How Much Does Front Leg Brace Play Into Velocity?

Joey Casadonte & Macon Langston, CSCS

Front Leg Bracing

Increasing pitch velocity is something that pitchers have been striving for across all levels of baseball. This is because pitch velocity is a major factor in determining success on the mound. So how can someone increase pitch velocity? The answer to the question is there is no one way to increase pitch velocity. There are multiple factors that can play a role. Another point to note is that every pitcher is unique and just because a certain way increases pitch velocity for one pitcher does not necessarily mean that it will for another.

Baseball biomechanics research over the years has looked at many kinematic and time dependent variables throughout the pitching sequence to determine any correlation with pitch velocity. As of recent, there has been a focus on bracing of the front leg and its association with pitch velocity. Front leg brace is the change in the angle of the front knee from foot contact to ball release. This technique has been shown to be associated with pitch velocity in youth, college, and professional pitchers.1–3 In youth pitchers, front knee angle at maximal external rotation and ball release was found to be significantly (p < 0.01) associated with pitch speed.3 However, the increased pitch speed found due to a more extended front knee was relatively small. To increase pitch speed by just 1 mph a more extended front knee of 18-19.5° is required.3 In college pitchers, a significant association was found between front knee flexion angle and pitch velocity (p = 0.010, r2 = 0.11), with a 10° increase in front knee flexion angle being associated with a 0.2 m/s reduction in pitch velocity.2 In professional pitchers, those who pitched with higher velocity (40.3 ± 0.9 m/s) had significantly greater (p < 0.001) lead knee extension angles (17 ± 13° vs 5 ± 14°) than lower velocity pitchers (36.1 ± 1.2 m/s), with lead knee extension angle being a positive predictor of pitch velocity (r2 = 0.352).1 These findings show that using a front leg bracing technique could help aid in maximizing pitch velocity.

Kinetic Chain

An explanation for the association of front leg bracing and pitch velocity could be due to more energy being transferred through the kinetic chain. The kinetic chain is a concept that describes the human body as a series of interrelated segments, with movement of one segment affecting neighboring segments.4 For example, when pitching the force applied into the ground from planting of the front leg is transferred back up through the lower body, up through the torso and then through the arm and hand reaching the ball at release. The amount of force that is transferred from the ground up through the ball all depends on how well energy is transferred up the kinetic chain. Inefficiencies in the pitching movement could cause either a break of the kinetic chain resulting in loss of energy or delayed arrival of energy at the end of the chain after the ball is out of the hand resulting in no effect.

The more energy created, and the more efficient energy is transferred up through the kinetic chain, the more energy is transferred to the ball resulting in higher pitch velocity. One way to create more energy initially could be through bracing of the front leg. An association was found between pitch velocity and lead leg braking force (posterior ground reaction force) for 27% – 35% of the period between foot contact and ball release.5 As a pitcher’s lead foot contacts the ground, extending of the front leg can allow the pitcher to apply more force into the ground resulting in greater braking force. The energy created can then be transferred up through the body and to the ball increasing velocity. However, bracing of the front leg is just the initial step in generating higher forces and just because a pitcher braces well with their front leg does not always mean an increase in velocity. As energy is transferred up the kinetic chain, if any of the other parts fail then the forces generated through bracing of the front leg are wasted.

Factors That Contribute to Front Leg Bracing

A pitcher’s ability to brace with the front leg can depend on factors such as strength and stability of the front leg as well as pelvis position at foot contact. To be able to absorb the initial force when the front foot lands and then extend the leg to generate force the front leg needs to be both strong and stable. Without a strong and stable front leg, you limit the ability to extend the leg which then limits the force that can be generated. The position of the pelvis can also contribute to a pitcher’s ability to brace with the front leg. In baseball, a pitcher’s pelvis position is calculated based on where the pelvis is facing in relation to home plate and other bases. A pelvis position of 0° is when the pelvis is facing directly towards home plate and a pelvis position of 90° is when the pelvis is facing 3rd base for right-handed pitchers and 1st base for left-handed pitchers. The pelvis is considered more “open” the closer it is to 0° and more “closed” the closer it is to 90°. A study looking into pelvis position at foot contact in professional pitchers found that those who landed with a more open pelvis (53° ± 7°) compared to a more closed pelvis (72° ± 7°) landed with greater knee flexion (open = 49°± 6°, closed = 47°± 10°, p =.043), produced greater lead knee extension (open = 20°± 15°, closed = 7°± 16°, p < .001), had faster peak lead knee extension velocity (open = 424 ± 158 °/s, closed = 325 ± 142 °/s, p < .001), and greater ball velocity (open = 39.1 ± 1.7 m/s, closed = 38.4 ± 2.1 m/s, p = .029).6 The thought behind this finding is that a more rotated or open pelvis at foot plant gives the pitcher a stronger base. With a stronger and sturdier base, it gives the pitcher the ability to extend more with the front leg, generating more force into the ground, that then can be transferred better back up the kinetic chain as energy in a more efficient way. So, if a pitcher is struggling with being able to brace with the front leg it may be due to a weak and unstable front leg or possibly a more closed pelvis position at front foot contact. Without a strong and stable front leg along with a good pelvis position at front foot contact, the ability to brace with the front leg will be limited which will reduce the amount of force that can be generated and then transferred up the kinetic chain, potentially costing pitch velocity.

