Every document here starts the same way: screen before you coach. This is the screen.
The point is not to generate a report. It is to answer one question at each joint — can he, or can't he — because a fault an athlete cannot physically avoid needs the opposite intervention from a fault he could. Twenty minutes on a table and a floor separates those two cases everywhere in the delivery, and without it you spend months coaching positions that were never available.
How to use it
Ground up, always
Run it in delivery order. A hip finding changes what a shoulder finding means, because the arm is frequently compensating for something below it. Reading the shoulder first inverts the logic.
Compare sides before norms
Side to side asymmetry is more informative than population averages for almost everything here. The athlete is his own control group.
Note the end feel
Soft and springy means tissue you can change. Hard, early and bony means structure you cannot. This single observation prevents more wasted work than any other item on the list.
Retest tired
Half of what matters only shows up under fatigue, and fatigue is the state most faults appear in. A pass when fresh is not a pass.
Ask where he feels things
The cheapest instrument you own. Location of effort separates loading from hiking, and apprehension from restriction, in about four seconds each.
A finding is a hypothesis
Confirm it on video before you act. A restriction that does not show up in the delivery may not be worth chasing.
The battery
Grouped by region, in the order to run them. The last column points at the document that covers what you found.
| Test | Flag if | What it means | Points to |
|---|---|---|---|
| Ankle knee to wall, both sides | Under about 4 inches, or a side difference | Gates stride length and how long he can apply force against the ground. | Deficiency, link 01 |
| Hip rotation, both directions, both sides | 5 degrees or more difference in inward rotation | The highest yield test on the list. A 5 degree deficit predicted back and abdominal injuries across 258 professional player seasons. | Swing or Rotate |
| Total hip rotation per side | Large asymmetry in the sum | Distinguishes a hip tight in one direction from a hip that has lost motion overall. Changes the plan. | Swing or Rotate |
| Single leg stance, 30 seconds, hands off hips | Pelvis drops or hikes | A drop is a weak side hip. A hike is the compensated version of the same weakness, and it is what a false load looks like standing still. | False Load |
| Same, under fatigue | Passes fresh, fails tired | Where most athletes get exposed, and it matches what the video shows across an outing. | False Load |
| Hip airplane | Cannot control rotation over the loaded leg | Separates passive range from usable range. Passing a table test and failing this is a control problem, not a mobility one. | Swing or Rotate |
| Single leg Romanian deadlift | Loses position, knee drifts | Can the front leg brake and hold. This is whether he can be an axle at all. | The Long Way Back |
| Drop and stick landing | Sinks, or the knee tracks outside the foot | Tests whether a stacked landing is available before you ask for it at full intent. | The Long Way Back |
| Copenhagen hold | Short hold time, or asymmetry | Adductor capacity, which decelerates the stride and resists the limb bowing. | The Long Way Back |
| Test | Flag if | What it means | Points to |
|---|---|---|---|
| Rib position at rest, and on a full exhale | Ribs flared, pelvis tipped forward | Do this before any mid back test. A flared rib cage makes rotation screens read better than they are. | Deficiency, link 08 |
| Seated mid back rotation, both directions | Limited, or asymmetric | Supplies most of the chest's usable turn. Stiff here and the chest rotates the instant the pelvis does. | Nothing Left to Turn |
| Mid back extension | Rounded, limited | Gates shoulder blade posterior tilt, so this is a shoulder test as much as a trunk one. | Allowed, Not Made |
| Single leg lift test, back leg, watching pelvic tilt | Swing much beyond about 6 degrees | Better drive leg pelvic control came with lower shoulder loading in high school pitchers. | False Load |
| Side plank hold, both sides | Asymmetry, or a hiked pelvis | Frontal plane trunk capacity, and whether he holds a level pelvis or hikes to get there. | False Load |
| Pallof press hold | Cannot resist rotation cleanly | Anti rotation capacity, which is what holding the chest closed against a turning pelvis actually is. | Nothing Left to Turn |
| Test | Flag if | What it means | Points to |
|---|---|---|---|
| Shoulder rotation both directions, lying face up at 90 degrees | Loss on the throwing side | Run it twice: once with the shoulder blade free, once with it held down. A large difference means the blade is the limiter, not the joint. | Adaptation or Loss |
