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An electromyographic analysis of sumo and conventional style deadlifts
... The dummy drag assessment has recruits squat down, wrap their arms around a supine 56-75 kg weighted mannequin, and then drag said mannequin 9-18 m. The dummy drag places a high amount of stress on the spinal erectors like that of traditional hip hinge exercises such as the deadlift [13,[22][23][24]. ...
... The hip hinge demands a high degree of activity from the spinal erectors and supportive roles for the hamstrings, abdominals, and gluteal muscles [22][23][24][25]. Depending on load and stance, the hip hinge's activity in the erector spinae from T10-L3 will be 88-98% of MVIC [24] and 24-100% of MVIC in the semimembranosus and semitendinosus [22,23], 60% of MVIC in the rectus abdominus [23], and 35-37% of MVIC in the gluteus maximus [23]. ...
... However, load carriage has been shown to effect muscle activity in the erector spinae for less strenuous tasks such as incline walking [56] and in the rectus abdominus and multifidus during standing [57]. Therefore, one potential explanation is that the intensity of the physical activity was such that any small changes produced by the 7.2 kg vest or the 7.2 kg LEO DB were masked by the magnitude of the activity from the hinging activities [22,58], meaning that the small sEMG signal change produced by the vest or LEO DB was insignificant compared to the larger signal change produced by the hip hinge task demands. ...
Sixty percent of all law enforcement officers (LEOs) experience low back pain (LBP), with the LEO duty belt (LEODB) commonly reported to be a contributing factor. The primary purpose of the study was to investigate the LEODB’s effect on muscular activity and compare it to a tactical vest, which is a commonly used alternative to an LEODB. In total, 24 participants (13 male, 11 female; mass, 73.0 ± 11.1 kg; height, 169.0 ± 10.0 cm; age, 24.0 ± 5.8 years) completed a progressive series of hip hinge tasks in a single testing session. All participants completed four conditions (no belt, leather belt, nylon belt, and weight VEST) in a randomized order. Surface electromyography (sEMG) sensors were placed bilaterally on the rectus abdominus, multifidus, biceps femoris, and rectus femoris. Across all tasks, no significant effects of load on muscle activity were found for any of the muscles. Participants rated the VEST condition as more comfortable (p < 0.05) and less restrictive (p < 0.05) than either LEODB. The findings suggest an LEODB does not alter muscle activity during bodyweight hip hinging or lifting objects from the ground. Future research should examine whether changes in muscle activity occur with durations of LEODB wear more similar to an actual work shift duration for LEOs (≥8 h).
... Some authors [7,8] propose that there are three main positions during the DL: (1) lift-off when force is applied to the bar to pull it from the floor; (2) mid-pull, when the bar is located immediately above the knees; and (3) lockout, when the lifter's trunk reaches the vertical position, with the bar positioned at its highest point during the DL. Other authors investigated DL performance in these positions [9][10][11] and there is a consensus that mid-pull is the most challenging DL position. The greatest force values assessed during DL are observed at the mid-pull position, with the same group later suggesting that this might be due to participants feeling more comfortable in this position [12]. ...
... A recent systematic review investigating electromyographic (EMG) records points out that the BF is the most frequently investigated muscle during DL, followed by the gluteus maximus (GLU), vastus lateralis (VL), and the ERE [12]. The semitendinous (ST) and RF follow-up, with the vastus medialis (VM), external oblique (EO), gastrocnemius medialis (GM), and lateralis (GAL) [10] also being frequently investigated. A study [10] compared muscle activation between two variations of DL exercise (conventional vs. sumo) with knee joint angles ranging between 30 • and 90 • . ...
... The semitendinous (ST) and RF follow-up, with the vastus medialis (VM), external oblique (EO), gastrocnemius medialis (GM), and lateralis (GAL) [10] also being frequently investigated. A study [10] compared muscle activation between two variations of DL exercise (conventional vs. sumo) with knee joint angles ranging between 30 • and 90 • . It was found that the activations of quadriceps and ERE muscles were greater when the knee joint was more flexed, while hamstring and gastrocnemii muscles were most activated as the knee flexion angle decreased during the eccentric phase [13]. ...
The aim of the study was to analyze muscle activation in the three positions of the deadlift (DL). Twenty male participants (33.4 ± 3.9 years; 42.2 ± 9.1 months of experience with DL; 91.0 ± 14.8 kg; and 1.78 ± 0.06 m) pulled a bar through isometric actions in three DL positions: lift-off, mid-pull, and lockout. Isometric strength, knee angle, and activation of the rectus femoris (RF), biceps femoris (BF), lateral gastrocnemius (GAL), and erector spinae (ERE) muscles were collected. The analysis of variance showed that the maximum isometric force presented differences between the positions (p = 0.001; η2 = 0.973) considered large with higher values at the mid-pull position. Interactions were found between muscles and position (p = 0.001; η2 = 0.527) considered large. The RF and ERE showed greater activation in the lift-off position, while in the mid-pull position, there was greater activation of the BF and GAL muscles. The DL positions produce different activations in the bi-articular and uni-articular muscles. The lift-off requires more activation from the RF and ERE positions. The mid-pull position, despite generating greater force, presented greater activations in the BF and GAL. The ERE showed higher activations as the external torque was greater.
... In particular, back squats (BSQ) have been used in practice, and many studies have reported satisfactory results [1][2][3][4][5][6][7][8], such as improved jumping [1,6], acceleration [3], and change of direction [4]. In contrast, deadlift (DL), which has similar core exercise as BSQ, has limited scientific evidence on its training effects compared to that of the BSQ [9][10][11]. Presently, there is only one study that reported the training effects of DL [11]. ...
... In terms of movement, DL prioritizes knee extension at the beginning, followed by hip extension, and finally reaching a standing position by extending both the hip and knee joints [12]. The quadriceps femoris, gluteus maximus, hamstrings, and gastrocnemius muscles are recruited during DL [10]. In contrast, BSQ extends the knee and hip joints simultaneously [12]. ...
... Furthermore, the moderate ES observed in the BSQ group for hip extension maximum moment/BW may have been influenced by the 90 • knee joint posture maintained during the isokinetic hip extension strength test, whereby the hip extension movement was greatly affected by the activity of the gluteus maximus muscles because the knee joint at 90 • relaxes the hamstrings of the bicipital muscles. This hypothesis is supported by studies reporting that BSQ is more likely to recruit the gluteus maximus [2], whereas DL is more likely to recruit both the gluteus maximus and hamstrings [10]. Therefore, the moderate ES for hip extension maximum moment/BW in the BSQ group may be attributed to the hip extension of the gluteus maximus muscle. ...
BACKGROUND: An advantage that deadlift (DL) has over back squat (BSQ) is that the latter requires additional equipment (i.e., squat rack). Accordingly, if DL can lead to positive effects on jumping, acceleration, and change of direction, DL could present as a more practical training exercise than that of BSQ. OBJECTIVE: This study aimed to compare the effects of DL and BSQ on jumping, acceleration, and change of direction. METHODS: Twenty-three men (12 in the DL group [age: 20.3 ± 1.4 years old, height: 169.6 ± 6.7 cm, body weight: 65.7 ± 11.2 kg] and 11 in the BSQ group [age: 20.2 ± 1.9 years old, height: 171.5 ± 4.8 cm, body weight: 70.1 ± 6.8 kg]) participated in this study. The participants performed five repetitions maximum (RM) of DL and BSQ, and the isokinetic strength of hip joint extension, muscle thickness of the gluteus maximus and hamstrings, countermovement jump (CMJ) height, 10 m sprint time, and T-test results were measured. The 1RM was estimated using the 5RM and normalized to body weight (BW). Both groups performed supervised DL and BSQ training for eight sessions. RESULTS: There were significant improvements on 1RM DL/BW (p< 0.01), 1RM BSQ/BW (p< 0.01), and 10 m sprint (p< 0.01) in the two groups. The effect sizes (d) of the DL and BSQ groups were 2.01 and 1.04 for 1RM DL/BW, 1.08 and 2.08 for 1RM BSQ/BW, 0.35 and 0.11 for CMJ height, and -0.94 and -0.54 for 10 m sprint, respectively. CONCLUSIONS: DL training might improve jumping and acceleration compared to those of BSQ training.
... Five repetitions per exercise were recorded electromyographically (18). Through the use of acoustic timer signals (Gymboss® Interval-Timer), the controlled execution of the concentric/eccentric movement phase and pause between repetitions was normalized to four seconds per repetition (13,21). This procedure was deliberately chosen to ensure a higher comparability of the integrated EMG signals, as the IEMG shows a more reliable relationship to produced force (32). ...
... This procedure was deliberately chosen to ensure a higher comparability of the integrated EMG signals, as the IEMG shows a more reliable relationship to produced force (32). A pause of approximately two seconds was inserted between the repetitions to separate the EMG data of the individual repetitions (13). The measurements were performed barefoot to exclude any potential influences of different footwear (2,34). ...
... 191 Following both measurements, the maximal-voluntary-isometric-contraction (MVIC) test was performed after a 5-minute rest period to normalize the recorded EMG data. The MVIC tests were carried out after testing, as in the previous EMG DL studies (1,12,13), because participants were warmed up but not fatigued. For each muscle, two MVIC tests with one-minute rest intervals were performed in randomized order to minimize errors due to accumulated fatigue (21). ...
The purpose of the study was to compare the normalized-electromyographic (NEMG) activity of the gluteus maximus (GMAX), gluteus medius (GMED), biceps femoris (BF) and erector spinae (ES) muscles during the single-leg deadlift (SLDL) and the conventional-deadlift (DL). Additionally, a potential influence of body height on the NEMG activity was examined. Fifteen training-experienced male subjects completed the study. SLDL showed significantly higher average concentric NEMG values of the GMED (77.6% vs. 59.3% [p = 0.002, ES = 1.0]) and BF (82.1% vs. 74.2% [p = 0.041, ES = 0.6]). Significantly lower NEMG levels were found only in the left strand of the ES muscle (67.2% vs. 82.7% [p = 0.004, ES = 0.9]). A significant influence of body height on EMG activity was also observed for all muscles, with the exception of the GMED, during the SLDL. Body height correlated negatively with the concentric EMG activity of the ES (r =-0.54 to-0.58), the BF (r =-0.63) and the GMAX (r =-0.85). In the DL there was a negative correlation only in the BF (r =-0.59) and the GMAX (r =-0.7). This means that subjects with a lower body height showed a higher NEMG activity in corresponding muscles. The results of this study indicate that the SLDL is preferable to the DL in training the BF, and GMED. In addition, coaches should be aware that athletes body height can influence the extent to which the respective muscles are activated.
... After carefully reading the selected articles five deadlift variations were selected for the analysis by agreement between the authors. The five deadlift variations included were (see Figure 2): VOLUME 15 | Proc4 | 2020 | S1265 -Conventional deadlift (12 studies): Stance width should be minor than shoulder-width, feet are close to the centre of the bar, hands are holding the bar per outside the legs (Escamilla et al., 2002). -Straight legs deadlift (6 studies): The same stance as the Romanian deadlift, yet the knees are fully extended. ...
... -Sumo deadlift (1 studies): Wider stance than the conventional deadlift. Stance width is major than shoulder-width (Escamilla et al., 2002). ...
... Several studies found the greater activation on the vastus lateralis or even the vastus medialis (Bezerra et al., 2013;Camara et al., 2016;Escamilla et al., 2002;Korak et al., 2018;Nijem et al., 2016;Robbins, 2011;Snyder et al., 2017). Only Fauth et al. (2010) found greater activation on the gluteus maximus compared to the vastus medialis. ...
The deadlift is one of the most widely used resistance exercises by different types of trainees and with different aims including aesthetics, performance and health. There are numerous variations of the deadlift exercise which have different effects on the exercise biomechanics and muscular activation. The main objective of this research was to systematically review the literature looking forward to gathering data on the muscular activation on the lower limbs with different variations of the deadlift exercise (conventional, sumo, Romanian, straight legs and hex-bar). 19 articles met the inclusion criteria and were included in the analysis. Quality of the articles was assessed through the PEDro scale. Main findings were that deadlift is a posterior-chain dominant exercise. Changes in activation between the variations majorly depend on the hip flexion in relation to the knee flexion. For instance, the straight-legs deadlift does not involve knee flexion and mainly activates hip extensors. Other factors such as the distance between the load and the centre of mass, the knee flexion planes, or the total intensity also condition the muscular activation. For example, the hex-bar deadlift allows the subject being in alignment with the load and performing the exercise with relatively vertical back, which provokes an increase on the activation of the knee extensors. In conclusion, this study may help the strength and conditioning professionals and practitioners with the exercise selection depending on the muscular targets and the individual characteristics of the athlete.
Keywords: Electromyographic activity; Resistance exercise; Quadriceps; Gluteus; Hamstrings; Calves.
... In addition to its use in competitive athletics and recreational training, the deadlift is a valuable tool used in postoperative and nonsurgical rehabilitation protocols (1). The exercise has been shown to be beneficial for reducing the risk of anterior cruciate ligament (ACL) injury and reducing low back pain (5). ...
... Choosing which specific exercise to use will depend on several factors, including muscle involvement, anthropometrics, and comfort. Muscle recruitment and development is essential for determining which exercise to choose (5). All variations of the deadlift recruit the following primary muscle groups to varying degrees: ...
... However, the conventional and sumo deadlift exercises additionally recruit the quadriceps musculature (i.e., rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius) (8). Electromyographic data have shown that there is greater quadriceps activity via the vasti muscles during the sumo deadlift compared with the conventional (5). Closed chain exercises (e.g., the deadlift and back squat) elicit moderate to high co-contraction from knee musculature and have been shown to minimize ACL strain (5). ...
Apply It!
From this article, the reader should:
• Understand what the deadlift exercise is and how it can be beneficial for anyone going through a resistance training program;
• Gain foundational knowledge about the similarities and differences between deadlift exercise variations;
• Be able to avoid the common errors associated with the deadlift exercises in order to stay safe and injury-free; and
• Know how to determine which deadlift exercise variation is best for a particular individual.