Importance of front leg bracing in overall Mechanics

As a pitcher, having proper mechanics can not only help reduce risk of injury but can also help increase performance. The pitching motion can be broken down into multiple phases: windup, stride, arm cocking, arm acceleration, arm deceleration, and follow-through.7 The windup phase starts with the initial lift of the from leg and ends when the lead leg reaches its maximum height. The stride phase begins when the lead leg starts to move down and toward the plate. The pitcher then pushes off the rubber with the back leg and this phase ends when the lead foot contacts the ground. The arm cocking phase occurs from foot contact to maximum shoulder external rotation, transitioning into the arm acceleration phase which ends at ball release. Arm deceleration and follow through then occur after ball release. It’s important to have proper mechanics in each phase, because what happens in one phase can impact all subsequent phases.

Front leg bracing plays an important role in overall mechanics. Front leg bracing again is the extension of the front leg that occurs from foot contact (end of stride phase) to ball release (end of arm acceleration phase). Extending of the front leg gives the pitcher a stronger and more stable base that can help generate more force into the ground resulting in greater breaking GRF5, that is then transferred as energy back up the kinetic chain. Lead knee extension can also help the pelvis rotate and allow the upper trunk to tilt forward7, setting up the body in an optimal position for the remainder of the pitching motion sequence. Therefore, bracing with the front leg can play a crucial role in a pitcher’s mechanics being the initial movement that generates force and that starts the chain reaction of movements to follow.

Utilizing our 3D motion capture system consisting of eighteen Qualisys cameras and our Advanced Mechanical Technology, Inc. (AMTI) force plate implemented mound, we were able to analyze 516 pitches from collegiate pitchers with ball velocities ranging from 71 to 94 MPH and found a correlation of 0.322 between front leg brace and ball velocity. Kinematic and kinetic data was interpreted utilizing HAS-Motion and the data set was broken down further in SQL.

All Pitchers are Unique

With a possible increase in pitch velocity that has been shown by using a front leg bracing technique, it is not a direct correlation, and is not something that will guarantee increases in ball velocity for all pitchers who extend more. With the amount of variability that occurs amongst pitchers in their mechanics and delivery, there is never a “cookie cutter” solution that can be applied to all pitchers. This factor is important to consider when modifying a pitcher’s mechanics and suggesting change. Each pitcher is unique and should be addressed as such. Bracing with the front leg is not the only contributing factor to increasing pitch velocity, there are multiple other factors throughout the pitching motion that can also contribute. However, using a front leg bracing technique could be a good starting point for pitchers trying to improve their velocity.

8ctane Baseball

References:

1.??????????? Dowling B, Manzi JE, Raab G, Coladonato C, Dines JS, Fleisig GS. The relationship among lead knee extension, fastball velocity and elbow torque in professional baseball pitchers. Sports Biomech. 2022;0(0):1-11. doi:10.1080/14763141.2022.2050801

2.??????????? Solomito MJ, Garibay EJ, Cohen A, Nissen CW. Lead knee flexion angle is associated with both ball velocity and upper extremity joint moments in collegiate baseball pitchers. Sports Biomech. 2022;0(0):1-11. doi:10.1080/14763141.2022.2046143

3.??????????? Van Trigt B, Schallig W, Van der Graaff E, Hoozemans MJM, Veeger D. Knee Angle and Stride Length in Association with Ball Speed in Youth Baseball Pitchers. Sports. 2018;6(2):51. doi:10.3390/sports6020051

4.??????????? Ellenbecker TS, Aoki R. Step by Step Guide to Understanding the Kinetic Chain Concept in the Overhead Athlete. Curr Rev Musculoskelet Med. 2020;13(2):155-163. doi:10.1007/s12178-020-09615-1

5.??????????? Wasserberger KW, Giordano KA. Ground reaction forces in baseball pitching: temporal associations with pitch velocity among high-velocity pitchers. Sports Biomech. 2023;0(0):1-15. doi:10.1080/14763141.2023.2284828

6.??????????? Dowling B, Knapik DM, Luera MJ, Garrigues GE, Nicholson GP, Verma NN. Influence of Pelvic Rotation on Lower Extremity Kinematics, Elbow Varus Torque, and Ball Velocity in Professional Baseball Pitchers. Orthop J Sports Med. 2022;10(11):23259671221130340. doi:10.1177/23259671221130340

7.??????????? Diffendaffer AZ, Bagwell MS, Fleisig GS, et al. The Clinician’s Guide to Baseball Pitching Biomechanics. Sports Health. 2022;15(2):274-281. doi:10.1177/19417381221078537

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