Youth Baseball Pitching Mechanics Analysis Across Age Groups

Written by David Besky, Knowledge Scientist II

As referenced in our take a look at velocity measurements throughout the youth knowledge we now have from our Driveline Academy athletes, we’re gathering knowledge on a large pattern of youth athletes as they age, and are extraordinarily excited concerning the analysis alternatives that may open up.

In that evaluation, we thought-about the distribution of metrics (pitch velocity, bat velocity, and exit velocity) throughout our totally different age teams to get an concept of how these have a tendency to vary as athletes age (with the caveat that we’re evaluating totally different athletes throughout every group). Right here, we take the same take a look at the biomechanics knowledge we’ve collected by having all Driveline Academy athletes throw in our movement seize lab.

Movement Seize Lab

Our markered movement seize lab is a staple of our coaching applications with our highschool, school and professional athletes, and it permits us to trace physique segments with submillimeter accuracy. This permits us to exactly quantify how athletes are transferring—providing distinctive alternatives for participant evaluation and analysis into what distinguishes how the very best athletes transfer.

When contemplating youth knowledge, we see a reasonably broad vary of heights and weights for the 8-14 12 months olds in our knowledge set. We do see athletes usually get larger as they age, however even inside a crew we see a large unfold by way of how huge (with out lack of generality) a 12 12 months outdated is.

For this evaluation, we largely contemplate joint angles and angular velocities, that are considerably agnostic to the load distinction throughout age teams. That’s, we’re how rapidly an athlete’s joints are transferring, which (versus power/torque/momentum) isn’t straight a perform of the athlete’s weight, so the numbers are naturally scaled to every athlete’s weight.

We had athletes mocap in November of 2020 after which once more in the summertime of final 12 months to get a test-retest comparability to trace their modifications. We repeated this course of with our elevated variety of athletes within the Academy this fall to generate extra baselines.

For this evaluation, we contemplate solely the primary mocap from every athlete (we’re nonetheless processing lots of the athletes from the autumn on the time of this writing). We selected to think about their first mocap in order that the pattern is minimally influenced by any coaching the athlete has achieved with us. We see 99 totally different athletes between the ages of 8 and 14.

Mocap Participant Rely by Age

To get a basic concept of what we’re working with, right here’s a take a look at the unfold of peak, weight, and velo by age throughout this inhabitants.

Weight by Age
Height by age

Actions differ on common between youthful and older athletes. Listed below are a number of of the core metrics we often contemplate necessary indicators of how an athlete is transferring, organizing them into decrease half metrics, arm motion metrics, and posture/core metrics.

Decrease Half

First, let’s check out the decrease half. We contemplate three metrics: entrance knee extension angular velo at ball launch (a measure of the lead leg block); heart of gravity (COG) velocity (how rapidly the athlete strikes their physique in the direction of the plate); and stride size.

Entrance knee extension angular velo at BR is fairly constant on common throughout age teams. We do see older athletes transfer their COG extra rapidly (which can be confounded by peak, since a taller athlete will transfer quicker in the event that they transfer the identical distance relative to their peak in the identical period of time as a shorter athlete).

Stride size (when taken as a proportion of the athlete’s peak) permits us to take a look at this similar transfer whereas controlling for the athlete’s peak. Once we do that, we do see older athletes nonetheless stride longer, although the impact is a bit of bit smaller than for COG velo.

Knee Extension Angular Velo at BR
Knee Extension Angular Velo at BR
Max COG Velo X
Max COG Velo X
Stride Length vs Age
Stride Size
Average Values for Lower Half Metrics for Each Age
Common Values for Decrease Half Metrics for Every Age

Arm Motion

Transitioning to arm motion, we usually contemplate a pair positions at foot-plant: shoulder abduction (if an athlete has a low elbow or is mountaineering it above the shoulders); shoulder exterior rotation (how flipped up the forearm is); and shoulder horizontal abduction (scap retraction). As well as, we’ll take a look at how a lot exterior rotation (layback) they get and the max elbow flexion (how a lot bend they get of their elbow) all through the supply.

The final principal arm motion metric we frequently reference is elbow extension velo and shoulder inner rotation velo (which measure how rapidly the arm is transferring in these two actions as they happen in the course of the throw).

