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Abstract

An essential exercise for strength training of the lower limbs is the squat exercise. During this exercise, changes in lumbar lordosis are commonly used to indicate when the descent of the squat should cease, yet the behavior of the lumbar-scarum segments remains unclear. The purpose of this study was to quantify the lumbar-sacrum movements during the back squat, because the movement of the sacrum is influenced by the width of stance, this variable was also investigated. Thirty trained subjects, 18 men with 1 repetition maximum (1RM) squat of 123% (13.9%) of bodyweight and 12 women with 1RM squat of 93% (15.6%), performed a set of narrow and wide stance squats, each carrying an additional 50% of body weight as load. The timing and movement of the lumbar angle (T12/L1), sacrum angle (L5/S1), and lumbar flexion angle (lumbar lordosis) were measured in 3 dimensions for the ascent and decent phases. Men and women achieved similar lumbar angles for both width of stance and phase. Sacrum angles, lumbar flexion angles, and timing differed significantly (p < 0.05) between gender and width of stance. The lumbar flexion range during the descent phase for women in narrow and wide stance was 12.9° and 12.6°, respectively; for men, this range was significantly (p < 0.05) larger at 26.3° and 25.4°, respectively. Men and women developed different movement patterns for the squatting movement, and therefore, this needs to be considered in strength development and screening procedures. The lumbar spine became kyphotic as soon as a load was placed on the shoulders, and any teaching cues to maintain a curved lumbar spine when squatting must be questioned.

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... There is, therefore, controversy regarding whether the Smith squat could be detrimental due to the unnatural path of the external load 1-3 . Nonetheless, several mode of strength training that helps beginners familiarise themselves with the squat movement, serves to occasionally change the routine and increase the lifted load in experienced athletes, accommodates the loads in individuals with injuries who may experience pain when executing the squat, and provides a safe form of closed kinetic-chain exercise for rehabilitation 11,[14][15][16][17] . Because a Smith machine allows the manipulation of foot placement, this type of equipment provides some control over the compressive and shear forces acting on the lower back 15,18 . ...
... In particular, shear forces can expose the athlete to disc or facet injury. To eliminate shear forces at the lumbo-sacral joint, the spine must remain neutral throughout the squatting movement [14][15][16] . However, shear forces are 15 . ...
... Hartmann et al. 6 reported the compressive strength (ex-vivo) of an L4/L5 vertebral segment for a 22-year-old man (8,800 N), that of an L3/L4 vertebral segment for a 22-year-old woman (6,200 N), and of a 39-year-old man (8,200 N). Thus, analysis of compressive strength suggests that females are at higher risk 6,14 due to a smaller end-plate cross-sectional area of the vertebral body than in males [14][15][16] . Consequently, the biomechanical analysis of high bar and low bar isometric Smith squats should be extended to the assessment of spinal loads in females. ...
Article
Introduction: The squat is one of the most effective exercises in athletic training. However, there is a scarcity of research that reports the muscular and joint loads in the lumbar region incurred when performing the high bar and the low bar isometric squat modalities in a Smith machine. Therefore, this study aims to determine the muscle force of the lower back extensors, and the compressive (R c) and shear (R s) forces at the lumbo-sacral joint for the one repetition maximum (1RM) high bar and low bar isometric parallel-depth Smith squats.
... The expressed fears of Walsh et al. [157] during the execution of the squat exercise are unfounded because the hip-joint angle changes. On the contrary, the deep squat involves the risk of dissolving the lordotic curvature in the turning point [159]. McKean et al. [159] determined a lower range of movement at the sacrum (p B 0.01) with a larger range of lumbar flexion (p B 0.01) in 18 males compared with 12 females while performing the descent phase in the parallel back squat with a narrow stance (pelvic width). ...
... On the contrary, the deep squat involves the risk of dissolving the lordotic curvature in the turning point [159]. McKean et al. [159] determined a lower range of movement at the sacrum (p B 0.01) with a larger range of lumbar flexion (p B 0.01) in 18 males compared with 12 females while performing the descent phase in the parallel back squat with a narrow stance (pelvic width). In contrast, females demonstrated less range of lumbar flexion and more anterior tilt of the sacrum compared with males. ...
... Women have a lower stiffness and greater range of motion between motion segments of the lumbar spine than men [160]. McKean et al. [159] therefore assume that the females were capable of developing more muscular stabilization of the lumbar spine that may explain their greater sacrum movement due to higher flexibility of the lumbar sacral region. Another contributing factor could be the greater hamstring flexibility that females have been shown to possess compared with males [161]. ...
Article
It has been suggested that deep squats could cause an increased injury risk of the lumbar spine and the knee joints. Avoiding deep flexion has been recommended to minimize the magnitude of knee-joint forces. Unfortunately this suggestion has not taken the influence of the wrapping effect, functional adaptations and soft tissue contact between the back of thigh and calf into account. The aim of this literature review is to assess whether squats with less knee flexion (half/quarter squats) are safer on the musculoskeletal system than deep squats. A search of relevant scientific publications was conducted between March 2011 and January 2013 using PubMed. Over 164 articles were included in the review. There are no realistic estimations of knee-joint forces for knee-flexion angles beyond 50° in the deep squat. Based on biomechanical calculations and measurements of cadaver knee joints, the highest retropatellar compressive forces and stresses can be seen at 90°. With increasing flexion, the wrapping effect contributes to an enhanced load distribution and enhanced force transfer with lower retropatellar compressive forces. Additionally, with further flexion of the knee joint a cranial displacement of facet contact areas with continuous enlargement of the retropatellar articulating surface occurs. Both lead to lower retropatellar compressive stresses. Menisci and cartilage, ligaments and bones are susceptible to anabolic metabolic processes and functional structural adaptations in response to increased activity and mechanical influences. Concerns about degenerative changes of the tendofemoral complex and the apparent higher risk for chondromalacia, osteoarthritis, and osteochondritis in deep squats are unfounded. With the same load configuration as in the deep squat, half and quarter squat training with comparatively supra-maximal loads will favour degenerative changes in the knee joints and spinal joints in the long term. Provided that technique is learned accurately under expert supervision and with progressive training loads, the deep squat presents an effective training exercise for protection against injuries and strengthening of the lower extremity. Contrary to commonly voiced concern, deep squats do not contribute increased risk of injury to passive tissues.
... The expressed fears of Walsh et al. [157] during the execution of the squat exercise are unfounded because the hip-joint angle changes. On the contrary, the deep squat involves the risk of dissolving the lordotic curvature in the turning point [159]. McKean et al. [159] determined a lower range of movement at the sacrum (p B 0.01) with a larger range of lumbar flexion (p B 0.01) in 18 males compared with 12 females while performing the descent phase in the parallel back squat with a narrow stance (pelvic width). ...
... On the contrary, the deep squat involves the risk of dissolving the lordotic curvature in the turning point [159]. McKean et al. [159] determined a lower range of movement at the sacrum (p B 0.01) with a larger range of lumbar flexion (p B 0.01) in 18 males compared with 12 females while performing the descent phase in the parallel back squat with a narrow stance (pelvic width). In contrast, females demonstrated less range of lumbar flexion and more anterior tilt of the sacrum compared with males. ...
... Women have a lower stiffness and greater range of motion between motion segments of the lumbar spine than men [160]. McKean et al. [159] therefore assume that the females were capable of developing more muscular stabilization of the lumbar spine that may explain their greater sacrum movement due to higher flexibility of the lumbar sacral region. Another contributing factor could be the greater hamstring flexibility that females have been shown to possess compared with males [161]. ...
Article
In the science and practice of strength training it is sometimes suggested that the deep squat entails an increased injury risk of the lumbar spine and the knee joint. Avoiding deep flexion is believed to minimize the magnitude of knee joint forces. Because within the first 50° of knee flexion calculated retropatellar compressive stress is lower, execution of quarter or half squats is recommended when overuse injuries and degenerative changes of the patella-tendon-complex exist. This recommendation is based on calculation of knee joint forces that occured during the execution of half- and deep-back squats. These values cannot be extrapolated to quarter squats because the following were not taken into account a) the influence of reversal of motion with minor retropatellar contact-zone and lower or missing tendofemoral support-surface and b) the different weights that can be tolerated with the particular squat. This misconception is particularly important when making recommendations for elite training: Due to the advantageous positions of the lever arms at the knee- and hip joints, quarter (and half) squats necessitate higher weights to induce effective training stimuli of the hip and leg extensors compared with deep squats. Accordingly this results in increased knee joint forces and requires a greater degree of torso stabilization to counteract impairing discal shear forces. These relationships were ignored in recent publications so far that have discussed spinal- and knee-joint forces at different squatting depths. Provided that the movement pattern is learned correctly under supervision of a qualified trainer and weights are gradually increased, the deep squat presents an effective training exercise for protection against injuries, particular in junior athlete development. Contrary to commonly voiced concerns, deep squats do not entail increased risks of injury of the passive tissues.
... [14][15][16] To ensure the safety and effectiveness of squat techniques, information about the lumbosacral inclination and posture are necessary. 17 These variables could change the patterns of the pressure distribution in the intervertebral discs and the magnitude of compressive and shear forces in the intervertebral joints. 6,15,18 To our knowledge, there are no studies reporting the lumbosacral inclination patterns in restricted and unrestricted squats. ...
... for example, the experimental design of adams and hutton 18 and arjmand and Shirazi-adl 14 did not consider different trunk inclinations associated with squat technique. McKean et al. 17 suggested that kyphosis of the lumbar spine in deep squatting is a natural part of the squat movement when using loads equal to 50% body weight and advised that the coaches should not prevent experienced squatters from allowing this to happen. however, they did not present any quantitative data to support this advice. ...
... The lumbar flexion could lead to an asymmetric stress distribution in the lumbar stricted half squats with average loads near 50% of the body weight (Table i), similar to previous biomechanical squat investigations. 12,17 This load intensity was chosen for injuries prevention during the experiments. Thus, it is reasonable to presume that the results of current study are in the context of rehabilitation process and weight training for beginners. ...
Article
Background: The main purpose of this study was to analyse the behaviour of the geometric curvature of the lumbar spine during restricted and unrestricted squats, using a novel investigative method. The rationale for our hypothesis is that the lumbar curvature has different patterns at different spine levels depending on the squat technique used. Methods: Spine motion was collected via stereo-photogrammetric analysis in nineteen participants (11 males, 8 females). The reconstructed spine points at the upright neutral position and at the deepest position of the squat exercise were projected onto the sagittal plane of the trunk, a polynomial was fitted to the data, and were quantified the two-dimensional geometric curvature at lower, central and higher lumbar levels, besides the inclination of trunk and lumbosacral region, the overall geometric curvature and overall angle of the lumbar spine. The mean values for each variable were analysed with paired t-test (P<0.05). Results: The lumbar presents a flexion from upright neutral posture to deepest point of the movement, but for the lower lumbar the flexion is less intense if the knees travel anteriorly past the toes. The trunk and the lumbosacral region lean forward in both squat techniques and these effects are also reduced in unrestricted squats. Conclusion: The data collected in the study are evidence that during barbell squats the lumbar curvature has different patterns at different spinal levels depending on the exercise technique. The lower lumbar spine appears to be less overloaded during unrestricted squats.
... Both experience (Chandler & Stone, 1991;Dunn et al., 1984;McLaughlin, Dillman, & Gardner, 1977;McLaughlin et al., 1978) and sex (Fry, Housh, Hughes, & Eyford, 1988;Fry, Kraemer, Bibi, & Eyford, 1991;Lynn & Noffal, 2012;McKean et al., 2010a;McKean, Dunn, & Burkett, 2010b) have been demonstrated to influence squat technical models, and also responses to loading (McKean et al., 2010a). With this in mind it would seem unlikely that WS would offer the same outcome for all athletic groups. ...
... Differences in squat movement and coordination patterns between sexes have previously been shown (Lynn & Noffal, 2012;McKean et al., 2010aMcKean et al., , 2010b. When unloaded, females had more hip flexion; this difference has also been shown to occur during a single leg squat (Zeller, McCory, Kibler, & Uhl, 2003). ...
... When unloaded, females had more hip flexion; this difference has also been shown to occur during a single leg squat (Zeller, McCory, Kibler, & Uhl, 2003). The differences in hip anatomy and flexibility between the sexes may account for this (McKean et al., 2010b); however, an understanding of the variations at the hip are yet to be fully explained (Lynn & Noffal, 2012;McKean et al., 2010a;Zeller et al., 2003) and is a topic for future research. In the current study, experienced males displayed larger ankle and hip moments and greater degrees of knee flexion when under load compared to experienced females. ...
Article
Full-text available
Weightlifting shoes (WS) are often used by athletes to facilitate their squat technique; however, the nature of these benefits is not well understood. In this study, the effects of footwear and load on the mechanics of squatting were assessed for 32 participants (age: 25.4 ± 4.4 years; mass 72.87 ± 11.35 kg) grouped by sex and experience. Participants completed loaded and unloaded back squats wearing both WS and athletic shoes (AS). Data were collected utilising a 3D motion capture system synchronised with a force platform and used to calculate kinematic and kinetic descriptors of squatting. For both load conditions, WS gave significantly (P < 0.05) reduced ankle flexion and increased knee flexion than AS, as well as a more upright trunk and greater knee moment for the unloaded condition. In addition, the experienced group experienced a significantly greater increase in knee and hip flexion with WS than the novices when unloaded. These results are consistent with the idea that WS permit a more knee flexed, upright posture during squatting, and provide preliminary evidence that experienced squatters are more able to exploit this effect. Decisions about footwear should recognise the effect of footwear on movement and reflect an athlete's movement capabilities and training objectives.
... Four cross-sectional studies could be found that reported data on the extent and incidence of abnormalities of the vertebral column in weightlifters compared to controls and athletes of different sports [29][30][31][32]. Another four publications used three-dimensional movement analysis techniques to investigate the movements of the lumbar spinal region during squats [33][34][35][36]. ...
