By Dan Blewett Strength Coach and Pitching Instructor
In parts one and two we covered the appendage that we ballplayers all know and love – the arm. The arm is very obviously a crucial piece of the throwing puzzle, but any pitching coach worth his salt knows that a substantial amount of velocity is generated from the action of the legs and core. Today we are going to get to the bottom of how the legs and core produce pitching power and find the muscles responsible for that exploding fastball. This installment is going to cover the pitching motion from the mound starting with the leg lift, and finishing with that last bit of oomph. Again, there is a lot at work here, so we are going to cover the most salient movements and muscles.
Two more important concepts we need to cover before we proceed are eccentric versus concentric actions. This is relatively simple – the concentric phase of movement is the “positive” motion, and the eccentric is the “negative” motion. In a biceps curl, for example, curling the dumbbell up is concentric elbow flexion, and lowering the dumbbell back down is eccentric elbow flexion. Got it? Now you are armed and ready (pun intended).
For term consistency, the leg in contact with the rubber will be referred to as the “drive leg” and the leg that strides toward the plate will be known as the “lead leg.”
To best describe the role of the muscles of the lower half and core, we will follow a slightly different format than in the previous throwing anatomy articles. Today we will divide the pitching delivery up into different actions, describing which muscles are at work to make those actions possible. Keep in mind that for every accelerating action there is a counteractive decelerating action, but we will not cover each of them in detail.
The Legs and Hips
Accelerating Action: Concentric Hip Flexion
Hip flexion is the act of lifting one’s lead leg up to the balance position, and though it doesn’t actually produce any acceleration of the arm, it sets the pitching motion into action and helps to load and store energy in the hips.
The hips are flexed, in part, by as many as nine different muscles, including those in the adductor, quadriceps and hip flexor groups. Yet, all you really need to know about hip flexion is that the prime mover is the iliopsoas, which is a group of two muscles called the iliacus and psoas major. When you hear the term “hip flexors,” the iliopsoas is what is being referred to. Hip flexor strength is usually secondary in pitchers to flexibility, which can greatly limit one’s ability to stride, rotate and reach forward in throwing. It is extremely common for even elite athletes to have extremely tight, nearly dysfunctional hip flexors.
(Hip flexion)
Accelerating Action: Concentric Hip Extension
This motion is the lifted lead leg moving back down toward the ground after the balance point. At this point the body begins to move forward aided by hip abduction and knee flexion in the drive leg, which makes the downward movement of the thigh more complex than the upward movement that was just discussed.
Accelerating Action: Concentric Hip Abduction
That motion of pushing off the rubber with the drive leg is hip abduction, moving the leg away from the midline of the body. This push is caused chiefly by the gluteus group, including the gluteus minimus, medius and maximus, and the hip external rotator group, including the piriformis, obturator externus, obturator internus, and two gemelllus muscles. The tensor fasciae latae, which inserts on the IT band, also aids in hip abduction. The prime mover of this motion is the gluteus medius, which can be strengthened by performing lots of lateral work. Strengthening the hip abductors is also one of the best ways to ward off knee injuries.
(Posterior view of the hip, showing the external rotators)
As the lead foot travels toward the plate with the ankle facing the batter, the foot starts to turn via external rotation of the hip, resulting in the lead toe landing pointed toward the plate. The chief external rotators responsible for this action are the gluteus maximus, piriformis, obturator internus and externus, and quadratus femoris. The biceps femoris, the most lateral hamstring muscle, also provides slight assistance in externally rotating the hip. This group of rotators is incredibly important, as they can dramatic influence the ease over which one rotates his hips, as we will see in the next movement…
Accelerating Action: Concentric Hip Internal Rotation
(Anterior hip, showing adductors and internal rotators)
Once the lead foot touches down, it is “go time” for the hips, and both the lead leg and drive leg powerfully internally rotate. As previously mentioned, the hip external rotator group has tremendous influence over this action. Why? Because the law of reciprocal inhibition states that opposing muscles must relax as their opposites contract. This means that if you have tight hip external rotators, which must relax during internal rotation, fluidly pivoting on your hip will be labored and difficult, as there will not be sufficient muscle length to allow full energy transfer and range of motion in internal hip rotation.
The internal rotators occupy the medial compartment of the thigh known as the groin, and the chief muscles at work are the adductor magnus, adductor longus and adductor brevis, the pectineus, gracilis and tensor fasciae latae.
Accelerating Action: Concentric Hip Extension
After the hips have rotated and the ball is released, or is about to be released, the drive leg lifts from the ground in a motion known as hip extension. The muscles responsible for this lift are the gluteus maximus and the hamstring group, which is made up of the biceps femoris, semimembranosus and semitendinosus. The prime movers are the gluteus maximus andbiceps femoris. As the leg lifts and swings forward as a result of the body’s rotational forces, the drive leg will remain internally rotated in the air before coming to rest with the toe facing the batter’s box. This should leave the pitcher in proper fielding position with his hips in a neutral position, square to the plate.
