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Biomechanics of front and back squat exercises

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Squat constitutes one of the most popular exercises to strengthen the muscles of the lower limbs. It is considered one of the most widely spread exercises for muscle sport training and is part of the competition movements comprised within olympic weight-lifting. In physical rehabilitation, squats are used for muscular recovery after different injuries of the lower limbs, especially the knee. In previous anterior cruciate ligament injuries, the mini-squats are generally used, in a knee flexion motion range from 0° to 50° because in this range the shear forces, the tibiofemoral and patellofemoral compression forces decrease related to greater flexion angles. The aim of this work is to make a comparative bidimensional study of the kinematic and dynamic variables of the excecution of the parallel squat exercise with the front and back bar. It is observed in the knee a better development of energy with the front bar, allowing a better muscular exercise with the same load. The mean power absorbed by the hip with the back bar is considerably greater, associated to the speed of the gesture.
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Biomechanics of front and back squat exercises
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Biomechanics of Front and Back Squat exercises
A A Braidot1, M H Brusa1, F E Lestussi1 and G P Parera2
1Laboratorio de Biomecánica FI-UNER. Ruta 11 Km 10 Oro Verde Entre Ríos
Argentina
2Licenciatura en Kinesiología y Fisiatría Universidad Abierta Interamericana. Sede
Regional Rosario.
E-mail: abraidot@bioingenieria.edu.ar
Abstract --Squat constitutes one of the most popular exercises to strengthen the muscles of
the lower limbs. It is considered one of the most widely spread exercises for muscle sport
training and is part of the competition movements comprised within olympic weight-lifting. In
physical rehabilitation, squats are used for muscular recovery after different injuries of the
lower limbs, especially the knee. In previous anterior cruciate ligament injuries, the mini-
squats are generally used, in a knee flexion motion range from 0º to 50º because in this range
the shear forces, the tibiofemoral and patellofemoral compression forces decrease related to
greater flexion angles. The aim of this work is to make a comparative bidimensional study of
the kinematic and dynamic variables of the excecution of the parallel squat exercise with the
front and back bar. It is observed in the knee a better development of energy with the front bar,
allowing a better muscular exercise with the same load. The mean power absorbed by the hip
with the back bar is considerably greater, associated to the speed of the gesture.
1. Introduction
Usually, within the popular knowledge, it is thought that squat is only synonymous of the
quadriceps muscle work, but this is a extremely limited vision.
In the scope of sport biomechanics, exercises are classified into closed kinetic chain (CKC) in
which the distal end remains fixed as in squat and the open kinetic chain exercises (OKC) in
which the distal end of the segment that moves is free, as the seated knee extensions [1][2]. In the
CKC, in addition to the quadriceps work it is originated a better recruitment and activation of
hamstrings, gluteus maximus and gastrocnemius muscles, as regards to the majority work of the
quadriceps such as in OKC exercises [3].
In addition, there is an important activation of muscles locking of the trunk, mainly abdominal and
spine muscles, this activation becomes better during the unstable execution of squat [4], [5].
It is shown in previous data, according to the adopted lumbar position during the execution of the
exercise, there will be variations in the patterns of rectus abdominis, spine and latissimus dorsi
muscles [6].
Related to the contribution of the gluteus maximus muscle, a better recruitment is observed during
deep squat in the concentric phase. There are not significant differences between the relative
contribution of the biceps femoris and vastus during this phase [7]
16th Argentine Bioengineering Congress and the 5th Conference of Clinical Engineering IOP Publishing
Journal of Physics: Conference Series 90 (2007) 012009 doi:10.1088/1742-6596/90/1/012009
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2007 IOP Publishing Ltd
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In the last years the reached speed and the peak of power produced in the force exercises have been
estimated with enough precision using force platforms and contact carpets [8].
As regards the cruciate ligaments, the peak of stress in the posterior cruciate ligament (PCL), is
double in exercises in CKC, and it is increased mean while the flexion of the knee is also increased.
However, the peak of tension of anterior cruciate ligament (ACL), takes place in the exercise of OKC
and near the total extension of the knee [3].
During ACL rehabilitation it is possible to minimize the shear forces by doing mini squat in angles
until 50º of knee flexion and the compression forces in the tibiofemoral and patelo femoral compared
to bigger flexions of this joint. [9].
