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Driveline’s Pitching Research Homepage

Biomechanics Research

Variability in Baseball Pitching Biomechanics among various levels of Competition 

Authors: Fleisig, G; Chu Y; Weber A; Andrews J

A total of 93 pitchers had 5 fastballs analysed: 20 youth, 19 high school, 20 college, 20 minor league, and 14 Major League pitchers. Kinematic, temporal, and kinetic parameters were examined with the goal of being able to compare individual standard deviations among groups.

A significant difference was found in six of the eleven kinematic parameters analysed: foot placement, knee flexion, pelvis angular velocity, elbow flexion, shoulder external rotation, and trunk forward tilt.

Youth pitchers had the largest variability in the placement of their front foot and of the amount of flexion at foot plant. A focus of practice for youth athletes should consider consistency of landing and flexion of the front leg.

There was no significant difference in the timing of biomechanics found between the various competition levels.

Standard deviations of variability tended to be the biggest for the youth pitchers and decreased as the level of competition increased. This means pitchers at high levels of competition exhibit less variability in their pitching motion. This is most likely because of increased years of repetition and greater neuromuscular development.

Baseball Pitching Biomechanics in Relation to Injury Risk and Performance (Open Access)

Authors: Fortenbaugh, Dave; Fleisig, Glenn S; Andrews, James R

This study reviewed all available literature on pitching biomechanics related to performance and injury. It is important to note that different institutions use an assortment of methods to measure biomechanics, which can make direct comparisons among them difficult.

This is a great review that touches on many aspects that should be of interest to coaches or trainers. Kinematics, kinetics, fatigue, youth pitchers, and pitch types are all covered along with what biomechanics markers have been shown to be helpful and harmful to pitchers across these studies. This is a great study for coaches and trainers who are looking to start educating themselves on biomechanics.

Remember that performance enhancement and injury prevention often go hand in hand when discussing pitching biomechanics.

Expand for Vocab
Pitching biomechanics – examining the forces applied to the body during the pitching motion to gain a greater understanding of how the body works and to reduce injuries

Kinematics – branch of mechanics that describes the motion of points using math and geometry to figure the velocity or acceleration of various points of the body, in this case of a pitcher

Kinetics – using physics to study motion and its causes, namely forces occurring in the pitching motion in this instance

Radio-ulnar joint supinates around ball release during baseball fastball pitching

Authors: Matsuo, Tomoyuki; Jinji, Tsutomu; Hirayama, Daisaku; Nasu, Daiki; Ozaki, Hiroki

A primer for pronation and supination: If you hold your arm up so your elbow is at 90 degrees with your thumb pointed at your ear, pronation would be moving the thumb to point at the front or anterior part of your body. Supination would be pointing your thumb behind you or at the posterior part of your body. It has been pointed out in previous studies that pronation of the hand/forearm is linked to internal rotation and supination in linked to external rotation.

The authors used a 16-camera–motion-analysis system at 1000 Hz to record the pitching motion of 20 healthy male semi-professional pitchers. A significant relationship was found between the pronation angle at the moment of ball release and the external rotation angle of the shoulder, as well as pronation angle and shoulder horizontal-adduction angle. There was a clear supination phase around the instant of ball release in all trials, but there was no consistent pattern among pitchers. The supination period lasted from just before to just after ball release.

It is reasonable to assume that the orientation of the palm correlates with the direction of the ball. After max external rotation, the arm goes into internal rotation at a very high speed. Nearing ball release, a supination phase may be needed for redirection of the ball towards its target.

Correlation of Shoulder and Elbow Kinetics with Ball Velocity in Collegiate Baseball Pitchers (Open Access)

With a group of 67 NCAA D1 pitchers, the researchers examined the correlations between elbow-valgus torque, shoulder-distraction force and shoulder external-rotation torque and ball velocity. The hypothesis was that there would be a moderate positive correlation between those factors and ball velocity. Meaning the harder that an athlete throws the more force and torque they experience on their arm.

