Download The Parallel Squat

By:
Michael E. Bewley, MA, CSCS, C-SPN, USAW-I,
President, Optimal Nutrition Systems
Strength & Conditioning Coach for Basketball
Sports Nutritionist for Basketball
University of Dayton
The Parallel Squat:
An Application to Athletic Performance
The squat has often been referred to as the “king of exercise.” As an
exercise of the popular American weightlifting sport of Power lifting, the squat is
a competitive movement where maximal performance is sought. However, what
relationship does the squat hold in terms of athletic performance among athletes?
In my opinion, the squat is the most important strengthening exercise an athlete
can do. Virtually all sports, with the exception of water sports and polo, are
“ground-based,” meaning the athlete’s legs are in contact with the ground
throughout the duration of the sports activity. The prime movers of sprinting
and jumping are the knee and hip extensor muscles, which are the prime movers
involved in squatting. Developing strength in these muscle groups in a
biomechanically similar pattern has been shown to improve running speed and
jumping ability over time in a number of populations, not the least of which are
trained athletes (3). Likewise, athletic performance can be enhanced through
specificity of training, which holds that training is most effective when resistance
exercises are similar to the sports activity in which improvement is sought (3).
The reason then that the squat has been called the “king of exercise” is
because of its ability to develop optimum physical growth development and
absolute strength---the maximal force that a muscle or muscle group can
generate at a specified velocity (1). No other lifting movement, with the
exception of the snatch and clean, places as much stress on the musculoskeletal
system as does the squat (4). Similarly, the squat is critical in strengthen the
body’s “power zone” (Figure1) for athletic power production. Athletic power
production involves three key factors: torso kinetic energy, torso rotational
energy and stored kinetic energy (4).
Figure 1 The Body’s “Power Zone”
Concentric circles radiate out from the body’s
largest and strongest muscle groups to the smaller
weaker groups. It spans the hip and knee joint,
hip flexors and extensors, spinal erectors,
abdominals, quadriceps and hamstrings.
Reprinted from Quantum Strength and Power Training: Gaining the
Winning Edge, 1994
Kinetic energy is the energy of motion and is related to both the mass of
the body and velocity (4). Torso kinetic energy is the movement that can be
generated with athletic-type lifts (e.g. Olympic lifts) that produce torso rotational
energy, thus allowing you to exert force in multiple directions (4). Torso
rotational energy is the energy that comes from a body segment. It involves large
muscle groups generating great force through and around the center of mass or
in this case, the body’s “power zone” (4). For example, bending and extending at
the hip joint when jumping for a rebound in basketball creates a high amount of
torque and force at the hip joint.
Stored kinetic energy or stored elastic energy applies to all movements
involving eccentric forces (4). When a muscle contracts eccentrically under
external force it stretches and stores energy. Subsequently, stored energy is
added to the muscle force generated during concentric contraction as both are
converted to kinetic energy for the eccentric action (4).
Analysis of the squat movement (Figure 2) illustrates the vital role stored
kinetic energy plays in high power production. In the execution of the squat, the
strong eccentric contraction during the descent mechanically stretches the hip
and quadricep extensors, resulting in kinetic energy being generated and stored
in the hips and quads (4). The transition from the descent to the ascent facilitates
the stretch reflex mechanism. In short, when a stretching movement stimulates a
muscle spindle a sensory neuron from the muscle spindle innervates a motor
neuron in the spinal column (1). The motor neuron then causes a contraction of
the muscle that was previously stretched---this is the stretch reflex mechanism
(1). Thus, the stretch reflex mechanism allows for stored kinetic energy that
enables for a strong concentric contraction and acceleration force for the upward
movement of the squat. Hence, maximal hip, quadricep force and rotational
energy are developed. The stretch reflex mechanism is a very important
phenomenon in sport since it occurs so frequently and is an integral component
of such activities as running and jumping. Techniques and training programs for
optimizing the use of the kinetic energy are important in developing superior
performance in athletes’.
Figure 2 Application to Torso Kinetic
Energy in Execution of a Squat
Reprinted from Quantum Strength and Power
Training: Gaining the Winning Edge, 1994
Stretching a two-joint muscle at one joint may increase the muscle’s ability
to generate force at the other joint (1). For example, the hamstring not only is
stronger but also uses less energy during knee flexion with the hip flexed than
with the hip extended (2). The improved function of the hamstring seems to be
related not only to the length-tension relationship of the hamstring but the use of
kinetic energy in the stretched muscle (2).
At this point, for clarity of communication, a brief definition of strength
and the word power are in order. Although the word strength is often associated
with slow speeds and word power with high-speed movements, both variables
reflect the ability to exert force at a given speed (1). If at any instant, any two of
the three variables --- force, velocity, and power --- are known the third can be
calculated. If at a particular velocity an individual can generate force or power,
precisely the same ability is being described; that is the ability to accelerate a
mass at that particular speed (1). Therefore, it is not correct to associate strength
with low speed and power with high speed. Strength is the capacity to exert
force at any given speed and power the mathematical product of force and
velocity at whatever the speed (1).