... The deadlift is an exercise that is often included in athlete strength and conditioning programs [1][2][3]. Traditionally the deadlift has been performed using a conventional barbell (conventional barbell deadlift: CBD) and the main deadlift variations have come in the form of the technique used to perform the lift, with lifters applying a conventional (hands gripping the barbell outside of the legs) or sumo (hands gripping the barbell between the legs) [2], in addition to different loading strategies [3,4]. The introduction of the hexagonal barbell provided one of the most common deadlift variations used by strength and conditioning coaches for their athletes; however there is a paucity of research on the effect its use has on the mechanical demands of the deadlift [1,3] (hexagonal barbell deadlift: HBD). ...
... The deadlift is an exercise that is often included in athlete strength and conditioning programs [1][2][3]. Traditionally the deadlift has been performed using a conventional barbell (conventional barbell deadlift: CBD) and the main deadlift variations have come in the form of the technique used to perform the lift, with lifters applying a conventional (hands gripping the barbell outside of the legs) or sumo (hands gripping the barbell between the legs) [2], in addition to different loading strategies [3,4]. The introduction of the hexagonal barbell provided one of the most common deadlift variations used by strength and conditioning coaches for their athletes; however there is a paucity of research on the effect its use has on the mechanical demands of the deadlift [1,3] (hexagonal barbell deadlift: HBD). ...
... In the second session, participants performed the CBD, lifting a load of 90% CBD 1RM. In powerlifting competition, lifters are given three attempts to maximize the amount of weight they can lift, and so participants performed three single lift repetitions in total (3 × 1 repetition) with a minimum of 2 min rest between each, with more rest taken if participants felt it was necessary to produce maximal performance [2]. In session three, participants repeated the process performed during the second session with the HBD. ...
This study compared typical mechanical variables of interest obtained directly from barbell motion during deadlift performance with a conventional (CBD) and a hexagonal barbell (HBD). Eleven men, proficient with both deadlift variations, volunteered to participate in the study (age: 20.3 ± 0.6 years; height: 175.5 ± 8.5 m; mass: 88.7 ± 19.0 kg; CBD 1RM: 183 ± 22 kg; HBD 1RM: 194 ± 20 kg). During the first session, CBD and HBD 1RM was assessed; during the second session, they performed 3 sets of 1 CBD repetition with 90% 1RM; and in session three, they repeated this process with the HBD. Barbell displacement was recorded at 1000 Hz and mechanical parameters derived from this. Significantly heavier loads were lifted during HBD (6%, p = 0.003). There were no significant differences between barbell displacement (p = 0.216). However, HBD was performed significantly faster (15%, p = 0.012), HBD load was accelerated for significantly longer (36%, p = 0.004), and significantly larger mean forces underpinned this (6%, p < 0.001), with more work having been performed (7%, p < 0.001) at greater power outputs (28%, p < 0.001). The results of this study showed that heavier HBD loads can be lifted through the same range of motion faster, and that this load is accelerated for significantly longer. The strategies used to achieve these differences could have a significant effect on training outcomes.
... Twenty-one studies assessed EMG of muscles while using LSO [7,8,12,[25][26][27][28][29][30][31][32][33][34][35][36][38][39][40]47,48,51]. The most frequently evaluated muscles included erector spinae (ES), external oblique (EO), and rectus abdominis (RA). ...
... Kawaguchi et al. [51] reported a decrease in RA activity. In the study by Escamilla et al. [27], there was a reduction in the EO activity and an increase in RA activity. Kurustien et al. [29] demonstrated a decrease in transversus abdominisinternal oblique (TrA-IO) activity in resting position (quiet stance) and an increase in RA activity during lifting movements. ...
... This indicates that the belt works as a resistance against the contraction of RA muscle; this muscle must therefore contract more than usual to shorten and move anteriorly in the presence of a belt [40]. This mechanism is mentioned as the possible reason for an increase in RA activity and agrees with results obtained in the studies of Escamilla et al. [27], Kurustien et al. [29], and Lee and Kang [34]. However, other studies reported a reduction or no change in the activity of abdominal muscles. ...
Background:
Wearing lumbosacral orthosis (LSO) is one of the most common treatments prescribed for conservative management of low back pain. Although the results of randomized controlled trials suggest effectiveness of LSO in reducing pain and disability in these patients, there is a concern that prolonged use of LSO may lead to trunk muscle weakness and atrophy.
Purpose:
The present review aimed to evaluate available evidence in literature to determine whether LSO results in trunk muscle weakness or atrophy.
Study design:
This is a systematic review.
Methods:
A systematic search of electronic databases including PubMed, Scopus, ScienceDirect, and Medline (via Ovid) followed by hand search of journals was performed. Prospective studies published in peer-reviewed journals, with full text available in English, investigating the effect of lumbar orthosis on trunk muscle activity, muscle thickness, strength or endurance, spinal force, and intra-abdominal pressure in healthy subjects or in patients with low back pain, were included. Methodological quality of selected studies was assessed by using the modified version of Downs and Black checklist. This research had no funding source, and the authors declare no conflicts of interest-associated biases.
Results:
Thirty-five studies fulfilled the eligibility criteria. The mean and standard deviation of the quality score was 64±9.7%. Most studies investigating the effect of lumbar orthosis on electromyographic activity (EMG) of trunk muscles demonstrated a decrease or no change in the EMG parameters. A few studies reported increased muscle activity. Lumbosacral orthosis was found to have no effect on muscle strength in some studies, whereas other studies demonstrated increased muscle strength. Only one study, which included ultrasound assessment of trunk muscle stabilizers, suggested reduced thickness of the abdominal muscles and reduced cross-sectional area of the multifidus muscles. Out of eight studies that investigated spinal compression load, the load was reduced in four studies and unchanged in three studies. One study showed that only elastic belts reduced compression force compared to leather and fabric belts and ascribed this reduction to the elastic property of the lumbar support.
Conclusion:
The present review showed that the changes in outcome measures associated with muscle work demands were inconsistent in their relation to the use of lumbar supports. This review did not find conclusive scientific evidence to suggest that orthosis results in trunk muscle weakness.
... The deadlift (DL), a resistance training exercise performed with a barbell, covers all these aspects and aims at increasing strength. 9,13,15,17,25 Studies on people without back pain have shown that both local and global stabilizing muscles are activated in this exercise, 13,17,25 and that the DL activates the stabilizing muscles to a greater extent than exercises performed on a gym ball. 25 In a pilot study, 18 this exercise was also shown to be effective in decreasing pain and disability in patients with LBP. ...
... The deadlift (DL), a resistance training exercise performed with a barbell, covers all these aspects and aims at increasing strength. 9,13,15,17,25 Studies on people without back pain have shown that both local and global stabilizing muscles are activated in this exercise, 13,17,25 and that the DL activates the stabilizing muscles to a greater extent than exercises performed on a gym ball. 25 In a pilot study, 18 this exercise was also shown to be effective in decreasing pain and disability in patients with LBP. ...
... To represent an HLL exercise, we chose the DL exercise, which activates the stabilizing muscles and focuses on maintenance of an optimal alignment of the spine during the lift. 13,17,25 The physical therapist selected appropriate initial weight on the bar, based on the anamnesis and findings in the physical examination. The physical therapist taught the participants an optimal lifting technique and ensured that the participants maintained a neutral alignment of the spine when performing the exercise. ...
... Deadlifts and their variations are widely used in strength and conditioning programs for an array of applications and appear in most phases of a periodisation cycle with varying intensities and techniques (6). Currently it is understood that when performed with proper technique, the deadlift utilises the posterior contralateral slings (a kinetic chain that links the latissimus dorsi through the thoracolumbar fascia to the opposite gluteus maximus and hamstrings) which provides optimised force transfer from the upper limbs, through the trunk to the lower extremities (6,10). ...
... Deadlifts and their variations are widely used in strength and conditioning programs for an array of applications and appear in most phases of a periodisation cycle with varying intensities and techniques (6). Currently it is understood that when performed with proper technique, the deadlift utilises the posterior contralateral slings (a kinetic chain that links the latissimus dorsi through the thoracolumbar fascia to the opposite gluteus maximus and hamstrings) which provides optimised force transfer from the upper limbs, through the trunk to the lower extremities (6,10). Due to this, it can be argued that training this movement may be useful, not only for sporting applications, but as an effective rehabilitation tool. ...
... Decreased shear force on the lumbar spine (8% reduction) (2) compared to conventional deadlifting. Develop strength in quadriceps, hamstrings and gluteals to lift heavy loads (6). ...
The sumo deadlift is an exercise becoming increasingly popular in the strength and conditioning environment, both for improving physical performance and as a potential rehabilitation tool. Its uses for performance and rehabilitation are primarily due to the high level of musculature recruited to perform the movement and the decreased shearing forces placed on the spine. This article provides a detailed outline of the sumo deadlift, optimal technique, variations, its role in athletic performance and rehabilitation, and the prescription of this exercise.
... It is frequently used for general strength and conditioning preparation in a variety of sports as well as in rehabilitation, and with the greatest specificity in the competitive sports of weightlifting and powerlifting. Notwithstanding significant biomechanical differences between different execution styles (based on the width of the stance [44], bar placement [45], and the orientation of the knee flexion planes [46], to name just a few), all variants of the squat involve synergistic hip and knee flexion in the descent to the desired depth, followed by knee and hip extension in the ascent which terminates with the lifter in the starting position [47,48]. This makes the squat an exercise primarily aimed at training the muscles of the lower body, specifically the quadriceps femoris, rectus femoris, hip extensors, adductors, and abductors [49], though many more muscles are involved in various supporting roles such as stabilisation and balance [50]. ...
... Though the difference may in part be a normative one, it is generally recognised that the style in which the deadlift is performed exhibits less variation than for the squat [60], the two most prominent being the so-called conventional style and the sumo style [60]. The former is characterised by a narrower stance (approximately shoulder width) and the feet in 10-15°of external rotation [47], and the latter by a 2-3 times wider stance and the feet in 40-45°of external rotation [47]. ...
... Though the difference may in part be a normative one, it is generally recognised that the style in which the deadlift is performed exhibits less variation than for the squat [60], the two most prominent being the so-called conventional style and the sumo style [60]. The former is characterised by a narrower stance (approximately shoulder width) and the feet in 10-15°of external rotation [47], and the latter by a 2-3 times wider stance and the feet in 40-45°of external rotation [47]. ...
Ever since it was first observed and especially so in recent years, the phenomenon of the so-called "sticking point'" in resistance training has attracted a substantial amount of sports and exercise science research. Broadly speaking the sticking point is understood as the position in the range-of-motion of a lift at which a disproportionately large increase in the difficulty to continue the lift is experienced. Hence the sticking point is inherently the performance bottleneck and is also associated with an increased chance of exercise form deterioration or breakdown. Understanding the aspects of lifting performance which should be analysed in order to pinpoint the cause of a specific sticking point and therefore devise an effective training strategy to overcome it, is of pervasive importance to strength practitioners and instrumental for the avoidance of injury and continued progress. In this paper we survey a range of physiological and biomechanical mechanisms which contribute to the development of sticking points, and led by this insight review and analyse the findings of the existing observational research on the occurrence of sticking points in three ubiquitous exercises: the bench press, the squat, and the deadlift. The findings of our analysis should be used to inform future research and current resistance training practice.
... Previous research has provided evidence that variations in body and limb positioning can affect muscle activation (Escamilla et al., 2002;McCaw & Melrose, 1995;Paoli et al., 2009). In addition, previous research has examined the biomechanical differences between the BHT and BGB among trained male participants (Korta & Peña, 2018). ...
... To date, no previous BHT study has utilised the 5-RM. Moreover, this load was selected to normalise each exercise's load to each exercise by taking into consideration the possibility of effects on muscular activity due to the presence of biomechanical and limb position variations (Escamilla et al., 2002;Korta & Peña, 2018;McCaw & Melrose, 1995;Paoli et al., 2009). Unlike previous BHT studies, foot position was standardised to the shoulder width of each subject, as noted in previous research (Contreras et al., 2011) to further standardised exercise set-up. ...
Hip extensor muscles are critical to sport performance as events requiring sprinting and forceful landings are highly dependent on these muscles. Despite biomechanical differences between the barbell hip thrust (BHT) and the barbell glute bridge (BGB), both are biomechanically efficient ways to load this musculature for training purposes. Research investigating the differences in muscular activity between the BHT and BGB has yet been conducted. The aim of this study was to investigate, through surface electromyography, if one exercise is more optimal than the other in producing greater muscle activation for specific hip extensor muscles. Ten male participants completed a two-part study protocol. Results revealed the BHT elicited significantly greater muscle activity within the vastus lateralis for peak and mean outcomes; however, the BGB elicited significantly greater muscle activity in the upper and lower gluteus maximus for peak and mean outcomes and mean outcome in the gluteus medius. Current findings suggest, the BGB is, at minimum, a superior substitute for the BHT for eliciting a larger magnitude of activity in the gluteus maximus. Future studies between the two exercises are warranted to discern which produces greater hypertrophy and whether adaption of the BHT or BGB transfers more optimally to sport performance.
... Neuromuscular measures: Surface EMG of the vastus lateralis (VL) and triceps brachii (TB) were measured during MTP and IBP, respectively. The VL is a muscle that is easily accessible for EMG, and studies have shown that both throughout the entire deadlift and during the final 60˚ of knee extension VL activation is similar to or higher than several hamstring muscles making it a suitable muscle to measure during the MTP (42,43). The TB is one of the agonist muscles during elbow extension and, as such, has a primary role during the bench press. ...