... The concerns by Walsh et al. [36] are unfounded, as the angle of the hip also changes. This is why in the deep squat at the turning point, the risk of delordosing of the lumbar spine is raised [35]. Video analyses have shown males exhibiting a smaller anterior pelvic tilt and a larger ventral flexion of the lumbar spine during the lowering phase of the parallel squat compared to females (p ď 0.001) [35]. ...
... This is why in the deep squat at the turning point, the risk of delordosing of the lumbar spine is raised [35]. Video analyses have shown males exhibiting a smaller anterior pelvic tilt and a larger ventral flexion of the lumbar spine during the lowering phase of the parallel squat compared to females (p ď 0.001) [35]. The gender differences could result from larger range of motion in the hip in females [87]. ...
Article
Full-text available
For the development of speed strength in professional sports, “specific” strength training in the half or the quarter squat have been recommended. Due to the better lever ratios, higher loads have to be used to induce the necessary training stimuli compared to the deep squat. Therefore, intradiscal pressure and compressive forces on vertebral bodies increase. Calculated compressive forces for the L3/L4 vertebral segment were revealed to be 6–10-fold bodyweight when the half or the quarter squat was performed with 0.8–1.6-fold bodyweight. After 10 weeks of training, physical education students have even been able to lift 3.89-fold bodyweight in the one repetition maximum (1-RM) of the quarter squat. The presented dependence of squatting depth, load and their influence on the spinal column have not been discussed before. A search for relevant scientific literature was conducted using PubMed. Concerns about increased risk of injuries in the deep squat have been disproven by plenty of cross-sectional studies with professional athletes. On the contrary, the comparably supramaximal weight loads in the half and the quarter squat should be regarded as increasing injury risks caused by the higher shear and compressive forces in the vertebral column. Therefore, we come to the conclusion that the half and the quarter squat should not further be recommended.
... Considering that people with low back disorders may not tolerate performing squats with higher loads, bodyweight squats promote more functional neuromotor recruitment [2,6,15], and there are no kinematic changes from using a barbell in lumbar and sacrum patterns versus the bodyweight squat version [15]. The aim of this study was to verify longissimus and iliocostalis muscle activity during superman exercises in unstable and stable conditions versus their activity in bodyweight squats. ...
... Considering that people with low back disorders may not tolerate performing squats with higher loads, bodyweight squats promote more functional neuromotor recruitment [2,6,15], and there are no kinematic changes from using a barbell in lumbar and sacrum patterns versus the bodyweight squat version [15]. The aim of this study was to verify longissimus and iliocostalis muscle activity during superman exercises in unstable and stable conditions versus their activity in bodyweight squats. ...
... Bodyweight squat: Participants began in a standing position with their hands in front of their chests, with a stance width of 100% of greater trochanter distance and feet slightly rotated outward. Participants were instructed to maintain a neutral spine curvature during all squat movement avoiding changes in muscle fiber angle [5,15]. Participants performed a knee flexion with the thighs parallel to the floor (knee flexion of approximately 1.70 radians), and then they performed the ascend phase, returning to a standing position while maintaining isometric contraction of the trunk muscles ( Figure 1a). ...
Article
Full-text available
The purpose of this study was to investigate the recruitment of the paraspinal muscles longissimus and iliocostalis during dynamic contractions of superman exercises on stable and unstable surfaces, and during unloaded bodyweight squats. Surface electromyography (EMG) was measured from these two muscles bilaterally while participants performed the exercises. Participants (n = 17, age 24 ± 3.1 years, body mass 78.5 ± 8.2 kg, height 1.81 ± 7.4 m) performed two sets of 10 repetitions for each exercise in a random order. Correlation analysis demonstrated a strong positive relation between both sides of the participants (longissimus pairs: r = 0.945; and iliocostalis pairs: r = 0.855), demonstrating a symmetric muscle recruitment in all exercises. However, there were no significant differences between the exercises for both muscles in a multiple comparison analysis (longissimus pairs: p = 0.496; and iliocostalis pairs: p = 0.296). The bodyweight squat produces similar muscle activity of the longissimus and iliocostalis compared with superman exercises on stable and unstable surfaces. Considering the dynamic nature of the bodyweight squat, and its implications on functional daily living activities and sports conditions, it seems a more reasonable choice for targeting paraspinal muscles if compared to superman exercises or unstable superman exercises.
... The expressed fears of Walsh et al. [157] during the execution of the squat exercise are unfounded because the hip-joint angle changes. On the contrary, the deep squat involves the risk of dissolving the lordotic curvature in the turning point [159]. McKean et al. [159] determined a lower range of movement at the sacrum (p B 0.01) with a larger range of lumbar flexion (p B 0.01) in 18 males compared with 12 females while performing the descent phase in the parallel back squat with a narrow stance (pelvic width). ...
... On the contrary, the deep squat involves the risk of dissolving the lordotic curvature in the turning point [159]. McKean et al. [159] determined a lower range of movement at the sacrum (p B 0.01) with a larger range of lumbar flexion (p B 0.01) in 18 males compared with 12 females while performing the descent phase in the parallel back squat with a narrow stance (pelvic width). In contrast, females demonstrated less range of lumbar flexion and more anterior tilt of the sacrum compared with males. ...
... Women have a lower stiffness and greater range of motion between motion segments of the lumbar spine than men [160]. McKean et al. [159] therefore assume that the females were capable of developing more muscular stabilization of the lumbar spine that may explain their greater sacrum movement due to higher flexibility of the lumbar sacral region. Another contributing factor could be the greater hamstring flexibility that females have been shown to possess compared with males [161]. ...
Article
It has been suggested that deep squats could cause an increased injury risk of the lumbar spine and the knee joints. Avoiding deep flexion has been recommended to minimize the magnitude of knee-joint forces. Unfortunately this suggestion has not taken the influence of the wrapping effect, functional adaptations and soft tissue contact between the back of thigh and calf into account. The aim of this literature review is to assess whether squats with less knee flexion (half/quarter squats) are safer on the musculoskeletal system than deep squats. A search of relevant scientific publications was conducted between March 2011 and January 2013 using PubMed. Over 164 articles were included in the review. There are no realistic estimations of knee-joint forces for knee-flexion angles beyond 50° in the deep squat. Based on biomechanical calculations and measurements of cadaver knee joints, the highest retropatellar compressive forces and stresses can be seen at 90°. With increasing flexion, the wrapping effect contributes to an enhanced load distribution and enhanced force transfer with lower retropatellar compressive forces. Additionally, with further flexion of the knee joint a cranial displacement of facet contact areas with continuous enlargement of the retropatellar articulating surface occurs. Both lead to lower retropatellar compressive stresses. Menisci and cartilage, ligaments and bones are susceptible to anabolic metabolic processes and functional structural adaptations in response to increased activity and mechanical influences. Concerns about degenerative changes of the tendofemoral complex and the apparent higher risk for chondromalacia, osteoarthritis, and osteochondritis in deep squats are unfounded. With the same load configuration as in the deep squat, half and quarter squat training with comparatively supra-maximal loads will favour degenerative changes in the knee joints and spinal joints in the long term. Provided that technique is learned accurately under expert supervision and with progressive training loads, the deep squat presents an effective training exercise for protection against injuries and strengthening of the lower extremity. Contrary to commonly voiced concern, deep squats do not contribute increased risk of injury to passive tissues.
... As a means of preventing from lumbar kyphosis, improving hip joint flexion mobility is a good way because the cause of lumbar kyphosis during SQ is a decrease of hip joint flexion mobility 5,6) . McKean et al. 6) compared lumbar motion between men and women during SQ and reported that women with less pelvic posterior tilt show less lumbar kyphosis than did men. ...
... As a means of preventing from lumbar kyphosis, improving hip joint flexion mobility is a good way because the cause of lumbar kyphosis during SQ is a decrease of hip joint flexion mobility 5,6) . McKean et al. 6) compared lumbar motion between men and women during SQ and reported that women with less pelvic posterior tilt show less lumbar kyphosis than did men. This report indicated that women with higher joint mobility 6) have a small degree of pelvic posterior tilt during hip joint flexion, which makes it easy to maintain lumbar lordosis. ...
... McKean et al. 6) compared lumbar motion between men and women during SQ and reported that women with less pelvic posterior tilt show less lumbar kyphosis than did men. This report indicated that women with higher joint mobility 6) have a small degree of pelvic posterior tilt during hip joint flexion, which makes it easy to maintain lumbar lordosis. ...
Article
Full-text available
[Purpose] To compare the lumbar lordosis angle and electromyographic activities of the trunk and lower-limb muscles in the hip neutral position and external rotation during back squats. [Subjects and Methods] Ten healthy males without severe low back pain or lower-limb injury participated in this study. The lumbar lordosis angle and electromyographic activities were measured using three-dimensional motion-capture systems and surface electrodes during four back squats: parallel back squats in the hip neutral position and external rotation and full back squats in the hip neutral position and external rotation. A paired t-test was used to compare parallel and full back squats measurements in the hip neutral position and external rotation, respectively. [Results] During parallel back squats, the average lumbar lordosis angle was significantly larger in hip external rotation than in the hip neutral position. During full back squats, lumbar erector spinae and multifidus activities were significantly lower in hip external rotation than in the hip neutral position, whereas gluteus maximus activity was significantly higher in hip external rotation than in the hip neutral position. [Conclusion] The back squat in hip external rotation induced improvement of lumbar kyphosis, an increasing of the gluteus maximus activity and a decrease of both lumbar erector spinae and multifidus activities.
... One of them is the relation of a joint's movement timing to squat performance. McKean et al. previously investigated the movement pattern of back squats in males and females showing significant differences in lumbar-sacral coordination and ranges but they did not measure squat depth (McKean et al., 2010b). ...
... Other valuable results from this study are: (1) squat depth was not correlated to pelvis and ankle ROMs in females and (2) squat depth was correlated to all investigated ROMs in males. It had been previously reported that there are significant differences in movement patterns between female and males during exercise performance (McKean et al., 2010a(McKean et al., , 2010b. Ankle mobility was considered in many studies to be crucial to keeping a proper movement pattern during squatting and squat depth (Dill et al., 2014;Macrum et al., 2012). ...
... Second, the ankle reaches its maximal angle of dorsiflexion and after that the spine, the knee and the hip reach their maximal angles almost simultaneously at the end of the descent phase. This is consistent with the findings of McKean et al., who showed a similar relation in the timing of lumbar flexion (McKean et al., 2010b) This author also reported that maximum hip and knee angles are achieved almost simultaneously with the deepest part of the squat (M. McKean and Burkett, 2012). ...
Article
Full-text available
The aim of this study was to analyze the relationship of range of motion (ROM) in the sagittal plane and timing parameters during a bodyweight squat to the depth of the squat. Sixty participants (20 females and 40 males) took part in this study. They were instructed to perform a bodyweight squat to the maximal depth position. Kinematic data were obtained using the optical motion capture system. The time for the descent phase of squatting was normalized from 0% (initial position, start of movement) to 100% (squat position-stop of movement). The ROM of ankle, knee, hip, pelvis and spine in the sagittal plane and the normalized time when the maximum joint angles occurred during the descent were analyzed to investigate the relationship between them and the squat depth in males and females. The knee ROM contributed most significantly, from all joints to squatting depth in both females and males (r = 0.92, p < 0.001). The squat depth was related to lumbar, hip and knee motion in females and to all kinematics parameters in males. Maximal ankle dorsiflexion and pelvis anterior tilt were reached earlier than the maximal angles of knee, hip and spine during squatting. Pelvis and ankle timing was negatively correlated with the squat depth (rs =-0.64, p < 0.001 and rs =-0.29, p = 0.02, respectively). This suggests that pelvis and ankle timing can be important to keeping balance during squatting and can lead to achieving the desired depth.
... This popular exercise has been subject to extensive biomechanical investigations that focus typically on the impact of load, squat depth, stance width and/or shoe design on lower limb mechanics (at the time of submission searches on Web of Science and PubMed using terms such as "Squat", "Kinematics" and "Biomechanics" revealed over relevant 100 manuscripts). However, of this extensive body of literature proportionally less focuses specifically on back squat spinal kinematics and/or kinetics (Charlton et al., 2017;Hartmann et al., 2013;Lee et al., 2019;List et al., 2013;Lorenzetti et al., 2018;McKean et al., 2010;Walsh et al., 2007;Whitting et al., 2016). ...
... Our spinal curvature data are similar to earlier research (List et al., 2013), with the small differences between these data due to the normalization adopted by the earlier group (i.e., their data were normalized to static posture). Similarly, our relatively large SD data may reflect the inclusion of both male and female participants, with research suggesting slight differences in squat technique between the sexes (McKean et al., 2010). Although slightly more exaggerated, the spinal curvatures of our novice participants did not differ significantly at any stage of the squat cycle from the regular weight trainers. ...
Article
Full-text available
This research assessed the influence of various heel elevation conditions on spinal kinematic and kinetic data during loaded (25% and 50% of body weight) high-bar back squats. Ten novice (mass 67.6 ± 12.4 kg, height 1.73 ± 0.10 m) and ten regular weight trainers (mass 66.0 ± 10.7 kg, height 1.71 ± 0.09 m) completed eight repetitions at each load wearing conventional training shoes standing on the flat level floor (LF) and on an inclined board (EH). The regular weight training group performed an additional eight repetitions wearing weightlifting shoes (WS). Statistical parametric mapping (SPM1D) and repeated measures analysis of variance were used to assess differences in spinal curvature and kinetics across the shoe/floor conditions and loads. SPM1D analyses indicated that during the LF condition the novice weight trainers had greater moments around L4/L5 than the regular weight trainers during the last 20% of the lift (P < 0.05), with this difference becoming non-significant during the EH condition. This study indicates that from a perspective of spinal safety, it appears advantageous for novice weight trainers to perform back squats with their heels slightly elevated, while regular weight trainers appear to realize only limited benefits performing back squats with either EH or WS.
