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Electromyographic Activity of Lower Body Muscles during the Deadlift and Stiff-Legged Deadlift

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The purpose of this study was to analyze eletromyographic (EMG) signal of biceps femoris (BF), vastus lateralis (VL), lumbar multifidus (LM), anterior tibialis (AT), and medial gastrocnemius (MG) during the deadlift (DL) and stiff-legged deadlift (SLDL). Fourteen men (26.71 ± 4.99 yrs; body mass 88.42 ± 12.39 kg; 177.71 ± 8.86 cm) voluntarily participated in this study. The data were obtained on three non-consecutive days separated by 48 hrs. In the first day, anthropometric measures and the repetition maximum testing (1 RM) for both exercises were applied in a counter-balanced cross-over design. On the second day, the 1 RM was re-tested. On the third day, both exercises were performed at 70% of 1 RM and the EMG data were collected. Parameters related to the RMS during the movement, temporal activation patterns, and relative times of activation were analyzed for each muscle. The maximum activation level for VL during the DL (128.3 ± 33.9% of the EMG peak average) was significantly different (P = 0.027) from the SLDL (101.1 ± 14% of the EMG peak average). These findings should be useful when emphasizing different muscle groups in a resistance training program.
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Journal of Exercise Physiologyonline
June 2013
Volume 16 Number 3
Editor-in-Chief
Tommy Boone, PhD, MBA
Review Board
Todd Astorino, PhD
Julien Baker, PhD
Steve Brock, PhD
Lance Dalleck, PhD
Eric Goulet, PhD
Robert Gotshall, PhD
Alexander Hutchison, PhD
M. Knight-Maloney, PhD
Len Kravitz, PhD
James Laskin, PhD
Yit Aun Lim, PhD
Lonnie Lowery, PhD
Derek Marks, PhD
Cristine Mermier, PhD
Robert Robergs, PhD
Chantal Vella, PhD
Dale Wagner, PhD
Frank Wyatt, PhD
Ben Zhou, PhD
Official Research Journal
of the American Society of
Exercise Physiologists
ISSN 1097-9751
Official Research Journal of
the American Society of
Exercise Physiologists
ISSN 1097-9751
JEPonline
Electromyographic Activity of Lower Body Muscles
during the Deadlift and Stiff-Legged Deadlift
Ewertton Souza Bezerra1, Roberto Simão2, Steven J Fleck3, Gabriel
Paz2, Marianna Maia2, Pablo B. Costa4, Alberto Carlos Amadio5,
Humberto Miranda2, Julio Cerca Serrão5
1Federal University of Amazonas, AM, Brazil; 2Federal University of
Rio de Janeiro, RJ, Brazil; 3Colorado College, CO, USA, 4California
State University, CA, USA, 5São Paulo University, SP, Brazil
ABSTRACT
Bezerra ES, Simão, R, Fleck SJ, Paz G, Maia M, Costa PB,
Amadio AC, Miranda H, Serrão JC. Electromyographic Activity of
Lower Body Muscles during the Deadlift and Stiff-Legged Deadlift.
JEPonline 2013;16(3):30-39. The purpose of this study was to
analyze eletromyographic (EMG) signal of biceps femoris (BF), vastus
lateralis (VL), lumbar multifidus (LM), anterior tibialis (AT), and medial
gastrocnemius (MG) during the deadlift (DL) and stiff-legged deadlift
(SLDL). Fourteen men (26.71 ± 4.99 yrs; body mass 88.42 ± 12.39
kg; 177.71 ± 8.86 cm) voluntarily participated in this study. The data
were obtained on three non-consecutive days separated by 48 hrs. In
the first day, anthropometric measures and the repetition maximum
testing (1 RM) for both exercises were applied in a counter-balanced
cross-over design. On the second day, the 1 RM was re-tested. On
the third day, both exercises were performed at 70% of 1 RM and the
EMG data were collected. Parameters related to the RMS during the
movement, temporal activation patterns, and relative times of
activation were analyzed for each muscle. The maximum activation
level for VL during the DL (128.3 ± 33.9% of the EMG peak average)
was significantly different (P = 0.027) from the SLDL (101.1 ± 14% of
the EMG peak average). These findings should be useful when
emphasizing different muscle groups in a resistance training program
Key Words: Resistance Training, Electromyography, Muscle Strength
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INTRODUCTION
The deadlift (DL) and variations are usually prescribed by strength and conditioning professionals to
strengthen the legs, hips, back, and torso musculature (6). The traditional DL begins with the knees
flexed in a squat type position. The elbows are extended and an alternating handgrip is used to grip
the bar, which is positioned over the metatarsal region of the lifter’s feet. During the concentric
exercise movement, the bar is raised from the floor to a mid-thigh position by extending the hip and
knee joints (8). In the stiff-legged deadlift (SLDL), the concentric phase begins with the knees almost
completely straight and the bar is moved from the floor to a mid-thigh position mainly by hip extension
keeping the knees slightly bent throughout the exercise movement.
Studies have compared the DL and the Sumo style deadlift using 3D kinematic analysis (10) and 2D
kinematic analysis (18). Kinematic analysis has also been used to compare DL technique of skilled
and unskilled lifters (4). Although several studies have examined the DL, only a few researchers have
investigated muscle activation during this exercise (5-8). The DL and Sumo technique have been
compared using electromyography (EMG) analysis. The data indicate that the vastus lateralis, vastus
medialis, gastrocnemius (medial head), and tibialis anterior showed greater muscle activation during
the Sumo style compared to the DL (9).
The SLDL has been compared to the leg curl (LC) and back squat (BS) using EMG techniques (19).