| Total rotational motion, both shoulders | Throwing side notably lower in the sum | More informative than either direction alone. This is the number that separates normal adaptation from actual loss. | Adaptation or Loss |
| End feel at the limit | Hard, early, abrupt | Bone rather than tissue. Stop working on it and build around it. | Allowed, Not Made |
| Small chest muscle length, lying face up | Shoulder sits up off the table | The most common mechanical block on layback. | Allowed, Not Made |
| Lat and teres major length, arms overhead, low back flat | Cannot reach without arching | Separates a genuine tissue restriction from a lumbar cheat. | Allowed, Not Made |
| Wall slide, watching the inner border of the blade | Winging, or no upward rotation | Serratus and lower trapezius. The force couple that lets the arm finish moving. | Allowed, Not Made |
| External rotation strength against internal | Back of the shoulder well outmatched | The deceleration muscles. Test fatigued as well as fresh, since that is the state they fail in. | Stopping It |
| Wrist tilt toward the thumb | Limited | The gate on any arm slot change. Without it, dropping the slot subtracts the pitch. | Who Should Drop |
| Grip strength, fresh and late in a session | Large drop when tired | Forearm endurance, which is the armour standing between elbow load and the ligament. | Position, Not Effort |
| Where he feels the end of shoulder range | Front of the joint, apprehension | Guarding rather than restriction, and it changes the plan completely. | Allowed, Not Made |
The three questions
Free, fast, and each one replaces a test you would otherwise have to run.
"At the top of your leg lift, where do you feel that?"
Loading
The tissue under tension is the tissue that drives the pitch.
Hiking
Real work in a plane the pitch does not use. Go to False Load.
"Where do you feel the throw itself?"
Carried
The chest is delivering rotation and the arm is along for the ride.
Pushed
The arm is generating what it should have inherited. Go to Push or Whip.
"Where are you sore the day after an outing?"
Expected
The deceleration muscles and the drive leg. Watch that it clears on schedule.
Compensating
The low back doing hip work, or the elbow paying its own deceleration bill.
What to capture on video
Three camera positions and four frames. Everything else is detail.
| Angle | What it shows | Frames to freeze |
|---|---|---|
| Open side, side on | Stride length, arm elevation, layback, forward tilt, block quality | Foot contact, peak layback, release |
| From behind | Belt line angle, femur direction at landing, whether the knee bows, arm path and finish | Peak leg lift, foot contact, the four frames after it |
| Front on | Chest orientation at landing, glove side behaviour, head line | Foot contact, release |
Foot contact is the frame that carries the most information
Chest orientation, arm elevation, elbow bend, femur direction, belt line angle and stride length are all decided there, and it is the last stable moment before everything spins. It is also the frame whose consistency has been associated with command.
If you only capture one thing well, capture foot contact from behind and front on.
What you can measure without a lab
Almost every position in this library
Stride length as a share of height, belt line angle, chest orientation at contact, femur direction, arm elevation and finish. Slow motion on a modern phone is enough for all of it.
Velocity, and its trend within an outing
The trend matters more than the peak. A pitcher losing velocity across innings while his mechanics degrade is the fatigue pattern.
Three of the four release numbers
Release height, side, extension and spin. The highest return per dollar of anything in a facility, because it prices mechanical changes in the currency that matters.
The three questions above
Location of effort and location of soreness. Genuinely diagnostic, and most people never ask.
Elbow load and joint kinetics
Cannot be estimated from video. If arm health is the question, this is what a capture session is for.
Peak segment velocities and timing
The sequence order and gaps. Visible in rough terms on video, measurable only with capture.
Sources
- Decreased Hip Internal Rotation Increases the Risk of Back and Abdominal Muscle Injuries, 258 player seasons
- Lumbopelvic-hip Control, Upper Extremity Joint Moments, and Drive Leg Ground Reaction Force in Adolescent Pitchers
- Driveline — Pitching Assessments and Changing Mechanics
- Driveline — Making Movement Changes in the Weight Room
- Driveline — The Interaction of Biomechanics and Command, foot plant consistency
- ASMI — The Clinician's Guide to Baseball Pitching Biomechanics
- Gluteus Medius and Scapula Muscle Activations in Youth Baseball Pitchers
- Cressey — The Importance of Hip Rotation