Russell and Phillips [10] show that no significant differences exist at the maximum peak of the
knee extensor moments, when comparing front and back squad exercises. The slight differences exist
in favour of front squat exercises.
Concerning the maximum extensor moments of the trunk, these are slightly higher in front squat
compared with back squat [10].
In relation to the maximum compression forces, are better in back squat, and shear forces are
slightly better in front squat, at lumbar level. The differences in trunk inclination change these forces
and also the risk of injuries at the level of the lumbar spine [10]. However, a quantification of the
muscular power has not been made in each joint during the exercise. There is no record of an
estimation of the energy generated and absorbed by muscles in the different variants of the squat
exercise.
In the present work we evaluated parallel squat, in which, starting off from the raised position, the
knees are flexed until the thighs are parallel approximately to the horizontal plane, in both variants.
Later, during the phase of ascent, the knees are extended, until returning again to the initial position. It
is compared the kinematics, dynamics, the power and the energy in the different joints during the
complete cycle from the exercise in the different variants of squat.
2. Materials and methods
The correct way to do parallel back squat is to straight up the segment trunk as well as possible so
as to minimize the forces that the lumbar spine can support. The opening of the feet must preferably be
comfortable, with a similar separation to the wide one of shoulders. The bar must be firmly placed on
shoulders, it is grip near them for exerting more pressure on the bar, and preventing that the back is
curved, generating an undesired effort on the lumbar spine. In front squat, the bar is hold up on
clavicles and the superior part of the chest, with the elevated elbows towards the front and with the
most erect trunk, preventing the risk of fall of the bar towards ahead [11].
We evaluated 10 sportsmen familiarized with the execution of the 2 variants of the exercise, which
do not present previous injuries of knees or lumbar spine.
The load to mobilize in the exercises is calculated on the basis of 50% of a maximum repetition (1
RM) of back squat [12]. The same load is used for both variants of the exercise.
Markers were placed to delimit the articulate segments, which are hemispheric of 10 millimeters of
diameter covered by retro reflective material. In figure 1 is the location of the markers: fifth
metatarsal, lateral malleolus, heel, fibula head, femoral lateral epicondyle, greater trochanter, iliaca
crest and the rib cage. The markers are placed in both sides of the body. Another retro reflective
marker was placed at the end of the bar.
The performers were filmed with a videocamera at 25 frames/sec. (corresponding to 50 fields of
image/sec) from the sagittal view with one of their feet on the force platform. The exercise was done
in the parallel line of the film plane.
During each session of exercises, the athletes does 4 consecutive repetitions of front squat, after
that repose 15 minutes before does 4 consecutive repetitions of back squat. Every man is instructed
about does the exercises at its normal speed of execution. This session is repeated with a day of
difference alternating the order of execution of the two variants. For each subject, eight repetitions of
each variant of the exercise by session are processed (four of the right lower limb and four of the left
16th Argentine Bioengineering Congress and the 5th Conference of Clinical Engineering IOP Publishing
Journal of Physics: Conference Series 90 (2007) 012009 doi:10.1088/1742-6596/90/1/012009
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one). Mean comparison were made considering the ten sportman, two sessions, four repetitions for
each leg, then 160 gestures for each variant of squat.
Angles between segments, positions and displacements of the centers of mass and speeds of the
anatomical segments, forces exerted on the force platform and between the segments and muscular net
moments in the joints in each variant of the exercise are evaluated. Also the net powers and energies in
each joint are calculated. The movements are considered bilateral and symmetrical, and they are only
developed in the sagittal plane, being considered the fifth metatarsolphalangeal joint of the foot fixed
to the floor.
In the present work a lot of care was taken
for the correct execution of the exercise.
Consequently the lateral motions in the frontal
plane or those of rotation in the transverse
plane are not considered because the
movement ranks are small and of few
relevance in the analysis.
The data are digitalized and filtered using a
Butterworth filter. A link segment model is
used to evaluate the dynamic changes in which
joints are considered pin joints and the forces
are concentrated in a point in each joint.
With the resolute model the muscular
powers and the energy generated and absorbed
are obtained in each joint. In order to be able to
apply a processing ANOVA (analysis of
variance) [13] represent each one of the
variables according to the percentage of the
cycle of exercise, corresponding 0% at the
moment at which the athlete leaves the raised
position and the end of the cycle (100%)
corresponds at the moment at which the
athletes returns again to the initial position.
This procedure allows to obtain the averages
and the deviations of each variables.