The results indicate that greater muscle activation of the biceps femoris (long head) and the
semitendinosus muscles takes place in each of the exercises during the concentric phase compared
to the eccentric phase. There were differences among the three exercises, with the LC and the SLDL
demonstrating greater biceps femoris and semitendinosus muscle activation vs. the BS exercise (19).
However, there is a lack of evidence to compare muscle activation between the DL and SLDL. Such
information may help coaches and strength and conditioning practitioners to optimize the resistance
training prescription, and also specify the performance of a target muscle during the execution of an
exercise. Thus, the purpose of this study was to analyze the EMG signal of biceps femoris (BF),
vastus lateralis (VL), lumbar multifidus (LM), anterior tibialis (AT), and medial gastrocnemius (MG)
during the DL and SLDL.
METHODS
Subjects
Fourteen men (26.71 ± 4.99 yrs; 88.42 ± 12.39 kg; 177.71 ± 8.86 cm; biacromial diameter 42.44 ±
2.46 cm; and bi-trochanteric diameter 44.54 ± 5.44 cm) voluntarily participated in the study. All
subjects had at least 2 yrs of recreational resistance training experience, no current injury to the lower
extremities, and experience in both the DL and the SLDL resistance exercises. Following an
explanation of the experimental procedures, the subjects read and signed an informed consent form.
This study was approved by the research ethics committee.
Procedures
To investigate muscle activation of selected lower body muscles during the DL and SLDL, data were
collected on three nonconsecutive test days. Forty-eight hours was chosen as the time period
between the 3 tests sessions as this is the minimum rest period needed to recovery between one
repetition maximum (1 RM) attempt (17). On the first test day, anthropometric measurements and the
1 RM for both exercises were determined in a counter-balanced cross-over design. On the second
test session, the 1 RM was re-tested. On third test session, both exercises were performed with 70%
of 1 RM and EMG data were measured for the BF, VL, LM, AT, and MG. Three repetitions using 70%
of the 1 RM was used as the percentage of 1 RM during collection of EMG data because it is often
32
used when performing resistance training (8,19). On third test session, 20 min of rest were provided
between the exercises (which were performed in a crossover design manner).
1 RM Test
The mass of all weight plates and bar (Buick®, São Paulo, SP, Brazil) used for measuring 1 RM were
determined with a precision scale. The data were assessed on two non-consecutive days, separated
by 48 hrs in a counter-balanced cross-over design. To minimize possible errors in the 1 RM tests, the
following strategies were adopted: (a) all subjects received standard instructions before testing on the
general routine of data assessment and the exercise technique of each exercise; (b) the exercise
technique of subjects during all testing sessions was monitored and corrected as needed; and (c) all
subjects were given verbal encouragement during the tests. Each subject’s 1 RM was determined
with a maximum of five 1 RM attempts for each exercise and 3 to 5 min rest intervals between
attempts. After the 1 RM for either the DL or SLDL was determined, a 10 min rest period was
provided before the first 1 RM for the second exercise was performed. Standard exercise techniques
were followed for both exercises. No pause was allowed between the eccentric and concentric
phases of a repetition. In addition, for a repetition to be successful, a complete range of motion as is
normally defined for the exercise had to be completed.
Maximum 1 RM tests were determined on 2 d separated by a 48-hr interval in order to determine test-
retest reliability. The subjects were not allowed to perform any exercise other than normal daily
activity during the period between the testing sessions. Excellent day-to-day reliability for each 1 RM
exercise was shown by this protocol. The 1 RM testing on the two occasions showed intraclass
correlation coefficients of r = 0.96 and r = 0.94 (P<0.05) for the DL and SLDL, respectively.
Additionally, the t tests revealed no significant difference between the 1 RM tests for either of the
exercises.
Characterization of the Movements Analyzed
The DL can be characterized with the barbell initially on the floor. The subject starts the exercise
movement with ~90° knee angle with the thigh parallel to the floor. The bar is grasped with an
alternating handgrip. The hips are flexed with the torso close to 45° from vertical with the scapulae
partially abducted. The hands are placed on the bar at approximately biacromial breadth apart.
During the concentric phase of the movement, the bar passes the shins while the hips and knees
extend. The trunk is raised to an upright standing position while the scapulae are adducted. The
concentric phase is complete once the upright position is achieved. The eccentric phase is performed
by returning the bar to the floor with all joint movements performed in reverse order. In the SLDL start
position the barbell is on the floor, the feet are spread to approximately bitrochanteric width, knees
are slightly flexed, shoulders are in a neutral position, scapula adducted, and hands are holding the
bar with an alternating grip at approximately biacromial breadth. During the concentric phase, the bar
passes the shins, while the hips extend, raising the trunk to an upright standing position while
extending the shoulders and adducting the scapulae. The concentric movement is completed once
the upright position is achieved. The eccentric phase is performed by returning the bar to the start
position with all joint movements performed in the reverse manner compared to the concentric phase.
Electromyographic and Kinematic Data
To examine muscle activity, surface electromyography signals were collected from the muscles to be
analyzed (EMG 1000, Lynx Inc. São Paulo, São Paulo, Brazil). Pre-amplified active electrodes, with a
20 times gain, band pass up to 4 KHz set on a polyurethane structure with two silver plates positioned
10 mm apart were used for all analyses of the muscles examined. Before the application of the
electrodes, the skin was shaved, abraded, and cleansed with alcohol. The electrodes were then
33
placed between the motor point and the distal tendon in each muscle studied in the direction of the
muscle’s fibers (14).
