The lower half movements of the pitching delivery would be labeled as the legs and hips. Many pitchers are told they need better lower half movements to throw harder or to become more accurate in the strike zone but many pitchers don’t know how. The first step to understanding the lower half movements is learning the biomechanics that elite pitchers use to throw at a high velocity. Once we have a good understanding of the biomechanics elite pitchers use then the next step is to measure the movements to help the pitcher understand the level at which they are performing them. Also to measure the pitcher's ability to achieve these movements and then compare their measurements to the elite measurements.
The lower half movements of the elite pitcher are the hips move forward and down at the same rate following the leg lift. The weight stays on the drive leg as the hips slightly counter-rotate. This puts the drive leg femur in a more externally rotated position to stabilize the drive leg. The shoulders also counter rotate slightly past the hip position with the lift leg foot remaining closed to the target. The momentum the drive leg reaches maximum triple flexion and the hip abduction is almost to end of range then the front leg opens 70 degrees towards the target from a closed position. The drive leg extends and internally rotates to drive the back hip into rotation as the front foot lands and stabilizes. The shoulders remain in line with the target as the glove side begins to tuck down and the throwing arm moves into the cocked position.
Now that we understand the biomechanics of the lower half movements lets begin to evaluate the movements and the pitcher's ability to perform them. The biomechanical performance outcome measures of the lower half movements in the pitching delivery are ground forces, EMG measurements of muscle activity, joint extension velocity, joint torque levels, force vector angles, linear joint velocities and kinematic sequencing. General performance outcome measures of the lower half movements of a pitcher are vertical jump, broad jump, lateral broad jump, 10 yard sprint, one leg step up, dorsiflexion/plantar flexion range of motion (ROM), hip abduction/adduction ROM, hip extension/flexion ROM, and hip internal/external rotation ROM.
Biomechanic Performance Outcomes of Lower Half Movements
The advantages of measuring ground forces with a force plate are you gain a ground force profile of how a pitcher builds ground force vertically and horizontally. Evidence suggests that high-velocity pitchers generate more ground forces than low-velocity pitchers (Lin, Chen, Wu, & Huang, 2007). In my own practice, I have noticed that high-velocity pitchers not only have high vertical ground forces but high horizontal ground forces, more than low-velocity pitchers. I hypothesis that horizontal ground forces are important because they support the linear trunk movements which are so critical to generating pitching velocity (Howenstein, Kipp, & Sabick, 2017). The disadvantages of measuring ground forces with a force plate are it is a measurement of potential energy which can be wasted when it converts into kinetic energy. Therefore, evidence suggests that the drive leg force production has a strong correlation to linear wrist velocity as opposed to ball velocity which proves drive leg force production can be manipulated and wasted preventing it from affecting the ball speed (MacWilliams, Choi, Perezous, Chao, & McFarland, 1998).
The advantages of measuring muscle activity are it gives a profile of what muscles are driving the ground force profiles. Is the muscle activity more quad dominate or glute dominate in the drive leg? A more glute dominate drive may support more hip extension which helps drive more hip rotation to support an efficient kinetic chain. I haven’t found any disadvantages of measuring muscle activity. Measuring muscle activity is a very powerful tool with force plate data to understand an athletes rate of force development which gives you a good understanding of their ability to be explosive.
Joint extension velocity is measured with a biomechanics motion capture system usually in degrees per second. The advantage of this metric is learning what joints are contributing to more of the speed. Also, it gives an understanding of the summation of speed principle and how effectively it is being used. The disadvantages of this measurement are it doesn’t define how well the extension velocity is driving force production. For example; the drive leg could be extending due to the trunk leaning forward as opposed to extending with the trunk leaning back. The trunk leaning back would be an indication that the drive leg extension is holding much more torque in the joints.
