Part I
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| Plotkin (2023) |
I wanted to take a closer look at squats because they
are one of the most commonly used exercises in both lower limb rehabilitation
and resistance training. Squats are also a competitive sport in weightlifting,
with its own regulations for proper squats. The recruitment of muscles, the
forces exerted on the knee joint and the skeleton of the lower extremities are
different depending on the placement of the legs and the depth of the squat,
but also on individual anthropometric differences. The width of the squat
position, the position of the feet and the depth of the squat can be varied
according to goals and individual differences. However, it should be noted that
various strain injuries, pain, damage to either the menisci or articular
cartilage, and spondylolysis are examples of what the wrong squat technique can
cause (Cappozzo et al. 1985, Comfort et al. 2018, Escamilla 2001, Fry et al.
2003, Miller et al. 1997, Vakos et al. 1994, Yack et al. 1993), so it is good
to familiarize yourself with performance optimization also from a technical
point of view. In this part, the first part, I will focus more on the muscular
responses of the squat, and in the second part I will focus more on the
technical aspects of the squat.
The differences between squat and hip thrust exercises
and gluteal hypertrophy were examined by Plotkin et al. (2023). Both movements
produced similar muscle growth, but the back squat also resulted in an increase
in the thigh muscle. Also Delgado et al. et al. (2019) investigated differences
in muscle activation in the back squat and hip thrust using surface
electromyography. The anterior femur muscle (m. vastus lateralis), the
hamstring muscle (m. biceps femoris) and the large gluteus muscle (m. gluteus maximus)
were examined. The study also compared the Romanian deadlift (RDL) to the
exercises mentioned before. According to the study, RDL was as effective as hip
thrust exercise in activating hip extensors (e.g., glutes), while back squats
simultaneously stimulate both hip and knee extensor muscles (quads). However,
the study used the same load on all subjects, which may have affected the
results to some extent.
In general, it is worth noting here that although
squats are considered an exercise for the muscles of the lower extremities, it
also activates other muscle groups. The core muscles, mainly the abdominal and
spinal muscles, are significantly activated. (Anderson et al. 2005, Oddsson et
al. 1999) However, according to the position of the lumbar spine, there is
variation in the activation of the straight abdominal muscle, spine and wide
back muscle (m. latissimus dorsi) (Vakos et al. 1994), and with respect to the
gluteal muscles (m. gluteus maximus), better recruitment can be observed during
deep squats. There do not appear to be significant differences in the relative
proportions of the hamstring muscle and quads in the performance of this type
of squat, according to the study. However, the proportion of quads (especially m.
vastus medialis) seems to increase with increasing squat depth. (Caterisano et
al. 2002) Thus, increased squat depth (half squat 45°, parallel squat 90°, full
deep squat 125°) appears to result in a more efficient percentage of glutes
during a full-depth squat. (Caterisano et al. 2002, Ninos 1997) In the
eccentric phase, i.e. the descent phase, the relative proportions of the four
muscle groups (m. vastus medialis, m. vastus lateralis, m. biceps femoris, m. gluteus
maximus) in the three depths tested did not differ statistically. (Caterisano
et al. 2002). Research generally suggests that, regardless of technique, squats
don’t activate the hamstring muscles much. (Escamilla et al. 1998 &; 2001,
Ninos et al. 1997, Signorile et al. 1995)
However, foot rotation (neutral, 30-40° medial, 80°
lateral rotation) has not been shown to have a noticeable effect on muscle
function when examining the activation of the anterior thighs (m. rectus
femoris, m. vastus medialis, m. vastus lateralis), thigh convergences (m.
adductor longus) and hamstrings (m. semimembranosus, m. semitendinosus and m. biceps
femoris). (Escamilla et al. 1998 &; 2001, Mc Caw et al. 1999, Ninos et al.