For the assessment of the kinematic data, spherical plastic markers (2.5 cm in diameter) covered with
reflective tape were positioned over the following bony landmarks: lateral malleolus of the right ankle,
proximal upper edge of the lateral tibial plateau of the right knee, greater trochanter of the right femur,
and lateral acromion process of the right shoulder. In addition, a piece of reflective tape (1 cm2) was
positioned on the third metatarsal head of the right foot. Data were collected at 30 HZ using a video
camera (SONY®, São Paulo, São Paulo, Brazil) during the performance of each exercise. The images
were analyzed using a Vicon Motion Analysis System (Vicon Corporation, Los Angeles, CA, USA).
The beginning and ending position of the eccentric and concentric phase for both exercises was
determined with the hip flexed to its greatest extent during the exercise movement. Hip angle was
defined as 0° in the fully flexed hip position.
EMG Analyses
The EMG of the BF, VL, LM, AT, and MG muscles were analyzed during the DL and the SLDL. These
muscles were chosen because they are superficial and biomechanically involved in the exercise
movements (1,8,19). Although the LM is regarded as a deep muscle in the lumbar region, it is slightly
more superficial and can be located by palpation of the spinous process of the 5th vertebra [1]. All
EMG signals were recorded at a sample frequency of 1000 Hz. For each muscle, temporal activation
patterns, muscle activation level, and contraction time were analyzed. Temporal activation patterns
were obtained using a linear wrap trace from the results of the EMG signal of each muscle after
normalization. Muscle activation level was obtained using the Root Mean Square (RMS) measure.
The RMS represents the greatest value obtained during the movement [15]. For the relative time of
activation, a time interval was determined for each muscle in which muscular activity was maintained
at a level over 50% of the peak EMG signal during the movement cycle including both eccentric and
concentric phases. The relative time of activation was expressed as a percentage representing how
long the EMG was above at least 50% of the peak EMG during the temporal activation patterns
(movement cycle) of each exercise.
The original signal of each muscle was smoothed using a butterworth filter (second order butterworth
low pass filter with a frequency of 500 Hz). After filtering, normalization of the EMG signal was
performed using the peak average for each muscle in three repetitions of the DL or SLDL. Briefly, the
maximum EMG value for each muscle was determined for each movement cycle, an average was
calculated, and then a peak muscle activation value for each subject was calculated. This value was
used as a reference value for 100% muscle activation. Thus, the entire signal was normalized using
this value that allowed for comparison among the different muscle groups, exercises, and subjects.
After normalization, the starting and ending points for each of the three repetitions were determined
and then, subsequently, the average EMG calculated. The muscle activation intensity value
represented by the muscular intensity estimation (RMS) was obtained from the original signal. For
normalization, RMS, and the relative time of activation of each muscle, an EMGONIO1 routine was
used (MATLAB 6.0 software; MathworksInc, Natick, Massachusetts, USA). The ORIGIN 6.0 software
(Microcal Software Inc, Massachusetts, USA) was used for graphic representations.
Statistical Analysis
The data were descriptively analyzed in which the mean and standard deviation for each dependent
variable were calculated. Data normality was checked using the Shapiro-Wilk test. The t test for
paired data was used to determine significant differences in maximum RMS and relative activation
time of muscles between the DL and SLDL exercises. The alpha level was set at P<0.05 for all
34
analyses. All statistical analyses were performed using SPSS 20.0 software for Windows (SPSS Inc.,
Chicago, IL, USA).
RESULTS
Comparisons of RMS revealed significant differences (P<0.05) between the DL and the SLDL for the
VL and MG muscles. However, no differences were found for the BF, LM, and AT muscles (Table 1).
Relative time of activation between the DL and the SLDL showed significant differences for the VL
only (P<0.05). No significant differences were found for the others muscles (BF, LM, AT, and MG)
(Table 1).
Table 1. Mean ±SD of EMG Variables Analyses.
DL SLDL
RMS
Mean
±SD
Mean
±SD
P
BF
100.1
24.7
98.6
28.5
0.699
VL
128.3*
33.9
101.1*
14.6
0.027
LM
112.7
42.7
106
20.5
0.609
MG
103.8*
12
108.3*
16.3
0.012
AT
104
18.8
109.2
15.3
0.130
DL SLDL
EMG/TIME
Mean
±SD
Mean
±SD
P
BF
32.00
16.66
31.08
23.86
0.890
VL
43.42*
18.85
21.11*
14.71
0.026
LM
10.53
5.85
20.41
18.83
0.109
MG
50.99
27.49
29.80
16.63
0.088
AT
40.43
35.16
37.83
38.61
0.709
RMS: Percentage normalization of the EMG peak average; EMG/TIME: relative time activation as
percentage of movement cycle above 50% of RMS; BF: biceps femoris; VL: vastuslateralis; LM:
lumbar multifidus; MG: medial gastrocnemius; AT: anterior tibialis; DL: Deadlift; SLDL: Stiff-legged
deadlift. *Significant differences between the DL and the SLDL (P<0.05).
The temporal activation between the DL and SLDL for the BF, LM, MG, and AT muscles
demonstrated similar patterns. However, the VL muscle showed a different activation pattern. During
the DL, the VL showed higher activation at the beginning of the ascent and ending of the descent
35
phases. In contrast, during the SLDL, the VL showed its highest activation at ~60° of ascent phase
(Figure 1).
Figure 1. Mean ±SD of the RMS for the Analyzed Muscles. BF: biceps femoris; VL: vastus
lateralis; LM: lumbar multifidus; MG: medial gastrocnemius; AT: anterior tibialis; DL: Deadlift; SLDL:
Stiff-legged deadlift. *Significant differences between the DL and the SLDL (P<0.05).