... normalization. The highest average EMG value obtained during MTP and IBP efforts for the VL and TB, respectively, was then compared with this value to normalize EMG.Studies have shown that the VL activation is similar to that of some of the hamstring muscles throughout the entire deadlift movement, additionally it is also easily accessible and therefore an appropriate muscle to measure muscle activation during the MTP(42,43). As the TB is one of the agonist muscles during the bench press, particularly at maximal intensities, it was deemed a suitable muscle to use to measure muscle activation during the IBP (95).Following EMG normalization contractions, participants performed CMJ's on a force plate. ...
Maximal strength is a physical quality imperative to success in strength sports and can also play a role in enhancing performance within many other sports. Tapering is a reduction in training load frequently undertaken prior to competitions in order to minimise training related fatigue and thus improve athletic performance. There is currently limited research for athletes and coaches to utilise when planning tapering to maximise strength at key events. This thesis investigated how strength-trained men can best structure the taper period to improve strength performance and attempted to identify the mechanisms underlying any performance improvements.
Two literature reviews (Chapters Two and Three) were performed to provide background information regarding training for maximal strength and summarise current knowledge on tapering for maximal strength. The literature revealed that maximal strength training should involve high intensity training (>80% one repetition maximum (1RM)), for multiple sets, with at least two sessions per week for each major muscle group. The current literature indicated that reductions in training volume (by 30-70%) with maintained, or slight increases, in intensity were most effective for improving maximal strength. However, optimal magnitudes of change during the taper were unclear. Short periods of training cessation (less than a week) were also found to be effective at enhancing, or maintaining, maximal strength.
The first study (Chapter Four) used a qualitative approach to determine strategies currently utilised by 11 elite New Zealand powerlifters (age = 28.4 ± 7.0 years, best Wilks score = 431.9 ± 43.9 points). Athletes reduced training volume by 58.9 ± 8.4%, while maintaining (or slightly reducing) training intensity. The taper lasted 2.4 ± 0.9 weeks, with the final resistance training session 3.7 ± 1.6 days out from competition. Tapering was performed to achieve maximal recovery, and practices were largely informed through trial and error, with changes based upon ‘feel’. Athletes usually removed accessory exercises and focused primarily upon the competition lifts during the taper.
The first training study (Chapter Five) involved a cross-over design to determine the effects of two durations, 3.5 or 5.5 days, of training cessation on performance following four-weeks of training. Eight resistance trained males (age = 23.8 ± 5.4 years, bodyweight (BW) = 79.6 ± 10.2 kg, relative deadlift 1RM = 1.90 ± 0.30 times BW) completed the study. Combined data showed significant performance improvements, compared to pre-training, for both countermovement jump (CMJ) height (P = 0.022) and isometric bench press (IBP) relative peak force (P = 0.011) following short term training cessation (both small effect size (ES) = 0.30). This significant improvement was not present on the final training day, showing that training cessation was an effective means of enhancing strength and power. No significant differences were observed between 3.5 and 5.5 days of training cessation for any measure. These results suggest that a short period of strength training cessation can have positive effects on maximal strength expression, perhaps due to decreased neuromuscular fatigue.
The second training study (Chapter Six) also had a cross-over design to determine the effects of two variations in intensity (+5% or -10%) during a one week strength taper with volume reductions (-70%), following four-weeks of training. Eleven strength-trained males (age = 21.3 ± 3.3 years, BW = 92.3 ± 17.6 kg, relative 1RM deadlift = 1.90 ± 0.20 times BW) completed the study. Combined data for both groups showed significant improvements in CMJ height over time (P < 0.001), with significant improvements across all time points (pre- to post-training P = 0.010, ES = 0.23; pre-training to post-taper P = 0.001, ES = 0.37; and, post-training to post-taper P = 0.002, ES = 0.14). Combined data for CMJ flight time: contraction time also showed significant improvements over time (P = 0.004), with significant improvements from pre- to post-training (P = 0.012, ES = 0.27). Combined data for isometric mid-thigh pull (MTP) relative peak force showed significant improvements over time (P = 0.033), with significant increases found from pre- to post-training (P = 0.013, ES = 0.25). The higher intensity taper produced small ES improvements following the taper for CMJ height (ES = 0.43), CMJ flight time: contraction time (ES = 0.42) and MTP relative peak force (ES = 0.37). In contrast, the lower intensity taper only produced a small ES improvement for CMJ height (ES = 0.30). However, differences between groups were not significant. These results indicate that a strength taper with volume reductions can have positive effects on maximal strength and power performance, with a tendency for higher intensity tapering to be more effective.
This thesis has documented current tapering practices of strength athletes and demonstrated both short term training cessation and volume reduced strength tapers as effective methods of improving maximal strength following training. When tapering, athletes should make substantial training volume reductions with little changes to training intensity. During a taper, training should focus on competition specific strength exercises, and strength training should cease a few days prior to important events.
... Historically, athletes and non-athletes alike have used deadlift, to strengthen the hip, thigh, and back musculature (Escamilla 2002 In contrast, the deadlift, however, the deadlift starts in a mechanically difficult position, requiring the lifter to generate the entire force needed to move the bar off the floor, without the assistance of the stretch shortening cycle (Rippetoe & Kilgore 2007). ...
... Quadriceps activity during a barbell deadlift however appears to be lower than more quad dominant exercises such as knee extensions, barbell squats, lunges and step ups (Ebben et al. 2009). In addition, Escamilla et al (2002), has also observed significant quadriceps activity during the deadlift. What these results suggest, is the barbell deadlift can be considered as an accessory or additional exercise to strengthen the quadriceps. ...
... The deadlift is an exercise that is often included in athletic strength and conditioning programs [6][7][8]. However, nothing is known about the load-velocity profile of the deadlift and whether the deadlift MVT matches the barbell velocity of 1RM deadlift performance. ...
... This represents a critical gap in the literature. The deadlift is considered one of, if not the most taxing resistance exercise [7,8]. Therefore, demonstrating that the load-velocity profiling approach could be accurately applied to the deadlift could provide strength and conditioning practitioners with a more energy-and training time-efficient method of assessing deadlift 1RM. ...
The aim of this study was to compare the actual deadlift one repetition maximum (1RM) and the deadlift 1RM predicted from individualised load-velocity profiles. Twelve moderately resistance-trained men participated in three deadlift sessions. During the first, 1RM was assessed; during the second, load-velocity profiles were recorded with six loads (65% to 90% 1RM) using a linear position transducer recording at 1000 Hz; and during the third, minimal velocity thresholds (MVT) were recorded from the velocity of the last repetition during sets to volitional fatigue with 70% and 80% 1RM with a linear position transducer recording at 1000 Hz. Regression was then used to generate individualised load-velocity profiles and the MVT was used as a cutoff value from which to predict deadlift 1RM. In general, velocity reliability was poor to moderate. More importantly, predicted deadlift 1RMs were significantly and meaningfully less than actual deadlift 1RMs (p < 0.05, d = 1.03-1.75). The main practical application that should be taken from the results of this study is that individualized load-velocity profiles should not be used to predict deadlift 1RM. Practitioners should not use this method in combination with the application of MVT obtained from the last repetition of sets to volitional fatigue.
... High-intensity exercises generate increased synchronization of motor units and stronger impulses from the central nervous system to motor units (14), which can motivate the implementation of such exercises. Performing dead-lift as a high load lifting (HLL) exercise can stress almost the entire muscular system, especially the back extensors and trunk stabilizing muscles (15). The exercise includes motor control components, since it activates the stabilizing muscles while the lumbar spine is held in a neutral position with a concurrent movement in the hip and knee, much like a functional dynamic stabilizing exercise. ...
... High load lifting exercise. The HLL intervention consisted of the dead-lift exercise that efficiently activates the stabilizing muscles of the lower back through optimal alignment of the spine (15)(16)(17). The exercise was performed as described in the pilot study (12), but with a reduced load and increased number of repetitions (18). ...
Objective:
The aim of this study was to compare the effects of a high load lifting exercise with low load motor control exercises on pain intensity, disability and health-related quality of life for patients with mechanical low back pain.
Design:
A randomized controlled trial.
Subjects:
Patients with mechanical low back pain as their dominating pain mechanism.
Methods:
The intervention programme consisted of a high load lifting exercise, while the control group received low load motor control exercises over 8 weeks (12 sessions) with pain education included in both intervention arms. The primary outcome was pain intensity and disability, and the secondary outcome was health-related quality of life.
Results:
Each intervention arm included 35 participants, analysed following 2-, 12- and 24-month follow-up. There was no significant difference between the high load lifting and low load motor control interventions for the primary or secondary outcome measures. Between 50% and 80% of participants reported a decrease in perceived pain intensity and disability for both short- and long-term follow-up.
Conclusion:
No difference was observed between the high low load lifting and low load motor control interventions. Both interventions included retraining of movement patterns and pain education, which might explain the positive results over time.
... Moreover, the empirical evidence on chains and bands is promising, although limited, with studies showing accommodating resistance to affect muscle activation (12,13), power (1,12,25), force (1,12,24,25), velocity (12), impulse (1,24), and rate of force development (RFD) (1,23). Increases in RFD may potentially be the result of a more rapid stretch-shortening cycle, which allows for faster initial concentric velocities (9). In addition, the few training studies available support the use of variable resistance as a means to increase strength and power (2,6,10,18), while also reducing joint stress (15). ...
... However, others have also found differences in the patterns of muscle activation through EMG during variations of the deadlift exercise. For example, muscle activation of the vastus medialis, vastus lateralis, and tibialis anterior were greater during the sumo deadlift than during the conventional deadlift exercise (9). These altered patterns of muscle activation with changes in technique and the use of chains emphasize the need for the strength and conditioning coach to carefully consider the implications of these methods on muscle activation and specificity of training. ...
Nijem, RM, Coburn, JW, Brown, LE, Lynn, SK, and Ciccone, AB. Electromyographic and force plate analysis of the deadlift performed with and without chains. J Strength Cond Res 30 (5): 1177–1182, 2016—The purpose of this study was to determine the effects of deadlift chain variable resistance on surface electromyography (EMG) of the gluteus maximus, erector spinae, and vastus lateralis muscles, ground reaction forces (GRFs), and rate of force development (RFD). Thirteen resistance-trained men (24.0 6 2.1 years, 179.3 6 4.8 cm, 87.0 6 10.6 kg) volunteered for the study. On day 1, subjects performed 1 repetition maximum (1RM) testing of the deadlift exercise. On day 2, subjects performed one set of 3 repetitions with a load of 85% 1RM with chains (CH) and without chains (NC). The order of the CH and NC conditions was randomly determined for each subject. For the CH condition, the chains accounted for approximately 20% (19.9 6 0.6%) of the 85% 1RM load, matched at the top of the lift. Surface EMG was recorded to differentiate muscle activity between conditions (CH, NC), range of motion (ROM; bottom, top), and phase (concentric, eccentric). Peak GRFs and RFD were measured using a force plate. Electromyography results revealed that for the gluteus maximus there was significantly greater EMG activity during the NC condition vs. the CH condition. For the erector spinae, EMG activity was greater at the bottom than the top ROM (p # 0.05). Force plate results revealed that deadlifting at 85% 1RM with an accommodating chain resistance of approximately 20% results in a reduction in GRFs (p # 0.05) and no change in RFD (p. 0.05). Collectively, these results suggest that the use of chain resistance during deadlifting can alter muscle activation and force characteristics of the lift.
... Strength and conditional professionals include the deadlift within their programs to strengthen the legs, hips, back, and torso musculature (1,8). Variations of the deadlift are often included within strength training programs with the rationale of strengthening speci c muscles through the use of speci c ranges of motion or equipment (2,3,5). Each variation is used to elicit a speci c response (2,3,5). ...
... Variations of the deadlift are often included within strength training programs with the rationale of strengthening speci c muscles through the use of speci c ranges of motion or equipment (2,3,5). Each variation is used to elicit a speci c response (2,3,5). A popular variation in equipment used for the deadlift is the hexagonal bar. ...
Kinesiology Department, California State University, Fullerton
The deadlift is commonly performed to develop strength and power, and to train the lower body and erector spinae muscle groups. However, little is known about the acute effects of using a hexagonal vs. a straight barbell. Purpose: To examine the hexagonal barbell in comparison to the straight barbell by analyzing electromyography (EMG) from the vastus lateralis, biceps femoris, and erector spinae, as well as peak force, peak power, and peak velocity. Methods: Twenty men completed a one-repetition maximum (1RM) test with each barbell on two separate occasions. Three repetitions at 65% and 85% 1RM were performed with each barbell on a third trial. Results: There was no significant difference for 1RM values between the barbells (mean ± SD in kg = 181.4 ± 27.3 vs. 181.1 ± 27.6, respectively) (p > 0.05). Significantly greater normalized EMG values were found from the vastus lateralis for both the concentric (1.199 ± 0.22) and eccentric (0.879 ± 0.31) phases of the hexagonal compared to the straight barbell deadlift (0.968 ± 0.22 and 0.559 ± 1.26), while the straight barbell led to significantly greater EMG values from the bicep femoris during the concentric phase (0.835 ± 0.19) and the erector spinae (0.753 ± 0.28) during the eccentric phase compared to the corresponding values for the hexagonal barbell deadlift (0.723 ± 0.20 and 0.614 ± 0.21) (p ≤ 0.05). The hexagonal barbell deadlift demonstrated greater peak force (2,553.20 ± 371.52 N), peak power (1,871.15 ± 451.61 W), and peak velocity (0.805 ± 0.165) compared to the straight barbell deadlift values (2,509.90 ± 364.95 N, 1,639.70 ± 361.94 W, and 0.725 ± 0.138 m/s) (p ≤ 0.05). Conclusion: The barbells led to different patterns of muscle activation, and the hexagonal barbell may be more effective at developing maximal force, power, and velocity.
... In proximal terms the aim is to ''flatten out'' the difficulty of the lift [80]. Specific examples of how this may be achieved include alterations to the grip [54] or the stance [81,82] width of the lifter, changes in the orientations of joint flexion/extension (or adduction/abduction) planes [3,4,82], adjustments in the synchronisation of movements across different joints [7], as well as numerous others [83]. ...
