Force-Plate Cockpit

Ground Reaction Force (foundation)

Definition

The force the ground pushes back with in reaction to your muscles pushing into it (Newton's 3rd law). Force precedes motion — you build the force before the body part moves.

The one distinction that prevents misreads

S2M is explicit: pressure can look perfect while force is weak. Always read magnitude (force) separately from distribution (pressure). (Ep.2 13:02–14:09; Ep.5 13:34)

The three forces + three torques (Greg Rose's "third-grade" language)

Forces (how you push): Lateral (side-to-side → lateral-force) · Vertical (up/down, the jump → vertical-force-peak) · Anterior–posterior (toward/away the ball → anterior-posterior-forces). Torques (how you twist): Twist (around the spine → rotational-force) · Rock-and-roll (side-bend/frontal plane) · Bend (forward/back).

Tour players are mostly "rockers" — "a rocking sport converted into twisting," not primarily rotary (Greg Rose).

Source positions

Consensus / divergence

• Agree: force/pressure ≠ static "weight"; all three separate what you do to the ground from standing weight.
• MG sharpens it: adds the COP vs COM axis — the practical key to not over-sliding → see center-of-mass-vs-pressure.

What / How / Why — read this before you "fix" anything (Greg Rose)

Force plates tell you HOW you move. They do not tell you WHY. Find the why first — it's one of four: 1. Fundamentals (grip, stance, alignment, ball position, posture — "98% of tour-player work"). 2. Physical (a body limitation — e.g. lead-hip internal rotation; TPI's specialty). 3. Equipment (lie angle, fit). 4. What the player's thinking (their mental model).

A force-plate fault shows you where to look, not the cause — "don't turn these tools into vices."

Forces precede motion (Newton's 1st law)

The GRF is visible before the body moves — pressure going right ≠ "moving right," it means you're pushing on the right foot (you might be about to move left). Read it as where you push, not weight shift. That's why force plates are predictive.

Tour magnitudes — reference (Greg Rose, n≈125 PGA/KFT/DP/LIV/LPGA)

Notes

This is the vocabulary card — read it first if a force vs pressure claim ever looks contradictory.

Centre of Mass vs Centre of Pressure

Definition

Centre of pressure (COP) = where you're pushing on the ground. Centre of mass (COM) = where your body mass actually is. They are different and move differently: you can shuttle COP quickly between the feet without moving COM much. What golfers call "weight shift" is really a pressure transfer.

Why this is the resolver

This is the distinction that reconciles the lateral-force debate (lateral-force): - Shift the lateral PRESSURE (COP) early → everyone agrees (S2M, TPI). - Don't slide the MASS (COM) → Measured Golf's caution. So "move your weight to the trail side" is a trap if you read it as mass — you over-slide, lose low-point control, and sway. Read it as pressure and you load without sliding.

Source positions

My data — current state

Matchups — more / less

Read it on the plate

• Watch the COP dot travel trail→lead while the body (COM) stays comparatively centered. Big COM/body slide with the COP = over-shifting mass.

Seen in the data (validation)

• Wyndham Clark (iron): over-goes lateral and starts late; TPI's fix is turn/load (coil the trail hip), not slide — so the shift starts earlier. Pressure/coil over mass-slide — exactly this card's point.

Dependencies & links

• Underlies: lateral-force, trail-pressure-load, cop-trace.
• Related: ground-reaction-force (force vs pressure).

Notes

Measured Golf's signature point, and arguably the single most clarifying idea across all three sources for the lost-strike problem: load by pressure + leg push, not by moving your body off the ball.

Kinetic Sequence & Timing

Definition

The order the three forces peak and when each peaks. Piece #1 of the Performance Pie and the first thing to check — a sequence error poisons every magnitude/point-of-application read below it.

The order (must hold)

Source positions

Consensus / divergence

• Agree on the order: S2M (forces: lateral→rotational→vertical) and TPI (weight shift→rock→twist→jump) describe the same ground-up sequence.
• KEY distinction — kinetic vs kinematic: S2M's kinetic sequence = the forces (cause; force plate). TPI's kinematic sequence = the segment speeds (effect; 3D capture). Forces cause motion — the kinetic sequence drives the kinematic one. Don't conflate the terms → see kinematic-sequence.
• Timing insight (TPI/JT): finishing the GRFs early (lead arm parallel, shaft still back) leaves more time to transfer energy up — complements S2M's "vertical peaks before impact, not at it."