DISCUSSION
The key findings of this study were the differences in RMS for the VL and MG muscles between the
DL and SLDL exercises. In addition, the VL demonstrated a higher relative activation time (i.e., time
above 50% RMS) than the other muscles during the DL. The VL muscle had a peak of activity during
the first 20° of the ascent phase due to its role in knee extension and indirectly hip extension (in that
the movement is a closed kinetic chain exercise). This finding is consistent with results from the
parallel squat (2), mini-squat (6), leg press, squat, and deadlift (8,11); all demonstrated an increased
level of activity in the VL muscle in the beginning of the concentric phase.
The changes in the VL muscle EMG potential during the DL may be associated with its role during
knee joint extension (ascent phase) and flexion (descent phase) of the DL movement and the
36
concomitant decrease of motor units used at the same resistance during the descent phase of the
movement. The percentage of activity in the data presented in this study is greater than reported by
Gullett and colleagues (12), who analyzed the differences in EMG activity of lower limb muscles as a
function of bar position (front or back to the trunk) in the squat exercise. In the Gullet et al. study (12),
the VL muscle activation was 60% of maximal voluntary isometric contraction (MVIC). However, it is
noteworthy that the forms of normalization of EMG signals were different, since the aforementioned
study used MVIC.
Proposed Mechanisms to Explain the EMG Activity
In the descent phase of the DL (between -40° to 0°), the RMS signal for the VL also increased but not
to the extent as it did in the ascent phase. The gradual increase of this muscle’s activity is due to the
changing need to exert more strength by the time the knee flexion becomes more acute during the
descent phase of the DL movement. Similar findings were noticed by Escamilla et al. (8,9) and Gullett
et al. (12) during the squat and the conventional style DL. The VL RMS during the SLDL showed a
constant activity during the descent phase of the movement (between -80° and 0°). However, it
shows an activity peak between 40° and 60° in the ascent phase of the SLDL movement, possibly
due to the factors of needing to increase the muscle activity at this knee angle of the movement and
to counteract the co-contraction of the long head of the BF that has an increased muscle activity
during the same movement phase. The increased VL RMS may also be essential for knee joint
stabilization, but more research is needed to confirm this point.
The MG activity during the DL and SLDL exercises increased slightly during the ascent phase. The
increased MG activity during the ascent phase could be explained by an increased plantar flexion
moment during this phase as shown by Escamilla et al. (2000) for the conventional style DL. Da Silva
et al. (5) found that the gastrocnemius muscle is more activated during leg press exercise with low
foot placement and 45° (near 80% of MVIC). This may have happened due to the increased plantar
flexion movement in the two exercises. However, the RMS showed significant differences with the
SLDL that may be attributed to the initial imbalance of the body caused by not bending the knee,
which required a greater involvement of stabilizing muscles with MG.
The BF behavior during the DL showed a muscle activity peak in the beginning of the ascent phase
between 20° and 40° of hip extension followed by a decrease in the last degrees (-20°) of movement
during the descent phase (hip flexion). However, this factor may not be attributed to a reduction of
muscle activation in the descent phase, since as previously shown, at the same force output eccentric
actions compared to concentric actions involve a smaller activation of motor units and, therefore, a
decrease in the EMG amplitude. The RMS average observed for BF during the initial ascent phase of
the DL is due to the role it muscle plays during hip joint extension. These findings were similar to
Escamilla and colleagues (9) who observed that for DL the movement during the execution of the
technique variations (e.g. sumo and conventional) and during movements such as the squat showed
higher muscle activity of BF during hip joint extension (19). During the SLDL, the BF showed the
same behavior as during the DL, with a peak of muscle activity in the ascent phase between 20° and
40° during hip extension. Similar results were observed for DL, it was showed also a decreasing in BF
activity in the descent phase (-80° to -20° of the movement) while the hip joint flexion was performed.
The behavior of the BF during the DL and the SLDL in ascent and descent phases were similar and
may be attributed to its role during both flexion (descent phase) and extension (ascent phase) of the
hip joint during the exercise movement.
Synergist Muscle Behavior during the Resistance Exercises
The findings of this study disagree with the findings of the Yamishita (20) study, who suggested that
agonist-antagonist concurrent activation may generate an inhibition in the activation of the muscles.
37
This hypothesis indicated that the single-joint exercise such as the SLDL may provide an increase in
hamstring muscle activity. Wright et al. (19) also observed that squat promoted less muscle activation
of BF and semitendinosus when compared to LC and SLDL. These studies are also in contrary to the
results found by Luttgens and Wells (16), who did not observed any significant difference in the
hamstring activity during hip and knee extension.
The LM activation during the DL and the SLDL may be characterized as a normal pattern of muscle
activity, since little variation was showed during the ascent and descent phases of the movements.
Similar results were observed by Escamilla et al. (9) for the sumo and conventional style deadlift.
Despite kinematic differences caused by an increased forward flexion of the trunk during the
conventional DL, variations regarding muscle activity of the LM did not occur, indicating that the
action of the LM does not change significantly during the DL. Hamlyn et al. (13) found that the erector
spine muscles in the lumbosacral region showed an increase of 34.5% in muscle activity while
performing a squat compared to the DL.
Although in the current study, there were no significant differences between the two movements. It is
noteworthy that the muscle activity was high (i.e., above 80% of MVIC) (3), which may indicate a high
stabilizing effect. The AT muscle activity remained constant at a low intensity during the DL and
SLDL. Relative time of activation showed high standard deviation values indicating a high variation
among subjects for both exercises, which indicates individual technique may be a factor that affects
muscle activity during the DL and SLDL.