... While many published studies refer to advanced squatters such as Olympic or national weightlifters [15,19] or powerlifters [20], the present study focusses on understanding the major influences of squat technique from a perspective of both more and less experienced participants working out in a gym. No studies have investigated a stance width below 10 cm, since most attention has been paid to shoulder or hip stance width [10,12,17,19,21]. ...
... Three stance widths were examined: narrow stance (NS) described a stance width of 10% of the distance from the greater trochanter to the floor; hip stance (HS) was a distance between the two anterior superior iliac spines; and a wide stance (WS) was twice the distance between the anterior superior iliac spines. The HS and WS equalled the two stance widths analysed by McKean and co-workers [21]. Based on previous study results [17], three different foot angle placements were examined (0°, 21°, and 42°). ...
Article
Full-text available
Background Squatting is a core exercise for many purposes. The tissue loading during squatting is crucial for positive adaptation and to avoid injury. This study aimed to evaluate the effect of narrow, hip and wide stance widths, foot position angles (0°, 21°, and 42°), strength exercise experience, and barbell load (0 and 50% body weight, experts only) during squatting. Methods Novice (N = 21) and experienced (N = 21) squatters performed 9 different variations of squats (3 stance widths, 3 foot placement angles). A 3D motion capture system (100 Hz) and two force plates (2000 Hz) were used to record mediolateral knee displacement (ΔD*), range of motion (RoM) at the hip and knee joints, and joint moments at the hip, knee, and lower back. Results Both stance width and foot placement angles affected the moments at the hip and knee joints in the frontal and sagittal planes. ΔD* varied with stance width, foot placement angles and between the subjects’ level of experience with the squat exercise as follows: increasing foot angle led to an increased foot angle led to an increased ΔD*, while an increased stance width resulted in a decreased ΔD*; novice squatters showed a higher ΔD*, while additional weight triggered a decreased ΔD*. Conclusions Suitable stance width and foot placement angles should be chosen according to the targeted joint moments. In order to avoid injury, special care should be taken in extreme positions (narrow stand-42° and wide stance-0°) where large knee and hips joint moments were observed. Electronic supplementary material The online version of this article (10.1186/s13102-018-0103-7) contains supplementary material, which is available to authorized users.
... descends, the cue to "sit back" should be coupled with one to facilitate "knees traveling forward toward the toes," ensuring that the bar descends in a vertical line in relation to the ground (7). Furthermore, it is imperative to maintain proper bracing of the muscles surrounding the lumbar spine to maintain control over the lifter's center of mass (24)(25)(26). The desired end range of motion for hip flexion and ankle dorsiflexion should be simultaneously reached at the deepest point of the squat, where the tops of the thighs are just below parallel to the ground without deviations at the knee, ankle, or hips (28,36). ...
... They may also elevate the hips with a sturdy pad to increase the amount of torso/hip extension. Finally, Table 2 Low-bar back squat common errors and associated "fixes" (7,10,13,24,(25)(26)(27)(28)31,39) ...
Article
The low-bar back squat (LBBS) is a barbell squat variation that emphasizes hip musculature through use of forward lean. This characteristic, among others, allows greater loads to be lifted and can facilitate rehabilitation in a compromised knee joint. Correct technique should be instructed to promote proper execution. This article aims to discuss the anatomical and technical differences between the high-bar back squat and LBBS, define LBBS-specific technique, and provide practitioners strategies to select the best version for their lifters.
... While many published studies refer to advanced squatters such as Olympic or national weightlifters [15,19] or powerlifters [20], the present study focusses on understanding the major influences of squat technique from a perspective of both more and less experienced participants working out in a gym. No studies have investigated a stance width below 10 cm, since most attention has been paid to shoulder or hip stance width [10,12,17,19,21]. ...
... Three stance widths were examined: narrow stance (NS) described a stance width of 10% of the distance from the greater trochanter to the floor; hip stance (HS) was a distance between the two anterior superior iliac spines; and a wide stance (WS) was twice the distance between the anterior superior iliac spines. The HS and WS equalled the two stance widths analysed by McKean and co-workers [21]. Based on previous study results [17], three different foot angle placements were examined (0°, 21°, and 42°). ...
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Following publication of the original article [1], the authors reported an error in the following sentence on page 8: “In general, knee varus (negative ΔD*) is a much more common deficit than valgus, and a more negative ΔD* value in the novice squatters compared to the experienced ones was therefore expected.”
... Ana li zu jąc róż nice w stra te gii ru chów mię dzy ko bie ta mi a męż czy zna mi w cza sie przy sia du z ob cią że niem umiej sco wionym na kar ku, McKean stwier dził więk szy za kres zgięcia od cin ka lę dź wio we go krę go słu pa u męż czyzn. U obu płci za ob ser wo wa no zwięk sze nie ty ło po chy lenia ko ści krzy żo wej i bar dziej ki fo tycz ne usta wie nie krę go słu pa w po zy cji star to wej przy sia du z wą skim roz sta wem stóp [37]. Zwięk sze nie do wol nej ak tyw ności mię śni sta bi li zu ją cych kom pleks lę dź wio wo -miednicz ny (głów nie mię śnia po przecz ne go brzu cha), skutku je mniej szym bocz no -przy środ ko wym prze mieszcze niem bio dra oraz więk szym za kre sem zgię cia w stawie ko la no wym w cza sie przy sia du. ...
... Studying the differences in movement strategies between women and men during squats with load placed on the nape of the neck, McKean found a wider range of lumbar spine flexion in male subjects. In both sexes,the stu dy revealed increased sacrum retroversion and a mo re kyphotic positioning of the vertebral column in the baseline position during squatting [37]. An increase in any activity of the muscles stabilizing the lumbopelvic complex (mainly the transverse abdominal muscle) results in a less pronounced lateromedial shift of the hip and a wider range of knee joint flexion during squatting. ...
Article
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The squat is a typical closed kinetic chain motion task. It is an important component of programs in physical therapy and sport training. It’s a complex activity, consisting of hip flexion, knee flexion and ankle dorsiflexion. For this reason, the squat can be used in nonobjective assessment of muscular strength and range of motion in functional activities. Different movement strategies applied during squatting are essential in patients with musculoskeletal dysfunctions, such as: patellofemoral pain syndrome, iliotibial band syndrome, cruciate ligaments injury, lumbar pain, femoro-acetabular impin­ge­ment. The aim of this study was to present biomechanical interdependencies in the lower limbs during the squat and the factors affecting musculoskeletal dysfunctions. This paper presents impor­tant tips for physiotherapy practice and sports training. The study took into account the findings from selected original works. The paper reviews the stu­dies involving the analysis of the ranges of motion during the squat, electromyography results and the impact of training on squat performance. It presents the importance of ankle mobility in maintaining knee stability in the frontal plane, and the impact of dynamic knee valgus on the occurrence of lower limb dysfunction. The impact of squat depth and feet spacing on muscle function is described. Moreover, the paper refers to the analysis of motion during single and double leg squats. Differences between hip-dominant and knee-dominant squats have also been explained. The role of the lumbo-pelvic complex during the squat and the existing relationships between joints of the lower limb during the squat is analyzed in the presented literature review. The last part of the report contains practical advice how to apply squat exercises in rehabilitation and sports training. A large variability of strategies during the squat tasks, observed between men and women, or between patients with different locomotor dysfunctions provide new opportunities for research on the biomechanics of squat exercise.
... The erector spinae significantly contributes to upright posture and extension of the lumbar and thoracic spine through the action of three groups of fibers-illiocostalis, longissimus and spinalis (6,26). Proper spinal extension allows for optimal positioning in other areas like the neck, shoulder, and hip (17,30). The scapula, which aligns with the thoracic region of the spine, glides across it with the help of the trapezius and serratus anterior (among other muscles). ...
... The scapula, therefore, must maintain dynamic stability while simultaneously providing controlled mobility (28); ultimately it arranges the glenohumeral joint in an optimal position for muscular function. Thoracic extension allows for all the aforementioned movements to occur so that the scapula may rotate upward to change the orientation of the glenoid fossa, allowing overhead position (13,17,18,28,30). ...
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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.
... Studies demonstrated the pelvic space diameters adaptation to patients' postures [2][3][4][5][6]. / Biomechanical research has highlighted an appreciable movement of the sacroiliac joints, the lumbosacral junction, and the pubic symphysis, which justifies the pelvis's ability to modify three-dimensionally its diameters and internal spaces [19][20][21]. It can be assumed that assessment of adequate pelvic mobility is pivotal in supporting vaginal deliveries and preventing labor dystocia. ...
... Previous studies showed the different shape and movement patterns of the Michaelis sacral area, explaining the differences in measurement between literature studies [15,16]. Argumentations about internal pelvic space modification in shifting positions are inferences based on indirect external measurements, albeit supported by a general agreement with biomechanical studies [2][3][4][5][6][7][8]20,26]. Our study was performed in a single-center. ...
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Dystocia in labor is still a clinical challenge. The "contracted pelvis" is the absence of pelvic mobility, which leads to fetal-pelvic disproportion, obstructed labor, and operative delivery. Maternal pelvis biomechanics studies by high technological techniques have shown that maternal shifting positions during pregnancy and labor can create more room in the pelvis for safe delivery. The external and internal pelvic diameters are related. The present study aims to evaluate the external obstetric pelvic diameters in shifting positions using a clinical technique suitable for daily practice in every clinical setting: the dynamic external pelvimetry test (DEP test). Seventy pregnant women were recruited, and the obstetric external pelvic diameters were measured, moving the position from kneeling standing to "hands-and-knees" to kneeling squat position. Results showed modification of the pelvic diameters in shifting position: the transverse and longitudinal diameters of Michaelis sacral area, the intertuberosities diameter, the bi-trochanters diameter, and the external conjugate widened; the bi-crestal iliac diameter, the bi-spinous iliac diameter, and the base of the Trillat's triangle decreased. The test showed good reproducibility and reliability. Linear correlations were found between diameters and between the range of motion of the diameters. The maternal pelvis is confirmed to modify the diameters changing its tridimensional shape. The pelvic inlet edge's inclination is inferred to be modified, facilitating the fetal descend. The pelvic outlet enlarged the transverse diameter, facilitating birth. The DEP test estimates the pelvic diameters' modification with postural changes, as magnetic resonance (MR) and computational biomechanics studies have demonstrated.
... La ricerca biomeccanica ha evidenziato un apprezzabile movimento delle articolazioni sacro-iliache, della giunzione lombosacrale, e della sinfisi pubica, che giustifica la capacità del bacino di modificare tridimensionalmente i propri diametri e spazi interni [19][20][21]. ...
... Studi precedenti hanno mostrato la diversa forma e differenti modelli di movimento dell'area sacrale di Michaelis, spiegando le differenze di misurazione tra gli studi presenti in letteratura [15,16]. Le argomentazioni sulla modifica dello spazio pelvico interno con il cambiamento della posizione sono inferenze indirette basate su misurazioni esterne, sebbene siano ben supportate da un generale accordo con tutti gli studi biomeccanici sull'argomento [2][3][4][5][6][7][8]20,26]. Il nostro studio è stato condotto in un unico centro. ...
Article
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La distocia in travaglio è una sfida clinica ancora aperta. La "pelvi contratta" è l'assenza di mobilità pelvica, che porta alla sproporzione fetale-pelvica, al travaglio ostruito e al parto operativo. Gli studi di biomeccanica del bacino materno con tecniche ad alta tecnologia hanno dimostrato che il cambiamento di posizione della mamma durante la gravidanza e il travaglio può creare più spazio nel bacino per un parto sicuro. I diametri pelvici esterno e interno sono correlati. Il presente studio si propone di valutare i diametri pelvici ostetrici esterni in posizioni differenti utilizzando una tecnica clinica adatta alla pratica quotidiana in ogni contesto clinico: il test di pelvimetria esterna dinamica (the Dynamic External Pelvimetry Test, DEP test). Sono state reclutate settanta donne in gravidanza e sono stati misurati i diametri pelvici esterni ostetrici, cambiando la posizione da eretta a "4 appoggi" a squat in ginocchio. I risultati hanno mostrato la modifica dei diametri pelvici spostando la posizione: i diametri trasverso e longitudinale dell'area sacrale di Michaelis, il diametro inter-tuberositario, il diametro bitrocanterico e la coniugata esterna sono aumentati; il diametro iliaco bi-crestale, il diametro iliaco bi-spinoso e la base del triangolo di Trillat sono diminuiti. Il test ha mostrato una buona riproducibilità e affidabilità. Sono state trovate correlazioni lineari tra i diametri e tra il range di movimento dei diametri. Viene confermato che il bacino materno modifica i diametri cambiando la loro forma tridimensionale. Si presume che l'inclinazione del bordo di ingresso pelvico sia modificata, facilitando la discesa fetale. L'outlet pelvico ha allargato il diametro trasversale per facilitare la nascita. Il test DEP riesce a stimare la modificazione dei diametri pelvici con i cambiamenti posturali, come avevano dimostrato studi di risonanza magnetica (RM) e biomeccanica computazionale.
... However, acute effects of barbell back squat exercise on each lumbar IVD have not been sufficiently investigated regardless of difference in external exercise load. Additionally, McKean et al 3 reported that the lordotic curvature is prone to collapse in the descent phase of the deep squat, which may elevate the risk of posterior protrusion of the lumbar IVDs. [6][7][8] Thus, lumbar load possibly increases with increasing squat depth, 9,10 but the relationship between the mechanical stress on the lumbar IVDs and squat depth has not been fully elucidated. ...
