Written by David Besky, Data Scientist II
As referenced in our look at velocity measurements throughout the youth knowledge we have now from our Driveline Academy athletes, we’re accumulating knowledge on a large pattern of youth athletes as they age, and are extraordinarily excited in regards to the analysis alternatives that may open up.
In that evaluation, we thought of the distribution of metrics (pitch velocity, bat pace, and exit velocity) throughout our totally different age teams to get an thought 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 have 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 motion capture lab is a staple of our coaching packages with our highschool, faculty 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 most effective 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 greater as they age, however even inside a group we see a large unfold when it comes to how huge (with out lack of generality) a 12 12 months previous is.
For this evaluation, we largely contemplate joint angles and angular velocities, that are considerably agnostic to the burden distinction throughout age teams. That’s, we’re how shortly an athlete’s joints are transferring, which (versus vitality/torque/momentum) isn’t immediately 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 most 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 accomplished with us. We see 99 totally different athletes between the ages of 8 and 14.
To get a common thought of what we’re working with, right here’s a have a look at the unfold of top, weight, and velo by age throughout this inhabitants.
Actions differ on common between youthful and older athletes. Listed here are a number of of the core metrics we normally contemplate vital indicators of how an athlete is transferring, organizing them into decrease half metrics, arm motion metrics, and posture/core metrics.
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); middle of gravity (COG) velocity (how shortly 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 shortly (which can be confounded by top, since a taller athlete will transfer quicker in the event that they transfer the identical distance relative to their top in the identical period of time as a shorter athlete).
Stride size (when taken as a share of the athlete’s top) permits us to have a look at this similar transfer whereas controlling for the athlete’s top. Once we do that, we do see older athletes nonetheless stride longer, although the impact is a little bit bit smaller than for COG velo.
Transitioning to arm motion, we usually contemplate a pair positions at foot-plant: shoulder abduction (if an athlete has a low elbow or is mountain climbing it above the shoulders); shoulder exterior rotation (how flipped up the forearm is); and shoulder horizontal abduction (scap retraction). As well as, we’ll have 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 shortly the arm is transferring in these two actions as they happen throughout the throw).
For these touchdown positions, we don’t see a transparent development for development as athletes age—and any potential development could be very small relative to the variability we see inside every age group with reference to their arm place at foot plant.
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 numerous variability between athletes round that development line.
We see a slight improve in common elbow extension velo and shoulder inner rotation velo as athletes become old. This improve might not be as giant as we’d anticipate, however the older athletes are greater, so even the identical velocities would correspond to extra momentum and vitality.
Lastly, we check out hip to shoulder separation (at foot-plant and the max worth) and torso/pelvis rotational velos.
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 capable of 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 far more vitality is generated from the athlete being heavier relative to a slight drop off in rotational velocity).
In complete, we see that some metrics have a tendency to extend barely amongst our older athletes, reminiscent of their skill 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 tendencies could outcome, partly, from the bodily growth of athletes, which permits them to get into and maintain a number of the deeper positions that we see our greater stage (faculty and professional) athletes use. This highlights an vital level: athletes’ mechanics could replicate technical or bodily limitations. Particularly with youth athletes however with our older athletes as nicely, exterior cueing and self-organization enable for athletes to work inside the constraints of their distinctive bodily traits to optimally obtain the purpose of throwing the ball arduous, effectively and successfully.
Whereas we will establish potential areas for motion enchancment based mostly on tendencies we see throughout a big physique of throwers, totally different athletes may have totally different idiosyncrasies that may drive how they transfer optimally, as evidenced by numerous variability in motion methods deployed efficiently by the arduous throwers in our database, together with MLB arms and throws as much as 100 mph.
In the case of youth athletes, we’re delicate to emphasizing exterior targets that enable them to make use of what athleticism they’ve as they’re nonetheless growing coordination. We don’t wish to rob them of that by making an attempt (seemingly futilely) to dictate a selected set of appropriate mechanics that they might not be bodily outfitted to do nicely at that time limit.
With most 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 mentioned, it’s true that the handful of metrics thought of on this evaluation don’t totally encapsulate every thing that’s happening mechanically, so there are components of coordination and the way athletes get into and out of positions that aren’t thought of right here. Nonetheless, these consistencies in mechanics counsel the significance of prioritizing getting bigger, stronger, and extra highly effective as a path to growing output, as that’s a notable distinction between the older athletes who throw tougher and the youthful athletes on this pattern.
There’s nonetheless rather a lot to discover throughout our youth movement seize knowledge, reminiscent of questions like: Do athletes who throw tougher for his or her age show related tendencies as we see when evaluating tougher throwers in our faculty/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/faculty/professional athletes?
We hope to the touch on these in future items as we dig deeper into these knowledge.