Limitations and Implications
One of the limitations of the current study is that only one set of each exercise was performed. A
traditional resistance training session is composed by multiple sets and exercises. Also, the relative
time of activation may be influenced by the subjects’ resistance training experience. However, in the
current study all subjects had at least 2 yrs of resistance training experience with the DL and SLDL
exercises. This suggests that other factors may be responsible for the relative time of activation such
as the number of sets, loads, and velocity. The BF and AT showed a similar mean relative time of
activation for both the DL and SLDL. The VL and MG had higher mean relative time of activation
during the DL while the LM had a higher mean during the SLDL. The lack of agreement in the
scientific literature related to muscle relative time of activation in dynamic movements (including the
DL and SLDL) is a limitation, which make the comparison between the exercises difficult. Thus, in
future studies other variables should be evaluated such as the influence of number of sets, exercise
velocity, load intensity and muscle groups in the muscle activation and relative time activation during
back squat exercises.
CONCLUSIONS
The EMG data indicate that the DL is more effective for activating the VL muscle than the SLDL.
However, the MG muscle showed higher muscle activation during the SLDL than the DL. These
findings should be useful when emphasizing different muscle groups in a resistance training program.
38
ACKNOWLEDGMENTS
Dr. Humberto Miranda is grateful to the Research and Development Foundation of Rio de Janeiro
State (FAPERJ).
Address for correspondence: Miranda H, PhD, School of Physical Education and Sports, Federal
University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil, ZIP CODE: 21941-590, Phone:+55 21 2287-
9329, Email: humertomirandaufrj@gmail.com.
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the editorial staff or the ASEP organization.
... 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 activation of BF peaked at the onset of concentric contractions during DL exercise while GM was more activated close to the lockout position. ...
... RF showed the lowest activation in the mid-pull position, with differences for the initial position. This result is similar to that found by [10], and a decreased activity in other quadriceps muscles has also been reported [13,14]. The decrease in activation in this position of muscles of the quadriceps group would occur by changing the position of the hip in extension [5,15]. ...
... BF showed higher activation in the mid-pull position. These results agree with other studies [4,10,[13][14][15]. This increased activation is the result of a position in which BF is acting as a hip extensor at an optimal angle. ...
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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.
... d that the walk-in deadlift machine has the potential to place less stress on the low back during the deadlift, with a generally more upright posture and ES activity depending on foot position.However, the authors also noted a general shift away from the GM and towards the knee extensors, limiting its long-term usefulness as a deadlift replacement.Bezerra, et al., 2013 The purpose of this study(5) was to analyze electromyography (EMG) signal of the biceps femoris (BF), vastus lateralis (VL), lumbar multifidus (LM), anterior tibialis (AT), and medial gastrocnemius (MG) during the deadlift (DL) and stiff-legged deadlift (SLDL). Fourteen men (mean ± SD; 26.71 ± 4.99 yrs, 88.42 ± 12.39 kg, 177.71 ± 8.86 c ...
... There were no differences between skill levels. The authors concluded that the walk-in deadlift machine has the potential to place less stress on the low back during the deadlift, with a generally more upright posture and ES activity depending on foot position.However, the authors also noted a general shift away from the GM and towards the knee extensors, limiting its long-term usefulness as a deadlift replacement.Bezerra, et al., 2013 The purpose of this study(5) was to analyze electromyography (EMG) signal of the biceps femoris (BF), vastus lateralis (VL), lumbar multifidus (LM), anterior tibialis (AT), and medial gastrocnemius (MG) during the deadlift (DL) and stiff-legged deadlift (SLDL). Fourteen men (mean ± SD; 26.71 ± 4.99 yrs, 88.42 ± 12.39 kg, 177.71 ± 8.86 cm) with two years of recreational resistance training experience performed exercises on three nonconsecutive days. ...
Thesis
BACKGROUND: The capacity to do work is greatly affected by high altitude exposure. Larger muscle groups of the lower body and exercises primarily aerobic in nature have been well investigated at high altitude. The present study examined acute altitude exposure on the number of repetitions to failure and electromyographic (EMG) repetition duration (Time), EMG root mean square (RMS) and EMG mean power frequency (MPF) during dynamic constant external resistance (DCER) exercise of the biceps brachii. METHODS: Thirteen subjects performed two sets of fatiguing DCER arm curl repetitions to failure at 70% of their one repetition maximum (1RM) obtained at 1067 m, in simulated normobaric elevations of 1067m, 2438m, and 3810m. Electromyography of the biceps brachii was analyzed for EMG Time, EMG RMS, and EMG MPF. Repetitions were selected as 25%, 50%, 75% and 100% of total repetitions completed. RESULTS: There was no significant three-way (altitude x set x percent of repetitions to failure) or two-way (altitude x set or percent of repetitions to failure) interaction for any variable. The number of repetitions to failure significantly decreased from (mean ± SEM) 18.2 ± 1.4 to 9.5 ± 1.0 with each set. In addition, EMG Time increased (25% < 50% < 75% < 100%), EMG RMS decreased (50% > 75% > 100%), and EMG MPF decreased (75% > 100%) as a result of fatiguing exercise. DISCUSSION: The changes in biceps brachii EMG variables indicated exercise caused myoelectric manifestations of fatigue, however, acute altitude exposure had no additional influence on rate of fatigue development or neuromuscular parameters.
... ence in biceps femoris (BF) activation between the conventional and Ro-Furthermore, Bezerra et al.[17] also investigated studies analyzing EMG signals in the lower extremities and lower back during conventional and stiff leg deadlift exercises. All the study was conducted on males, and all of the exercises were conducted at 70% of the one repetition maximum. ...