1997, Signorile et al. 1995) On the other hand, however, variations in posture
width change muscle recruitment patterns, as a position larger than shoulder
width increases the activity of the adductor muscles. (Ninos et al. 1997,
Signorile et al. 1995)
The optimal squat technique minimizes the risk of
injury, but maximally activates the muscles of the lower extremities. According
to studies, this position is precisely the wide position of the feet, with the
feet at a natural angle (Escamilla et al. 1998 &; 2001, Mc Caw et al. 1999,
Ninos et al. 1997, Signorile et al. 1995), heels remain on the floor, knees
move freely over the feet (Fry 2003, Panerillo 1994), and gaze is forward or
upward. A full squat depth (115-125° knee angle) would be preferable, assuming
that lower back lordosis, i.e. natural lumbar curve, remains good. (Caterisano
et al. 2002, Ninos et al. 1997) It has previously been recommended that squats
be performed at a knee angle of 0– (Escamilla et al. 2001) because the forces
exerted on the knee structures increase with increased flexion (Escamilla et
al. 2001) However, performance seems to improve when the squat is performed
with a larger range of motion (Hartmann et al. 2002, Weiss et al. 2000) or when
the low squat is used as a supplementary exercise for a full deep squat.
(Bazyler et al. 2014) The results of the study of Kubo et al. (2019) suggest
that full deep squat training is more effective in developing the muscles of
the lower extremities, with the exception of the hamstring muscles.
Based on a review of Ribeiro et al. (2023), squats are
an effective exercise to promote muscle growth of the foreleg muscles
(especially m. vastus lateralis, medialis and intermedius, as well as m. rectus
femoris, although less so in the latter one). According to this review, back
squats appear to produce little or no hamstring muscle growth. Although the
gluteus maximus is clearly mechanically involved in the posterior squat, there
still seem to be relatively few longitudinal studies on the subject. However,
deep squats may be more conducive to muscle growth for the glutes, and a squat
depth exceeding the knee angle of 90° does not appear to increase hypertrophy
of the knee extensors (quads).
Picture:
Plotkin (2023): https://pmc.ncbi.nlm.nih.gov/articles/PMC10349977/figure/F5/
According to Plotkin et
al. (2003) on a study of the effects of squats and hip thrust on glutes. In the
picture, MRI (magnetic resonance imaging) muscle cross-sectional areas (a) left
+ right (L+R) upper so-called MRI scan. large gluteus maximus, b) L+R middle
so-called. large gluteal muscle (m. gluteus maximus), c) L+R lower m. gluteus
maximus, d) L+R m. gluteus medius+minimus. The graphs contain change points in
which the values of individual participants are represented as points. (e)
Three MRI scans before and after the MRI image are performed by the same
participant with white polygon tracing of the upper gluteus maximus and gluteus
medius+minimus (top) of L+R, the middle gluteus maximus of L+R (middle) and the
lower gluteus maximus of L+R (bottom).
Anderson K & Behm DG. (2005):
Trunk muscle activity increases with unstable squat movements
Bazyler CD, Sato K, Wassinger
CA, Lamont HS, & Stone MH. (2014): The efficacy of incorporating partial
squats in maximal strength training
Behrens M, Mau-Moeller A &
Bruhn S. (2012): Effect of exercise- induced muscle damage on neuromuscular
function of the quadriceps muscle
Bryanton MA, Kennedy MD, Carey
JP & Chiu LZF. (2012): Effect of squat depth and barbell load on relative
muscular effort in squatting
Cappozzo A, Felici F, Figura F
& Gazzani F. (1985): Lumbar spine loading during half-
squat exercises
Caterisano A, Moss RF,
Pellinger TK, Woodruff K, Lewis VC, Booth W & Khadra T. (2002): The effect
of back squat depth on the EMG activity of 4 superficial hip and thigh muscles
Comfort P, McMahon JJ &
Suchomel TJ. (2018): Optimizing squat technique-revisited
Cooke DM, Haischer MH, Carzoli JP, Bazyler CD, Johnson
TK, Varieur R, Zoeller RF, Whitehurst M & Zourdos MC (2019) : Body Mass and
Femur Length Are Inversely Related to Repetitions Performed in the Back Squat
in Well-Trained Lifters
Delgado J, Drinkwater EJ, Banyard
HG, Haff GG & Nosaka K. (2019): Comparison Between Back Squat,
Romanian Deadlift, and Barbell Hip Thrust for Leg and Hip Muscle Activities
During Hip Extension
Demers E, Pendenza J, Radevich
V & Preuss R. (2018): The effect of stance width and anthropometrics on
joint range of motion in the lower extremities during a back squat
Escamilla RF. (2001): Knee
biomechanics of the dynamic squat exercise
Escamilla, RF, Fleisig, GS,
Lowry, TM, Barrentine, SW & Andrews, JR. (2001): A three dimensional
biomechanical analysis of the squat during varying stance widths
Escamilla RF, Fleisig GS, Zheng
N, Barrentine SW, Wilke KE , & Andrews JR. (1998): Biomechanics of the knee
during closed kinetic chain and open kinetic chain exercises
Escamilla RF, Fleisig GS,
Zheng N, Lander JE, Barrentine SW, Andrews JR, Bergemann BW & Moorman CT. (2001):
Effects of technique variations on knee biomechanics during the squat and leg
press
Fry AC, Smith JC &
Schilling BK. (2003): Effect of knee position on hip and knee torques during the barbell squat
Gomes J, Neto T, Vaz JR,
Schoenfeld BJ & Freitas SR. (2020) Is there a relationship be- tween back
squat depth, ankle flexibility, and Achilles tendon stiffness?