Greg Rose: the 70% / 98% rule, timing & the lead-foot brace

70% sequence (largest pro DB): lateral → rock-and-roll → twist → bend → jump. 70% of pros (30%, incl. major champions, don't — not mandatory). Simplified 98% rule: lateral → twist → jump. - Lateral first — for sequence and power (Newton: a weight shift lets you push harder → more force). - "Shallow early to steepen late" — the rock-and-roll shallows the club early so you can steepen late; great players don't steepen early then scramble to shallow. (Directly your stuck/shallow battle.) - Then twist (club to the front) → bend / jump (post + release).

Timing numbers: lateral peaks ~0.23 s before impact, vertical ~0.1 s. The last force (vertical) finishes ~lead-arm-parallel / shaft-vertical, mid-downswing (Greg prefers lead-arm-parallel — "more hand path, farther from the wall"). Earlier = more time to transfer ("push from 30 ft from the wall, not 1 ft"). Amateurs: forces & torques way too late. The whip: if the tip cracks first, who cares how hard the handle moved — sequence > magnitude.

Lead-foot brace — the "75% rule" (advanced): on the lead foot, ~75% of big hitters peak AP first, then lateral-brake + vertical together, within ~0.05 s — clustered right before release. This anchors you to convert linear → angular (release; a 150 mph swing can pull you forward ~200 lb). Best players use all three lead-foot mechanisms (lateral brake, vertical, side-bend); weaker players use one.

My data — current state

Matchups — failure modes

Read it on the plate

• One graph does it: the kinetic-sequence graph shows all three peaks; confirm order, eyeball each peak's swing position, and each has its own threshold dotted line (sequence + timing + magnitude in one view, Ep.6 21:43).

Seen in the data (validation)

• Justin Thomas (r9d): starts his GRFs late but finishes early (shaft still back at lead-arm-parallel) — the order holds even compressed. Lesson: finishing early beats starting early.
• Wyndham Clark (iron): his lateral starts after the top — TPI: "if we started your forces earlier it'd be better." Late sequence = speed left on the table.

Dependencies & links

• Governs: lateral-force, rotational-force, vertical-force-peak (their timing lives here).
• Related: line-of-pressure, vertical-unweighting.

Notes

Fix order → timing → point of application → magnitude → shape. Don't add force to a mis-sequenced pattern.

Kinematic Sequence (segment speeds)

Definition

The order and speed of the body segments — pelvis → trunk → arms → club — and how each transfers energy to the next (the "whip"). This is the motion/output side. It is caused by the kinetic (force) sequence — see the distinction below.

Kinetic vs Kinematic — don't conflate them

Forces (kinetics) drive motion (kinematics). A clean kinetic sequence is how you produce a clean kinematic one. They're two lenses on the same chain, not competing models.

Source positions

My data — current state

Matchups — failure modes

Read it

• The 3D kinematic-sequence graph (4 lines: pelvis/trunk/arm/club). Check progressive speed gain + the left-to-right deceleration order.

Seen in the data (validation)

• Ernie Els (H3tfA3AeDUA): textbook — each segment adds speed, clean deceleration/firing order. The reference picture.
• Jamie Sadlowski 2010→2024 (xrvg8NiUY3I): traded thoracic lift + posture-loss + more X-factor separation (52°→45°) — i.e. power — for staying down / maintaining posture — i.e. accuracy. A 2× long-drive champ living the power↔consistency matchup.
• Wyndham Clark: TPI — "driver → 3D matters more, iron → force plate matters more; you need both." Validates reading kinetics + kinematics together.

Dependencies & links

• Caused by: kinetic-sequence (forces).
• Feeds: club-head speed.
• Related: vertical-force-peak, rotational-force.

Notes

TPI's home turf (3D capture). When force data (S2M) and segment-speed data (TPI) are both available, read them together: force = input, speed = output.

Lateral Force

Definition

Side-to-side ground-reaction force. It initiates the shift, then the lead leg uses it as a brake. The first force to peak — it sets up everything after it.