Figure. 1: Disposition of anatomical markers
3. Results
The average angles of the hip, knee and ankle and their standard deviations appear in figure 2. The X-
axis represents the percentage of squat cycle.
16th Argentine Bioengineering Congress and the 5th Conference of Clinical Engineering IOP Publishing
Journal of Physics: Conference Series 90 (2007) 012009 doi:10.1088/1742-6596/90/1/012009
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Figure 2: Joints angles in function of the average of cycle for each repetition.
The curves of
average obtained in
the frontal exercise
of squat are red. The
back squat curves
are blue. The angle
of the hip for back
squat is greater than
the other variant.
This indicates a
greater compromise
at low back due to
the possible lumbar
shear forces. The
mean values for the
knee and ankle joints
are similar for both
variants of the
exercise. The
smaller deviation
observed in the
curves of angles
indicates a better
stability in the
repetitions of the
exercise for the
backward variant.
The average and the deviation (Figure 3) of the net muscular moments of hip, knee and ankle are
normalized with the weight of the athlete plus the load used during the exercise. A significant
difference for both variants is not observed at the hip, knee and ankle.
16th Argentine Bioengineering Congress and the 5th Conference of Clinical Engineering IOP Publishing
Journal of Physics: Conference Series 90 (2007) 012009 doi:10.1088/1742-6596/90/1/012009
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Figure 3: Normalized net muscular moment of the joints of the lower limb
based on the percentage of the cycle of each repetition.
The average and the
deviation (Figure 4) of
the net muscular power
of hip, knee and ankle
are normalized with
the weight of the
athlete plus the load
used during the
exercise.
We observed a
maximum difference of
22% in the averages of
the net powers for the
hip (corresponding to
34% and 58% of the
cycle of squat), being
greater for the
backward variant. On
the other hand, few
differences in the
curves morphology for
net power of the knee
and ankle for both
variants are observed.
4. Discussion
In addition to the analysis of the powers throughout the cycle of squat, it is interesting to study of the
net joint powers in energy terms. First, the total energy absorbed or generated in each repetition is
evaluated. For the absorbed energy,
( )
=f
i
t
tjj dttPowerEa (1)
where j is j-nth repetition, t is the time and ti and tf are the initial and final times in which the power is
negative. The average for the N repetitions of both gestures,
N
Ea
N
jj
Ea
=
=1 (2)
16th Argentine Bioengineering Congress and the 5th Conference of Clinical Engineering IOP Publishing
Journal of Physics: Conference Series 90 (2007) 012009 doi:10.1088/1742-6596/90/1/012009
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Figure 4: Normalized net muscular power of the joints of the lower limb based
on the percentage of the cycle of each repetition.
The standard
deviation are also
obtained. Equivalent
expressions are used
to obtain the
generated energy.
The energies
absorbed and
generated in both
variants of squat are
shown in Tables 1-2
where,
1. Front: front squat,
2. Back: back squat,
3. Gen: Generated
energy
4. Abs: Absorbed
energy.
Table 1. Absorbed and generated energies in the
hip, knee and ankle front exercises
Joint Front-Abs
(mean)
Front-Abs
(standard
deviation)
Front-
Gen
(mean)
Front-Gen
(standard
deviation)
Hip -77,50 17.40 79.97 17.95
Knee -63.06 16.04 64.45 17.18
Ankle -7.42 4.41 9.31 3.95
Table 2. Absorbed and generated energies in the
hip, knee and ankle back exercises
Joint Back-Abs
(mean)
Back-Abs
(standard
deviation)
Back-Gen
(mean)
Back-Gen
(standard
deviation)
Hip -79.69 12.62 78.62 11.81
Knee -58.71 12.03 59.93 11.69
Ankle -6.31 3.36 8.43 3.54
The mean powers absorbed and generated in each variant of squat are reported in Tables 4 - 5 for
each joint. For the absorbed power of each repetition in a joint it is obtained,
( )
( )
=f
i
t
tj
if
jdttPower
tt
PMa 1
(3)
The standard deviation means are obtained too.