... Although the detailed reasons why the smaller lumbar lordosis and anterior pelvic tilt were induced during parallel squat exercise are unclear in this study, the lumbar and pelvic movements may be related to individual intrinsic factors such as the muscle strength and joint flexibility in the regions of the trunk and lower extremity, and the interdependent movements of the hip, knee, and ankle joints. [1][2][3][4]9,10,31 Moreover, muscle fatigue of the trunk and/or lower extremity might significantly influence the results. 10,32 In fact, it might have been hard for most participants to complete parallel squat exercise under exercise condition of the present study. ...
Article
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We aimed to evaluate the acute physiological effects of high‐load barbell back squat exercise on each lumbar intervertebral disk with varying squat depths. Thirteen subjects (age, 23.3 ± 3.5 years) performed parallel and half‐squat exercises (80% of one repetition maximum, eight repetitions, five sets) using a Smith machine. Sagittal magnetic resonance diffusion‐weighted and spin‐echo images of lumbar intervertebral disks were obtained by using a 1.5‐Tesla MR system before and after each squat exercise; apparent diffusion coefficient (ADC; an index of water movement) and T2 relaxation time (an index of water content level) of the nucleus pulposus were calculated at all lumbar intervertebral disks. Additionally, we measured the angles of lumbar lordosis and anterior pelvic tilt at the bottom position of each squat using a three‐dimensional motion‐capture system. The nucleus pulposus of L4/5 (−5.0%, P < .01) and L5/S1 (−6.6%, P < .01) intervertebral disks showed decreased ADC values after parallel squat exercise. Moreover, post‐exercise ADC value in parallel squat exercise was lower than that in half‐squat exercise at L5/S1 intervertebral disk (P < .05). In contrast, the nucleus pulposus of all lumbar intervertebral disks had no significant T2 change before and after both squat exercises. The angles of lumbar lordosis (P < .01) and anterior pelvic tilt (P < .01) were smaller in parallel squat than in half‐squat. Lower lumbar intervertebral disks are subject to greater mechanical stress during high‐load parallel back squat exercise, which may result from smaller lumbar lordosis and anterior pelvic tilt angles at the bottom position during parallel squat.
... Walsh et al. (2007) Lendenwirbelsäule (McKean et al., 2010b). Videoanaly- sen von McKean et al. (2010b) ergaben für männliche Pro- banden in der exzentrischen Phase der parallelen Kniebeuge (hüftbreiter Stand) eine geringere anteriore Beckenkippung (p < 0.001) und eine stärkere Ventralflexion der Lendenwir- belsäule (p < 0.001) im Vergleich zu den weiblichen Proban- den. Nach den Untersuchungen von Brown et al. (2002) wei- sen Frauen eine geringere Steifigkeit und ein grösseres Bewegungsausmass zwischen den Wirbelsegmenten der Len- denwirbelsäule auf als Männer. ...
... Nach den Untersuchungen von Brown et al. (2002) wei- sen Frauen eine geringere Steifigkeit und ein grösseres Bewegungsausmass zwischen den Wirbelsegmenten der Len- denwirbelsäule auf als Männer. McKean et al. (2010b) ver- muten daher bei Frauen eine grössere Beweglichkeit des Lumbosakralbereiches, die über eine höhere muskuläre Sta- bilisierung der Lendenwirbelsäule eine ausgeprägtere ante- riore Beckenkippung ermöglicht im Vergleich zu Männern. Bei den weiblichen Probanden war eine geringere Lumbal- flexion und eine stärkere anteriore Beckenkippung in der ex- zentrischen Phase der parallelen Nackenkniebeuge im Ver- gleich zu den männlichen Probanden festzustellen. ...
Article
In Wissenschaft und Praxis des Krafttrainings wird mitunter angenommen, dass die tiefe Kniebeuge eine erhöhte Verletzungsgefahr der Lendenwirbelsäule und des Kniegelenks aufweist. Ein Verzicht auf tiefe Gelenkpositionen soll das Ausmass der Kniegelenkskräfte minimieren. Entsprechend wird bei Überlastungsbeschwerden und degenerativen Veränderungen des Patella-Sehnen-Komplexes die Durchführung der viertel oder halben Kniebeuge empfohlen, da innerhalb der ersten 50° Kniebeugung die geringsten retropatellaren Druckbeanspruchungen berechnet wurden. Diese Empfehlung basiert auf Kalkulationen von Kniegelenkskräften, die bei Ausführung der tiefen und halben Nackenkniebeuge auftraten. Diese Werte können jedoch nicht auf die viertel Kniebeuge übertragen werden, da hierbei a) der Einfluss der Bewegungsumkehr bei geringerer retropatellarer Kontaktzone und geringerer oder fehlender tendofemoraler Unterstützungsfläche und b) die unterschiedlichen Lasthöhen der jeweiligen Kniebeugevariante unberücksichtigt blieben. Dies ist insbesondere im Leistungssport von trainingspraktischer Relevanz: Aufgrund der günstigeren Hebelverhältnisse in Knie- und Hüftgelenken sind in der viertel (und halben) Kniebeuge höhere Lasten als in der tiefen Kniebeuge erforderlich, um Trainingsreize der Hüft- und Beinextensoren zu applizieren. Dies resultiert in einer entsprechenden Zunahme der Kniegelenkskräfte und erfordert eine grössere Stabilisierungsarbeit im Rumpf, um schädigenden discalen Scherkräften entgegenzuwirken. Diese Zusammenhänge blieben in renommierten Publikationen bisher unberücksichtigt, in denen die Kniegelenk- und Wirbelsäulenbelastung in unterschiedlichen Kniebeugetiefen diskutiert wurde. Vorausgesetzt, dass unter professioneller Trainerbetreuung die Bewegungstechnik korrekt erlernt und die Belastung allmählich gesteigert wird, stellt die tiefe Kniebeuge eine effektive verletzungsprotektive Trainingsmassnahme auch im Nachwuchsbereich dar und birgt, entgegen der landläufigen Meinung, keine erhöhten Verletzungsrisiken des passiven Bewegungsapparates.
... Taking the calculations of Cappozzo et al. (16) into account, compressive forces acting on the L3-L4 segment may have exceeded 20 times of the body weight. Performing the squat until failure with high loads involves the risk of forward leaning (63) and ventral flexion (68). Ventral flexion causes diminished activity of the m. ...
Article
Es existieren keine Vergleichsstudien über die Entwicklung der Sprungleistung in Squat (SJ) und Countermovement Jump (CMJ) durch unterschiedliche Kniebeugevarianten, die eine Bevorzugung einer bestimmten Beugetiefe rechtfertigen könnten. Aus diesem Grund wurden in zwei Forschungsprojekten an 23 weiblichen und 36 männlichen Sportstudierenden (24,11±2,88 Jahre) die Auswirkungen eines periodisierten Maximalkrafttrainings in der tiefen Frontkniebeuge (Gruppe FKB, n= 20), tiefen Nackenkniebeuge (Gruppe NKB, n= 20) und der viertel Nackenkniebeuge bis 120° Kniegelenkwinkel (Gruppe NKB¼, n= 19) auf die Schnellkraftleistung in SJ und CMJ untersucht. Die Parallelisierung der drei Versuchsgruppen erfolgte auf Basis der Sprunghöhen im CMJ. Zusätzlich wurde eine Kontrollgruppe (K, n= 16) gebildet (Alter: 24,38±0,50 Jahre). Das zehnwöchige periodisierte Krafttraining (2 Tage / Woche) resultierte in signifikanten (p≤0,001) Steigerungen der dynamischen Maximalkraft in der spezifischen Kniebeugevariante der jeweiligen Trainingsgruppe. Gruppe FKB und Gruppe NKB zeigten signifikante und nahezu gleichwertige Zunahmen in den Sprunghöhen von SJ (p≤0,001) und CMJ (p≤0,001), ohne einen Gruppenunterschied zwischen diesen beiden Gruppen aufzuweisen (p= 0.852 und p= 0.626). Für Gruppe NKB¼ und Gruppe K waren keine statistisch signifikanten Veränderungen des Schnellkraftvermögens in SJ und CMJ zu ermitteln. Der Ausgangstest im SJ erbrachte für Gruppe FKB und Gruppe NKB jeweils signifikant höhere Schnellkraftleistungen gegenüber Gruppe K (p= 0,013; p= 0,029). Während in diesem Test für Gruppe NKB kein statistisch bedeutsamer Gruppenunterschied zur Gruppe NKB¼ festzustellen war (p= 0,116), zeigte Gruppe FKB tendenziell höhere Sprungleistungen als Gruppe NKB¼ (p= 0,052). Der Ausgangstest im CMJ war für Gruppe FKB und Gruppe NKB jeweils mit signifikant höheren Sprungleistungen gegenüber Gruppe NKB¼ (p= 0,000) und Gruppe K (p= 0,000) verbunden. Die Ergebnisse der beiden Forschungsprojekte führten zu folgenden, für die Sportpraxis relevanten, Erkenntnissen: 1) Eine winkelspezifische Zunahme der dynamischen Maximalkraft in der viertel NKB erbringt keine leistungsfördernden Übertragungseffekte auf das Schnellkraftverhalten der Bein- und Hüftextensoren in konzentrischer Arbeitsweise (SJ) und im langen Dehnungsverkürzungs-Zyklus (CMJ). 2) Zur Steigerung des Schnellkraftvermögens in SJ und CMJ sind aus funktioneller Sicht tief durchgeführte Front- und Nackenkniebeugen als effektive Trainingsmaßnahmen zu betrachten, da ausschließlich in tiefen Gelenkpositionen die erforderliche Reizapplikation zur positiven Beeinflussung des Beschleunigungsablaufs gewährleistet wird. Diese Übungen sollten als ein grundlegender Bestandteil des allgemeinen Krafttrainings in Sportarten dienen, in denen ein hohes Schnellkraftvermögen der unteren Extremitäten von entscheidender Bedeutung ist. Gefördert durch das Bundesinstitut für Sportwissenschaft (BISp). Aktenzeichen der Forschungsprojekte des BISp: AZ 070509/2007 und AZ 070510/2008
... The front squat, which is used extensively in strength training programs at the collegiate level and higher [1], is one of the few exercises which can develop the majority of the lower body musculature as well as increase abdominal and lower back strength and stability [2]. Strength training programs are often created based on percentages of a one repetition maximum (1RM) in order to train for the desired results (e.g., hypertrophy, strength, power). ...
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This study was designed to assess the effectiveness of mental imagery supplemented with video-modeling on self-efficacy and front squat strength (three repetition maximum; 3RM). Subjects (13 male, 7 female) who had at least 6 months of front squat experience were assigned to either an experimental (n = 10) or a control (n = 10) group. Subjects′ 3RM and self-efficacy for the 3RM were measured at baseline. Following this, subjects in the experimental group followed a structured imagery protocol, incorporating video recordings of both their own 3RM performance and a model lifter with excellent technique, twice a day for three days. Subjects in the control group spent the same amount of time viewing a placebo video. Following three days with no physical training, measurements of front squat 3RM and self-efficacy for the 3RM were repeated. Subjects in the experimental group increased in self-efficacy following the intervention, and showed greater 3RM improvement than those in the control group. Self-efficacy was found to significantly mediate the relationship between imagery and front squat 3RM. These findings point to the importance of mental skills training for the enhancement of self-efficacy and front squat performance.
... Stability during the squat is enhanced with muscular stiffness of all muscles around the lumbar spine. Failure to stiffen the lower back musculature, combined with poor lifting mechanics, increases the potential to overload spine and back tissues to the point of injury, especially when repeated over time (27,29). A more upright lumbar posture increases load onto lower extremity levers, which may reduce low back stress. ...
Article
Full-text available
Fundamental movement competency is essential for participation in physical activity and for mitigating the risk of injury, which are both key elements of health throughout life. The squat movement pattern is arguably one of the most primal and critical fundamental movements necessary to improve sport performance, to reduce injury risk and to support lifelong physical activity. Based on current evidence, this first (1 of 2) report deconstructs the technical performance of the back squat as a foundation training exercise and presents a novel dynamic screening tool that incorporates identification techniques for functional deficits that limit squat performance and injury resilience. The follow-up report will outline targeted corrective methodology for each of the functional deficits presented in the assessment tool.
... Differences between genders in lumbar behaviour have been reported previously for back squatting where the loaded bar rested across the shoulders. 33 The current study supported this finding and suggested female subjects were less able to maintain normal lumbar flexion during overhead pressing with 3RM loads. This may be due to a reduced or different trunk muscle function, and suggests females are less able to maintain normal spine posture when overhead pressing. ...
Article
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Background: Using a cross-sectional design comparison was made of two overhead press techniques (in-front of the head or behind the head). The purpose of this study was to determine the impact of behind the head or in-front of the head overhead pressing technique on shoulder range of movement (ROM) and spine posture. The overhead press is commonly prescribed exercise. The two techniques (in-front of the head or behind the head) may influence joint mechanics and therefore require an objective analysis. Methods: Passive shoulder ROM quantified using goniometric measures, dynamic ROM utilised three dimensional (3D) biomechanical measures (120 Hz) of 33 participants performing overhead pressing in a seated position. The timing and synchronisation of the upper limb shoulder and spine segments were quantified and influence of each technique investigated. Results: The in-front technique commenced in lordotic position, whilst behind the head technique commenced in kyphotic position. Behind the head technique started with less thoracic extension than in-front condition. The thoracic spine remained extended and moved between 12� and 15� regardless of gender or technique. The techniques resulted in a significant difference between genders. Males were able to maintain a flat or normal lumbar lordosis, whereas females tended to kyphotic. Conclusion: Shoulder ROM was within passive ROM for all measures except external rotation for males with the behind the head technique. To avoid possible injury passive ROM should be increased prior to behind the head protocol. Females showed greater spine movements, suggesting trunk strengthening may assist overhead pressing techniques. For participants with normal trunk stability and ideal shoulder ROM, overhead pressing is a safe exercise (for the shoulder and spine) when performed either in-front or behind the head.