... In proximal terms the aim is to ''flatten out'' the difficulty of the lift [80]. Specific examples of how this may be achieved include alterations to the grip [54] or the stance [81,82] width of the lifter, changes in the orientations of joint flexion/extension (or adduction/abduction) planes [3,4,82], adjustments in the synchronisation of movements across different joints [7], as well as numerous others [83]. ...
In the context of resistance training the so-called "sticking point" is commonly understood as the position in a lift in which a disproportionately large increase in the difficulty to continue the lift is experienced. If the lift is taken to the point of momentary muscular failure, the sticking point is usually where the failure occurs. Hence the sticking point is associated with an increased chance of exercise form deterioration or breakdown. Understanding the mechanisms that lead to the occurrence of sticking points as well as different training strategies that can be used to overcome them is important to strength practitioners (trainees and coaches alike) and instrumental for the avoidance of injury and continued progress. In this article we survey and consolidate the body of existing research on the topic: we discuss different definitions of the sticking point adopted in the literature and propose a more precise definition, describe different muscular and biomechanical aspects that give rise to sticking points, and review the effectiveness of different training modalities used to address them.
... For example, wearing a weight belt during the squat or deadlift has been proposed to reduce lower back injury risk. The mechanism of the weight belt is that it increases intra-abdominal pressure and thus reduces spinal disk compressive force [51][52][53][54][55][56] . This seems to be empirically true, although one must inhale before each repetition properly to reduce spinal *CNS 5 central nervous system, LBP 5 lower back pain, NSAID 5 nonsteroidal anti-inflammatory drug, PT 5 physical therapy, SSRI 5 selective serotonin reuptake inhibitor, and TCA 5 tricyclic antidepressant. ...
» Chronic lower back pain (LBP) is common in both nonathletes and weight lifters, but the diagnosis and treatment should be approached differently in these 2 populations based on the unique movement patterns causing the pain.
» Injury rates of weight lifters are far less than those of contact sports, ranging from 1.0 to 4.4 injuries per 1,000 workout hours. However, the lower back was consistently one of the top 2 injury sites for weight lifters, accounting for anywhere from 23% to 59% of all injuries. LBP was most often associated with the squat or deadlift.
» Guidelines for evaluating general LBP are applicable to weight lifters, including a thorough history and physical examination. However, the differential diagnosis will change based on the patient's lifting history. Of the many etiologies of back pain, weight lifters are most likely to be diagnosed with muscle strain or ligamentous sprain, degenerative disk disease, disk herniation, spondylolysis, spondylolisthesis, or lumbar facet syndrome.
» Traditional recommended therapies include nonsteroidal anti-inflammatory drugs, physical therapy, and activity modification, which are often insufficient to resolve pain and prevent injury recurrence. Because most athletes will want to continue to lift weights, lifting-specific behavior modifications focused on improved technique and correcting mobility and muscular imbalances are important aspects of management in this patient population.
... These studies focused primarily on young male civilian powerlifters, limiting the generalizability of the results to military populations. [7][8][9][10][11][12] Currently, the ACFT is graded by soldiers who have completed training and validation through the U.S. Army Physical Fitness School, U.S. Army Center for Initial Military Training, or through an ACFT Non-Commissioned Officer in Charge/Officer in Charge at their local installation. There is no requirement for additional or advanced specialty fitness certification. ...
Introduction
The U.S. Army is updating the physical fitness assessment for soldiers to the six-event Army Combat Fitness Test (ACFT). A paucity of data regarding the ACFT maximum deadlift (MDL) event, especially in military populations, has increased concern over the objectivity of the test. The reliability of scoring the MDL has not been established. It is unknown if grader professional experience impacts the reliability of scoring, and if so, what level of experience is required for reliable assessment. Performance and assessment of the MDL could impact military occupational selection, promotion, and retention within the Army. The purposes of this study were to determine the inter- and intra-rater reliabilities of raters with varying degrees of professional experience on scoring the MDL and to determine the relationships between load lifted, overall lift success, sex, and body mass index (BMI).
Methods
The design is a reliability study. Approval was granted by the Naval Medical Center—Portsmouth Institutional Review Board. Fifty-five healthy soldiers and cadets from the U.S. Military Academy were recruited. Participants completed one data collection session, performing one MDL attempt. The attempt was video recorded using three devices: two handheld tablets placed perpendicular to the sagittal and frontal planes recording at 240 Hz and one digital camera positioned at a 45° angle recording at 30 Hz. A reference standard was established through slow-motion analysis of the sagittal and frontal plane recordings. Six raters with varying degrees of professional experience viewed the 45° camera recordings at real-time speed independently, in a random order, on two separate occasions. Lift success was dichotomously assessed as successful or unsuccessful according to the MDL standards. Cohen’s kappa was computed to determine inter- and intra-rater reliabilities among raters. Bivariate correlation was used to assess associations among load lifted, BMI, and sex. A chi-squared test of independence assessed the relationship between sex and overall lift success.
Results
Inter-rater reliability between the six raters ranged from 0.29 to 0.69. Inter-rater reliability between the raters to the reference standard ranged from 0.28 to 0.61. Intra-rater reliability ranged from 0.51 to 0.84. Inter-rater reliability of raters who had attended a Training and Doctrine Command–approved ACFT certification course ranged from 0.51 to 0.66, while those who had not ranged from 0.34 to 0.46. BMI and sex were associated with load lifted (r = 0.405, P = .002; r = −0.727, P < .001, respectively). Overall lift success was not associated with load lifted (r = −0.047, P = .731). Overall lift success was not related to sex (χ2 = 0.271, P = .602).
Conclusion
Inter-rater reliability of the six raters ranged from poor to substantial, while intra-rater reliability ranged from moderate to excellent. Compared to a reference standard, inter-rater reliability ranged from poor to substantial. The wide range in consistency demonstrated in this study, both between and within raters, brings into question the current subjective methods used to grade the MDL. More research is needed to understand the most feasible, valid, and reliable way to assess performance standards like the MDL that may affect a soldier’s career progression.
... Historically, athletes and non-athletes alike have used deadlift, to strengthen the hip, thigh, and back musculature [1]. Interestingly, many strength coaches believe the squat and deadlift have very similar characteristics. ...
... Electromyography recorded during the two DL styles suggests greater knee extensor muscle activity during the sumo, compared with the conventional DL [19]. McGuigan and Wilson [20] provided a thorough description of the kinematic differences between the two styles of deadlift in competitive powerlifters during competition; the authors observed that the sumo DL has a shorter range of motion than the conventional DL while both lifts take the same time to complete. ...
The competition in powerlifting has been divided into two divisions, with gear equipment (EQ)
and without gear equipment (RAW). When competing in the EQ division, additional supportive gear can be
worn by the athletes, while in the RAW division such gear is not allowed. The aim of the study was to compare
the results of the RAW and EQ powerlifting divisions based on the results of world championships and current
world records. One-hundred and twenty powerlifters (63 men, 57 women) were included to the analysis. Post
hoc analysis for the results of men’s world championships indicated significantly higher results of the barbell
squat (SQ; p < 0.001; ES = 1.31), bench press (BP; p < 0.001; ES = 1.27) and deadlift (DL; p < 0.001;
ES = 0.37) for EQ compared to the RAW division. Post hoc analysis for the results of women’s world championships
indicated significantly higher results of the SQ (p < 0.001; ES = 1.31), BP (p < 0.001; ES = 1.13) and DL
(p < 0.001; ES = 0.71) for the EQ compared to the RAW division. Post hoc analysis for men’s world record
indicated significantly higher results in the SQ (p < 0.001; ES = 1.32) and BP (p < 0.001; ES = 1.24) for the
EQ compared to the RAW division. Furthermore, there were no significant differences in the results of world
records in the DL (p = 0.901; ES = 0.26) between the EQ and RAW divisions. Post hoc analysis for women’s
world records indicated significantly higher results in the SQ (p < 0.001; ES = 1.22) and BP (p < 0.001;
ES = 1.99) for the EQ compared to RAW division. The main finding of the study was that supportive gear
increases maximal load lifted during powerlifting competition.
... [4,6,8,9,10,11,12], 이러한 동작 들은 모두 조정경기력과 높은 상관관계가 보고되었다 [13,14]. [11,12,19]. ...
OBJECTIVES The purpose of this study was to analyze the relationship between isokinetic leg strength and maximum Isometric Med-Thigh Pull Test(IMTP) and maximum height of Counter Movement Jump (CMJ) in Korean national rowers.METHODS Each eight male and female athletes were participated in the study. Isometric IMTP, CMJ, and isokinetic trunk, hip, and knee strength were measured to analyze the relationship between the IMTP, CMJ and isokinetic strength. The correlation between variables was analyzed by the step-wise method of multiple regression analysis after analyzing the correlation between dependent and independent variables.RESULTS Knee, Hip and trunk isokinetic flexion and extension strength showed high correlation with maximum IMTP with the all participants. Knee extension and trunk flexion isokinetic strength showed higher correlation with IMTP. Knee extension isokinetic strength showed high correlation with CMJ.CONCLUSIONS For strengthening exercise of National rowers, ipsilateral strength balance and agonistantagonist strength balance of leg and trunk should be considered to improve performance efficiently.
... The primary movers during a hexbar RDL are the hamstrings group (biceps femoris, semitendinosus, and semimembranosus) and gluteals (maximus, medius, and minimus). Stabilizers, which include musculature of the trunk and spine (rectus abdominis, internal and external obliques, transverse abdominis, and erector spinae group), work isometrically to brace the spinal column and ensure that no spinal flexion or extension occurs (8,14,21). ...
This column provides a description of the correct technique for a hexagonal bar Romanian deadlift (RDL). The use of the hexagonal bar provides a unique variation of the conventional RDL to promote a more advantageous upright body posture, thereby allowing greater loads to be lifted and reductions in spinal compression forces. Additionally, the use of the hexagonal bar RDL can aid in the development in the musculature of the posterior chain benefiting those who are required to sprint and jump regularly.
... While there are a multitude of DL variations, this study focused solely on the conventional DL as it is it most frequently implemented in resistance training programmes. Future studies could examine other DL variations, e.g. the sumo DL which is deemed to be biomechanically different to the conventional DL and may therefore change the EMG activation of various muscle groups (Escamilla et al., 2002). Finally, this study only measured muscle activation of the right arm. ...
Muscle activation, peak velocity (PV) and perceived technical difficulty while using three grip variations and three loads during a deadlift exercise (DL) were examined. Twenty-nine resistance-trained athletes (15 males, age: 22.2±2.7 years; 14 females, age: 24.8±7.0 years) performed the DL with 50%, 70% and 90% of their one repetition maximum (1RM) using hook grip (HG), mixed grip (MG) and double overhand (DOH) grip. Surface electromyography (EMG) of the brachialis (BS), brachioradialis (BR) and flexor carpi ulnaris (FCU) was recorded. PV and perceived technical difficulty of each grip were also measured. Regardless of load and grip, females exhibited greater BS activation compared to males (p<0.05; ES=0.69) while males displayed greater BR activation, significant at 90% load (p<0.01; ES=1.01). MG elicited the least BR and FCU activation regardless of load and sex (p<0.01; ES=0.64-0.68) and was consistently ranked as the easiest grip for any load. Males achieved significantly greater PV than females at 50% and 70% (p<0.01; ES=1.72-1.92). Hand orientation did not significantly impact PV. A MG may be beneficial in reducing the overall perceived technical difficulty when performing a maximal DL. Athletes aiming to maximise muscle activation and potentially develop their grip strength should utilise a DOH grip or HG.
... Conventional deadlifting is also commonly used in lower body RT. Not only does the deadlift (DL) elicit high activation of knee musculature, but also shares biomechanic and muscle activation similarities around the hip and knee joints with sport specific movement patterns such as vertical jumping (Escamilla et al., 2002). Additionally, the hip thrust (HT) has seen increasing prevalence in RT due to its versatility in increasing lower limb strength within different training scenarios (Collazo García et al., 2018). ...
Measurement of muscle specific contractile properties in response to resistance training (RT) can provide practitioners valuable information regarding physiological status of individuals. Field based measurements of such contractile properties within specific muscle groups, could be beneficial when monitoring efficacy of training or rehabilitation interventions. Tensiomyography (TMG) quantifies contractile properties of individual muscles via an electrically stimulated twitch contraction and may serve as a viable option in the aforementioned applications. Thus, aims of this study were; (i) to investigate the potential use of TMG to quantify training adaptations and differences, in response to exercise specific lower limb RT; and (ii) investigate any associations between TMG parameters and accompanying muscle architectural measures. Non-resistance trained male participants (n = 33) were randomly assigned to 1 of 3 single-exercise intervention groups (n = 11 per group); back squat (BS), deadlift (DL), or hip thrust (HT). Participants completed a 6-week linearized training program (2× per week), where the assigned exercise was the sole method of lower body training. Pre- and post-intervention testing of maximal dynamic strength was assessed by one repetition maximum (1RM) of BS, DL, and HT. Radial muscle belly displacement (Dm) and contraction time (Tc) were obtained via TMG from the rectus femoris (RF) and vastus lateralis (VL) pre- and post-intervention, alongside muscle architectural measures (pennation angle and muscle thickness). All three groups displayed significant increases all 1RM strength tests (p < 0.001; pη2 = 0.677–0.753). Strength increases were accompanied by significant overall increases in RF muscle thickness (p < 0.001, pη2 = 0.969), and pennation angle (p = 0.007, pη2 = 0.220). Additionally, an overall reduction in RF Dm (p < 0.001, pη2 = 0.427) was observed. Significant negative relationships were observed between RF Dm and pennation angle (p = 0.003, r = −0.36), and with RF Dm and muscle thickness (p < 0.001, r = −0.50). These findings indicate that TMG is able to detect improved contractile properties, alongside improvements in muscle function within an untrained population. Furthermore, the observed associations between Dm and muscle architecture suggest that TMG contractile property assessments could be used to obtain information on muscle geometry.