Source positions

Direction convention

• Positive = push away from target → ground pushes you toward target → COM moves to target (what you want at transition).
• Negative = the reverse → COM drifts away from target (hang-back). A line isn't positive until it crosses zero (Ep.6 11:38).

Consensus / divergence

• Agree (S2M + TPI): lateral peaks FIRST, at/just before transition; its absence (early rotation) is the fault — over-the-top / "hiking" / early extension.
• Apparent CONFLICT (MG): Measured Golf pushes back on "horizontal force is the secret sauce" and warns against over-sliding at the target.
• Why + reconciliation — pressure vs mass: all three want the lateral pressure shift first; MG's caution is against over-shifting mass (sliding) and using lateral magnitude as a substitute for torque. So lateral-pressure-first = yes (all); lateral-mass-slide / horizontal-only = no (MG). Not a true contradiction — a depth/over-application warning. See center-of-mass-vs-pressure.

My data — current state

Interventions tried

Matchups — more / less (matchups.md → L2)

Read it on the plate

• Graph: yellow = total, blue = lead, red = trail; the 0-axis splits positive/negative.
• Kinetic sequence: lateral should be the 1st peak; threshold dotted line at 20%.
• Vector tilts toward target when positive.

Seen in the data (validation)

• Cameron Tringale (BT_FQfPYxuA, "hiking"): little/no lateral shift at the top → rotates early → right hip high & stays high → steep. The lateral-skip fault, on tour.
• Justin Thomas (r9d): lateral peaks late yet works — because he finishes early. The window is personal; the order is not.
• Wyndham Clark (iron): lateral starts after the top; TPI's fix = turn/load the trail hip so the shift can start earlier (load enables the shift).

Dependencies & links

• Feeds: sets up rotational-force and vertical-force-peak; governs low point.
• Related: kinetic-sequence, trail-pressure-load, impulse (lateral impulse).

Notes

Below 20% it's "very unlikely they're doing what they need" and it inhibits everything later in the swing (Ep.6 21:24).

Rotational Force (horizontal-plane torque)

Definition

The force couple — trail foot pushes one way, lead foot the other — that spins you around the vertical axis and brings the club from behind you to the front.

Source positions

Direction convention

• Positive = rotation toward target (orange circle in app). Negative = away (black circle).
• Generated from a positive line of pressure (lead COP ahead of trail), which flips negative as you release into the finish (Ep.7 14:15–15:14).

Consensus / divergence

• Agree: rotation must follow lateral (peaks 2nd); rotating early = over-the-top (S2M & TPI's "hiking").
• MG emphasis: under-developed torque is the common amateur miss — build it from a stable, loaded trail side, then turn the upper body against it.

My data — current state

Interventions tried

Matchups — more / less (matchups.md → L1)

Read it on the plate

• AP-force graph: red & blue lines push opposite directions = the couple; yellow circle = net rotation (orange = positive).
• Kinetic sequence: rotational = 2nd peak; threshold dotted line at 85 N·m/kg.
• Check the line of pressure is positive while it's building.

Seen in the data (validation)

• Cameron Tringale (BT_FQfPYxuA, "hiking"): rotates before the lateral shift → right hip stays high, steep/over-the-top — rotation-too-early on tour.
• Wyndham Clark: power comes from coiling/loading the back hip first ("loading the gun") — torque needs the load before it.

Dependencies & links

• Requires: positive line-of-pressure; follows lateral-force in sequence.
• Feeds: club path, face-to-path, delivery.
• Related: kinetic-sequence, line-of-pressure.

Notes

Peaking before lateral is the classic over-the-top fault — "throwing things over and around the ball" (Ep.7 12:58). Sequence beats magnitude here.

Vertical Force — Peak Magnitude

Scope: full swing. Vertical force in chipping/putting is a different concept (stability, not a jump) — those get their own cards under concepts/chipping and concepts/putting.

Definition

The up/down ground-reaction force at its peak — the "jump." Of the three full-swing forces it's the one most highly correlated with club-head speed, and the one amateurs most often leak.