... Stability during the squat is enhanced with muscular stiffness of all muscles around the lumbar spine. Failure to stiffen the lower back musculature, combined with poor lifting mechanics, increases the potential to overload spine and back tissues to the point of injury, especially when repeated over time (27,29). A more upright lumbar posture increases load onto lower extremity levers, which may reduce low back stress. ...
Article
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THE BACK SQUAT IS A WELL-RESEARCHED AND WIDELY USED EXERCISE TO ENHANCE FUNDAMENTAL MOVEMENT COMPETENCY THAT CREATES A FOUNDATION FOR OPTIMAL MECHANICAL STRATEGIES DURING A BROAD RANGE OF ACTIVITIES. THE PRIMARY COMMENTARY INTRODUCED THE BACK SQUAT ASSESSMENT (BSA): A CRITERION-BASED ASSESSMENT OF THE BACK SQUAT THAT DELINEATES 30 POTENTIALLY OBSERVABLE FUNCTIONAL DEFICITS. THIS FOLLOW-UP COMMENTARY PROVIDES A TARGETED SYSTEM OF TRAINING CUES AND EXERCISES TO SUPPLEMENT THE BSA TO GUIDE CORRECTIVE INTERVENTION. WE PROPOSE A CRITERION-DRIVEN APPROACH TO CORRECTIVE EXERCISE THAT CAN SUPPORT PRACTITIONERS IN THEIR GOAL TO HELP INDIVIDUALS ACHIEVE MOVEMENT COMPETENCY IN THE BACK SQUAT.
... Such issues are listed below. @BULLET Squat and lunge patterns – movement of the knee relative to the toes [8,9], lumbar posture [10,11] @BULLET Push and pull patterns – thoracic posture [12,13] @BULLET Hinge pattern – lumbar posture [14,15] @BULLET Brace pattern – control of the core16171819 @BULLET Rotation pattern – seated, standing posture and point of rotation202122 In order to further develop the knowledge of the assessment and importance of these basic movement competencies, further research is required and agreement over the performance of these competencies must be more clearly defined. Several strategies towards this are available: ...
Article
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Physical education in schools has become an important issue in the fight against obesity and maintenance of general health. The concept of physical literacy is not a new one and has become a key aspect of modern philosophies underpinning physical education [1]. Physical literacy has been identified by the United Nations General Assembly in 2002 [2] and is defined as the fundamental movement skills that allow a child to react and respond efficiently and effectively to the environment and to others with control in a wide range of physical activities [3,4]. There has been much published on the importance of physical literacy, however the common definitions of physical literacy fail to include the ability of the individual to move their body the way it was designed to move.
... Because the exclusion criteria for the present study eliminated subjects with mobility restrictions that might alter the DST to a greater degree than the DSTB or DSTO, it is possible that the significant difference between conditions was due to the novelty of the DST. research showing that a change in stance width alters muscle activation, joint kinematics, and joint forces (9,10,23). Our results are also consistent with evidence that self-selected foot angles for squatting were approximately 30 degrees of abduction (10). ...
Article
The Functional Movement Screen (FMS) was developed as an evaluation tool for assessing the fundamental movement patterns thought to be prerequisites for functional activity. However, some of the FMS component movements, such as the Deep Overhead Squat test (DST), likely represent novel motor challenges on which poor performance might reflect inexperience with the task rather than a movement impairment. The purpose of this study was to examine the effects of positional variations on DST scores in a population of young, healthy adults. We hypothesized that self-selecting foot positioning, removal of an overhead component, or changing both aspects of the DST would result in improvement in FMS scores. Twenty healthy subjects completed four squatting conditions in a counterbalanced sequence to eliminate carry over effects: DST; modified squat with hands at chest level and feet in the DST position (DSTO); modified squat with arms in the DST position and selfselected foot placement (DSTF); and modified squat with hands at chest level and self selected foot placement (DSTB). A Friedman's ANOVA and Wilcoxon signed ranks post-hoc analysis revealed a significant difference between all squat conditions (ρ=0.036), between DSTB-DST groups (ρ<0.001), DSTO-DST groups (ρ=0.004) and DSTO-DSTB groups (ρ=0.046). Each modified squat condition had an average score higher than the DST. These findings suggest that the FMS DST might underestimate an individual's ability to squat during functional tasks that involve self-selected foot and arm placement.
... Interestingly, previous research found that physical therapists were less accurate at identifying spinal movement in the barbell back squat and deadlift exercises, compared to an objective data collection device (Falk et al., 2021). The authors found >34° of posterior pelvic tilt was required before visual detection was possible, which is greater than the typical lumbar flexion experienced in other gym-based movements (McGill & Marshall, 2012;McKean et al., 2010;Vigotsky et al., 2015). Therefore, the accuracy of subjectively assessing the core using "coaching-eye" seems unlikely to be an effective means of evaluating core function. ...
Thesis
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Introduction: Exercises designed to improve the function of the core are a centerpiece of many athletic training programs. Current core stability (CS) ideology, testing protocols, and training methods originated from research into low back pain, yet are commonly applied within the sports performance domain. CS is a controversial concept with significant debate around how effective core stability training (CST) is for athletic populations. The majority of CS exercises and assessments currently emphasize muscular endurance. This exclusive focus may not be appropriate when training or monitoring athletes involved in dynamic sporting activities. To improve our understanding on this topic, the goal of this thesis is to investigate current perspectives and viewpoints, relating to CS and CST, held by practitioners in the sports performance domain. Methods: An online questionnaire and semi-structured interview were performed to gather subjective data from industry experts and professionals working with athletes. Both studies were designed to understand current thoughts and opinions around three key themes; current understanding of CS, how CS is being monitored in practice, and how practitioners are training CS. Results: The online questionnaire was completed by 64 respondents, while 10 industry experts were interviewed. There was a lack of a universal language amongst industry professionals when describing CS and many differing opinions related to key CS concepts. An important finding was that very few practitioners are objectively assessing the core, with little consideration given to monitoring maximal core strength. It was found that nearly all participants implement direct CS exercises, however, opinions on how to best train the core varied significantly. The results of this thesis demonstrate wide ranging viewpoints and opinions related to CS and CST amongst industry professionals, despite over 30 years of related research. Discussion and Practical Implications: The findings from this thesis highlight the extent of divided industry perspectives. Specifically, five key areas were identified to improve our understanding in this area. The alignment of terminology and the development of an evidence-based CST framework are needed to streamline coaching practice. Maximal core strength is an underappreciated area and research exploring its relationship to athletic performance is desperately needed. Moreover, the development of cheap field tests to assess this quality are needed. Finally, longer term intervention studies are also required to substantiate the effectiveness of CS programs. Key Words: Core Stability, Core Stability Training, Trunk, Lumbopelvic Control
... Although the unilateral exercises used in the study are not direct comparisons with either FW or SM bilateral squats, they are indications that there are possible gender differences during the squat movement. Similarly, in 2 separate studies, McKean et al. observed that men and women exhibit different movement patterns during the squat exercise, possibly because of dissimilar lumbar and sacrum movement (24) and potential differences in lower limb length (23). ...
Article
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Standardized methods of testing power are instrumental in planning and implementing training regimens for many athletes, as well as in tracking training adaptations. Previous work has demonstrated that the Kansas Squat Test (KST), is a valid test for measuring indices of mean and peak power when compared to the Wingate Anaerobic cycle Test (WAnT). While the KST was designed for use with a Smith machine, many power athletes utilize free-weights for training. The purpose of this study was to determine the feasibility of a using free-weights (FW) for the KST by comparing it with the Smith machine modality (SM). Twenty-three track and field athletes participated (mean ± SD; 69.7 ± 10.6 kg; 20.1 ± 1.1 years). Each completed familiarization sessions with the FW and SM modalities prior to data collection. A 1RM squat was also determined for both the FW and SM. Correlation coefficients indicated significant relationships between the FW- and SM-KST on measures of peak test power (r = 0.955, p < .01) and mean test power (r = 0.959, p < .01), but not for relative fatigue (r = -0.198, p > .05), or post-test lactate (r = 0.109, p > .05). Paired-samples t-tests indicated that the FW-KST resulted in significantly higher measures of peak power and mean power (p = < 0.01), although no differences were observed for relative fatigue or lactate (p > 0.05). These data indicate that the FW-KST is a valid and feasible alternative to the SM-KST measuring peak and mean power.
... All participants were verbally instructed with a demonstration, and practice trial were performed to ensure the completion of bodyweight squat. The distance between the feet were twice the distance between the anterior superior iliac spine [32], and the knee should track over the toes throughout the squat motion without knee displacement either medially or laterally. The upper body was kept vertical to the ground during squatting, and the feet were not allowed to leave the ground during squatting. ...
Article
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Background: Females with different practice experience may show different body postures and movement patterns while squatting in different depths, which may lead to changes of biomechanical loadings and increase the risks of injuries. Methods: Sixteen novice female participants without squat training experience participated in this study. A 3D motion capture system was used to collect the marker trajectory and ground reaction force data during bodyweight squatting in different depths. The participants' kinematic data and joint moment were calculated using OpenSim's inverse kinematics and inverse dynamics algorithm. In this study, authors adapted a model especially developed for squatting and customized the knee joint with extra Degree-of-Freedom (DoF) in the coronal and horizontal plane with adduction/abduction and internal/external rotation. A paired-sample t-test was used to analyze the difference of joint range of motions (ROM) and peak moments between full-squat (F-SQ) and half-squat (H-SQ). One-Dimensional Statistical Parametric Mapping (SPM1D) is used to analyze the difference of joint angle and moment between the process of squatting F-SQ and H-SQ. Results: (1) Compared with H-SQ, F-SQ showed larger ROM in sagittal, coronal, and transverse planes (p < 0.05). (2) SPM1D found that the difference in joint angles and joint moments between F-SQ and H-SQ was mainly concentrated in the mid-stance during squatting, which suggested the difference is greatly pronounced during deeper squat. (3) Peak hip extension moment, knee extension moment, hip adduction moment, and plantar flexion moment of F-SQ were significantly higher than H-SQ (p < 0.05). (4) Difference of hip and knee extension moments and rotation moments between the F-SQ and H-SQ were exhibited during descending and ascending. Conclusions: The study found that novice women had larger range of joint motion during the F-SQ than H-SQ group, and knee valgus was observed during squatting to the deepest point. Greater joint moment was found during F-SQ and reached a peak during ascending after squatting to the deepest point. Novice women may have better movement control during H-SQ. The findings may provide implications for the selection of lower limb strength training programs, assist the scientific development of training movements, and provide reference for squat movement correction, thus reducing the risk of injury for novice women in squatting practice.
... For instance, Lee et al. [14] analysed women, implemented a load of 80% of onerepetition maximum, and did not instruct par ticipants to squat as deep as possible; in turn, Whit ting et al. [15] also analysed loaded conditions (50%, 70%, and 90% of onerepetition maximum). consider ing that there are significant differences in kinemat ics between sexes [25] and that loading affects move ment kinematics [15] during back squat, we propose that these differences might explain the distinct out comes between our analyses. More pressingly, the in struction not to squat as deep as possible hinders fur ther comparisons between the experiments, especially when considering the notion of achieving maximal roMs. it could be speculated that reduced anterior trunk inclination promoted by a heel elevation would only be observable when squatting at a full depth, as halfsquats do not require excessive inclination of the trunk to maintain balance and perform the exercise. ...
Article
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Purpose. Back squat (BS) is a popular exercise owing to its capacity to develop lower limb strength. During BS, trunk incli nation and knee range of motion (roM) are relevant aspects of a proper technique, and these movement kinematics parameters can be positively altered with official weightlifting shoes lifting the heel 13 mm above the ground. Wedges are a lowcost alternative to lifting the heel to different heights, but movement kinematics adaptations with higher elevations, above 25 mm, are not well described in the literature. thus, we compared the effect of different heights of heel wedges on BS kinematics. Methods. Fifteen experienced recreational weightlifters (22 ± 5.4 years; 83 ± 11 kg; 179 ± 6 cm; 5 ± 2.1 years of BS experience) were conveniently selected. three randomized conditions were applied: barefoot (B), 25mm (W25), and 50mm wedges (W50). BS movement was assessed by kinematic analysis with an optoelectronic camera system. Results. After ANOVA, the posthoc indicated significant roM differences in reducing trunk (F = 27.27; p < 0.01) and increasing knee (F = 16.87; p < 0.01) flexions between conditions. Posthoc analysis verified decreasing trunk inclination (B > W25 > W50; p < 0.05) and increasing knee (B < W25 < W50; p < 0.05) roM with increasing wedge height. Conclusions. Higher wedges allowed positive adaptations by promoting a more upright trunk position and greater BS depth. Using a heel wedge can be a lowcost and viable strategy to optimize BS technique in a variety of training settings and contexts.
... A number of biomechanical studies have investigated the effects of manipulating features of the squat exercise to alter muscle activity and kinetic output. These manipulations include changes to foot position (20,25), barbell position (11), stability of the surface on which the exercise is performed (1,9,(16)(17)(18), mode of the resistance (19,25), and depth of movement (5,22). In addition, further biomechanical studies have compared muscle activity and kinetic output of common variations of the squat exercise. ...