Hartmann H, Wirth K, Klusemann M,
Dalic J, Matuschek C & Schmidtbleicher D. (2012)
Influence of squatting depth
on jumping performance
Kim S, Miller M, Tallarico A,
Helder S, Liu Y, Lee S. (2021): Relationships between physical characteristics
and biomechanics of lower extremity during the squat
Kubo K, Ikebukuro T & Yata H. (2019): Effects of squat training with
different depths on lower limb muscle volumes
Mc Caw, ST, & Melrose DR. (1999):
Stance width and bar load effects on leg muscle activity during the parallel
squat
Mc Kean M & Burkett
BJ. (2012): Does Segment Length Influence the Hip, Knee and Ankle Coordination
During the Squat Movement?
Miyamoto K, Iinuma N, Maeda M,
Wada E & Shimizu K. (1999): Effects of abdominal belts on intra-abdominal
pressure, intra- muscular pressure in the erector spinae muscles and
myoelectrical activities of trunk muscles
Miller JP, Sedory D &
Croce RV. (1997): Leg rotation and vastus medialis oblique/vastus lateralis electromyogram
activity ratio during closed chain kinetic exercises prescribed for patellofemoral
pain
Ninos JC, Irrgang JJ, Burdett
R & Weiss JR. (1997): Electromyographic analysis of the squat performed in
self-selected lower extremity neutral rotation and 30° of lower extremity
turn-out from the self-selected neutral position
Nogueir AdeC, Vale RG, Gomes
AL & Dantas EH. (2011): The effect of muscle actions on the level of
connective tissue damage
Oddsson LIE, Persson T,
Cresswell AG & Thorstensson A. (1999): Interaction between voluntary and
postural motor commands during perturbed lifting
Panerillo
RA, Backus SI & Parker JW. (1994): The effect of the squat exercise on
anterior-posterior knee translation in professional football players
Plotkin DL, Rodas, MA,
Vigotsky AD, McIntosh MC, Breeze E, Ubrik R, Robitzsch C, Agyin-Birikorang, A, Mattingly
ML, Michel JM, Kontos NJ, Frugé AD, Wilburn CM, Weimar WH, Adil Bashir A,
Beyers RJ, Henselmans M, Contreras BM & Roberts MD. (2023): Hip thrust and
back squat training elicit similar gluteus muscle hypertrophy and transfer
similarly to the deadlift
Ribeiro AS, Santos ED, Nunes JP, Nascimento MA,
Graça Á, Bezerra ES, Mayhew JL (2023): A Brief Review on the Effects of the
Squat Exercise on Lower-Limb Muscle Hypertrophy
Signorile JF, Kwiatkowski K,
Caruso JF & Robertson B. (1995): Effect of foot position on
electromyographical activity of the superficial quadriceps muscles during the
parallel squat and knee extension
Vakos JP, Nitz AJ, Threlkeld
AJ, Shapiro R & Horn T. (1994): Electromyographic activity of selected trunk and hip muscles
during a squat lift. Effect of varying the lumbar posture
Weiss LW, Fry AC, Wood LE,
Relyea GE & Melton C. (2000): Comparative effects of deep versus shallow
squat and leg-press training on vertical jumping ability and related factors
Yack HJ, Collins CE & Whieldon
TJ. (1993): Comparison of closed and open kinetic chainexercise in the anterior
cruciate ligament-deficient knee