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The deadlift is a fundamental exercise in resistance training, essential for the development of overall strength and power. This review synthesizes current research on kinematics and electromyographic (EMG) activity during deadlifts, highlighting the effects of different variations and techniques on performance and muscle activation. Kinematic studies have revealed significant differences in joint angles and movement patterns between conventional and sumo deadlifts, emphasizing the importance of technique and experience in optimizing performance and reducing injury risk. EMG analysis has also revealed distinct muscle activation profiles for key muscles, such as the vastus lateralis, gluteus maximus, and hamstrings, across different deadlift variations. These findings are critical for designing effective, individualized training programs in strength and conditioning, as well as developing targeted rehabilitation and injury prevention strategies in sports medicine. By understanding the biomechanical and neuromuscular dynamics of the deadlift, practitioners can improve performance, minimize injury risk, and tailor interventions to the specific needs of athletes. Thus, this review provides a comprehensive overview of the current understanding of deadlift kinematics and EMG activity, offering valuable insights for optimizing training and rehabilitation protocols.
... Unlike the RH and CP, muscle activation of the RDL has been compared to other exercise variants in several different studies (2,6,14,16,17,20). For example, Lee and colleagues compared the EMG activation of the RDL to the conventional deadlift (DL) and found increased activation of the GM and BF during the DL (14). ...
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Hinge exercises are critical to building a balanced resistance training program in concert with 'knee-dominant' (e.g., squat, lunge) exercises. Biomechanical differences between various straight-legged hinge (SLH) exercises may alter muscle activation. For example, a Romanian deadlift (RDL) is a closed-chain SLH, while a reverse hyperextension (RH) is open-chain. Likewise, the RDL offers resistance via gravity while the cable pull-through (CP) offers redirected-resistance through a pulley. A deeper understanding of the potential impact of these biomechanical differences between these exercises may improve their application to specific goals. Participants completed repetition-maximum (RM) testing on the RDL, RH, and CP. On a follow-up visit, surface electromyography of the longissimus, multifidus, gluteus maximus, semitendinosus, and biceps femoris, muscles that contribute to lumbar/hip extension, was recorded. After a warm-up, participants completed maximal voluntary isometric contractions (MVICs) in each muscle. They then completed five repetitions of the RDL, RH, and CP at 50% of estimated one RM. Testing order was randomized. A one-way, repeated-measures ANOVA test was used in each muscle to compare activation (%MVIC) across the three exercises. Shifting from a gravity-(RDL) to a redirected-resistance (CP) SLH significantly decreased activation in the longissimus (-11.0%), multifidus (-14.1%), biceps femoris (-13.1%), and semitendinosus (-6.8%). Alternately, changing from a closed-(RDL) to an open-chain (RH) SLH significantly increased activation in the gluteus maximus (+19.5%), biceps femoris (+27.9%), and semitendinosus (+18.2). Alterations in the execution of a SLH can change muscle activation in lumbar/hip extensors.
... The distance between subjects feet on the footrest was the same as distance between their anterior superior iliac spines (R. F. Escamilla et al., 2001) in all 3 test conditions. Data recording began as the motion started (Bezerra et al., 2013). A prefabricated semi-rigid medial arch support with 2 degrees of medial wedge used in this study was made by Kinsiofit Company in Iran and the shoes were commonly known as squat shoes by athletes (Figure 1). ...
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Background: Nowadays, different types of exercise machines are being used in the field of athletic training, recreation, post-injury and post-operation rehabilitation. Leg press is a commonly-used one that retrains muscles and simulates natural functional activities. In this activity, feet are in contact with a footrest to exert muscular forces. In addition, the footrest inserts reactive forces to feet and from the feet load would transfer to structures that are more proximal. Any misalignment in foot structure may interfere its function. Objective: The aim of this study was to assess the effect of shoes and using a prefabricated medial arch support on the activity of Tibialis anterior and medial gastrocnemius muscles while doing leg press exercise in normal feet subjects. Method: 14 men with normal Medial Longitudinal Arch and normal Body Mass Index aged between 18-35 years old, with at least 6 months experience of doing leg press volunteered to participate in this study. Medial gastrocnemius and Tibialis anterior activity were measured by surface electromyography while doing leg press with 70% of subjects 1 Repetition Maximum. To increase accuracy, motion was divided into knee flexion and knee extension phases. Peak Amplitude, Time to Peak Amplitude and Root Mean Square variables were used for analysis. Wilcoxon nonparametric test was used to compare the results. Results: No statistically significant difference was found in the electromyographic parameters of Medial gastrocnemius nor Tibialis anterior in any phases of motion, except for an increase in Tibialis anterior time to peak amplitude in shod condition compared with barefoot in knee extension phase of motion (p-value=0.008) and Tibialis anterior RMS in knee flexion phase in orthotic condition compared to shod (p-value=0.03). Conclusion: It seems that in high loads shoes or medial arch supports cannot change electromyographic parameters in Medial gastrocnemius nor Tibialis anterior in any phase of motion while working with leg press device.