Article
The purpose of this study was to compare muscle activity and kinetics during the back squat and overhead squat performed at three relative intensities (60, 75 and 90% 3RM). Fourteen subjects (age: 26 ± 7 yrs, height: 182.5 ± 13.5 cm, body mass: 90.5 ± 17.5 kg) performed each exercise using a within-subjects crossover design. In addition, a selection of trunk isolation exercises were included to provide additional comparisons. Squats were performed on a force platform with electromyographic (EMG) activity of the anterior deltoid (AD), rectus abdominis (RA), external oblique (EO), erector spinae (ES), gluteus maximus (GM), vastus lateralis (VL), biceps femoris (BF), and lateral gastrocnemius (GA) recorded throughout. The overhead squat demonstrated significantly greater (p<0.05) activity in the anterior trunk muscles (RA and EO) during the eccentric phase. However, the magnitudes of the differences were relatively small (∼ 2 to 7%). In contrast, the back squat displayed significantly greater (p<0.05) activity in the posterior aspect of the trunk (ES) and all lower-body muscles during the concentric phase. Kinetic comparisons revealed that significantly greater peak force (p<0.05) was developed during the back squat. EMG comparisons between the trunk isolation exercises and squat variations demonstrated substantially greater anterior trunk activity during the isolation exercises, whereas the highest activity in the posterior aspect of the trunk was obtained during the squats (p<0.05). The results of the study do not support the hypothesis that the overhead squat provides a substantially greater stimulus for developing the trunk musculature compared with the back squat.
... However, the squat for a prolonged period of time can cause excessive patellofemoral forces and stresses, which can cause or even increase patellofemoral pain (Neumann, 2013). 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). ...
... rehabilitation. Several studies have shown that manipulating the amplitude ofthe squat exercise results in altered muscle activity [1][2][3] however, research on pelvic movements in the squat are limited [4]. ...
... fair reliability, 0.70-0.90 good reliability and > 0.9 excellent reliability 30 . Reliability close to one indicates that the measurement is consistent with no big change in trait size between measurements. ...
Article
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The purpose of this study is to compare recreationally physically active females and males with regard to spine, pelvis and lower limb joints peak angles in each plane of motion during a single leg squat (SLS). The second aim is to investigate the relationship between kinematics and SLS depth in females and males. Fifty-eight healthy, young adults performed 5 repetitions of a single right leg squat to maximal depth while keeping their balance. Kinematic data were obtained using an optical motion capture system. At the hip, greater adduction and greater internal rotation were observed in females than in males. Females had more extended spines and less outward bended knees throughout the SLS than did men. In males, squat depth was significantly, positively correlated with the maximal angle of the ankle (r = 0.60, p < 0.001), the knee (r = 0.87, p < 0.001), the hip (r = 0.73, p < 0.001) and the pelvis (r = 0.40, p = 0.02) in the sagittal plane. A positive significant correlation was found between SLS depth and maximal angle of the knee (r = 0.88, p < 0.001) and the ankle (r = 0.53, p = 0.01) in the sagittal plane in females. Males and females used different motor strategies at all levels of the kinematic chain during SLS.
... rehabilitation. Several studies have shown that manipulating the amplitude ofthe squat exercise results in altered muscle activity [1][2][3] however, research on pelvic movements in the squat are limited [4]. ...
Article
Full-text available
Strength training is commonly performed at two different knee flexion amplitudes: partial (to 90 degrees) or total (to 140 degrees). During these amplitudes, both the pelvis and the tibia are moved to ensure control of the center of gravity and displacement of the external overload. Forward or backward movement of the pelvic tilt may indirectly influence the internal load on the spine. Objective: To measure the effect of squat amplitude on pelvictilt and tibia inclination. Eighteen male subjects (age: 26 ± 6 years, height: 178 ± 7 cm, total body mass: 81.3 ± 11 kg, resistance training experience: 5 ± 4 years) were evaluated. Pelvic tilt and tibial inclination were measured by a digital inclinometer (Max Measure, USA, accuracy: ± 0.02°, resolution: 0.05°) during isometric squatting at partial and full amplitudes. The digital inclinometer was fixed on the sacrum and on the tibia, with aneutral spine position. A paired student t-test and a significance of 5% were used. There were significant differences in pelvic tilt between partial and full amplitudes (+ 32.4° ± 10.9 and-21.7° ± 12.3, respectively, P<0.001). Maximum tibial inclination values were not significantly different between partial and total amplitudes (19.1 ± 6.6 and 20.1 ± 7.4, respectively, P = 0.225). It was concluded that the partial squat position produces anterior pelvic tilt while the full squat produces backward pelvic tilt. Inclination of the tibia is similar in both amplitudes of the squat. rehabilitation. Several studies have shown that manipulating the amplitude ofthe squat exercise results in altered muscle activity [1-3] however, research on pelvic movements in the squat are limited [4]. Some research methodologies suggest a correct way to perform the squat [5], but the correct technique is still controversial, with suggestions that the lumbar curve should be maintained throughout the squat [6], where as others suggest avoiding a rounded lumbar spine [7]. For heavy squats [8,9] suggest the squat should be performed to full depth as long asthe lordotic curve is maintained. The alignment of the pelvis is correlated with spine curvature and it has also been found to influence lifting function, withan anterior tilt of thepelvis providing increased trunk muscle activity [10]. The majority of research on squat technique provide no quantified measure or description of the pelvic tilt. Therefore, the purpose of the present study was to measure the effect of squat amplitude on pelvic tilt and tibia inclination. Materials and Methods Participants Eighteen male subjects (age: 26 ± 6 years, height: 178 ± 7 cm, total body mass: 81.3 ± 11 kg, resistance training experience: 5 ± 2 years) were evaluated. Subjects had no previous lower back injury, surgery in the lower extremities, and no history of injury with residual symptoms (pain, " giving-away " sensations) in the lower limbs within the last year. This study was approved by the University research ethics committee and all subjects read and signed an informed consent document (#68/2016). Procedures Subjects were instructed in proper isometric back squat technique for both conditions (partial: at 90° knee flexion, and full: at 140° knee flexion). Knee angle was measured by a goniometer. Their feet were positioned at hip width and vertically aligned with the barbell. The barbell was positioned on the shoulders (high-bar position) and all subjects performed each isometric squat condition three times for 3-s (rest between reps?). During each squat, the degree of pelvic tilt and tibial inclination were measured, and the highest value was used. Pelvic tilt and tibial inclination were measured by a digital inclinometer (Max Measure, USA, accuracy: ± 0.02°, resolution: 0.05°) fixed on the sacrum and on the tibia, at an orthostatic position with a neutral spine. For pelvic tilt, positive values refer to anterior/forward and negative to posterior/backward positions. A rest period of 5-min was provided between conditions. All measures were performed at the same hour of the day, between 5 and 7 PM, and by the same researcher. A paired student t-test and a significance of 5% was
... rehabilitation. Several studies have shown that manipulating the amplitude ofthe squat exercise results in altered muscle activity [1][2][3] however, research on pelvic movements in the squat are limited [4]. ...
Article
Full-text available
Strength training is commonly performed at two different knee flexion amplitudes: partial (to 90 degrees) or total (to 140 degrees). During these amplitudes, both the pelvis and the tibia are moved to ensure control of the center of gravity and displacement of the external overload. Forward or backward movement of the pelvic tilt may indirectly influence the internal load on the spine. Objective: To measure the effect of squat amplitude on pelvictilt and tibia inclination. Eighteen male subjects (age: 26 ± 6 years, height: 178 ± 7 cm, total body mass: 81.3 ± 11 kg, resistance training experience: 5 ± 4 years) were evaluated. Pelvic tilt and tibial inclination were measured by a digital inclinometer (Max Measure, USA, accuracy: ± 0.02°, resolution: 0.05°) during isometric squatting at partial and full amplitudes. The digital inclinometer was fixed on the sacrum and on the tibia, with aneutral spine position. A paired student t-test and a significance of 5% were used. There were significant differences in pelvic tilt between partial and full amplitudes (+ 32.4° ± 10.9 and-21.7° ± 12.3, respectively, P<0.001). Maximum tibial inclination values were not significantly different between partial and total amplitudes (19.1 ± 6.6 and 20.1 ± 7.4, respectively, P = 0.225). It was concluded that the partial squat position produces anterior pelvic tilt while the full squat produces backward pelvic tilt. Inclination of the tibia is similar in both amplitudes of the squat. rehabilitation. Several studies have shown that manipulating the amplitude ofthe squat exercise results in altered muscle activity [1-3] however, research on pelvic movements in the squat are limited [4]. Some research methodologies suggest a correct way to perform the squat [5], but the correct technique is still controversial, with suggestions that the lumbar curve should be maintained throughout the squat [6], where as others suggest avoiding a rounded lumbar spine [7]. For heavy squats [8,9] suggest the squat should be performed to full depth as long asthe lordotic curve is maintained. The alignment of the pelvis is correlated with spine curvature and it has also been found to influence lifting function, withan anterior tilt of thepelvis providing increased trunk muscle activity [10]. The majority of research on squat technique provide no quantified measure or description of the pelvic tilt. Therefore, the purpose of the present study was to measure the effect of squat amplitude on pelvic tilt and tibia inclination. Materials and Methods Participants Eighteen male subjects (age: 26 ± 6 years, height: 178 ± 7 cm, total body mass: 81.3 ± 11 kg, resistance training experience: 5 ± 2 years) were evaluated. Subjects had no previous lower back injury, surgery in the lower extremities, and no history of injury with residual symptoms (pain, " giving-away " sensations) in the lower limbs within the last year. This study was approved by the University research ethics committee and all subjects read and signed an informed consent document (#68/2016). Procedures Subjects were instructed in proper isometric back squat technique for both conditions (partial: at 90° knee flexion, and full: at 140° knee flexion). Knee angle was measured by a goniometer. Their feet were positioned at hip width and vertically aligned with the barbell. The barbell was positioned on the shoulders (high-bar position) and all subjects performed each isometric squat condition three times for 3-s (rest between reps?). During each squat, the degree of pelvic tilt and tibial inclination were measured, and the highest value was used. Pelvic tilt and tibial inclination were measured by a digital inclinometer (Max Measure, USA, accuracy: ± 0.02°, resolution: 0.05°) fixed on the sacrum and on the tibia, at an orthostatic position with a neutral spine. For pelvic tilt, positive values refer to anterior/forward and negative to posterior/backward positions. A rest period of 5-min was provided between conditions. All measures were performed at the same hour of the day, between 5 and 7 PM, and by the same researcher. A paired student t-test and a significance of 5% was
... Taking the calculations of Cappozzo et al. (16) into account, compressive forces acting on the L3-L4 segment may have exceeded 20 times of the body weight. Performing the squat until failure with high loads involves the risk of forward leaning (63) and ventral flexion (68). Ventral flexion causes diminished activity of the m. ...
Article
Es existieren keine Vergleichsstudien über die Auswirkungen eines periodisierten Maximalkrafttrainings in unterschiedlichen Kniebeugevarianten auf das Einer-Wiederholungsmaximum und das isometrische Explosiv- und Maximalkraftvermögen im 120 Grad Kniegelenkwinkel. Ziel war es, im Rahmen von zehnwöchigen Längsschnittstudien mit 23 weiblichen und 36 männlichen Sportstudierenden (24,11 ± 2,88 Jahre) herauszufinden, ob durch eine Steigerung der dynamischen Maximalkraft in der Viertel-Nackenkniebeuge (120 Grad Kniegelenkwinkel) größere Zugewinne der isometrischen Explosiv- und Maximalkraft in Form eines winkelspezifischen Transfereffektes zu erzielen sind als durch erworbene Maximalkraftzunahmen in der tiefen Front- und Nackenkniebeuge. Die beiden Forschungsprojekte führten zu folgenden, für die Sportpraxis relevanten Erkenntnissen: 1. Ein Krafttraining in der Viertel-Nackenkniebeuge hat hochsignifikante Übertragungsverluste auf das isometrische Explosiv- und Maximalkraftvermögen im 120-Grad-Kniegelenkwinkel zur Folge, was die in der Trainingspraxis angenommene Grundidee von überlegenen winkelspezifischen Transfereffekten widerlegt. 2. Zur effektiven Steigerung der dynamischen Maximalkraft der unteren Extremität ist die Durchführung der tiefen Front- oder Nackenkniebeuge erforderlich, da die tieferen Beugepositionen intensivere Spannungsreize für die Hüft- und Beinextensoren bieten als die geringe Bewegungsamplitude der Viertel-Kniebeuge. Gefördert durch das Bundesinstitut für Sportwissenschaft (BISp). Aktenzeichen der Forschungsprojekte des BISp: AZ 070509/2007 und AZ 070510/2008
... Lumbar deviations have been reported between 5.9-22.1° during the back squat in previ-ous investigations (Walsh et al., 2007, McKean et al., 2010). In the current study, the manual long-lever hip abduction MVIC applied in the current study did not exert significant changes in lumbar flexion, lateral flexion, or rotational ROM during the barbell back squat exercise. ...
Article
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Background: Post-activation potentiation (PAP) is a neuromuscular phenomenon that has been shown to augment muscular force generating attributes as well as neural and sensory recruitment. While PAP has demonstrated to acutely enhance muscular performance during high-intensity activities, the effect of PAP on lumbopelvic kinematics under load remains unknown. Objectives: The purpose of this study was to examine the potential PAP effect of a hip abduction maximal voluntary isometric contraction (MVIC) on lumbar motion and power output during the barbell back squat. Methods: Nine resistance-trained men (22.9±2.3 y; 85.0±13.8 kg; 174.3±5.1 cm) performed a set of 5 repetitions of the barbell back squat using 80% one-repetition maximum with and without a hip abduction MVIC prior to performance. Experimental and control trials were randomized and counterbalanced among participants. MVIC was carried out via manual long-lever hip abduction. During the back squat exercise, lumbar motion analysis was performed using wireless motion-sensor technology, and power output was assessed via an accelerometer. Results: No significant differences were observed between trials for lumbar flexion range of motion (ROM) (p=0.32), lumbar flexion maximum deviation (p=0.32), lumbar lateral flexion ROM (p=0.81), lumbar lateral flexion maximum deviation (p=0.98), lumbar rotation maximum deviation (p=0.70), average peak power (p=0.98), or average mean power output (p=0.99) during the squat protocol. Conclusions: Implementation of a manual long-lever hip abduction MVIC prior to the back squat exercise did not significantly alter lumbar motion or augment power output in resistance trained males.
