What biomechanical principals are used to achieve maximum speed and accuracy when pitching in baseball?

Introduction

The baseball pitch is often the first part of any given play to occur in a baseball match. There are many variations to the pitch including the fastball, curveball, slider and splitter. This blog will focus on the fastball specifically, a pitch which as the name suggests, is fast and straight. What is the most effective way to gain the maximum velocity in this pitch? The answer lies within the biomechanical principals of the movement, all of which will be discussed below. 

Six stages of a baseball pitch

Figure 1: Six Stages of the Baseball Pitch (Crotin & Ramsey, 2014)

As shown in Figure 1, the baseball pitch can be broken down into six key phases; the wind-up, stride, arm cocking, arm acceleration, arm deceleration and follow-through. Below each phase will be deconstructed to allow the biomechanical principals to be explained.

Wind-up

The wind-up phase of the baseball pitch is crucial; it is described as the time between the first initiation of motion and the point at which the ball is removed from the glove. The wind-up is said to serve three separate purposes; to establish rhythm in order to accomplish the correct timing in subsequent movements. Secondly the wind-up is used to distract and conceal the ball from the hitter, adding deception. Thirdly, and critically important, the wind-up places the body into a position which allows all segments of the body to contribute to the propulsion of the ball (Pappas, Zawacki & Sullivan, 1985). This is the first movement of the kinetic chain, evident during a throwing motion when the joint movements extend in a sequential fashion, one after another (Blazevich, 2010). This phase begins by the leg which is contralateral to the pitching arm, pushing off from the pitching mound; this pushing motion is to move the center of gravity of the body in a forward motion instead of upward when the ipsilateral leg extends in the moments to follow (Pappas, et al., 1985). The pitchers arms remain stationary, often tucked in toward the chin, as evident in Figure 2, Having a tucked in stance will assist with conserving angular momentum later in the pitching sequence (Blazevich, 2010).

Figure 2: Wind-up phase of the baseball pitch 

Stride

The second phase of the baseball pitch is the stride. This movement is the beginning of the conversion of energy, from potential to mechanical. This phase has a key beginning and end point, the start occurs when the pitching hand separates from the glove, and ends when the front foot becomes grounded again. During this phase the hips are rotated forward and momentum from the back foot pushing in the previous phase is continued in a forward direction. The back foot pushing is evidence of Newton's Third Law, every action has an equal and opposite reaction. When vertical downward force is applied as the foot contacts the ground, equal and opposite force causes acceleration and momentum forward, toward the catcher (Blazevich, 2010). As the hands separate the pitcher begins to increase the moment of inertia gained from pushing forward with his grounded foot (Blazevich, 2010). As shown in Figure 3, the length of the stride should be slightly less than the pitchers height and the front foot should land directly in front of the already planted trailing foot, with the toes pointing inward slightly (Dillman, Fleisig & Andrews, 1993). The knee of the grounded leg should be slightly flexed to allow the centre of gravity to be lowered, this will help with balance, allowing the pitcher's eyes to be level assisting with accuracy (Pappas, et al., 1985).

Figure 3: Stride phase of baseball pitch (Robb, et al., 2010) 

Arm Cocking

In the arm cocking phase the kinetic chain begins at the foot, transferring energy through the legs and trunk before it travels down through the arm and hand. The trunk continues to rotate forward whilst the shoulder is reaching approximately 90° of abduction and between 90° and 120° of external rotation. The elbow is also flexed whilst the wrist remains in a neutral position. Hip rotation is initiated as the body is preparing for the maximum elastic energy transfer (Pappas, et al., 1985).

Arm Acceleration

The arm acceleration phase is the shortest phase accounting for only 2% of the entire pitching sequence, averaging only 50 ms in major league pitchers (Pappas, et at., 1985). This phase begins when the throwing shoulder is at the point of maximum external rotation and ceases when the ball is released from the hand. This movement is incredibly explosive with all aspects of the kinetic chain being key to releasing the ball with the maximum amount of kinetic energy as possible. In order for this to occur, there must be a small delay between the occurrence of elbow flexion and shoulder internal rotation, which will allow reduce inertia which is rotated at the shoulder. This will then result in the internal rotation torque which is generated at the shoulder allowing a greater angular velocity (Dillman, et al., 1993). Upon the release an almost fully extended elbow is evident and the pitchers trunk will be tilted forward as shown in Figure 4. As the leading elbow is pulled down past the body, this causes Newton's Third Law to assist in forcing the pitching arm forward, gaining greater velocity in the pitch (Blazevich, 2010).

Figure 4: Arm Acceleration phase of the baseball pitch

Arm Deceleration

During the arm deceleration phase the pitching arm decelerates at a comfortable pace allowing the muscles used to begin relaxation and occurs in approximately 50ms of the pitching sequence (Pappas, et al., 1985). This phase begins as the ball is released from the hand and terminates when the internal rotation of the pitching arm reaches a position of approximately 0° (Dillman, et al., 1993). During the deceleration of the arm breaking forces are generated by the bicep muscles and posterior shoulder girdle musculature whilst the elbow undertakes a rebound effect, flexing to almost 45° (Pappas, et al., 1985). The stride leg flexes at the knee, absorbing acceleration forces and promoting balance (McLeod, 1985).