You can measure joint torques with data from a biomechanics motion capture system and some fancy mathematical equations. The advantage of measuring joint torque levels is you understand how much stress is landing on that joint. Obviously, it would be more advantageous to distribute torque evenly across all joints to not only enhance performance but reduce injury. The disadvantages of measuring joint torques are not all joint stress is equal to all body types. Somebody types can handle more joint stress than others while not effecting ball speed.
There are many ways to measure force vector angles; one is with a simple camera and two is with a motion capture system and more fancy math. A simple measurement of a force vector angle is the vector from the ankle to the knee. When ground forces are generated in the leg drives the forces will travel in the direction of the force vectors of the ankle to knee. Each segment of the kinetic chain has a force vector angle illustrating the direction the force is traveling. This is important to understanding how the summation of speed principle is occurring in the kinetic chain of any movement.
You can measure linear joint velocities using a Tendo unit or a biomechanics motion capture system. These measurements usually are recorded in meters per second in peak and mean speeds. Peak speeds give you a good understanding of how fast the joint is moving at its highest moment and mean speeds give you a good understanding of how fast the joint is moving over time. The goal, with a power movement like high-velocity pitching, is it is best to generate joint speeds that peak high and generate more speed over time. The disadvantage of this metric is it isn’t giving you a direction of speed which is important to understand how effectively the speed will travel up the kinetic chain towards the baseball.
Kinematic sequencing will give you a good understanding of the timing of movements. This would be the best way to measure using the summation of speed principle. This will show you when each segment is peaking in a linear progression. The disadvantage of these measurements is they are usually angular which doesn’t give a good understanding of linear energy which in pitching is as critical or more critical than angular movements.
General Performance Outcomes of Lower Half Movements
Now that we have a good understanding of how to measure the biomechanics of the lower half movements of the pitching delivery we need to measure the pitcher to evaluate his ability to optimize the lower half movements of the pitching delivery. This includes measuring the general performance outcomes of the pitcher as listed above.
The advantage of measuring vertical jump is it gives you a good measurement of vertical leg power which evidence suggests is higher in high-velocity pitchers (Lin, Chen, Wu, & Huang, 2007). You need to know the pitcher's body weight to calculate with the Harman Formula the power output of the vertical jump (Harman, Rosenstein, Frykman, Rosenstein, & Kraemer, 1991). Elite vertical jumps in my practice are around 30 inches for a 200-pound athlete. The disadvantage of this measurement is it doesn’t best convert to all planes of movement. For example, a pitcher can have an elite vertical jump and a below average lateral drive which studies also link to ball velocity (Lehman, Drinkwater, & Behm, 2013).
You can measure broad jump to get a better understanding on top of their vertical jump how well they express power in a linear movement. This means they are mobile and strong enough to direct the vertical power into a forward movement. The elite broad jumps in my practice are over nine feet for a 200-pound athlete. The disadvantages of this measurement are it doesn’t best convert to all planes of movement.
Measuring the lateral jump is the final jump metric to defining the athlete's ability to express bilateral leg power in all directions. Evidence suggests that lateral jumping has a strong correlation with pitching velocity (Lehman, Drinkwater, & Behm, 2013). The elite lateral jumps in my practice are usually no less that one foot short of their broad jumps. The disadvantages of this measurement don’t always mean the pitcher has poor lateral leg power because it could be a mobility restriction preventing their leg power from freely moving into the frontal plane.
The advantage of measuring 10-yard sprint is it gives a good understanding of the pitcher's ability to activate movement quickly. The distance is short enough to measure explosive strength but not endurance strength like a 60-yard dash which is a very common metric in baseball. The elite 10-yard sprints in my practice are 1.55 seconds. The disadvantage of the measurement is it measures more speed than power which power is more valuable than just speed in the high-velocity pitching delivery.