16th Argentine Bioengineering Congress and the 5th Conference of Clinical Engineering IOP Publishing
Journal of Physics: Conference Series 90 (2007) 012009 doi:10.1088/1742-6596/90/1/012009
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Table 3. Percentage difference between the
energies absorbed and generated for both variants,
calculated according to the expression:
100%
=back
backfront
Joint Percentage Abs
(mean) Percentage Gen
(mean)
Hip -2.75 1.7
Knee 7.4 7.5
Ankle 17.6 10.44
Table 4. Absorbed and generated power mean
for front squat
Joint Front-
Abs
(mean)
Front -
Abs
(standard
deviation)
Front -
Gen
(mean)
Front -
Gen
(standard
deviation)
Hip -1.16 0.20 1.29 0.24
Knee -0.97 0.29 1.05 0.26
Ankle -0.12 0.07 0.15 0.07
The percentage differences in the absorbed and generated average powers for each joint are shown
in Table 6.
Table 5. Absorbed and generated power mean
for back squat
Joint Back-
Abs
(mean)
Back-
Abs
(standard
deviation)
Back-
Gen
(mean)
Back-Gen
(standard
deviation)
Hip -1.34 0.38 1.35 0.28
Knee -0.99 0.29 1.01 0.22
Ankle -0.11 0.06 0.14 0.07
Table 6. Percentage difference between the
absorbed and generated mean power for both
variants, calculated according to the expression:
100%
=back
backfront
Joint Percentage Abs
(mean) Percentage Gen
(mean)
Hip -13.43 -4.44
Knee -2.02 3.96
Ankle 9.09 7.14
In the knee, the total energy in front squat is greater than back squat in a 7.5%, this would allow a
greater muscular exercise for the same load. In addition, the back squat exercise is performed (in
average) in less time so the mean powers in the knee have similar values (Tables 4, 5 and 6).
Particularly, in back squat the absorbed mean power hip is considerably greater, i.e. an average of
13.43%. This basically would be associated to fact that the exercise is done faster due to the greater
stability obtained in locating the bar backwards.
References
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Journal of Physics: Conference Series 90 (2007) 012009 doi:10.1088/1742-6596/90/1/012009
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[4] K. Anderson y D. G. Behm, “Trunk muscle activity increases with unstable squat movements”,
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[11] J. de Hegedus, “Enciclopedia de la musculación deportiva”, Buenos Aires: Editorial Stadium,
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[13] Norman, GR; Streiner, DL. Bioestadística. Mosby/Doyma. Madrid, 1996.
16th Argentine Bioengineering Congress and the 5th Conference of Clinical Engineering IOP Publishing
Journal of Physics: Conference Series 90 (2007) 012009 doi:10.1088/1742-6596/90/1/012009
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... Although the between-exercise differences in torso and hip movement patterns are readily apparent, kinematic differences at other joints (e.g., knee) are not as clear. The lack of clarity may be attributed to inconsistencies in experimental designs, where studies have compared the front squat and backs squat exercises at absolute loads (e.g., 50% BS-1RM) (Braidot et al., 2007;Diggin et al., 2011), and relative loads (e.g., 70% BS and FS 1-RM; BS-1RM vs FS-1RM) (Gullett et al., 2009;Yavuz et al., 2015). Beyond differences in joint kinematics, the back squat and front squat are also associated with differences in joint kinetics (Braidot et al., 2007;Gullett et al., 2009), which have major implications about the mechanical demands placed upon the musculoskeletal system and any subsequent neuromuscular adaptations that would occur with training. ...
... The lack of clarity may be attributed to inconsistencies in experimental designs, where studies have compared the front squat and backs squat exercises at absolute loads (e.g., 50% BS-1RM) (Braidot et al., 2007;Diggin et al., 2011), and relative loads (e.g., 70% BS and FS 1-RM; BS-1RM vs FS-1RM) (Gullett et al., 2009;Yavuz et al., 2015). Beyond differences in joint kinematics, the back squat and front squat are also associated with differences in joint kinetics (Braidot et al., 2007;Gullett et al., 2009), which have major implications about the mechanical demands placed upon the musculoskeletal system and any subsequent neuromuscular adaptations that would occur with training. ...
... Specifically, the peak knee extensor NJM were significantly greater in the front squat than the back squat at the 80% FS-1RM load, whereas the peak hip extensor NJM were significantly greater in the back squat than the front squat at the 60% and 80% FS-1RM loads. With respect to the knee extensor NJM, previous research comparing the front and back squat exercise at the same absolute load reported no significant differences in knee NJM (Braidot et al., 2007;Russell & Phillips, 1989). Considering the interaction between exercise and load reported in the current study, one potential cause for the lack of differences in previous studies may have occurred because mechanical demands were only compared at a single load. ...