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Trahey, KM, Lapp, EM, Talipan, TN, Guydan, TJ, Krupka, AJ, and Ellis, CE. The effect of lifting straps on deadlift performance in females. J Strength Cond Res 37(10): 1924–1928, 2023—Using lifting straps (LS) while deadlifting may increase the total number of repetitions performed and barbell velocity, and preserve grip strength; however, research in this area has only been conducted on men. This study investigated the effects of lifting straps on the total number of repetitions, mean and peak barbell velocity, and grip strength during the deadlift exercise in women. Ten women (20.1 ± 1.1 years; 165.4 ± 5.6 cm, 68.9 ± 10.3 kg) with 3.2 ± 2.1 years of resistance training experience participated in the study. After completing a 1-repetition maximum (1RM) test without LS, subjects completed 2 protocols: performing 3 sets of as many repetitions as possible of 80% 1RM with lifting straps (WS) and without lifting straps (NS). During both protocols, mean and peak barbell velocity were measured during each set, and grip strength was recorded before deadlifting and after each set. Repeated-measures analysis of variance were used to examine differences in the variables of interest, with an alpha level of 0.05 used to establish statistical significance. The WS condition allowed participants to perform significantly more reps while resulting in no statistically significant differences in mean or peak barbell velocity. The magnitude of grip strength loss was significantly lower during the WS condition. Results indicate that using LS while deadlifting allows women to perform more repetitions with greater preserved grip strength without negatively affecting barbell velocity. Thus, LS appear beneficial for deadlift performance in women and should be considered during resistance training involving the deadlift exercise.
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Deadlift is a measure of the overall strength of the whole body and it is one of the three exercises in the powerlifting competition. There are conventional and sumo variant of deadlift. The aim of this study was to determine the differences between the two lifting techniques from the aspect of kinematics, kinetics and electromyography. Nine physically active men, average age 29.1 ± 3.3 years, body height 181.0 ± 1.0 cm, body weight 82.3 ± 13.3 kg and body massindex 25.0 ± 3.8 kg/m2 were recruited forthisstudy. Each subject lifted weight close to his own body weight with three repetitions, in three series, for each of the techniques. The speed of one lift was 3 seconds for each of the phases (concentric and eccentric). The angles and amplitudes for the following figurative points were monitored: trunk in relation to the horizontal plane (angle), center of the hip joint and center of the knee joint in the "liftoff" (LO - position in which the weight separates from the ground) and "knee passing" (KP - position in which the weight passes in front of the knee position), i.e. in the liftoff-knee passing (LO-KP), knee passing-lift completion (KP-LC; LC - final, i.e. completely upright body position) and liftoff-lift completion (LOLC) phase. The mechanical work was monitored as a one of the kinetic variables. Electromyographic activity was monitored for the following muscles: m. vastus medialis, m. vastus lateralis, m. rectus femoris, m. gluteus Maximus, m. erector spinae (L3-L4), m. semimembranosus and m. biceps femoris caput longum. The monitored electromyographic variablewasthe average normalized amount of muscle activation in relation to maximal voluntary contraction, for all 18 individual deadlift repetitions (3 series × 3 repetitions × 2 techniques). One-way analysis of variance with repeated measurements (for the amount of muscle activation and performed mechanical work) and two-way analysis of variance with repeated measurements (for angles and amplitudes) were used for statistical data processing. Significant differences were found between techniques in the initial angular positions in all monitored joints (p<0.05), except for the angle in the knee joint where the trend was observed (p=0.0996), as well as in the transit position for the trunk angle relative to the horizontal plane and angle at the hip joint (p<0.05). There was a statistically significant difference between techniques in amplitudes in the hip joint during KP-LC phase (p<0.05) and total amplitude (p<0.05), as well as in the knee joint during LO-KP phase (p<0.05) and total amplitude in the form of a trend (p=0.0996). The performed mechanical work is significantly higher when lifting the load with the conventional deadlift technique (DLcon) (p<0.05). Activation of medial and lateral heads of m. quadriceps femoris is significantly higher (p<0.05) when lifting with sumo deadlift technique (DLsu). It was noticed that activation of postural muscle groups (m. erector spinae, m. gluteus maximum, m. semitendinosus and m. biceps femoris caput longum) is higher when lifting the load with DLcon, but not significantly (p>0.05).
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Variations of the deadlift can be executed using the hexagonal (hex) bar by altering, for instance, the knee and torso angles while maintaining a constant hip angle at the start position. Purpose: To examine muscle activation patterns of the biceps femoris, rectus femoris, and erector spinae during three deadlift variations using the hex bar. Methods: Twenty resistance-trained male and female subjects performed hex bar deadlift variations in three different starting knee flexion positions: 128.4 ± 8.5°, 111.9 ± 8.7°, and 98.3 ± 6.5°. Subjects performed three repetitions at 75% of their three-repetition maximum. Electromyography sensors were placed on the dominant biceps femoris, rectus femoris, and lumbar erector spinae. A one-way repeated measures ANOVA was used to detect differences in mean and peak EMG values normalized to maximum voluntary isometric contraction (MVIC) (p < 0.05). Results: As knee flexion increased at the starting position, mean activation of the rectus femoris increased (24.7 ± 21.5 → 35.5 ± 25.4 → 62.1 ± 31.3% MVIC, p < 0.001), while biceps femoris (40.6 ± 17.9 → 34.0 ± 16.4 → 28.1 ± 14.5% MVIC, p = 0.003) and erector spinae (73.0 ± 27.6 → 65.9 ± 34.4 → 54.9 ± 32.5% MVIC, p = 0.009) activation decreased. Peak activation of the rectus femoris increased (46.9 ± 33.0 → 60.9 ± 38.7 → 99.3 ± 41.6% MVIC, p < 0.001) while decreasing in the erector spinae (118.6 ± 47.1 → 105.9 ± 49.4 → 89.1 ± 40.1% MVIC, p = 0.008). The rectus femoris experienced the greatest mean differences of the three muscles. Conclusions: Practitioners should consider the muscular goals when adjusting the starting position of a hex bar deadlift as posterior chain recruitment diminished and quadriceps activation increased as knee flexion increased.