Shoulder Abduction at FP
Shoulder Abduction at FP
Shoulder External Rotation at FP
Shoulder Exterior Rotation at FP
Shoulder Horizontal Abduction at FP
Shoulder Horizontal Abduction at FP

For these touchdown positions, we don’t see a transparent development for development as athletes age—and any potential development may be very small relative to the variability we see inside every age group with reference to their arm place at foot plant.

Max Elbow Flexion
Max Shoulder Exterior Rotation

We see common max elbow flexion maintain fairly regular throughout the totally different groups, however do see a point of an upward development for shoulder exterior rotation (with annually of age, avg MER will increase by ~ 2 levels), although there’s a number of variability between athletes round that development line.

Max Elbow Extension Velo
Max Shoulder Internal Rotational Velo
Max Shoulder Inner Rotational Velo

We see a slight enhance in common elbow extension velo and shoulder inner rotation velo as athletes grow old. This enhance is probably not as massive as we’d anticipate, however the older athletes are larger, so even the identical velocities would correspond to extra momentum and power.

Common Values for Arm Motion Metrics for Every Age


Lastly, we check out hip to shoulder separation (at foot-plant and the max worth) and torso/pelvis rotational velos.

Rotation Hip Shoulder Separation at FP
Rotation Hip Shoulder Separation at FP
Max Rotation Hip Shoulder Separation
Max Rotation Hip Shoulder Separation
Max Torso Rotational Velo
Max Torso Rotational Velo
Max Pelvis Rotational Velo
Max Pelvis Rotational Velo

Right here we see that older athletes are likely to have extra hip to shoulder separation (each at its max worth and at foot-plant, which we contemplate to see how successfully they’re in a position to time up their max hip to shoulder separation). Trying on the torso and pelvis rotation velos, we see them maintain regular throughout the age teams or drop off barely (which can simply be a product of how rather more power is generated from the athlete being heavier relative to a slight drop off in rotational velocity).

Average Values for Posture/Core Metrics
Common Values for Posture/Core Metrics


In whole, we see that some metrics have a tendency to extend barely amongst our older athletes, comparable to their capability to coordinate their physique to shift their weight down the mound, get hip to shoulder separation, and get into extra shoulder exterior rotation.

For HSS and exterior rotation, these traits might end result, partially, from the bodily growth of athletes, which permits them to get into and maintain a few of the deeper positions that we see our larger degree (school and professional) athletes use. This highlights an necessary level: athletes’ mechanics might replicate technical or bodily limitations. Particularly with youth athletes however with our older athletes as nicely, exterior cueing and self-organization permit for athletes to work inside the constraints of their distinctive bodily traits to optimally obtain the objective of throwing the ball exhausting, effectively and successfully.

Whereas we will establish potential areas for motion enchancment primarily based on traits we see throughout a big physique of throwers, totally different athletes can have totally different idiosyncrasies that may drive how they transfer optimally, as evidenced by a number of variability in motion methods deployed efficiently by the exhausting throwers in our database, together with MLB arms and throws as much as 100 mph.

Relating to youth athletes, we’re delicate to emphasizing exterior targets that permit them to make use of what athleticism they’ve as they’re nonetheless growing coordination. We don’t need to rob them of that by trying (doubtless futilely) to dictate a selected set of appropriate mechanics that they is probably not bodily geared up to do nicely at that cut-off date.

With lots of the different metrics (lead knee extension velo, arm positions at foot-plant, torso and pelvis rotational velos), we don’t see a big distinction between the totally different age teams. That stated, it’s true that the handful of metrics thought-about on this evaluation don’t absolutely encapsulate every little thing that’s occurring mechanically, so there are parts of coordination and the way athletes get into and out of positions that aren’t thought-about right here. Nonetheless, these consistencies in mechanics counsel the significance of prioritizing getting bigger, stronger, and extra highly effective as a path to rising output, as that’s a notable distinction between the older athletes who throw more durable and the youthful athletes on this pattern.

There’s nonetheless so much to discover throughout our youth movement seize knowledge, comparable to questions like: Do athletes who throw more durable for his or her age show comparable traits as we see when evaluating more durable throwers in our school/professional inhabitants? Will we see decreased variability in mechanics on a throw-to-throw foundation for older athletes in comparison with youthful athletes? How does our energy evaluation knowledge (from soar testing) relate to those mocap knowledge, and do these relationships mirror what we see with our HS/school/professional athletes?

We hope to the touch on these in future items as we dig deeper into these knowledge.


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