Source positions

Consensus / divergence

• Agree (S2M + TPI): vertical = the speed force, peaks last/tallest. Thresholds line up — S2M 165% floor / 190–200% strong / 230–250% elite; TPI tour norm ~200% (211% example).
• TPI adds: finishing the vertical/GRFs early matters as much as magnitude (JT).
• MG caution: vertical without torque is wasted — sequence/rotation first.
• Divergence axis: TPI's body-first lens — mobility/strength may gate output; a countermovement-jump test on the plates separates force-capacity from technique.

My data — current state (summary; full series in data/measurements.csv)

What my data shows — outcome links

• Trackman (proximate): does my peak vertical track with club speed / smash / low point in MY data? → —
• On the course (lagging): should surface in SG: Off-the-Tee / SG: Approach — tracked at the program dashboard level, not attributed to this card alone.
• My observed correlation: e.g. "vertical peak vs club speed r≈?, n=?" → —

Interventions tried

Matchups — more / less (full map in matchups.md → L3)

Read it on the plate (Smart2Move app)

• Kinetic-sequence graph: vertical = 3rd and tallest peak.
• Threshold line: dotted line at 165% — peak should clear it.
• Point of application at peak: lead-foot COP (blue dot) in the ball of the foot, not the heel.

Seen in the data (validation)

• Ryan Gerard (4OZ7Fh1u2MQ): peak ~211% BW (vs PGA norm ~200%) — clears S2M's 165% floor comfortably.
• Wyndham Clark: the harder he swings, the better his mechanics get (early extension drops, timing improves) — a real "more can be better" matchup for certain players. TPI: don't leave 20% on the table.

Dependencies & links

• Requires: positive line of pressure (line-of-pressure), lead-foot ball-of-foot COP (cop-trace), unweighting valley ~63–65% (vertical-unweighting).
• Feeds / affects: club speed, attack angle, low-point location, strike quality.
• Related cards: kinetic-sequence (timing), vertical-unweighting, cop-trace — all full-swing.

Notes

Magnitude is piece #3 of the Performance Pie — chase it only after sequence, timing, and point of application are right (Ep.8). Force on a good pattern = speed; on a bad one = injury risk.

Anterior–Posterior Forces (rotation + pelvis space)

Definition

The toward/away-the-ball forces. Anterior = positive = toward the ball; posterior = negative = away. They do two jobs at once: (1) form the rotational couple that creates twist, and (2) drive the linear motion of the pelvis toward/away the ball — i.e. whether you create space or thrust into the ball.

Source positions

Why this is your lever

This is the force-plate root of stuck / pull-hook: if your trail AP dominates, the pelvis thrusts toward the ball → early extension → "slack in the boat" (Greg Rose) → you can't deliver the club → trapped/stuck → flip to save → pull hook. The fix is to get the lead leg pushing away from the ball so the pelvis creates space to deliver from.

My data — current state

Matchups — more / less

Read it on the plate

• AP graph: trail above the line (+, toward ball), lead below (−, away). Check lead > trail and the net AP impulse is negative.
• If the lead line stops pushing away / trail carries it → thrust/early-extension pattern.

Dependencies & links

• Feeds: rotational-force (the couple), club path, low point, early extension.
• Related: impulse (net impulse), hips-spinning-open, center-of-mass-vs-pressure, line-of-pressure.

Notes

The single most direct force-plate read for your miss — if it's trail-dominant, that's the early-extension engine behind the stuck/flip.

Trail-Side Pressure (backswing load)

Definition

How much of your pressure is on the trail foot at its peak in the backswing — and, just as important, when that peak happens. This is distribution, not force (see ground-reaction-force).

Source positions

The timing is the point

Best players load and start shifting back before the top. A late peak (or pressure stuck on the trail into the downswing = hang-back) is the classic strike-killer.

Consensus / divergence

• Agree: ~75–80% trail at peak (S2M ~80–81%; MG 75–80%). Both stress it's pressure, not "weight."
• MG adds the HOW (body-first): load the hip (up/back/around) by pushing the trail leg and holding posture — don't shove mass right (that wrecks low-point control; see center-of-mass-vs-pressure).
• Conflict (location): trail pressure to the heel (S2M) vs cuboid/midfoot, not heel (MG) — see line-of-pressure.
• Tool note: MG uses Swing Catalyst (pressure mat); S2M uses force plates. Pressure % is comparable; true force is S2M-only.