... Relative intra-trial repeatability could be used to evaluate the consistency of the spinal alignment within a training session when performing repetitive repetitions of the squat or deadlift, and hence gain a better understanding of whether lifters perform the exercises in a similar manner across repetitions. To our knowledge, only one previous study has investigated the relative reliability of repeated measures of spinal alignment during squat performance (McKean, Dunn, & Burkett, 2010). In that study, calculation of the intrarater test-retest relative reliability was reported with good (>0.7) to excellent (>0.9) intraclass correlation coefficients (ICC) indicating low intraindividual variability of the lumbar and pelvic movements between repetitions when the squat was performed with 50% of body weight. ...
Article
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The aims of the study were to evaluate the relative and absolute variability of upper (T11-L2) and lower (L2-S2) lumbar spinal alignment in power- and weightlifters during the deadlift and back squat exercises, and to compare this alignment between the two lifting groups. Twenty-four competitive powerlifters (n = 14) and weightlifters (n = 10) performed three repetitions of the deadlift and the back squat exercises using a load equivalent to 70% of their respective one-repetition maximum. The main outcome measures were the three-dimensional lumbar spinal alignment for start position, minimum and maximum angle of their spinal alignment, and range of motion measured using inertial measurement units. Relative intra-trial reliability was calculated using the two-way random model intraclass correlation coefficient (ICC) and absolute reliability with minimal detectable change (MDC). The ICC ranged between 0.69 and 0.99 and the MDC between 1°-8° for the deadlift. Corresponding figures for the squat were 0.78–0.99 and 1°-6°. In all participants during both exercises, spinal adjustments were made in both thoracolumbar and lumbopelvic areas in all three dimensions. In conclusion, when performing three repetitions of the deadlift and the squat, lumbar spinal alignment of the lifters did not change much between repetitions and did not differ significantly between power- and weightlifters.
... Exercise with standing upright, squatting, and bending postures is considered as a core exercise for flexing and extending the hip, knee, and ankle joints to activate a wide range of supporting muscles of the lower trunk [8,9]. Some studies suggest squatting posture training for the lumbar region [10,11]; however, the methods shown in these studies cover insufficient references to the lumbar spine flexion and extension [12,13]. Besides, bending exercises have shown a greater trunk flexion on a decline standing position while an incline standing position triggers a greater trunk extension [13]. ...
Article
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This study investigates changes in lumbar erector spinae (LES) muscle endurance, perceived low-back pain (LBP), and perceived exercise fatigue in older adults, and analyzes the trends of these changes during a 5-week lumbar exercise. Sixteen older adults with LBP were equally and randomly divided into two groups: the experimental group with incline-standing and the control group with the level-standing positions. They were separately treated with lumbar exercise tasks and 10 seconds of muscle endurance tests using surface electromyography (sEMG). There was a trend of changes in both groups. The exercise tasks led to increase LES muscle endurance in the experimental group (53.7%) and the control group (45.4%) and decrease perceived LBP score significantly with the incline-standing position. There was no significant difference between the two groups in perceived exercise fatigue (p>0.05). Trunk flexion and extension with an incline-standing position can be an effective method to increase LES muscle endurance and reduce LBP in older adults.
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The aim of this study was to verify the contribution of "biohealth circuits" for older people to achieve the recommended levels of physical activity. This study examined catalogues from 23 companies who build and distribute exercise equipment for "biohealth circuits". In addition, we analyzed the physical qualities and muscle groups that each equipment exercises, and the extent to which the equipment follows the physical activity guidelines. This study concluded that "biohealth circuits" have the potential to help older adults to achieve the physical activity guidelines. However, they present limitations regarding strength training, since weight cannot be modified, and most machines use only the upper body. This study recommends designing equipment that also exercises balance and flexibility.
Article
Background A neutral spinal alignment is considered important during the execution of the deadlift exercise to decrease the risk of injury. Since male and female powerlifters experience pain in different parts of their backs, it is important to examine whether men and women differ in spinal alignment during the deadlift. Objectives The purpose of this study was to quantify the spinal alignment in the upper (thoracolumbar, T11-L2) and lower (lumbopelvic, L2-S2) lumbar spine during the deadlift exercise in male and female lifters. Secondary aims were to compare lumbar spine alignment during the deadlift to standing habitual posture, and determine whether male and female lifters differ in these aspects. Study Design Observational, Cross-sectional. Methods Twenty-four (14 men, 10 women) lifters performed three repetitions of the deadlift exercise using 70% of their respective one-repetition maximum. Spinal alignment and spinal range of motion were measured using three inertial measurement units placed on the thoracic, lumbar and sacral spine. Data from three different positions were analyzed; habitual posture in standing, and start and stop positions of the deadlift, i.e. bottom and finish position respectively. Results During the deadlift, spinal adjustments were evident in all three planes of movement. From standing habitual posture to the start position the lumbar lordosis decreased 13° in the upper and 20° in the lower lumbar spine. From start position to stop position the total range of motion in the sagittal plane was 11° in the upper and 22° in the lower lumbar spine. The decreased lumbar lordosis from standing habitual posture to the start position was significantly greater among men. Conclusions Men and women adjust their spinal alignment in all three planes of movement when performing a deadlift and men seem to make greater adjustments from their standing habitual posture to start position in the sagittal plane. Level of Evidence 3
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Movement pattern differences may contribute to differential injury or disease prevalence between individuals. The purpose of this study was to identify lower limb movement patterns in high knee flexion, a risk factor for knee osteoarthritis, and to investigate kinematic differences between males and females, as females typically develop knee osteoarthritis more commonly and severely than males. Lower extremity kinematic data were recorded from 110 participants completing 4 variations of squatting and kneeling. Principal component analysis was used to identify principal movements associated with the largest variability in the sample. Across the tasks, similar principal movements emerged at maximal flexion and during transitions. At maximal flexion, females achieved greater knee flexion, facilitated by a wider base of support, which may alter posterior and lateral tibiofemoral stress. Principal movements also detected differences in movement temporality between males and females. When these temporal differences occur due to alterations in movement velocity and/or acceleration, they may elicit changes in muscle activation and knee joint stress. Movement variability identified in the current study provides a framework for potential modifiable factors in high knee flexion, such as foot position, and suggests that kinematic differences between the sexes may contribute to differences in knee osteoarthritis progression.
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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.
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ABSTRACT An effective and often prescribed compound exercise for the lower limb is the squat movement. The purpose of this research was to determine if the leading joint hypothesis exists when squatting, that is one joint creates a dynamic foundation for motion of the entire limb. To contribute to future exercise prescription guidelines the influence of mediolateral and anteroposterior movement, the timing of the knees, and the influence of segment lengths were investigated in 29 subjects from a cross sectional back ground of sport and strength training. Subjects performed two types of squats; unloaded body weight squats and barbell squats with 50% body weight added. The 3D kinematics of the lower limb and torso were assessed with the independent variables of load, stance, phase and gender. The movement of the knees when squatting was found to support the leading joint hypothesis. The knee changed mediolateral and anteroposterior position to accommodate variations in load and stance width. The knee was also found to move past the alignment of the anteroposterior displacement of the knee, did not remain aligned with heel width, direction of the toes or anterior position of the toes. The amount of anteriorposterior displacement of the knee, with respect to the foot, varied between gender and this movement is considered anatomically appropriate and therefore should be encouraged in exercise prescription. Despite the literature, and this current research, generally supporting deep squats and the freedom for the knee to move anterior of the toes, there exists an inappropriate perception in some practical settings to restrict this movement pattern. Based on this research practitioners should allow an athletes' knees move in both mediolateral and anteroposterior direction when squatting and not remain aligned with heel width, direction of the toes, or anterior position of toes. Knee behaviour in squatting appears to be strategic and occurs in a specific order of the timing in the squat movement. Movement anterior of the toes is a normal and required part of the squat movement that should be encouraged where appropriate and when practitioners feel the clients' knees are healthy or normal.
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summary: There are many variations of the squat technique, including stance width, foot positioning, and squat depth. However, research indicates that the optimal squat technique is a wide stance (>= shoulder width) with natural foot positioning, unrestricted movement of the knees, and full depth while the lordotic curve of the lumbar spine is maintained with a forward or upward gaze. (C) 2007 National Strength and Conditioning Association
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Isometric quadriceps exercises are used early in knee rehabilitation. Varying knee or foot position is hypothesized to selectively activate specific quadriceps muscles. This study examined the activities of the vastus medialis oblique, vastus lateralis, and rectus femoris during isometric contractions at 90 degrees, 150 degrees, and 175 degrees knee angles with internally rotated, neutral, and externally rotated foot positions. Subjects performed three perceived maximal isometric contractions at each knee angle/foot position while electromyographic activity (EMG) was collected. Statistical analysis consisted of a three-way repeated measures multiple analysis of variance, with post hoc analysis as was appropriate. Although no significant differences were detected among foot positions for the rectus femoris at 90 degrees, this knee angle produced significantly greater EMG activity for the neutral position compared with 150 degrees or 175 degrees. The 90 degrees angle was also superior to 175 degrees for the externally rotated position. The results for both the vastus medialis and vastus lateralis were similar, with the 90 degrees angle producing greater EMG activity than 175 degrees in the externally rotated position. In addition, the neutral position produced significantly more activity than the internally rotated position at 90 degrees. At 150 degrees, the neutral position was superior to the externally rotated position. Finally, at the 175 degrees knee angle, the highest level of EMG activity was with the foot internally rotated. Considering the combination of effects for EMG activity across all muscles tested, the 90 degrees knee angle with a neutral foot position may provide the most effective condition for rehabilitation of all muscles tested.(ABSTRACT TRUNCATED AT 250 WORDS)
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To determine if vertebral bone densities or vertebral body sizes contribute to gender differences in vertebral bone mass in adults. Cancellous and cortical bone densities and dimensions of three lumbar vertebrae in 25 women and 18 men were measured with quantitative computed tomography (CT) and statistically analyzed. Neither cancellous nor cortical vertebral bone densities differed in healthy adults. Vertebral bodies in women had lower cross-sectional areas (8.22 cm2 +/- 1.09 [standard deviation] versus 10.98 cm2 +/- 1.25, P < .001) and volumes (22.42 cm3 +/- 2.40 versus 30.86 cm3 +/- 2.6, P < .001). These differences also were evident in men and women matched for age, weight, vertebral bone density, and vertebral body height. Overall cross-sectional areas of vertebral bodies are 25% smaller in women than men. Vertebral bone densities do not differ between sexes. Estimates of mechanical stress within vertebral bodies are 30%-40% higher in women than men for equivalent applied loads. Smaller vertebral bodies in women confer biomechanical disadvantages that may contribute to more vertebral fractures in elderly women.
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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.
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The importance of different motion patterns in the assessment of work technique is rarely addressed in the literature and even less information can be found regarding gender differences. In this study the possible gender differences in lifting technique from lifting experiments on 12 female and 10 male participants were examined. The participants performed squat and stoop lifts of a box. Movements were measured by means of opto-electronic measurement systems. Kinematic data derived from the measurements revealed some differences between the men and the women, e.g. in trunk motion and knee angle ranges. The hip-knee interjoint coordination was more synchronized for women than for men in terms of the relative phase angle. It is concluded that so far gender differences in motion patterns have not been sufficiently explored and that men and women need to be considered separately in the evaluation of work technique in manual handling tasks. Advantages and disadvantages of different coordination patterns need to be further investigated.
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Despite the well-recognized role of lifting in back injuries, the relative biomechanical merits of squat versus stoop lifting remain controversial. In vivo kinematics measurements and model studies are combined to estimate trunk muscle forces and internal spinal loads under dynamic squat and stoop lifts with and without load in hands. Measurements were performed on healthy subjects to collect segmental rotations during lifts needed as input data in subsequent model studies. The model accounted for nonlinear properties of the ligamentous spine, wrapping of thoracic extensor muscles to take curved paths in flexion and trunk dynamic characteristics (inertia and damping) while subject to measured kinematics and gravity/external loads. A dynamic kinematics-driven approach was employed accounting for the spinal synergy by simultaneous consideration of passive structures and muscle forces under given posture and loads. Results satisfied kinematics and dynamic equilibrium conditions at all levels and directions. Net moments, muscle forces at different levels, passive (muscle or ligamentous) forces and internal compression/shear forces were larger in stoop lifts than in squat ones. These were due to significantly larger thorax, lumbar and pelvis rotations in stoop lifts. For the relatively slow lifting tasks performed in this study with the lowering and lifting phases each lasting approximately 2 s, the effect of inertia and damping was not, in general, important. Moreover, posterior shift in the position of the external load in stoop lift reaching the same lever arm with respect to the S1 as that in squat lift did not influence the conclusion of this study on the merits of squat lifts over stoop ones. Results, for the tasks considered, advocate squat lifting over stoop lifting as the technique of choice in reducing net moments, muscle forces and internal spinal loads (i.e., moment, compression and shear force).