... although some studies investigated the seMG activity during resistance training exercises 6,8,15,18 and others besides that compared different roMs 2,3,10,[12][13][14]19 to our knowledge, this is the first study that evaluated the triceps brachii long and lateral heads activation levels between two usual resistance exercises using high loads. The seMG signal of the concentric and eccentric 1 khz by a 16 bits a/d converter (4.8 khz and ±10 V dynamic range; Spider8, hottinger Baldwin Messtechnik, darmstadt, he, Germany). ...
Background:
Elbow extension exercises in different shoulder positions are selected to raise distinct effort levels among the triceps brachii heads. Because there are several triceps exercises, its choice is a big challenge on resistance training prescription. The present study aimed to compare the electromyographic signal of triceps brachii long and lateral heads among three different elbow ranges of motion (ROM) during two commonly prescribed elbow extension exercises: overhead dumbbell elbow extension (OD) and lying dumbbell elbow extension (LD).
Methods:
The long and lateral heads electromyographic signals were acquired from 21 resistance-trained men. One to two maximal repetition of each exercise was performed with a 40% load of a maximal voluntary isometric contraction test. The signals of concentric and eccentric phases were divided into three equal ROMs each (initial, middle, and final).
Results:
Eccentric phase elicited less muscular activity than concentric in both exercises. Concentric contraction presented the same pattern during OD (long and lateral heads) and LD (lateral head). Initial and middle intervals elicited higher muscle activity than final interval. This behavior was also present in the eccentric contraction (initial demanded less activity than middle and final during both exercises).
Conclusions:
Since both exercises presented similar activation patterns, the prescription of OD and LD on the same training routine should be avoided.
... The conventional deadlift style was used in this study. The conventional deadlift uses a narrower stance (feet about 32 to 35 cm apart) with hand/grip placement outside the stance feet compared to the sumo style (Escamilla, Francisco, Fleisig, Barrentine, Welch, Kayes, & Andrews, 2000;Escamilla Francisco, Kayes, Speer, & Moorman, 2002) which involves a placement of the hands outside the stance feet. Aside from the 5-week training program, separate days were provided each for the (1) Orientation and practice session of the deadlift, (2) pretesting of the 1-RM deadlift, (3) pretesting of the Bunkie test, (4) post testing of the 1-RM deadlift and (5) post testing of the Bunkie test. ...
The purpose of this study was to examine the effect of the deadlift, a heavy compound exercise, on core strength as determined through the 1-RM deadlift and the Bunkie tests. The deadlift is a multi-joint movement that involves picking up a barbell from the floor and standing up to an upright position. This movement includes plenty of muscle activation, mainly the lower back, upper back, quadriceps, hamstrings and abdominals. The core is a collection of muscles in the abdominal and lower back areas although it is commonly mistaken as simply the abdominal muscles. This study investigated the effect of deadlift training on core strength through a pretest-posttest comparison in the 1-RM deadlift to assess maximum muscular strength and the Bunkie test for core strength. 21 previously-untrained male college students participated in a 5-week deadlift strength program using progressive overload with no direct core training involved. The 5-week deadlift program resulted in significant increases in both the 1-RM deadlift, derived from the Brzycki formula, and Bunkie test scores most notably in the posterior stabilizing line and the medial stabilizing line. Deadlift strength training, even without direct core training, was able to produce significant improvements in core strength in previously-untrained male college students.
... EMG electrodes (Ambu Blue Sensor, Denmark) were placed on the vastus lateralis of the right leg in accordance with the recommendations of Hermens et al. (2000) and a ground electrode was placed on the patella. Previous studies have shown that the vastus lateralis is highly active during lower body strength exercises and therefore offers an appropriate sampling site for EMG during such movements (Ebben et al. 2009;Escamilla et al. 2002). The EMG signal was sampled at 1000 Hz, amplified (BioAmp, ADInstruments, Australia) and then band-pass filtered (10-500 Hz) and full wave rectified in Chart for Windows V8.1 (ADInstruments, Australia). ...
Purpose:
Ammonia is used as a stimulant in strength based sports to increase arousal and offset fatigue however little is known about its physiological and performance effects. The purpose of this study was twofold (1) establish the physiological response to acute ammonia inhalation (2) determine whether the timing of the physiological response corresponds with a performance enhancement, if any.
Methods:
Fifteen healthy males completed two trials. Trial one investigated the beat-to-beat middle cerebral artery blood flow velocity (MCAv), heart rate (HR) and mean arterial pressure (MAP) response to ammonia inhalation. During trial two, participants performed a maximal single mid-thigh pull (MTP) at various time points following ammonia inhalation in a randomised order: MTPs were conducted immediately, 15, 30 and 60 s following ammonia inhalation. A MTP with no ammonia inhalation served as the control. During this trial maximal MTP force, rate of force development (RFD) and electromyography (EMG) activity were recorded.
Results:
MCAvmean increased and peaked on average by 6 cm s(-1) (P < 0.001), 9.4 ± 5.5 s following ammonia inhalation. Similarly, HR was increased by 6 ± 11 beats per minute 15 s following ammonia inhalation (P < 0.001). MAP remained unchanged following inhalation (P = 0.51). The use and timing of ammonia inhalation had no effect on maximal force, RFD or EMG (all P > 0.2) compared to control.
Conclusions:
MCAv was elevated despite no increase in MAP occurring; this is indicative of a cerebrovascular vasodilation. Despite the marked cerebrovascular and cardiovascular response to ammonia inhalation no ergogenic effect was observed during the MTP, irrespective of the timing of administration.
... In addition, previous studies have considered the use of surface electromyography (sEMG) as a method of assessing lumbar extensor activation to hypothesise training efficacy. Deadlift variations (6,10), and roman chair exercises (8,26) have shown activation of the lumbar muscles measured by sEMG where subsequent training interventions have failed to demonstrate a chronic strength adaptation. This might be a result of the significant limitations of sEMG including the effects of crosstalk, an issue especially prominent in the low back (9,37). ...
The aim of the present study was to use a Fatigue Response Test (FRT) to measure the muscular fatigue (defined as a reduction in torque production) sustained by the lumbar extensors after a single set of kettlebell swings (KBS) in comparison to isolated lumbar extensions (ILEX), and a control condition (CON). The purpose of which is to measure the physiological response of KBS against an already established modality. Subsequent data provides insight of the efficacy of kettlebells swings in strengthening the lumbar muscles and lower back pain treatment. Eight physically active males participated in a repeated measures design where participants completed all conditions. There were statistically significant reductions in maximal torque, reported as strength index (SI), following both KBS and ILEX exercise. A statistically significant difference was found for reductions in maximal torque (POST-PRE) between CON and both KBS (p = 0.005) and ILEX (p = 0.001) and between KBS and ILEX (p = 0.039). Mean reduction and effect sizes were -1824 ± 1127.12(SI) and -1.62 for KBS and -4775.6 ± 1593.41(SI) and -3.00 for ILEX. In addition a statistically significant difference was found between KBS and ILEX for rate of perceived exertion (p = 0.012). Data suggests that both KBS and ILEX were able to fatigue the lumbar extensors. ILEX was able to generate a greater level of fatigue. However, contrary to previous research, the kettlebell swing was able to elicit a physiological response despite the lack of pelvic restraint supporting the potential to strengthen the lumbar extensors.
Sprinting speed plays a crucial role in many sports, and it is considered a fundamental motor skill. Various training methods can be used to improve sprinting speed. Researchers have shown strength and plyometric training (PT) to be effective in improving sprinting speed. However, most studies have reviewed the effects of strength and PT on sprinting performance in adults and young males. There is a paucity of research that has reviewed the effects of strength and PT on sprinting performance in young females across maturation (pre-peak height, mid-peak height, and post-peak height velocity: peak height velocity student athletes, age 10–16 years). Moreover, no previous review has provided practical strength and PT strategies for young female student-athletes that acknowledge important factors such as growth, forces, and enjoyment. Therefore, this review highlights the importance of progressive strength and PT on sprinting performance in young females and provides practical training programs that can be implemented within a school curriculum. More specifically, this review provides exercise progressions in strength and power training for an eight-week training block that can be easily implemented by strength and conditioning coaches within a school term.
Background:
Squatting is a core exercise for many purposes. However, there is still controversy surrounding the practice of targeting specific muscle groups when performing the back squat with different stance widths or foot positions. Therefore, this study aimed to assess lower limb muscle activation during different form of back squat when adopting three different foot angles.
Methods:
Eight male active participants (age 24.0±0.8 years, height 1.80±0.63m and mass 85.8±8.7kg) performed maximal isometric squat, back squat with an overload of 80% of 1 repetition maximum, and countermovement jump (CMJ) when adopting three foot rotation angles: parallel (0°); +10° outward (external rotation); +20° outward (external rotation). We calculated the root mean square of the electromyographic signals recorded from eight participant's dominant leg muscles.
Results:
During the descending phase of the back squat, the 20° external foot rotation elicited greater activation of the biceps femoris (+35%; p = 0.027) and gastrocnemius medialis (+70%; p = 0.040) compared to parallel foot. There were no significant differences among the other muscles and exercise conditions.
Conclusions:
The +20° foot position increased BF and GasM muscle activity only during the downward phase of the back squat. Strength coaches should consider the present findings when selecting specific resistance exercises aiming to improve athletes' strength and physical fitness.
Objectives
To investigate the accuracy of visual assessments made by physical therapists of lumbo-pelvic movements during the squat and deadlift and how much movement is considered injurious.
Design
Quantitative Cross-sectional.
Participants
14 powerlifters, 10 Olympic weightlifters and six physical therapists.
Setting
The lifters were recorded simultaneously by video and an inertial measurement unit (IMU) system while performing squats and deadlifts. The physical therapists assessed the videos and rated whether specific lumbo-pelvic movements were visible during the lifts and whether the movement amplitude was considered injurious.
Main outcome measures
The nominal visual assessments, if there was a movement and if it was considered injurious, were compared to the degrees of movement attained from the IMU system.
Results
During the squat, a posterior pelvic tilt of ≥34° was required to visually detect the movement. For other lumbo-pelvic movements, there was no significant difference in the amount of movement between those who were assessed as moving or not moving their lumbo-pelvic area, nor was there a difference in movement amplitude between those who were assessed as having an increased risk of injury or not.
Conclusions
Physical therapists did not consistently detect lumbo-pelvic movements during squats and deadlifts when performed by competitive lifters.
The main purpose of this review was to systematically analyze the literature concerning studies which have investigated muscle activation when performing the Deadlift exercise and its variants. This study was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis Statement (PRISMA). Original studies from inception until March 2019 were sourced from four electronic databases including PubMed, OVID, Scopus and Web of Science. Inclusion criteria were as follows: (a) a cross-sectional or longitudinal study design; (b) evaluation of neuromuscular activation during Deadlift exercise or variants; (c) inclusion of healthy and trained participants, with no injury issues at least for six months before measurements; and (d) analyzed “sEMG amplitude”, “muscle activation” or “muscular activity” with surface electromyography (sEMG) devices. Major findings indicate that the biceps femoris is the most studied muscle, followed by gluteus maximus, vastus lateralis and erector spinae. Erector spinae and quadriceps muscles reported greater activation than gluteus maximus and biceps femoris muscles during Deadlift exercise and its variants. However, the Romanian Deadlift is associated with lower activation for erector spinae than for biceps femoris and semitendinosus. Deadlift also showed greater activation of the quadriceps muscles than the gluteus maximus and hamstring muscles. In general, semitendinosus muscle activation predominates over that of biceps femoris within hamstring muscles complex. In conclusion 1) Biceps femoris is the most evaluated muscle, followed by gluteus maximus, vastus lateralis and erector spinae during Deadlift exercises; 2) Erector spinae and quadriceps muscles are more activated than gluteus maximus and biceps femoris muscles within Deadlift exercises; 3) Within the hamstring muscles complex, semitendinosus elicits slightly greater muscle activation than biceps femoris during Deadlift exercises; and 4) A unified criterion upon methodology is necessary in order to report reliable outcomes when using surface electromyography recordings.
fferences between the front and back squat and conventional and sumo deadlift. J Strength Cond Res XX(X): 000-000, 2019-The average concentric velocity (ACV) of a resistance exercise movement is inversely related to the load lifted. Previous work suggests that different resistance exercises differ in ACV at the same relative load. Currently, there is limited evidence to determine whether the style of exercise (e.g., front or back squat [BS]; sumo-style or conventional-style deadlift) also affects the load-velocity profile or other kinematic variables such as the peak concentric velocity (PCV) and linear displacement (LD). The purpose of this study was to compare the kinematics (ACV, PCV, and LD) between the front squat (FS) and BS as well as between the conventional deadlift (CD) and sumo deadlift (SD). In a randomized order, 24 men and women (22 ± 3 years) performed a 1 repetition maximum (1RM) protocol for the FS, BS, CD, and SD over 4 visits to the laboratory. Barbell kinematics were recorded during all submaximal and maximal repetitions performed during the 1RM protocol using the Open Barbell System. Kinematic data were pooled into categories based on the percentage of the 1RM lifted in 10% increments (e.g., 30-39% 1RM, 40-49% 1RM, etc.) and compared between exercises. Correlations between kinematic data for the FS and BS and for the CD and SD were examined at each relative load. No differences in kinematics were observed between the FS and BS at any load (p > 0.05). However, FS and BS ACV was weakly correlated (r < 0.4) at high (>80% 1RM) loads. Differences in LD were apparent between the SD and CD at all loads (30-100% 1RM) with the SD having a smaller LD compared with the CD (p < 0.05). Average concentric velocity was not different between the SD and CD at the 1RM (0.25 ± 0.09 vs. 0.25 ± 0.06 m·s; p = 0.962) but was different at 80-89% 1RM (0.35 ± 0.08 vs. 0.40 ± 0.07; p = 0.017), 70-79% 1RM (0.41 ± 0.08 vs. 0.46 ± 0.06; p = 0.026), and 40-49% 1RM (0.66 ± 0.09 vs. 0.77 ± 0.08; p < 0.001). In addition, SD and CD ACV values showed no relationships (p > 0.05) at any loads except at the 1RM (r = 0.433; p < 0.05). These results suggest individual load-velocity profiles for the FS and BS as well as for the CD and SD should be used for training purposes.