Follow Through
The final stage of the pitching sequence can be viewed as a naturally occurring, momentum guided movement which dissipates the large masses of energy created in the prior phases. Tremendous forces placed on the shoulder and elbow can be negated with a good follow through, allowing pitchers to avoid injury. The trailing leg is raised during this phase, stabilizing the pitcher before continuing forward along with the trunk. By doing so this allows the trailing leg to make contact with the ground again in front of the pitchers body, which then cushions any further forward momentum. The pitcher will then often lower the centre of gravity to ensure a stable fielding position (Braatz & Gogia, 1987)

When all of the phases are combined effectively, the final product is a pitch which is of maximum velocity and accuracy. The full pitching sequence is demonstrated below in Video 1.

Video 1: Chang-Yong Lim slow motion baseball pitch

Achieving maximum velocity

Generally a ball that is thrown at a higher velocity will prove harder to hit for the batter. Although strength and conditioning training can provide added speed to a pitch, this section will focus on what biomechanical elements can be adjusted to increase the speed of the pitch. For an individual to reach maximum velocity in the pitch it requires a well timed and rhythmic technique allowing all body parts to work together toward one goal in the kinetic chain, as shown in Figure 5. The kinetic chain in baseball can be listed as beginning in the motion of hip rotation, trunk rotation, upper trunk extension, elbow flexion, shoulder internal rotation finishing with pronation of the forearm (Dillma, et al., 1993) A critical part of the pitching sequence when talking about velocity is the stride phase. This is the conversion section of kinetic energy stored from the wind-up phase of the sequence into mechanical energy, used to propel the body and arm toward the catcher. As described earlier in this blog, Newtons Third Law is evident when the back foot pushes the pitcher forward from the pitching mound, the more pressure exerted into the ground will result in more momentum being carried forward into the pitch. Secondly, as the front foot makes contact with the ground, knee flexion occurs in the front leg. This flexion helps prevent injury which may occur if the leg is planted completely straight. However, the less knee bend that is exhibited will result in less absorption of inertia, further resulting in more velocity being carried forward by the pitcher into the pitch (Blazevich, 2010), as described in a study which showed that in the high velocity group, less lead knee flexion was evident than the low velocity group (Matsuo, Escamilla, Fleisig, Barrentine & Andrews, 2001). A study undertaken in 2002 by Montgomery and Knudson found that an increased velocity was clearly evident when stride length was increased, without sacrificing any accuracy.

Figure 5: The kinetic chain

The answer

Biomechanical principals are evident throughout all phases of the pitching sequence, beginning in the wind-up where potential energy is stored before being converted to mechanical energy during the stride phase, where the kinetic chain becomes apparent. Newton's Third Law applies to the planting of the foot and leading knee flexes to create a lower centre of gravity. The arm cocking phase sees the kinetic chain continue into the arm whilst kinetic energy is transmitted from the legs, hips and trunk during the stride phase. The arm acceleration stage sees explosive movement in which the shoulder rotation, elbow flexion and wrist translation continue the transfer of built up kinetic energy. Throughout this phase the forces are summated into the ball to achieve the maximum velocity. Whilst in the arm deceleration stage and follow through phase breaking forces are generated whilst the knee flexes to absorb the acceleration forces achieved throughout the previous phases of the pitching sequence. The kinetic chain plays the main role in achieving a maximum velocity pitch, applying all of the sequence in perfect order and rhythm.

How else can this information be used?

The information provided in this blog is useful for pitchers to fully understand and analyse their own pitching technique but can also be used by fielders on the team to maximise their throwing velocity and accuracy. A faster throw coming in from a fielder to a base may result in the batter being run out. Other sports requiring single arm throws will also benefit from this study. Sports which apply a skill beginning from a stationary position requiring the kinetic chain to be in perfect synchronisation like a volleyball spike may also benefit due to the use of Newton's Third Law applying force to the ground in order to move upward through the legs, hips, trunk, arms and through the ball in a kinetic chain. The knowledge and understanding of biomechanical principals enable athletes of any calibre to analyse their action and make adjustments to make the movement more efficient, and enhance their skill.


References

Blazevich, A.J. (2010). Sports biomechanics the basics: optimising human performance. Bloomsbury, London, UK.

Braatz, J. H., & Gogia, P. P. (1987). The mechanics of pitching. Journal of Orthopaedic & Sports Physical Therapy, 9(2), 56-69.

Crotin, R.L & Ramsey, D.K. (2014) Lower Extremity Review Magazine, Influence of stride length on mechanics of pitching. Available online at: http://lermagazine.com/article/influence-of-stride-length-on-mechanics-of-pitching

Dillman, C. J., Fleisig, G. S., & Andrews, J. R. (1993). Biomechanics of pitching with emphasis upon shoulder kinematics. Journal of Orthopaedic & Sports Physical Therapy, 18(2), 402-408.

Matsuo, T., Escamilla, R. F., Fleisig, G. S., Barrentine, S. W., & Andrews, J. R. (2001). Comparison of kinematic and temporal parameters between different pitch velocity groups. Journal of Applied Biomechanics, 17(1), 1-13.

McLeod, W. D. (1985). The pitching mechanism. Injuries to the Throwing Arm. Philadelphia, Pa: WB Saunders, 22-28.

Montgomery, J., & Knudson, D. (2002). A Method to Determine the Stride Length For Baseball Pitching. Applied Research in Coaching and Athletics Annual, 75-84.

Pappas, A. M., Zawacki, R. M., & Sullivan, T. J. (1985). Biomechanics of baseball pitching A preliminary report. The American journal of sports medicine,13(4), 216-222.

Robb, A. J., Fleisig, G., Wilk, K., Macrina, L., Bolt, B., & Pajaczkowski, J. (2010). Passive ranges of motion of the hips and their relationship with pitching biomechanics and ball velocity in professional baseball pitchers. The American journal of sports medicine, 38(12), 2487-2493.