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Heavy weight lifting using a squat bar is a commonly used athletic training exercise. Previous in vivo motion studies have concentrated on lifting of everyday objects and not on the vastly increased loads that athletes subject themselves to when performing this exercise. Athletes significantly alter their lumbar spinal motion when performing squat lifting at heavy weights. Controlled laboratory study. Forty-eight athletes (28 men, 20 women) performed 6 lifts at 40% maximum, 4 lifts at 60% maximum, and 2 lifts at 80% maximum. The Zebris 3D motion analysis system was used to measure lumbar spine motion. Exercise was performed as a "free" squat and repeated with a weight lifting support belt. Data obtained were analyzed using SAS. A significant decrease (P < .05) was seen in flexion in all groups studied when lifting at 40% maximum compared with lifting at 60% and 80% of maximum lift. Flexion from calibrated 0 point ranged from 24.7 degrees (40% group) to 6.8 degrees (80% group). A significant increase (P < .05) was seen in extension when lifting at 40% maximum was compared with lifting at 60% and 80% maximum lift. Extension from calibrated 0 point ranged from -1.5 degrees (40% group) to -20.3 degrees (80% group). No statistically significant difference was found between motion seen when exercise was performed as a free squat or when lifting using a support belt in any of the groups studied. Weight lifting using a squat bar causes athletes to significantly hyperextend their lumbar spines at heavier weights. The use of a weight lifting support belt does not significantly alter spinal motion during lifting.
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This paper discusses the role of activity modification advice regarding safe squatting methods for low back and knee pain patients. Safe squats for the back involve maintaining mild lumbar lordosis and should not be performed early in the morning or after prolonged sitting. Safe squats for the knees avoid excessive anterior patello-femoral shear and knee valgosity.
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This article reviews the empirical and theoretical bases for recommendations regarding lifting technique. Lifting from postures involving extreme lumbar vertebral flexion, (approximately 60° of lumbar flexion, characterised by absence of electromyographical activity in erector spinae) has the potential to contribute to damage to ligaments and intervertebral discs, especially if combined with lateral flexion or rotation. The only appropriate recommendation regarding posture of the lumbar spine during lifting is to avoid postures involving extreme lumbar vertebral flexion (and rotation and lateral flexion). There is no empirical basis for avoiding postures involving moderate lumbar vertebral flexion, and no justification for advocating lifting from a full squat posture. Further, lifting from semi-squat postures, involving a moderate range of flexion at both knees and trunk, allows a pattern of interjoint coordination which appears to be functional in reducing muscular effort. Lifting training is generally ineffective, and there is unlikely to be a single “best” technique which is appropriate in all situations. Consequently, it may be preferable to provide education in general lifting guidelines and assist lifters to discover individually appropriate postures and patterns of movement. The article concludes by presenting recommendations for lifting technique which are justified by current knowledge.Relevance to industryLifting from a full squat posture is frequently recommended as a means of reducing the likelihood of back injury. This recommendation is not justified, and training of this type should not be provided. Education in the general lifting guidelines provided here may be beneficial.
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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.
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The purpose of this study was to examine the effects of two different alignments of the pelvis and three different loads on electromyographic (EMG) activity of the erector spinae and oblique abdominal muscles during squat lifting and lowering. Each of 15 healthy subjects lifted and lowered loads with the pelvis aligned both in an anterior tilt and in a posterior tilt. Based on total duration, both the lift and the lower were divided into two equal phases. The EMG activity of each muscle was quantified for each half of both the lift and the lower and was normalized to the total EMG produced by the muscle during a maximal voluntary isometric contraction. The results indicate (1) that the EMG activity of the erector spinae muscles was greater when subjects maintained an anterior tilt than when they maintained a posterior tilt; (2) that the EMG activity of the oblique abdominal muscles was greater in the first half of the lift than in the second half for both lifting styles, although the opposite was true for both lowering styles; and (3) that the EMG activity increased with increasing loads. The results suggest that the greater trunk muscle activity occurring with the anterior tilt position may ensure optimal muscular support for the spine while handling loads, thereby reducing the risk for low back injury.
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In order to determine the effect of loads worn or carried on walking mechanics, 11 men and 11 women were filmed using high speed cinematography as they performed overground walking at 1·78 m/s under five load conditions. The loads included a baseline condition in which subjects carried no added load, and additional loads of approximately 9, 17, 29 and 36 kg consisting of standard military items. The latter two loads were added in the form of a framed rucksack system. Values for several variables frequently used to described temporal and kinematic characteristics of walking were quantified from the film. These included stride length, stride rate, single leg support time, double-support time, swing time and the forward inclination of the trunk. The results of the study demonstrated that the males and females displayed significantly different gait patterns under all load conditions. Not unexpectedly, the females required a higher rate of stepping than the males because of their shorter stride lengths. The results also demonstrated that the walking patterns of both the male and female subjects were affected by the increases in carried load. In general, stride length and swing time decreased while stride rate and double-support time increased with increases in load. There was also an increased forward inclination of the trunk but only for the two heaviest loads which were carried in a rucksack. While the changes in gait characteristics were relatively small for the male subjects, the females were affected to a greater extent thereby demonstrating a greater sensitivity to load magnitude. It was concluded that careful consideration must be given to the absolute loads carried by males and females. Not only is it important for load requirements to be lower for females because of the physiological implications but also because of biomechanical implications and the associated mechanical stresses which must be endured during locomotion. While this study was directed primarily towards military applications, the results should also have implications for load carrying in a variety of situations and environments, including industrial and recreational applications.
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The data which are usually quoted on normal ranges of joint mobility are not based on information from population surveys. In order to remedy this, sex and side standardized measurements were obtained in 2 populations, one in Sweden and one in Iceland. These populations included 517 females and 203 males with an age span of 33 to 70 yr. Special instruments were built and shown to measure reliably well defined parts of movement in the shoulders, wrist, metacarpophalangeal joint I (MCP), and hip. Mobility of joints was found to be influenced by age, sex and side. Females had greater joint mobility than males. These differences might be explained by initial biological variation, differences in pain threshold and the cumulative damage caused by micro and macro traumata. The MCP I joint showed the greatest biological variation and was not subject to the same reduction of mobility with age as the other 3 joints. Some ethnic differences were found in wrist mobility but these await further investigation.
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The femoral head is significantly smaller for females than for males in relation to the dimensions of the pelvis. This may result in an increased stress level in the hip joint of females. This difference in the geometrical properties is more distinct than the difference in the width to height ratio of the pelvis reported in the literature. It may be used to discriminate female from male skeletons.
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Eight Swedish national class weightlifters performed "high-bar" squats and six national class powerlifters performed "low-bar" squats, with a barbell weight of 65% of their 1 RM, and to parallel- and a deep-squatting depth. Ground reaction forces were measured with a Kistler piezo-electric force platform and motion was analyzed from a video record of the squats. A computer program based on free-body mechanics was designed to calculate moments of force about the hip and knee joints. EMG from vastus lateralis, rectus femoris, and biceps femoris was recorded and normalized. The peak moments of force were flexing both for the hip and the knee. The mean peak moments of force at the hip were for the weightlifters 230 Nm (deep) and 216 Nm (parallel), and for the powerlifters 324 Nm (deep), and 309 Nm (parallel). At the knee the mean peak moments for the weightlifters were 191 Nm (deep) and 131 Nm (parallel), and for the powerlifters 139 Nm (deep) and 92 Nm (parallel). The weightlifters had the load more equally distributed between hip and knee, whereas the powerlifters put relatively more load on the hip joint. The thigh muscular activity was slightly higher for the powerlifters.
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Develop a gender specific database of trunk muscle cross-sectional areas across multiple levels of the thoracic and lumbar spine and develop prediction equations for the physiological cross-sectional area as a function of gender and anthropometry. This study quantified trunk muscle cross-sectional areas of male and female spine loading muscles. There is a lack of comprehensive data regarding the female spine loading muscle size. Although biomechanical models often assume females are the same as males, little is known regarding gender differences in terms of trunk muscle areas and no data exist regarding the prediction of trunk muscle physiological cross-sectional areas from commonly used external anthropometric measures. Magnetic resonance imaging scans through the vertebral bodies from T(8) through S(1) were performed on 20 females and 10 males. Muscle fiber angle corrected cross-sectional areas were recorded at each vertebral level. Linear regression techniques taking into account anthropometric measures were utilized to develop prediction equations for the physiological cross-sectional area for each muscle of interest, as well as tests for differences in cross-sectional areas due to gender and side of the body. Significant gender differences were observed for the prediction of the erector spinae, internal and external obliques, psoas major and quadratus lumborum physiological cross-sectional areas. Anthropometric measures about the xyphoid process and combinations of height and weight resulted in better predictions of cross-sectional areas than when using traditional anthropometry. This study demonstrates that the trunk muscle geometry of females and males are different, and that these differences should be considered in the development of biomechanical models of the torso. Relevance. The prediction of physiological cross-sectional areas from external anthropometric measures provide gender specific equations to assist in estimation of forces of muscles which load the spine for biomechanical purposes.
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The purpose of this study was to quantify biomechanical parameters employing two-dimensional (2-D) and three-dimensional (3-D) analyses while performing the squat with varying stance widths. Two 60-Hz cameras recorded 39 lifters during a national powerlifting championship. Stance width was normalized by shoulder width (SW), and three stance groups were defined: 1) narrow stance squat (NS), 107 +/- 10% SW; 2) medium stance squat (MS), 142 +/- 12% SW; and 3) wide stance squat (WS), 169 +/- 12% SW. Most biomechanical differences among the three stance groups and between 2-D and 3-D analyses occurred between the NS and WS. Compared with the NS at 45 degrees and 90 degrees knee flexion angle (KF), the hips flexed 6-11 degrees more and the thighs were 7-12 degrees more horizontal during the MS and WS. Compared with the NS at 90 degrees and maximum KF, the shanks were 5-9 degrees more vertical and the feet were turned out 6 degrees more during the WS. No significant differences occurred in trunk positions. Hip and thigh angles were 3-13 degrees less in 2-D compared with 3-D analyses. Ankle plantar flexor (10-51 N.m), knee extensor (359-573 N.m), and hip extensor (275-577 N.m) net muscle moments were generated for the NS, whereas ankle dorsiflexor (34-284 N.m), knee extensor (447-756 N.m), and hip extensor (382-628 N.m) net muscle moments were generated for the MS and WS. Significant differences in ankle and knee moment arms between 2-D and 3-D analyses were 7-9 cm during the NS, 12-14 cm during the MS, and 16-18 cm during the WS. Ankle plantar flexor net muscle moments were generated during the NS, ankle dorsiflexor net muscle moments were produced during the MS and WS, and knee and hip moments were greater during the WS compared with the NS. A 3-D biomechanical analysis of the squat is more accurate than a 2-D biomechanical analysis, especially during the WS.
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The specific aim of this project was to quantify knee forces and muscle activity while performing squat and leg press exercises with technique variations. Ten experienced male lifters performed the squat, a high foot placement leg press (LPH), and a low foot placement leg press (LPL) employing a wide stance (WS), narrow stance (NS), and two foot angle positions (feet straight and feet turned out 30 degrees ). No differences were found in muscle activity or knee forces between foot angle variations. The squat generated greater quadriceps and hamstrings activity than the LPH and LPL, the WS-LPH generated greater hamstrings activity than the NS-LPH, whereas the NS squat produced greater gastrocnemius activity than the WS squat. No ACL forces were produced for any exercise variation. Tibiofemoral (TF) compressive forces, PCL tensile forces, and patellofemoral (PF) compressive forces were generally greater in the squat than the LPH and LPL, and there were no differences in knee forces between the LPH and LPL. For all exercises, the WS generated greater PCL tensile forces than the NS, the NS produced greater TF and PF compressive forces than the WS during the LPH and LPL, whereas the WS generated greater TF and PF compressive forces than the NS during the squat. For all exercises, muscle activity and knee forces were generally greater in the knee extending phase than the knee flexing phase. The greater muscle activity and knee forces in the squat compared with the LPL and LPH implies the squat may be more effective in muscle development but should be used cautiously in those with PCL and PF disorders, especially at greater knee flexion angles. Because all forces increased with knee flexion, training within the functional 0-50 degrees range may be efficacious for those whose goal is to minimize knee forces. The lack of ACL forces implies that all exercises may be effective during ACL rehabilitation.
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Prospective trial. To test an intraoperative diagnostic tool to determine if it provided the surgeon with a safe, reproducible, accurate, quantitative measure of lumbar spine motion segment stability. Several devices have been developed to measure motion segment stiffness, however, few have been tested intraoperatively on humans, and none, to the best of the authors' knowledge have been tested as extensively as the device described in this study. Objective criteria, such as those provided by an intraoperative gauge, can be helpful in determining when and what type of fusion of a degenerated spinal motion segment unit should be performed following decompressive surgery. The spinal stiffness gauge, placed between spinous processes of adjacent vertebrae, applies a controlled, constant loading rate along the spine's longitudinal axis, producing a load-displacement curve from which stiffness, range of motion, and hysteresis can be computed. Measurements from this tool were then used to investigate differences in stiffness of the motion segment before and after decompressive surgery, between spine levels, and between male and female subjects. The spinal stiffness gauge stiffness measurements correlated with the surgeon's subjective stiffness measurements on the same motion segments. The stiffness measurements had excellent repeatability. Stiffness was dependent on the spine level, gender, and degree of disc degeneration. This study demonstrated the efficacy of the spinal stiffness gauge for providing an objective, quantitative, intraoperative stiffness (stability) measurement of the lumbar spine motion segment.
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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.
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A biomechanical model of a squat exercise performed on a device using a bar that is restricted to a linear motion was developed. Hip and knee moments were evaluated at varying foot positions. The range of motion of the exercise was limited by the knee joint angle beginning at an 80 degrees angle (flexed) to a 179 degrees joint angle (extended). Variations in foot placement were evaluated for differences in torque applied about the transverse axes of the user's knee and hip joints. Because the user's feet were positioned farther forward (anterior), the moment about the knee decreased whereas the moment about the hip increased. Positive moments were those that resulted in forces to flex the knee and hip joints. Positive knee moments were determined in all conditions when the knee was flexed and became negative when the knee was at or near full extension. The model always produced positive moments about the hip. Thus, foot position is a critical factor in hip and knee moments, and therefore in the muscle groups stressed, in a linear motion squat type exercise.