Born, DP, Stöggl, T, Petrov, A, Burkhardt, D, Luethy, F, and Romann, M. Analysis of freestyle swimming sprint start performance after maximal strength or vertical jump training in competitive female and male junior swimmers. J Strength Cond Res XX(X): 000-000, 2019-To investigate the freestyle swimming sprint start performance before and after 6 weeks of maximal strength compared with vertical jump training. With a between-group repeated-measure design, 21 junior swimmers (12 female and 9 male) competing in national and international championships performed 2 weekly sessions of either maximal strength (heavy-loaded back squat and deadlift exercise) or vertical jump training (unloaded box jumps) for 6 weeks during the precompetition phase of the seasonal main event. Session ratings of perceived exertion were used to compare the load of both training programs. Before and after the training period, sprint start performance was investigated on a starting block equipped with force plates synchronized to a 2-dimensional motion capture system. Total training load did not differ between the 2 groups. Sprint start performance and most kinematic and kinetic parameters remained unaffected. In pooled data of the U17 swimmers, however, 5-m, 15-m, and 25-m split times were improved with maximal strength (p 5 0.02, 0.03, and 0.01), but not with vertical jump training (p 5 0.12, 0.16, and 0.28). Although there was no global effect, focus on the subgroup of U17 swimmers showed an improved sprint start performance with 2 sessions of maximal strength training integrated into a 16-hour training week. Although outcomes of the conditioning program seemed to be affected by the training history and performance level of the athletes involved, strength and conditioning coaches are encouraged to introduce maximal strength training at a young age.
Heelas, T, Theis, N, and Hughes, JD. Muscle activation patterns during variable resistance deadlift training with and without elastic bands. J Strength Cond Res XX(X): 000-000, 2019-The purpose of this study was to determine the effects of band-assisted variable resistance training on muscular activity in the lower limbs and barbell kinematics during the concentric phase of the deadlift. Fifteen resistance trained men (mean ± SD: 28.7 ± 9.3 years; 1.80 ± 0.90 m; 92.5 ± 15.1 kg) performed 6 deadlift repetitions during 4 loading conditions: 100-kg bar (no band), 80-kg bar with 20-kg band tension (B20), 75-kg bar with 25-kg band tension (B25), and 70-kg bar with 30-kg band tension (B30). Muscle activity from the medial gastrocnemius (MG), semitendinosus (ST), vastus medialis (VMO), vastus lateralis (VL), and gluteus maximus (GM) were recorded using surface electromyography during the concentric phase of the lift and expressed as a percentage of each muscle's maximal activity, recorded during a maximal isometric contraction. Barbell power and velocity were recorded using a linear position transducer. Electromyography results showed that muscle activity significantly decreased as band resistance increased in the MG and ST (p < 0.05) and progressively decreased in the GM. No changes were observed for the VMO or VL. Peak and mean bar velocity and power significantly increased as band resistance increased. Performing the deadlift with band-assisted variable resistance increases bar power and velocity, while concurrently decreasing muscle activation of the posterior chain musculature. Practitioners prescribing this exercise may wish to include additional posterior chain exercises that have been shown to elicit high levels of muscle activation.
Patellofemoral pain (PFP) is a common musculoskeletal-related condition that is characterized by insidious onset of poorly defined pain, localized to the anterior retropatellar and/or peripatellar region of the knee. The onset of symptoms can be slow or acutely develop with a worsening of pain accompanying lower-limb loading activities (eg, squatting, prolonged sitting, ascending/descending stairs, jumping, or running). Symptoms can restrict participation in physical activity, sports, and work, as well as recur and persist for years. This clinical practice guideline will allow physical therapists and other rehabilitation specialists to stay up to date with evolving PFP knowledge and practices, and help them to make evidence-based treatment decisions. J Orthop Sports Phys Ther. 2019;49(9):CPG1-CPG95. doi:10.2519/jospt.2019.0302.
Collazo García, CL, Rueda, J, Suárez Luginick, B, Navarro, E. Differences in the electromyographic activity of lower-body muscles in hip thrust variations. J Strength Cond Res XX(X): 000-000, 2018-Coaches often use variations of an exercise to train a specific muscle. The purpose of this study was to analyze motor patterns in 4 variations of one of the most popular strength training exercises for the lower body: the barbell hip thrust. Seven experienced personal trainers performed a series of 8 repetitions of each variation with a load of 40% one repetition maximum. Subjects rested 3' between series. Electromyographic (EMG) muscle activity was measured in the rectus femoris, vastus medialis; vastus lateralis; gluteus maximus; gluteus medius; biceps femoris; and semitendinosus. Variations of the hip thrust exercise were performed by changing the position of the feet (feet were moving away from the body) and the direction of force exerted by subjects (intentional force aimed at hip's external rotation and knee's flexion). Repeated-measures analysis of variance revealed significant differences in EMG in all muscles except for the gluteus medius, where no differences were observed among variations. The results obtained suggest that hip thrust variations have different motor patterns, which can be exploited to adapt an exercise to the individual needs of each athlete.
The purpose of this study was to examine the biomechanical differences between two set up variations during the isometric initiation of conventional barbell deadlifts (DL): Close-bar DL (CBDL), where the bar is positioned above the navicular, and far-bar DL (FBDL), where the bar is placed above the 3rd metatarsophalangeal joint. A cross-sectional, randomized, within-participant pilot study was used. Experienced powerlifters and weightlifters (n = 10) performed three individual isometric pulls of the initiation of both conditions. The CBDL resulted in lower tibia and knee angles and greater pelvis and torso angles than the FBDL (p < 0.05), as well as greater electromyography (EMG) activity in the biceps femoris and upper lumbar erector spinae, but lower activity in the vastus lateralis, and a lower knee extensor moment (p < 0.05). There were no statistical differences for ground reaction force, joint reaction lumbar shear and compression forces between the two conditions. Despite the differences in pelvis and torso angles between lifting conditions, the internal joint net moment, internal shear forces, and internal compressive forces were not different between the two lifting styles. The CBDL set up also resulted in greater posterior chain (hamstrings and erector spine) EMG amplitude, whereas the FBDL set up resulted in more anterior chain (quadriceps) amplitude. Lifters and coaches may choose either deadlift style, according to preferences or training goals, without concern for differences in lumbar spinal loading.
The aim of this study was to determine the acute effect of static stretching on hamstring and quadriceps muscles’ isokinetic strength when applied for various durations to elite athletes, to investigate the effect of different static stretching durations on isokinetic strength, and finally to determine the optimal stretching duration. Fifteen elite male athletes from two different sport branches (10 football and five basketball) participated in this study. Experimental protocol was designed as 17 repetitive static stretching exercises for hamstring and quadriceps muscle groups according to the indicated experimental protocols; ((A) 5 min jogging; (B) 5 min jogging followed by 15 s static stretching; (C) 5 min jogging followed by 30 s static stretching; (D) 5 min jogging, followed by static stretching for 45 s). Immediately after each protocol, an isokinetic strength test consisting of five repetitions at 60°/s speed and 20 repetitions at 180°/s speed was recorded for the right leg by the Isomed 2000 device. Friedman variance analysis test was employed for data analysis. According to the analyzes, it was observed that 5 min jogging and 15 s stretching exercises increased the isokinetic strength, whereas 30 and 45 s stretching exercises caused a decrease.
Low back strength has been shown to significantly impact performance in a plethora of sports. Aside from its effect on sport performance, low back strength is strongly associated with low back pain. A sport that heavily involves the lower back musculature is powerlifting. The present study looked to compare isolated lumbar extension (ILEX) strength in competitive and non-competitive powerlifters and recreationally trained males. Thirteen competitive powerlifters (CPL group; 31.9 ± 7.6 years; 173.4 ± 5.5 cm; 91.75 ± 18.7 kg), 10 non-competitive powerlifters (NCPL group; 24 ± 3.5 years; 179 ± 4.8 cm; 92.39 ± 15.73 kg, and 36 recreationally trained males (RECT group; 24.9 ± 6.5 years; 178.5 ± 5.2 cm; 81.6 ± 10.0kg) were tested for isolated lumbar extension strength (ILEX). ILEX strength was measured at every 12° throughout participant’s full range of motion and expressed as the following: ’strength index’ calculated as the area under a torque curve from multiple angle testing (SI), average torque produced across each joint angle (AVG) and maximum torque produced at a single angle (MAX). Deadlift and squat strength was measured using 1 repetition maximum (1RM) for the competitive and non-competitive powerlifters. The following powerlifting characteristics were recorded for the competitive and non-competitive powerlifters: primary deadlift stance, primary squat bar position, use of belt, use of performance enhancing drugs (PEDs) and use of exercises to target the lower back musculature. Significant between group effects were found for participant characteristics (age, stature, body mass, and range of motion). However, analysis of covariance with participant characteristics as covariates found no significant between group effects for SI (p=0.824), AVG (p=0.757), or MAX (p=0.572). In conclusion this study suggests that powerlifting training likely has little impact upon conditioning of the lumbar extensors.
The purpose of this study is to analyze biomechanical differences between the bounce and pause styles of deadlifting. Twenty physically active males performed deadlifts at their 75% one repetition maximum testing utilizing both pause and bounce techniques in a within-subjects randomized study design. The average peak height the barbell attained from the three bounce style repetitions was used to compute a compatible phase for analysis of the pause style repetitions. Net joint moment impulse (NJMI), work, average vertical ground reaction force (vGRF), vGRF impulse and phase time were computed for two phases, lift off to peak barbell height and the entire ascent. Additionally, the ankle, knee, hip, and trunk angles at the location of peak barbell height. During the lift off to peak barbell height phase, although each of the joints demonstrated significantly less NJMI and work during the bounce style, the hip joint was impacted the most. The average vGRF was greater for the bounce however the vGRF impulse was greater for the pause. The NJMI results for the ascent phase were similar to the lift off to peak barbell height phase, while work was significantly less for the bounce condition compared to the pause condition across all three joints. Strength and conditioning specialists utilizing the deadlift should be aware that the bounce technique does not allow the athlete to develop maximal force production in the early portion of the lift. Further analyses should focus on joint angles and potential vulnerability to injury when the barbell momentum generated from the bounce is lost.
The kinetics of a conventional deadlift in shod (S) versus unshod (US) footwear conditions in 10 male participants (mean ± SD, age = 27.0 ± 5.8 years; weight = 78.7 ± 11.5 kg; height = 175.8 ± 8.2 cm; 1RM deadlift = 155.8 ± 25.8 kg) was assessed in two testing sessions. A counterbalanced, crossover experimental design was used with different loads (60% and 80% 1RM). Four sets of four repetitions were prescribed per session with two sets per shoe and with each shoe condition involving one set per load. Peak vertical force (PF), rate of force development (RFD), time to peak force (TPF), anterior-posterior (COP-AP) and medio-lateral (COP-ML) center of pressure excursion, and barbell peak power (PP) data were recorded during all repetitions. Except for RFD (F = 6.389; p = 0.045; ηp = 0.516) and ML-COP (F = 6.696; p = 0.041; ηp = 0.527), there were no other significant main effects of shoe. There were significant main effects of load for PF (p < 0.05), COP-AP (p = 0.011), TPF (p = 0.018) and COP-AP (p = 0.011). There were no significant interactions found between session, shoe and load (p range from 0.944 to 0.086). While the unshod condition may have produced changes in RFD and ML-COP compared with the shod condition, there is only limited evidence in the current study to support this lifting technique for the conventional deadlift. Further investigation is required to clarify any possible implications of this result and its benefit to lifters.
THE SUMO DEADLIFT IS A COMMON VARIATION OF THE DEADLIFT USED IN POWERLIFTING COMPETITIONS. THE EXERCISE USES EXTENSION OF THE BACK, HIPS, AND KNEES IN UNISON TO LIFT A LOADED BARBELL FROM THE GROUND TO A FULLY ERECT STANDING POSITION. THIS COLUMN OFFERS A DETAILED DESCRIPTION OF PROPER SUMO DEADLIFTING TECHNIQUE. A VIDEO ABSTRACT DESCRIBING THIS ARTICLE CAN BE FOUND IN SUPPLEMENTAL DIGITAL CONTENT 1, HTTP://LINKS.LWW.COM/SCJ/A204.
Ammonia inhalant (AI) use by powerlifters and weightlifters is a prevalent practice with little research support for improved performance. The purpose of this study was to investigate the effects of ammonia as a stimulant on athletic performance during a dead lift one maximal repetition (1-RM) absolute strength test. Subjects (n=10 men, mean±SD age=21±1 years, mass=72.5±6.8 kg; n=10 women, age=22±5 years, mass=66.2±8.1 kg) were required to have at least two years of resistance training experience while lacking a history of asthma, lightheadedness, fainting, anaphylaxis, sickle cell traits, and other respiratory disorders. After a baseline 1-RM test, subjects were paired by 1-RM performance and gender, then randomly assigned in a counterbalanced treatment order to control (water) or ammonia trials after a minimum 72-hour recovery period for another 1-RM test involving attempts at 100.0%, 102.5%, 105.0%, and 107.5% of the established 1-RM value. Testing was then repeated after the minimum rest period for the remaining trial. Results revealed the expected gender main effect for absolute dead lift 1-RM (93.0±29.5 [women]; 152.0±29.5 kg [men] (p<0.001), but no trial main effect (p=0.874) or gender by trial interaction effect (baseline=93.0± 15.3, 151.8±42.3 kg; water=92.0±12.5, 150.9±37.8 kg; ammonia=92.5±16.4, 153.4±37.9 kg) for women and men, respectively (p=0.559). Within the limitations of this study, there is no support for the practice of ammonia inhalation to improve dead lift 1-RM in training or competition.