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The present study examined the posterior chain muscle excitation in different deadlift variations. Ten competitive bodybuilders (training seniority of 10.6 ± 1.8 years) performed the Romanian (RD), Romanian standing on a step (step-RD), and stiff-leg deadlift (SD) with an 80% 1-RM. The excitation of the gluteus maximus, gluteus medius, biceps femoris, semitendinosus, erector spinae longissimus, and iliocostalis was assessed during both the ascending and descending phases. During the ascending phase, the RMS of the gluteus maximus was greater in the step-RD than in the RD (effect size (ES): 1.70, 0.55/2.84) and SD (ES: 1.18, 0.11/2.24). Moreover, a greater RMS was found in the SD than in the RD (ES: 0.99, 0.04/1.95). The RMS of the semitendinosus was greater in the step-RD than in the RD (ES: 0.82, 0.20/1.44) and SD (ES: 3.13, 1.67/4.59). Moreover, a greater RMS was found in the RD than in the SD (ES: 1.38, 0.29/2.48). The RMS of the longissimus was greater in the step-RD than in the RD (ES: 2.12, 0.89/3.34) and SD (ES: 3.28, 1.78/4.78). The descending phase had fewer differences between the exercises. No further differences between the exercises were found. The step-RD increased the overall excitation of the posterior chain muscles, possibly because of the greater range of movement and posterior muscle elongation during the anterior flexion. Moreover, the RD appeared to target the semitendinosus more than the SD, while the latter excited the gluteus maximus more.
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To compare the effectiveness of 3 weight-training movements for the hamstrings, 11 weight-trained men performed 3 repetitions at 75% of 1 repetition maximum of the leg curl (LC), stiff-leg deadlift (SLDL), and back squat. Integrated electromyography (EMG) and peak EMG were analyzed in the biceps femoris and semitendinosus independantly during the concentric (CON) and eccentric (ECC) phase of each exercise. Results were as follows: CON-LC and CON-SLDL elicited the greatest integrated EMG activity, with no significant difference between exercises. The CON-squat showed approximately half as much integrated EMG activity as CON-LC and CON-SLDL. Highest peak EMG was found in the CON-LC and CON-SLDL, with no significant difference in these exercises. The CON-squat produced a peak EMG that was approximately 70% of LC and SLDL. We conclude that LC and SLDL involve the hamstrings to a similar degree; however, the back squat involves only about half as much hamstring integrated EMG activity as LC and SLDL. (C) 1999 National Strength and Conditioning Association
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The purpose of this study was to document the differences in kinematics between the Sumo and conventional style deadlift techniques as performed by competitive powerlifters. Videotapes of 19 conventional and 10 Sumo contestants at two regional New Zealand powerlifting championships were analyzed. It was found that the Sumo lifters maintained a more upright posture at liftoff compared to the conventional lifters. The distance required to lift the bar to completion was significantly reduced in the Sumo technique. No significant difference was found between the techniques as to where the sticking point (first decrease in vertical bar velocity) occurred. (C) 1996 National Strength and Conditioning Association
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Six experienced lifters performed 3 squats in each of 4 foot positions: -10[degrees] inward, 0[degrees], 10[degrees] outward, and 20[degrees] outward. These were performed at 2 weight conditions: 65 and 75% of 1 repetition maximum. Surface electromyographic activity of the vastus medialis, vastus lateralis, and rectus femoris on the right leg was analyzed in terms of the activity duration and peak levels of activity. Results and analysis of variance indicated that the foot rotation position did not influence the mean peak activity or mean duration of activity of vastus medialis, vastus lateralis, or rectus femoris. The practice of adopting foot rotation to selectively strengthen individual muscles of the quadriceps group was not supported by this study, which involved smaller, more readily adopted, and comfortable levels of foot rotation than did those previously investigated. (C) 2000 National Strength and Conditioning Association
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The purpose of the present study was to investigate the effects of exercise order on the tonic and phasic characteristics of upper-body muscle activity during bench press exercise in trained subjects. The preexhaustion method involves working a muscle or a muscle group combining a single-joint exercise immediately followed by a multi-joint exercise (e.g., flying exercise followed by bench press exercise). Twelve subjects performed 1 set of bench press exercises with and without the preexhaustion method following 2 protocols (P1-flying before bench press; P2-bench press). Both exercises were performed at a load of 10 repetition maximum (10RM). Electromyography (EMG) sampled at 1 kHz was recorded from the pectoralis major (PM), anterior deltoid (DA), and triceps brachii (TB). Kinematic data (60 Hz) were synchronized to define upward and downward phases of exercise. No significant (p > 0.05) changes were seen in tonic control of PM and DA muscles between P1 and P2. However, TB tonic aspect of neurophysiologic behavior of motor units was significantly higher (p < 0.05) during P1. Moreover, phasic control of PM, DA, and TB muscles were not affected (p > 0.05). The kinematic pattern of movement changed as a result of muscular weakness in P1. Angular velocity of the right shoulder performed during the upward phase of the bench press exercise was significantly slower (p < 0.05) during P1. Our results suggest that the strategies set by the central nervous system to provide the performance required by the exercise are held constant throughout the exercise, but the tonic aspects of the central drive are increased so as to adapt to the progressive occurrence of the neuromuscular fatigue. Changes in tonic control as a result of the muscular weakness and fatigue can cause changes in movement techniques. These changes may be related to limited ability to control mechanical loads and mechanical energy transmission to joints and passive structures.