squat rather than a front squat. ...
... Gullett et al. (2009) reported that the maximum knee-extension NJM was greater during back than front squats, but did not report on hip or ankle NJM. The results of Gullett et al. (2009), and the current use of a harness, distributing the load to the shoulders and the back, suggests that the present flywheel squat resembles a conventional barbell back squat rather than a front squat. ...
The aim was to compare the musculoskeletal load distribution and muscle activity in two types of maximal flywheel leg-extension resistance exercises: horizontal leg press, during which the entire load is external, and squat, during which part of the load comprises the body weight. Nine healthy adult habitually strength-training individuals were investigated. Motion analysis and inverse dynamics-based musculoskeletal modelling were used to compute joint loads, muscle forces, and muscle activities. Total exercise load (resultant ground reaction force; rGRF) and the knee-extension net joint moment (NJM) were slightly and considerably greater, respectively, in squat than in leg press ( p ≤ 0.04), whereas the hip-extension NJM was moderately greater in leg press than in squat ( p = 0.03). Leg press was performed at 11° deeper knee-flexion angle than squat ( p = 0.01). Quadriceps muscle activity was similar in squat and leg press. Both exercise modalities showed slightly to moderately greater force in the vastii muscles during the eccentric than concentric phase of a repetition ( p ≤ 0.05), indicating eccentric overload. That the quadriceps muscle activity was similar in squat and leg press, while rGRF and NJM about the knee were greater in squat than leg press, may, together with the finding of a propensity to perform leg press at deeper knee angle than squat, suggest that leg press is the preferable leg-extension resistance exercise, both from a training efficacy and injury risk perspective.