The aim of this study was to determine the effects of two different durations of training cessation on upper and lower body maximal strength performance, and to investigate the mechanisms underlying performance changes following short term training cessation. Eight resistance trained males (23.8 +/- 5.4 years, 79.6 +/- 10.2 kg, 1.80 +/- 0.06 m, relative deadlift 1RM of 1.90 +/- 0.30 times bodyweight) each completed two four-week strength training periods followed by either 3.5 days (3.68 +/- 0.12 days) or 5.5 days (5.71 +/- 0.13 days) of training cessation. Testing occurred pre-training (T1), on the final day of training (T2) and following each respective period of training cessation (T3). Participants were tested for salivary testosterone and cortisol, plasma creatine kinase, psychological profiles, and performance tests (countermovement jump (CMJ), isometric mid-thigh pull (MTP) and isometric bench press (IBP)) on a force plate. Participants' bodyweight increased significantly over time (P = 0.022). CMJ height and IBP peak force showed significant increases over time (P = 0.013, 0.048 and 0.004, respectively). Post-hoc testing showing a significant increase between T1 and T3 for both CMJ height and IBP peak force (P = 0.022 and 0.008 with effect sizes (ES) of 0.30 and 0.21, respectively). No other significant differences were seen for any other measures. These results suggest that a short period of strength training cessation can have positive effects on maximal strength expression, perhaps due to decreases in neuromuscular fatigue.
Powerlifters routinely focus on three exercises: bench press, squat, and deadlift. This focus may predispose them to the development of muscle imbalances in either the upper or lower extremity which might also influence posture. Therefore, the purpose of the present study was to examine the agonist:antagonist strength ratios and their relationship to postural measures among powerlifters. An expost facto study design compared fifteen male powerlifters (35.3±13.7 years old) and fifteen age-matched controls (34.9±14.6 years old). Maximal isometric strength tests were conducted using handheld dynamometry. Posture was evaluated using pectoralis minor length, pelvic tilt, thoracic kyphosis, and lumbar lordosis. Strength imbalances were observed for shoulder horizontal adduction:abduction (2.57±0.58 vs. 1.78±0.28; p<0.001) and knee flexion:extension (0.61±0.15 vs. 0.50±0.10; p=0.033). Pectoralis minor length was significantly shorter among the powerlifters (6.1±1.9 vs. 4.2±1.4; p=0.005), however, there was no statistical difference in thoracic kyphosis (37.7±9.4 vs. 39.1±10.9; p=0.722), pelvic tilt (10.6±3.6 vs. 11.3±3.7; p=0.622), or lumbar lordosis (25.0±7.6 vs. 23.0±8.4; p=0.500) angles. Strength imbalances, including shoulder horizontal adduction:abduction and knee flexion:extension, and a shortened pectoralis minor may evolve as training adaptations among powerlifters while thoracic kyphosis, pelvic tilt, and lumbar lordosis remain unchanged.
Those training for strength and power commonly use different bars and different lifts. The hexagonal barbell (HBar) and Olympic barbell (OBar) are frequently used training implements, and the mid-thigh pull and deadlift are two popular exercises. Therefore, the purpose of this study was to compare force between an HBar and OBar for a mid-thigh pull (MTP), deadlift (DL) and countermovement jump (CMJ). Twenty resistance trained men (age = 24.05 +/- 2.09 yrs, ht = 178.07 +/- 7.05 cm, mass = 91.42 +/- 14.44 kg) volunteered to participate and performed MTP and DL utilizing both bars, and a CMJ. Joint angles were recorded for all pulls and the bottom position of the CMJ. Peak ground reaction force (PGRF) was greater in the MTP (3186.88+/-543.53N) than DL (2501.15+/-404.04N) but not different between bars. MTP joint angles were more extended than DL, and the strongest correlations between isometric and dynamic performance were seen between DL PGRF and CMJ impulse (OBar r=0.85; HBar r=0.84). These findings are likely due to the different anatomical characteristics between the MTP and DL as well as the similarity in joint angles between the DL and CMJ. Therefore, the deadlift may be an optimal choice for athletes in jump dependent sports, regardless of bar. Copyright (C) 2016 by the National Strength & Conditioning Association.
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.
To evaluate the effects of abdominal belts on lifting performance, muscle activation, intra-abdominal pressure and intra-muscular pressure of the erector spinae muscles.
Simultaneous measurement of intra-abdominal pressure, intra-muscular pressure of the erector spinae muscles was performed during the Valsalva maneuver and some isometric lift exertions.
While several hypotheses have been suggested regarding the biomechanics of belts and performance has been found to increase when lifting with belts, very little is known about the modulating effects on trunk stiffness. At present, there is no reason to believe that spine tolerance to loads increases with belts.
An abdominal belt designed for weightlifting was used. Intra-abdominal pressure, intra-muscular pressure of the erector spinae muscles and myoelectric activities of trunk muscles (erector spinae, rectus abdominis and external oblique) were measured simultaneously during the Valsalva maneuver as well as three types of isometric lifting exertions (arm, leg and torso lift). A paired t-test was used to analyze for statistical differences between the two conditions (without-belt and with-belt) in intra-abdominal pressure, intra-muscular pressure of the erector spinae muscles and in the integrated EMG of the trunk muscles.
Intra-muscular pressure of the erector spinae muscles increased significantly by wearing the abdominal belt during Valsalva maneuvers and during maximum isometric lifting exertions, while maximum isometric lifting capacity and peak intra-abdominal pressure were not affected. Integrated EMG of rectus abdominis increased significantly by wearing the abdominal belt during Valsalva maneuvers (after full inspiration) and during isometric leg lifting.
Wearing abdominal belts raises intra-muscular pressure of the erector spinae muscles and appears to stiffen the trunk. Assuming that increased intra-muscular pressure of the erector spinae muscles stabilizes the lumbar spine, wearing abdominal belts may contribute to the stabilization during lifting exertions.
To overcome many of the complications after ACL reconstruction (prolonged knee stiffness, limitation of complete extension, delay in strength recovery, anterior knee pain), yet still maintain knee stability, we developed a rehabilitation protocol that emphasizes full knee extension on the first postoperative day and immediate weightbearing according to the patient's tolerance. Of 800 patients who underwent intraarticular ACL patellar tendon-bone graft reconstruction, performed by the same surgeon, the last 450 patients have followed the accelerated rehabilitation schedule as outlined in the protocol. A longer than 2 year followup is recorded for 73 of the patients in the accelerated rehabilitation group. On the 1st postoperative day, we encouraged these patients to walk with full weightbearing and full knee extension. By the 2nd postoperative week, the patients with a 100° range of motion participated in a guided exercise and strengthening program. By the 4th week, patients were permitted unlimited activities of daily living and were allowed to return to light sports activities as early as the 8th week if the Cybex strength scores of the involved extremity exceeded 70% of the scores of the noninvolved extremity and the patient had completed a sport-specific functional/agility program. The patient database was compiled from frequent clinical examinations, periodic knee questionnaires, and objective information, such as range of motion measurements, KT-1000 values, and Cybex strength scores. A series of graft biopsies obtained at various times have revealed no adverse histologic reaction. The evidence indicates that in this population, the accelerated rehabilitation program has been more effective than our initial program in reducing limitations of motion (particularly knee extension) and loss of strength while maintaining stability and preventing anterior knee pain.
The purpose of this study was to examine the effectiveness of weight-belts during multiple repetitions of the parallel back squat exercise. Five subjects were filmed (50 fps) as they performed eight consecutive trials at each of two weight-belt conditions [with belt = WB, without belt = WOB] in random order at their eight-repetition maximum effort. Other parameters examined were ground reaction forces, intra-abdominal pressure (IAP), and mean electromyography (mEMG) for the external oblique (EO), erector spinae (ES), vastus lateralis (VL), and bicep femoris (BF) muscles. All parameters were collected and interfaced to a computer via an A/D converter. WB repetitions were generally performed faster than WOB repetitions, especially by the later repetitions (3.34 vs 3.56 s). WB IAP values were consistently greater (P less than 0.05) than WOB values by 25-40%. IAP increased by approximately 11.5% from the first to the last repetitions. No differences were observed for ES and EO mEMG for belt usage, but values increased by up to 20% across repetitions. Several differences were observed between WB and WOB for the VL and BF mEMG, with WB values being significantly greater. These data suggest that a weight-belt aids in supporting the trunk by increasing IAP, and that any differential effect due to wearing a weight-belt did not occur over eight repetitions.
The reaction moments at the knee, hip, and L4/L5 joints, and the compressive and shearing forces on L4/L5 are documented in powerlifters competing in a national powerlifting championship. Analyses were made of 13 female and 44 male competitors. The joint moments and forces were estimated from a linked segment model (WATBAK) that incorporated functional low back extensor musculature with a moment arm of 6 cm and a line action that was oriented 5 degrees posteriorly to the L4/L5 compression axis. This oblique orientation of the extensor muscles reduced the anterior shearing load on the vertebral motion unit. Average compressive loads on L4/L5 were estimated up to 17,192 N while the highest average L4/L5 and hip moments were 988 and 1047 N.m, respectively. The sumo deadlift style resulted in a 10% reduction in the joint moment and 8% reduction in the load shear force at the L4/L5 level when compared with the conventional lifting style. Formulation of linear regression equations to predict the load lifted using reaction joint moments yielded substantial unexplained variability, though significant relationships were found. This analysis suggested that there is large variability in the pattern of loading joints among national class powerlifters.
Biomechanical analysis of the two-dimensional models composed from roentgenographic pictures and electromyographic analysis of the shear force exerted on the tibia during standing on both legs were conducted in 21 young adult males. The simultaneous contraction of the quadriceps and hamstrings was observed in all electromyograms. Amplitude observed on electromyograms of the hamstrings increased as the trunk flexion angle increased. The calculated average values of shear force were negative at every knee flexion angle (negative value means posteriorly directed force). As the trunk flexion angle increased, posterior drawer force increased at knee flexion angles of 30 degrees and 60 degrees. The simultaneous contraction of the quadriceps and the hamstrings was considered to be the main factor that influenced these results. Standing on both legs with knee and trunk flexion was considered to be applicable in the early stages after anterior cruciate ligament reconstruction.
Rehabilitation is recognised as a critical component in the treatment of the anterior cruciate ligament (ACL) injured athlete, and has been the subject of intense research over the past decade. As a result, sound scientific principles have been applied to this realm of sports medicine, and have improved the outcome of both surgical and nonsurgical treatment. Possibly the most intriguing of these principles is the use of the kinetic chain concept in exercise prescription following ACL reconstruction.
The hip, knee, and ankle joints when taken together, comprise the lower extremity kinetic chain. Kinetic chain exercises like the squat recruit all 3 links in unison while exercises such as seated quadriceps extensions isolate one link of the chain. Biomechanical assessment with force diagrams reveals that ACL strain is reduced during kinetic chain exercise by virtue of the axial orientation of the applied load and muscular co-contraction.
Additionally, kinetic chain exercise through recruitment of all hip, knee, and ankle extensors in synchrony takes advantage of specificity of training principles. More importantly, however, it is the only way to reproduce the concurrent shift of ‘antagonistic’ biarticular muscle groups that occurs during simultaneous hip, knee, and ankle extension. Incoordination of the concurrent shift fostered by exercising each muscle group in isolation may ultimately hamper complete recovery. Modifying present day leg press and isokinetic equipment will allow clinicians to make better use of kinetic chain exercise and allow safe isokinetic testing of the ACL reconstructed knee. Reconstruction of the ACL with a strong well placed graft to restore joint kinematics, followed by scientifically sound rehabilitation to improve dynamic control of tibial translation, will improve the outcome after ACL injury.
The purpose of this study was to determine whether abdominal belts such as those prescribed to industrial workers reduced trunk muscle activity and/or increased intra-abdominal pressure (IAP). In this study, six subjects lifted loads (72.7 to 90.9 kg) both with and without wearing a weightlifter belt. In addition, further trial conditions required that subjects lifted both with the breath held or continuously expiring on lifting effort. Dynamic hand loads were recorded together with intra-abdominal pressure (IAP) and abdominal, intercostal and low back EMG. Every subject demonstrated an increase in IAP when wearing the belt during both breathing conditions: 99 mmHg with no belt; 120 mmHg wearing belt (p less than 0.0001). However, it was also found that significant increases in IAP occurred (p less than 0.017) when the breath was held versus exhaling with or without the belt. One would expect that if the belt relieved either the direct compressive load on the spine or assisted IAP to produce an extensor moment then this would be reflected in diminished extensor muscle activity. Erector spinae activity tended to be lower with the breath held suggesting a reduced load on the lumbar spine although wearing a belt did not augment this reduction. In the case studies with subjects wearing an ergogenic corset designed for use by industrial manual materials handlers, perceptions of improved trunk stability were reported. However, the muscle activity and IAP results of this study during short duration lifting tasks make it difficult to justify the prescription of abdominal belts to workers.
The purpose of this study was to examine the effectiveness of weight-belts during the performance of the parallel squat exercise. Six subjects were filmed (40 fps) as they performed three trials at each of three belt conditions (NB, none; LB, light; HB, heavy) in random order and three load conditions (70, 80, 90% 1RM (one repetition maximum] in increasing order. The parameters examined were collected and interfaced to a computer via an analog-to-digital (A/D) converter: ground reaction forces, intra-abdominal pressure (IAP), and EMG for the rectus abdominus (RA), external oblique (EO), and erector spinae (ES) muscles. Most differences were observed during the 90% 1RM condition, and only they are presented in this paper. Maximum IAP values were always greater (P less than 0.05) for the weight-belt conditions (LB, 29.2; HB, 29.1 greater th an NB, 26,8 kPa). Similar results were observed for the mean IAP. The integrated EMG (iEMG) activity of the muscles and adjusted mean values for back compressive force and back muscle force followed a similar but opposite pattern, with NB being the greatest. ES mEMG/(L5/S1) values for HB (18.1%) were the least, followed by LB (20.01%) and NB (22.3%). Few differences were observed between belt types. These data suggest that a weight-belt can aid in supporting the trunk by increasing IAP.