Accelerating Action: Concentric Knee Extension
(Lead leg knee extension and drive leg hip extension, which requires good hamstring flexibility)
After the lead knee partially collapses and the hips and torso come through to deliver the ball, energy is still moving forward and the lead leg has to work to absorb it. As the drive foot moves forward and lifts off the ground, the lead leg straightens fully or partially, depending on the pitcher, via the quadriceps to allow the torso and arm to continue moving forward. This last movement of the lead leg allows the final finish for the pitch, and if hamstring flexibility is poor, finish and follow through will be restricted. This movement is slowed to a final pause by the posterior chain (chiefly the glutes and hamstring group). The posterior chain slows the action of the quadriceps to allow the pitcher to finish in a stable position, absorbing the last of his linear momentum.
The Core
The “core” of your body most commonly refers to the muscles that cover your torso and extend from your pelvis, attaching somewhere on the spine or rib cage. This is also referred to as the “trunk.” The core has a very strong influence on the body and produces movement on all planes of the spine.
It is doubtful that there is a bigger buzzword in the fitness and sports industry today than on the core, but rightfully so – a strong core is a major contributor of the exceptional body control needed by an elite athlete. Pitching is both a linear and rotational movement, and the power produced by the legs and hips is transmitted and increased by the core. The final product of all of this is a pitch thrown holistically by the body but delivered by the arm.
Accelerating Action: Trunk Flexion
(Muscles of the core, showing abdominals, external obliques and lats)
As the body strides forward, the lower back arches as the muscles controlling the lumbar spine contract. This arching of the low back, called back extension, sets the stage for powerful trunk flexion, which is the opposing action, helping to drive the chest and shoulder girdle toward the plate. The prime mover of back extension is the erector spinae group, which is composed of the longissimus, iliocostalis, and spinalis.
(Billy Wagner's trunk flexing forward)
As the pitch is delivered, the trunk flexes forward, causing the erector spinae to relax as the muscles of the anterior core fire and take over. The prime movers of trunk flexion are the rectus abdominis, and the external and internal oblique. These core muscles are also assisted by the hip flexor iliopsoas.
Accelerating Action: Trunk Rotation
When the lead foot lands, the trunk almost immediately begins to rotate to bring the upper body through and the arm toward the plate. This is the biggest role of the core in throwing, as the linear power must be translated into rotational power to bring the arm forward. The core muscles involved in rotating the trunk are the rectus abdominis, external oblique, and internal oblique.
Accelerating Action: Trunk Rotation and Lateral Flexion
As the trunk begins to rotate, the “off-arm”, or non-throwing arm, tucks at the side and is pulled down to aid the rotation of the body. Throwers who do not perform a quality tuck and pull of the off arm limit themselves, as this motion recruits powerful muscles to aid in trunk rotation and lateral flexion. The back muscles quadratus lumborum, longissimus and iliocostalis all aid in laterally flexing the trunk, and the powerful latissimus dorsi is the prime mover of tucking the arm back into extension. Many hard-throwing pitchers talk about the feeling of really pulling down hard with their off arms, which is brought upon by pulling with their lats and flexing their trunks laterally. Every pitcher is different in the amount of off-arm usage and lateral trunk flexion they exhibit.
Final Thoughts
It is important for one to have a working knowledge of his body, if he is to extract every bit of potential from it. Biomechanics and anatomy can become very dense, but even a rudimentary understanding of the disciplines can make the difference in taking your pitching and training to the next level.
Remember, though we singled out muscles and muscle groups, the body works holistically, and any training regimen should reflect that. Though a stronger rotator cuff, core, chest, back, etc. may increase performance, do not forget that everything works together. The reason we focused on accelerating muscles and decelerating muscles is to illustrate this very point, that strengthening any one muscle is never more than half the equation. For more baseball performance knowledge, visit my website at www.danblewett.com.
In parts one and two we covered the appendage that we ballplayers all know and love – the arm. The arm is very obviously a crucial piece of the throwing puzzle, but any pitching coach worth his salt knows that a substantial amount of velocity is generated from the action of the legs and core. Today we are going to get to the bottom of how the legs and core produce pitching power and find the muscles responsible for that exploding fastball. This installment is going to cover the pitching motion from the mound starting with the leg lift, and finishing with that last bit of oomph. Again, there is a lot at work here, so we are going to cover the most salient movements and muscles. 
The hips are flexed, in part, by as many as nine different muscles, including those in the adductor, quadriceps and hip flexor groups. Yet, all you really need to know about hip flexion is that the prime mover is the iliopsoas, which is a group of two muscles called the iliacus and psoas major. When you hear the term “hip flexors,” the iliopsoas is what is being referred to. Hip flexor strength is usually secondary in pitchers to flexibility, which can greatly limit one’s ability to stride, rotate and reach forward in throwing. It is extremely common for even elite athletes to have extremely tight, nearly dysfunctional hip flexors.
As the trunk begins to rotate, the “off-arm”, or non-throwing arm, tucks at the side and is pulled down to aid the rotation of the body. Throwers who do not perform a quality tuck and pull of the off arm limit themselves, as this motion recruits powerful muscles to aid in trunk rotation and lateral flexion. The back muscles quadratus lumborum, longissimus and iliocostalis all aid in laterally flexing the trunk, and the powerful latissimus dorsi is the prime mover of tucking the arm back into extension. Many hard-throwing pitchers talk about the feeling of really pulling down hard with their off arms, which is brought upon by pulling with their lats and flexing their trunks laterally. Every pitcher is different in the amount of off-arm usage and lateral trunk flexion they exhibit.