Article
The purpose of this study was to examine load-dependent differences in lower-extremity biomechanics between the back squat (BS) and front squat (FS) exercises. Eleven NCAA Division-I athletes performed three repetitions of the BS and FS at loads of 40%, 60%, and 80% of their FS one repetition maximum (FS-1RM). Kinematic and kinetic data were collected during each squat repetition and used to calculate lower extremity peak joint angles and peak net joint moments (NJM). Peak angles and NJM were compared with a 2 × 3 repeated measures ANOVA. Peak hip extensor NJM were greater during the BS at 60% and 80% of FS-1RM. In comparison, peak knee extensor NJM were greater during the FS at 80% of FS-1RM. However, regression-based prediction of NJM at 100% of FS and BS 1RM indicated that at maximal loads, peak knee NJM are (~3%) higher during the BS. The experimental results suggest that when performed at the same absolute load, the BS and FS are characterized by greater respective mechanical demands imposed on the hip and knee extensors muscles groups. However, prediction-based results suggest that the knee extensor NJM demands are comparable when performed at the same relative load (i.e., with respect to each exercise's RM).
... Both squats mainly target back, hip, knee, and ankle extensors (Bird & Caswy, 2012), but the different load placements in the anterior-posterior direction have attracted interests from researchers. However, previous studies have observed inconsistent findings in joint moments and muscle activities between the two squats (Braidot et al., 2007;Comfort et al., 2011;Gullett et al., 2009;Korak et al., 2018;Russell & Phillips, 1989;Yavuz et al., 2015). These discrepancies could be due to different testing populations and load magnitudes (relative loads vs. absolute loads). ...
... The pooled standard errors of the mean of the difference at the parallel position were 0.03 and 0.03 for the descending and ascending phases, respectively. squats with a straight bar (Hecker et al., 2019) as well as in front squats with a straight bar compared to back squats with a straight bar (Braidot et al., 2007;Yavuz et al., 2015). However, the current study observed increased low-back moments but similar trunk flexion angles between the back and front squats with a straight bar. ...
... As a result of the posterior movement of the load, hip and ankle moments decreased, and knee moments increased. These increased knee moments were consistent with a previous study (Braidot et al., 2007), demonstrating a 7.5% increase in knee energy for the straight-bar front squat compared to the straight-bar back squat. Yavuz et al. (2015) also observed increased vastus medialis activities and decreased semitendinosus activities for the straight-bar front squat compared to the straight-bar back squat. ...
Article
The purpose was to quantify trunk and lower extremity biomechanics among back and front squats with a straight bar and four squats with different anterior-posterior load placements imposed by a transformer bar. Ten males and eight females performed six squat conditions: back and front squats with a straight bar, back and front squats with a transformer bar, and squats with more posteriorly or anteriorly placed loads with a transformer bar. A constant load of 70% of the participant’s one-repetition maximum in the straight-bar front squat was used. Kinematic and kinetic data were collected to quantify joint biomechanics at an estimated parallel squat position in the descending and ascending phases. Squats with more anteriorly placed load significantly decreased trunk flexion and pelvis anterior tilt angles with large effect sizes but increased low-back extension moments with medium to large effect sizes. Hip, knee, and ankle extension moments were generally similar among most conditions. Participants adjusted their trunk and pelvis to mediate the effects of load placements on low-back and lower extremity moments. While lower extremity loading was similar among different squats, the different trunk and pelvis angles and low-back moments should be taken into consideration for people with low-back impairment. KEYWORDS: Low back, hip, knee, squatting, load placement
... On the other hand, squat movement is a widely used resistance exercise. When it is executed correctly it promotes mobility and balance of different joints of the body [8]. This exercise consists of the flexo-extension of the knee and hip obtaining a descent angle of approximately 90° degrees [8] - [10]. ...
... When it is executed correctly it promotes mobility and balance of different joints of the body [8]. This exercise consists of the flexo-extension of the knee and hip obtaining a descent angle of approximately 90° degrees [8] - [10]. This articulated movement makes the squat one of the most used exercises for body training [8]. ...
... This exercise consists of the flexo-extension of the knee and hip obtaining a descent angle of approximately 90° degrees [8] - [10]. This articulated movement makes the squat one of the most used exercises for body training [8]. Physical conditioning plays an important role in the muscular development of the human being, giving greater stability and less risk of injury [11], [12]. ...