Another inherent value associated with squatting is that it stimulates
optimal physical growth and development. Some of the important physiological
benefits are (3):
1. Increased bone density together with a corresponding increase in
ligament tendon strength, which leads to greater joint stability.
2. Development of large muscle groups in the body’s “power zone.”
3. Greater neuromuscular efficiency, making for excellent transfer of
power to other biomechanically similar movements requiring a
powerful thrust from the hips and thighs; jumping, running, throwing,
lifting and pushing with the lower body.
Despite the inherent physiological benefits of the squat, knowledge regarding
both safe and efficient execution of the movement has led to many falsified
theories regarding the overall safety of the movement. The degree of safety
however, is all relative to the squat technique employed (4). The depth and speed
at which one squats will have an effect on the knee joint structure and function.
In squatting at a downward velocity greater than 30° per second, the hip flexors
and quadriceps are unable to provide sufficient braking force to generate a
strong eccentric contraction and prevent the lifter from being driven down into a
rock-bottom or hyper-flexed knee position (3). In order to compensate from this
poor mechanical position, the lifter will resort to bouncing to gain upward
momentum. Very high sheer stress and strains are developed from this type of
squatting, which can damage the knee joint. Hyperflexion of the knee in a deep
squat can cause a sequence of ligament injuries including, initial tearing of the
deep medial cruciate ligament, tearing of the tibial collateral ligament and
tearing of the anterior cruciate ligament (3).
The solution? Practice good form and technique when performing the parallel
squat. Do not fall victim, as many athletes do, with the amount of weight being
lifted --- rather, be concerned with exercising proper technique. It must be
emphasized that by executing a parallel squat correctly, the knee joint is not
exposed to excessive forces that will in any way damage it (4). Remember, when
performing the squat as with any exercise; never sacrifice form for function.
Due to their overall lack of knowledge in executing the parallel squat, some
athletes and coaches believe substituting the parallel squat for the partial squat is
an ulterior means to injury prevention. Unfortunately, nothing could be further
from the truth. From a biomechanical standpoint there are a number of reasons
for this. First, to develop maximum hip or knee joint strength, the joint must be
worked through a full range of movement (4). Total leg strength is critical to
athletic performance, as well as to the protection of the knee joint. Even though
the knee ligaments are considered the first line of defense against injury, they are
dependent upon the strength of the leg musculature that crosses the knee joint
for protection when stresses against the joint are excessive (3). Second, an
optimal neuromuscular training effect is not realized in the partial squat (4). The
greater the range of motion to perform a given strength movement, the greater
the motor recruitment. When you execute a full squat (tops of the thighs just
break 90° angle), the knee joints are close to maximum flexion. Recovering from
this requires greater quadricep muscle fiber recruitment than does a partial
squat. In this respect, the deeper the squat, the greater the neuromuscular
involvement, thus creating a greater overall training benefits (3). Thirdly,
overuse of the partial squat leads to over-development of the quadriceps at the
expense of the hamstrings (4). On the basis of research related to the knee and its
structural integrity, the stability of the joint is best supported by the hamstring
(3). The result is an imbalance in the hamstrings–quadricep strength ratio, which
can contribute to both knee and hamstring injury (4).
In addition to the parallel squat, there are other variation exercises (Figure
3) designed to isolate and strengthen the muscles of the body’s power zone,
which can be incorporated into an athlete’s total strength program. Simply
stated, by stressing the nerves and muscles in wide variety of ways, one will
produce optimal training results. Overall, the application of the movement
variation will: 1) produce greater muscle balance development, 2) reduce injury
potential, 3) help prevent overtraining or staleness and 4) maintain the high level
of motivation necessary for long-term training progress.
Figure 3 Movement Variation Exercises
Front Squat
Romanian Dead-lifts (RDL)
Good Mornings
Back Extensions
Plyometrics
Leg Extension
DB or BB Lunges
Torso Rotational Movements
DB or BB Split Squat
Glute/Hams
Reverse Hypers
Torso-Rotational Movements
Kettle Bell Squats
Leg Curl
DB BB Step-ups
Olympic Weightlifting
In closing, when working with novice lifters light weights should be used
initially so that proper form can be established while the joints and their
surrounding musculature develop the proper motor pathways and flexibility
needed to perform the lift properly and safely (3). Maximizing form and
technique when squatting will correspondingly develop strength and power in a
functional way for your sport. “Strength without technique is impotent”---J.P.
O’Shea.
Resources
1. Beachle, T.R. (1994). Essentials of Strength Training and Conditioning, NSCA.
Human Kinematics, Champaign, IL.
2. Hunter, G.R., T. Szabo, & A. Schnitzlr. Metabolic Cost/Vertical Work
Relationship During Knee Extension and Knee Flexion Weight Training
Exercise (1992). Journal of Applied Sports Science 6(1): 42-48.
3. Coaches Roundtable: The squat and its application to athletic performance.
(1984). NSCA Journal 6(3): 10-19.
4. O’Shea, J. P. (1995). Quantum Strength and Power Training: Gaining the
Winning Edge. Patrick’s Books, Corvallis, OR.
5. O’Shea, J. P. (1985). The Parallel Squat. NSCA Journal 7(1): 4-7.