The load on the lumbar spine was calculated in eight power lifters when they executed an extremely heavy lift. The calculated load on L3 as well as the total load lifted during training in the last year were related to the bone mineral content (BMC) in the L3 as determined with dual photon absorptiometry. The loads on L3 in the lifters ranged between 18.8 and 36.4 kN. The BMC values were extremely high and closely correlated to the amount of weight lifted during training (r2 = 0.82). The study showed that intensive training will increase the BMC to an extent that the spine can tolerate extraordinary loads.
The purpose of the study was to investigate the effects of load height on selected performance characteristics of a squat exercise. A lower center of mass bar was designed that allowed the integrity of the squat exercise to be maintained while possibly reducing the chances of injury. Five trials were performed with the center of mass of the bar was set at shoulder height (C1) and lowered 18% (C2) and 36% (C3) of the subject's height below the normal bar position using the inverted "U" bar. All trials were filmed as the subjects lifted on a force platform. A balloon catheter was inserted into the subject's recta to monitor intra-abdominal pressure (IAP). High correlations were found between IAP, joint moment, and force data. Many of the critical parameters occurred just after the lowest squat position. Significant differences (P less than 0.05) in trunk angle excursion and trunk angular velocity indicated a greater ease of hip extension for the center of mass bar conditions. No differences were observed between conditions for thigh and knee angles and joint moments indicating kinematic similarity for the lower extremity. IAP was always least for C2 and C3, while compression, shear, and back muscle forces did not differ. It was estimated that the greater IAP was responsible for relieving back muscle forces and compression by up to 15 and 21%, respectively, and increased stress with the weight at shoulder height stimulated a response for greater IAP to help alleviate the stresses on the spine.
The purpose of this study was to quantify the amount of anterior tibial displacement occurring in anterior cruciate ligament-deficient knees during two types of rehabilitation exercises: 1) resisted knee extension, an open kinetic chain exercise; and 2) the parallel squat, a closed kinetic chain exercise. An electrogoniometer system was applied to the anterior cruciate ligament-deficient knee of 11 volunteers and to the uninvolved normal knee in 9 of these volunteers. Anterior tibial displacement and the knee flexion angle were measured during each exercise using matched quadriceps loads and during the Lachman test. The anterior cruciate ligament-deficient knee had significantly greater anterior tibial displacement during extension from 64 degrees to 10 degrees in the knee extension exercise as compared to the parallel squat exercise. In addition, the amount of displacement during the Lachman test was significantly less than in the knee extension exercise, but significantly more than in the parallel squat exercise. No significant differences were found between measurements in the normal knee. We concluded that the stress to the anterior cruciate ligament, as indicated by anterior tibial displacement, is minimized by using the parallel squat, a closed kinetic chain exercise, when compared to the relative anterior tibial displacement during knee extension exercise.
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.
We chose to investigate tibiofemoral joint kinetics (compressive force, anteroposterior shear force, and extension torque) and electromyographic activity of the quadriceps, hamstring, and gastrocnemius muscles during open kinetic chain knee extension and closed kinetic chain leg press and squat. Ten uninjured male subjects performed 4 isotonic repetitions with a 12 repetition maximal weight for each exercise. Tibiofemoral forces were calculated using electromyographic, kinematic, and kinetic data. During the squat, the maximal compressive force was 6139 +/- 1708 N, occurring at 91 degrees of knee flexion; whereas the maximal compressive force for the knee extension exercise was 4598 +/- 2546 N (at 90 degrees knee flexion). During the closed kinetic chain exercises, a posterior shear force (posterior cruciate ligament stress) occurred throughout the range of motion, with the peak occurring from 85 degrees to 105 degrees of knee flexion. An anterior shear force (anterior cruciate ligament stress) was noted during open kinetic chain knee extension from 40 degrees to full extension; a peak force of 248 +/- 259 N was noted at 14 degrees of knee flexion. Electromyographic data indicated greater hamstring and quadriceps muscle co-contraction during the squat compared with the other two exercises. During the leg press, the quadriceps muscle electromyographic activity was approximately 39% to 52% of maximal velocity isometric contraction; whereas hamstring muscle activity was minimal (12% maximal velocity isometric contraction). This study demonstrated significant differences in tibiofemoral forces and muscle activity between the two closed kinetic chain exercises, and between the open and closed kinetic chain exercises.
The purpose of this study was to analyze intersegmental forces at the tibiofemoral joint and muscle activity during three commonly prescribed closed kinetic chain exercises: the power squat, the front squat, and the lunge. Subjects with anterior cruciate ligament-intact knees performed repetitions of each of the three exercises using a 223-N (50-pound) barbell. The results showed that the mean tibiofemoral shear force was posterior (tibial force on femur) throughout the cycle of all three exercises. The magnitude of the posterior shear forces increased with knee flexion during the descent phase of each exercise. Joint compression forces remained constant throughout the descent and ascent phases of the power squat and the front squat. A net offset in extension for the moment about the knee was present for all three exercises. Increased quadriceps muscle activity and the decreased hamstring muscle activity are required to perform the lunge as compared with the power squat and the front squat. A posterior tibiofemoral shear force throughout the entire cycle of all three exercises in these subjects with anterior cruciate ligament-intact knees indicates that the potential loading on the injured or reconstructed anterior cruciate ligament is not significant. The magnitude of the posterior tibiofemoral shear force is not likely to be detrimental to the injured or reconstructed posterior cruciate ligament. These conclusions assume that the resultant anteroposterior shear force corresponds to the anterior and posterior cruciate ligament forces.
During an unloaded squat, hamstring and quadriceps co-contraction has been documented and explained via a co-contraction hypothesis. This hypothesis suggests that the hamstrings provide a stabilizing force at the knee by producing a posteriorly-directed force on the tibia to counteract the anterior tibial force imparted by the quadriceps. Research support for this hypothesis, however, is equivocal. Therefore, the purposes of this study were 1) to determine muscle recruitment patterns of the gluteus maximus, hamstrings, quadriceps, and gastrocnemius during an unloaded squat exercise via EMG and 2) to describe the amount of hamstring-quadriceps co-contraction during an unloaded squat. Surface electrodes were used to monitor the EMG activity of six muscles of 41 healthy subjects during an unloaded squat. Each subject performed three 4-s maximal voluntary isometric contractions (MVIC) for each of the six muscles. Electrogoniometers were applied to the knee and hip to monitor joint angles, and each subject performed three series of four complete squats in cadence with a metronome (50 beats.min-1). Each squat consisted of a 1.2-s eccentric, hold, and concentric phase. A two-way repeated measures ANOVA (6 muscles x 7 arcs) was used to compare normalized EMG (percent MVIC) values during each arc of motion (0-30 degrees, 30-60 degrees, 60-90 degrees, hold, 90-60 degrees, 60-30 degrees, 30-0 degrees) of the squat. Tukey post-hoc analyses were used to quantify and interpret the significant two-way interactions. Results revealed minimal hamstring activity (4-12% MVIC) as compared with quadriceps activity (VMO: 22-68%, VL: 21-63% of MVIC) during an unloaded squat in healthy subjects. This low level of hamstring EMG activity was interpreted to reflect the low demand placed on the hamstring muscles to counter anterior shear forces acting at the proximal tibia.
Little research is available on the muscle activity patterns of the lower extremity muscles during dynamic closed chain squatting activities. The purpose of this study was to examine the effect of lower extremity position during an Olympic squat on the muscle activity patterns of the vastus medialis, vastus lateralis, semimembranosus/semitendinosus, and biceps femoris. Twenty-five healthy, untrained subjects, 18-35 years old, were randomly assigned initial squatting positions of either self-selected neutral or 30 degrees of lower extremity turn-out from the self-selected neutral position. Surface electromyography and motion analysis data were collected simultaneously in 10 degrees intervals and analyzed from 10-60 degrees of knee flexion in both the ascending and descending phases of the squat. A four-way analysis of variance indicated that the main effect of lower extremity position and the interaction of extremity position and knee joint angles were not found to cause significant changes in muscle activity patterns. Significant changes in muscle activity did occur with changes in knee flexion angles in the vastus medialis and vastus lateralis but not in the semimembranosus/semitendinosus or biceps femoris.
Although closed (CKCE) and open (OKCE) kinetic chain exercises are used in athletic training and clinical environments, few studies have compared knee joint biomechanics while these exercises are performed dynamically. The purpose of this study was to quantify knee forces and muscle activity in CKCE (squat and leg press) and OKCE (knee extension).
Ten male subjects performed three repetitions of each exercise at their 12-repetition maximum. Kinematic, kinetic, and electromyographic data were calculated using video cameras (60 Hz), force transducers (960 Hz), and EMG (960 Hz). Mathematical muscle modeling and optimization techniques were employed to estimate internal muscle forces.
Overall, the squat generated approximately twice as much hamstring activity as the leg press and knee extensions. Quadriceps muscle activity was greatest in CKCE when the knee was near full flexion and in OKCE when the knee was near full extension. OKCE produced more rectus femoris activity while CKCE produced more vasti muscle activity. Tibiofemoral compressive force was greatest in CKCE near full flexion and in OKCE near full extension. Peak tension in the posterior cruciate ligament was approximately twice as great in CKCE, and increased with knee flexion. Tension in the anterior cruciate ligament was present only in OKCE, and occurred near full extension. Patellofemoral compressive force was greatest in CKCE near full flexion and in the mid-range of the knee extending phase in OKCE.
An understanding of these results can help in choosing appropriate exercises for rehabilitation and training.
The purpose of this study was to selectively challenge the vastus medialis oblique muscle in comparison with the vastus lateralis, the vastus intermedius, and the vastus medialis longus muscles by performing nine sets of strengthening exercises. These knee rehabilitation exercise included isometric knee extension with the hip at neutral, 30 degrees external, and 30 degrees internal rotation; isokinetic knee extension through full range; isokinetic knee extension in the terminal 30 degrees arc; sidelying ipsilateral and contralateral full knee extension; and stand and jump from full squat. Electrical activity of the vastus medialis oblique, the vastus lateralis, the vastus intermedius, and the vastus medialis longus muscles was measured in eight uninjured subjects. Our study showed that isometric exercises in neutral and external rotation of the hip will challenge both the vastus medialis oblique and the vastus lateralis muscles. The results suggest that the electromyographic activity of the vastus medialis oblique muscle was not significantly greater than that of the vastus lateralis, the vastus intermedius, and the vastus medialis longus muscles during the nine sets of exercises. Results suggest that the vastus medialis oblique muscle cannot be significantly isolated during these exercises.
Strength athletes often employ the deadlift in their training or rehabilitation regimens. The purpose of this study was to quantify kinematic and kinetic parameters by employing a three-dimensional analysis during sumo and conventional style deadlifts.
Two 60-Hz video cameras recorded 12 sumo and 12 conventional style lifters during a national powerlifting championship. Parameters were quantified at barbell liftoff (LO), at the instant the barbell passed the knees (KP), and at lift completion. Unpaired t-tests (P < 0.05) were used to compare all parameters.
At LO and KP, thigh position was 11-16 degrees more horizontal for the sumo group, whereas the knees and hips extended approximately 12 degrees more for the conventional group. The sumo group had 5-10 degrees greater vertical trunk and thigh positions, employed a wider stance (70 +/- 11 cm vs 32 +/- 8 cm), turned their feet out more (42 +/- 8 vs 14 +/- 6 degrees). and gripped the bar with their hands closer together (47 +/- 4 cm vs 55 +/- 10 cm). Vertical bar distance, mechanical work, and predicted energy expenditure were approximately 25-40% greater in the conventional group. Hip extensor, knee extensor, and ankle dorsiflexor moments were generated for the sumo group, whereas hip extensor, knee extensor, knee flexor, and ankle plantar flexor moments were generated for the conventional group. Ankle and knee moments and moment arms were significantly different between the sumo and conventional groups, whereas hip moments and moments arms did not show any significantly differences. Three-dimensional calculations were more accurate and significantly different than two-dimensional calculations, especially for the sumo deadlift.
Biomechanical differences between sumo and conventional deadlifts result from technique variations between these exercises. Understanding these differences will aid the strength coach or rehabilitation specialist in determining which deadlift style an athlete or patient should employ.
Improper lifting techniques may increase injury risks and decrease performance. The aim of this study was to compare and contrast biomechanical parameters between sumo and conventional style deadlifts and between high- and low-skilled lifters who participated in the powerlifting event during the 1999 Special Olympics World Games.
Two synchronized video cameras collected 60 Hz of data from 40 subjects. Parameters were quantified at barbell liftoff (LO), when the barbell passed the knees (KP), and at lift completion.
Compared with the conventional group, the sumo group had a 100% greater stance width, 20% smaller hand width, 10% less vertical bar distance, a more vertical trunk at LO, a more horizontal thigh at LO and KP, a less vertical shank at KP, and greater forefoot abduction. The sumo group generated ankle dorsiflexor, knee extensor, and hip extensor moments, whereas the conventional group produced ankle plantar flexor, knee flexor and extensor, and hip extensor moments. Compared with low-skilled lifters, high-skilled lifters had a 40% greater barbell load, 15% greater stance width (sumo group only), greater knee flexion at LO (conventional group only), greater knee extension at KP, a less vertical shank position at LO (sumo group only), 15% less vertical bar distance, less first peak bar velocity between LO and KP (conventional group only), smaller plantar flexor and hip extensor moment arms at LO and KP, and greater knee extensor moment arms at LO.
The sumo deadlift may be more effective in working ankle dorsiflexors and knee extensors, whereas the conventional deadlift may be more effective in working ankle plantar flexors and knee flexors. High-skilled lifters exhibited better lifting mechanics than low-skilled lifters by keeping the bar closer to the body, which may both enhance performance and minimize injury risk.
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.