Chapter
Full-text available
Biomechanical analyses provide an extensive source of data that are deeply explored by physicians, engineers and trainers from the mechanical and physiological point of view. This data includes kinetic and kinematic parameters that are quite useful to study human locomotion. However, most of these analyses stay on a very superficial level. Recently data and computational science expanded their coverage to new areas and new analysis tools are available. These analyses include the use of machine learning tools for data mining processes. All of these new tools open a total new level of data analysis, thus newer and deeper questions are proposed in order to provide more accurate prediction results with strict decision support. On the other hand, Squat is an exercise widely used for physical conditioning since it puts into operation various muscles at the same time of the lower and upper train. However bad squatting could drive to injuries at the back and knee level. These injuries are especially common in patients without physical conditioning. In this study, squat data is analyzed using Self-Organizing Maps (SOM) to identify possible relevant parameters from the subjects that could affect the movement performance especially at the knee joint.
... The squat is considered the most popular exercise for strengthening the lower limbs as well as being widely used for muscle sport training, forming a major part of competition movements prevalent in Olympic lifting (Braidot et al., 2007). An individual's development of a squat supports key aspects of daily activity, however more specifically the squat pattern is considered a fundamental exercise used in strength and conditioning to improve athletic performance (strength and power) (Kritz, Cronin andHume, 2009 andSaeterbakken andFimland, 2013). ...
... It was hypothesised that both maximal strength and peak force at maximal lift will increase when squats are performed at a declining angle. This study's hypothesis can be accepted for further investigation providing participant sample size is increased to provide necessary improvements to the overall power of this study.The squat is widely considered the most popular and most effective exercise for strengthening the lower limbs and forms the foundation of Olympic lifting movements(Braidot et al., 2007). Previous studies that have incorporated angled surface variables have primarily focused on scientifically clinical applications -observing differences in muscle activation(Escamilla, 2001, Kongsgaard et al,, 2006, Purdam et al., 2004 and Richards et al., 2016) and biomechanical posture (Legg et al., 2016, Purdam et al., 2004 and Youdas et al., 2007). ...
Thesis
Full-text available
The squat is considered the most popular exercise for strengthening the lower limbs as well as being widely used for muscle sport training and competition. An individual’s development of a squat supports key aspects of daily activity as well as being a fundamental exercise used in strength and conditioning to improve both strength and power. Muscle sports such as powerlifting and weightlifting are heavily dependent on both strength and force – their assessment can be used for training interventions, talent identification and competition. The aim of this study is to compare maximal strength (1RM) and peak force at maximal lift variables at different declining squat angle protocols in resistance trained individuals. It is hypothesised that maximal strength and peak force at maximal lift will increase when squats are performed at a declining angle. Seven participants (age 30.4 ± 8.9 years, height 1.8 ± 0.1 m, weight 85.3 ± 6.8 kg) performed 1RM testing at each declining surface variable (0°, 5°, 10° and 15°) – data was collected for both maximal strength (kg) and peak force at maximal lift (N). There was no significance in data for both maximal strength (F(3) = 1.167, p = 0.35, h2 = 0.163) and peak force at maximal lift (F(1.705) = 0.0179, p = 0.806, h2 = 0.029) between conditions. Although no main effect was observed, post hoc calculations for the comparative analysis of effect size (Cohen’s d) was made. A moderate effect size was observed when comparing maximal strength data at 0° (flat) vs. 5° (0.69) and 5° vs. 10° (0.48). Despite this study suffering from being underpowered (35% of the suggested sample size), contemporary studies have suggested that whilst data may not be statistically significant (p-value), moderate-to-large effect size (Cohen’s d) calculations provide an alternative representation for the magnitude of data. This study serves as one of the first comprehensive explorations into the effects of declining squat protocols on athletic performance. Future research should focus on improving statistical significance of the data through meeting estimated sample size calculations (20 participants). Keywords: squat • maximal strength • peak force • decline • performance
... 1-2 repetición al 80%). Tras el 90% del 1RM, el incremento de la carga es progresivo (de 2 a 10 kilogramos) hasta el fallo en la ejecución del sujeto (17) con pausas de tres a cinco minutos de descanso (11), asumiendo el valor del RM como aquel que corresponde al último peso levantado exitosamente (29). pág. ...
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