A weak positive correlation was found between ball velocity and shoulder-distraction force (r=0.257) but no significant correlations were observed between ball velocity and elbow-valgus torque or ball velocity and shoulder external-rotation torque.

This is an interesting finding considering other research pointing toward increase in velocity being and increase in stress on the arm. What it does suggest is that changes in forces of the arm are more individualized than previously believed.

The researchers also bring up an interesting point that having a sample size of D1 baseball players may bring a type of ‘survival bias’ into play. The relationship very well may change when looking at a different sample of pitchers.

A Biomechanical Comparison of Pitching From a Mound Versus Flatground Adolescent Baseball Pitchers

Fifteen adolescent pitchers between the ages of 9 and 14 were recruited for the study. The athletes were asked the throw 7 pitches, from a mound and flatground, to a standard strike zone 45 feet away.

The researchers found that, for adolescents, pitching off the mound was slightly more stressful than pitching off of flatground: 33.6 Nm vs 31.7 Nm for the shoulder and 33.3 Nm vs 31.4 Nm for the elbow.

The researchers also proposed that a 6% increase in stress, though small, was equivalent to the percentage decrease in the timing of specific phases of the pitching motion. This may imply that the slope of the mound may cause a decrease in the time available to complete a pitch, which may cause a change in kinetic values.

It’s unknown if this relationship is the same for adult pitchers.

Do Baseball Pitchers Improve Mechanics After Biomechanical Evaluations?

Forty-six baseball pitchers were evaluated twice in a biomechanical analysis to see if there were any changes between analysis. The average time between analysis was 12 months with a range of 2 to 48 months. Ten full-effort fastballs were used in the study to compare evaluations.

Pitchers were judged to have “flaws” in their mechanics if they were outside of the normative range, either too high or too low. Overall there were 138 “flaws” detected in the pretest and 61 (44%) of them were corrected by the second test. The 46 pitchers had 223 biomechanical parameters in the normal range and 41 parameters (18%) developed new “flaws” by the second evaluation.

The study didn’t look at any specific teaching or coaching methodology, which raises the interesting point that mechanics are fluid and change over time at all ages. However, there wasn’t a big enough group to compare if amateurs or professional were able to make more changes than the other.

Correlation of Torque and Elbow Injury in Professional Baseball Pitchers

Through a mixed-model analysis, a comparison of elbow-valgus (EV) torque throughout the pitching motion found a near-significant statistical trend between the injured and non-injured groups. A further analysis of differences determined that a statistically significant difference occurred only at the event of maximum external rotation (p=.0130).

At other events, a statistically significant difference of EV torque did not occur. At maximum external rotation, the non-injured group had a mean EV torque of 74.7 Nm (± 22.38) and the injured group had a mean EV torque of 91.62 Nm (± 22.96).

The non-injured group also experienced less maximum shoulder external-rotation (ER) torque at maximum external rotation. Max ER torque is the force that the arm lies back into external rotation.

Other studies have examined differences of elbow-valgus torque at maximum external rotation, but it is clear that maximum ER is the point at which there is the most stress on the elbow. Furthermore, the force that the arm lies back into external rotation is an important factor in elbow torque.

Kinematic and Temporal Parameters of High School Baseball Pitchers in Different Velocity Groups (Open Access)

The researchers compared twelve kinematic and nine temporal parameters between the ten pitchers with the greatest hand velocity and the ten pitchers with the lowest hand velocity.

There were no differences between any of the temporal parameters, but researchers did find differences in a number of kinematic variables. The high velocity group had greater peak trunk rotational velocity, elbow angular extension velocity, and maximum knee extension angular velocity at ball release.

Surprising to the researchers, they found no differences in maximal external shoulder rotation or forward trunk tilt between the two groups. Theses two variables have been shown to be significant in other studies. Because of this, the authors note that there may be larger differences between high school, college, and professional pitchers than currently believed.