The one leg step up is a good way to assess a pitcher’s ability to stabilize and extend one leg at a time to move the body. This is important because pitchers perform on one leg through the pitching delivery. The assessment should put the pitcher on one leg step up on a box at hip height. This way the pitcher is forced to fully flex and extend the leg and to extend from a fully flexed position which ultimately shows the body’s ability to stabilize and extend the leg in the most challenging position. If a pitcher can perform the step ups it gives the coach confidence, he can load and power both legs in the pitching delivery. Elite pitchers can easily performance 2-3 sets of 10 reps per leg.
You can measure dorsiflexion/plantar flexion ROM with a geometer. Ankle mobility is critical for deep squatting and loading and driving the drive leg in the pitching delivery. Pitchers with limited dorsiflexion can struggle to build leg strength. The optimal active range of motion is 15 degrees’ dorsiflexion and 65-degree plantar flexion. I find more value in measuring an active range of motion than passive. The optimal active range of motion gives an indication that the joint has integrity. I find no disadvantages in measuring ankle mobility.
The advantage of measuring hip abduction/adduction ROM is it gives you a good understanding of the pitcher’s freedom to move laterally. Pitchers who have strong legs but poor lateral power usually have poor hip abduction ROM. Optimal hip abduction ROM is 60 degrees. Good hip abduction ROM also means the pitchers have a lot of room to drive internal rotation of the femur which supports hip rotation. I find no disadvantages in measuring hip abduction/adduction ROM.
Hip extension/flexion ROM is another critical movement to support the leg drives for the high-velocity pitcher. More hip extension allows the back leg to drive the back hip into rotation. The optimal measurement of hip extension for the high-velocity pitcher is 35 degrees and 90 degrees for hip flexion. More hip flexion allows the front leg to extend to support moving the trunk forward into pitch release. Evidence suggestions achieving front leg extension before pitch release strongly correlates to an increase in pitching velocity (Matsuo, Escamilla, Fleisig, Barrentine, & Andrews, 2001).
The advantage of measuring Hip internal/external rotation ROM is it supports a more stable drive leg in external rotation and the ability to drive more hip rotation with optimal hip internal rotation ROM. The ideal hip internal and external rotation ROM is 35 degrees for both. I find no disadvantages to measuring hip internal/external rotation ROM.
In my evaluation of pitchers, I use all of these measurements because more information is always better. Some of these measurements hold more value than the others for each individual pitcher. Once the pitcher is fully evaluated I then give them their measurements in comparison to the optimal ranges of the elite pitchers. This way I can program the pitchers training to help enhance their deficiencies. Through their training we continue to test and retest until they reach their goals then the focus is to maintain the elite ranges. If an elite range is unattainable then we attempt to enhance more of another range to overcompensate unless it creates inefficiencies in the kinetic chain. The lower half movements is the best place to start optimizing the delivery because it is the foundation of the kinetic chain.
Lower Half Movements Reference:
Harman, E., Rosenstein, M., Frykman, P., Rosenstein, R., & Kraemer, W. (1991). Estimation of human power output from vertical jump. Journal of Applied Sport Science Research, 5(3), 116-120.
Howenstein, J., Kipp, K., & Sabick, M. (2017). Energy Flow in Youth Baseball Players in Relation to Pitching Performance and Efficiency. 41st Annual Meeting of the American Society of Biomechanics.
Lehman, G., Drinkwater, E., & Behm, D. (2013). Correlation of throwing velocity to the results of lower-body field tests in male college baseball players. Journal Strength Conditioning Research, 27(4), 902-8.
Lin, C., Chen, C., Wu, H., & Huang, C. (2007). Characteristic ground-reaction force in beginner baseball pitching. Journal of Biomechanics, 40, S742.
MacWilliams, B., Choi, T., Perezous, M., Chao, E., & McFarland, E. (1998). Characteristic ground-reaction forces in baseball pitching. The American Journal of Sports Medicine, 26, 1.
Matsuo, T., Escamilla, R., Fleisig, G., Barrentine, S., & Andrews, J. (2001). Comparison of kinematic and temporal parameters between different pitch velocity groups. Journal of Applied Biomechanics, 17,1.