My data — current state

Interventions tried

Matchups — more / less

Backswing setup → enables the transition shift · fix the backswing first

The downswing slide/stuck is mostly a compensation for a poor load. The backswing is slow and controllable, so fix it first — a good load removes the need for the difficult downswing saves. A backswing that sets up a clean shift shows up as: - Load early, ease back before the top — trail % peaks ~75–80% by P2–P3 and is already dropping before P4. Still loading at the top = late shift = rushed slide → stuck. - Pressure, not mass — push the trail leg/hip with COM centered (no sway) so you're already positioned to push off forward (center-of-mass-vs-pressure). - To the cuboid/midfoot (not heel/toes) — you can only push from the midfoot → enables the shift and a positive line-of-pressure. - Posture + trail-knee flex held — a loaded spring to push from (stand up = nothing to push off). - Enough turn — fuller turn → hands deeper → matches downswing rotation → less need to slide (Shauheen, hips-spinning-open).

Backswing target: load ~75–80% trail, to the cuboid, mass centered, peaking by P3 and easing back before the top. Light / late / toe-based / swayed = why transition feels rushed and you get stuck.

Read it on the plate

• Pressure distribution % (lead vs trail) and the COP dots; scrub to P2–P3 and read the trail %.
• Remember: high pressure % ≠ high force (Ep.5 13:34).

Seen in the data (validation)

• Wyndham Clark: "load the gun" — coil/load the back hip first; without loading the trail hip "you haven't loaded the chamber" → no power. Loading it also lets the lateral shift start earlier.

Dependencies & links

• Feeds: the forward shift (lateral-force), line-of-pressure, cop-trace.
• Related: cop-trace, kinetic-sequence.

Notes

~80% is a reference, not a mandate — calibrate to your own solid strikes. The early-then-decreasing shape matters more than the exact number.

Line of Pressure

Definition

The tilt of the line connecting trail-foot COP (red) and lead-foot COP (blue) — i.e. the "angle of pressure." It's the point-of-application input to rotational force.

Source positions

Consensus / divergence

• Agree: want a positive line at transition to enable torque + shallowing; a non-positive line → over-the-top / early extension.
• CONFLICT — where the trail pressure sits: S2M says bias the trail push "toward the heel." Measured Golf says move toward the heel but stop at the cuboid/midfoot — explicitly NOT the heel.
• Why MG differs: full-heel load forces the trail leg to extend → pressure in the heel "where you can't push/jump" → early extension (MG says this reverses their own 2018 "load the heel" cue, crediting Dr. Joe Lacaus / Fast Eddie Fernandes).
• Reconciliation: likely wording, not physics — S2M's "a little toward the heel" ≈ MG's "to the cuboid, not all the way." Net target: back from the toes/ball, toward—but not into—the heel. Confirm on your own trace.
• Greg Rose adds the direction: the line ("force alignment") should run level or slightly in-to-out through the swing — out-to-in → path/plane issues, and it can be wrong even with square feet. He rates it above stance alignment. (For your stuck/pull-hook: also watch it's not too far in-to-out = over-shallow.)

My data — current state

Matchups — more / less

Read it on the plate

• The line between the red (trail) and blue (lead) COP dots; look for a positive right-to-left slope at the top.
• The app also outputs a numeric line-of-pressure value — track that number against your own swings.

Seen in the data (validation)

• Cameron Tringale (BT_FQfPYxuA, "hiking"): early rotation without lateral = the negative / over-the-top pattern this card warns about.
• Wyndham Clark: ~3" of early extension on driver (only 1.7" when he swings harder) → block-right / occasional-left misses — early extension is the downstream symptom of a non-positive line.

Dependencies & links

• Feeds: rotational-force (point of application).
• Related: trail-pressure-load, cop-trace, kinetic-sequence.

Notes

This is the trace tied to over-the-top. Given the lost-strike history, a negative/flat line at transition is a prime suspect.

Centre-of-Pressure Trace

Definition

The path of the overall COP (the yellow dot) and each foot's COP through the swing — where on the feet you're pushing, moment to moment.

Source positions

Consensus / divergence

• Agree: push from the balls of the feet (not heels); COP migrates while COM stays relatively stable.
• MG link: the COP vs COM distinction is the practical core → see center-of-mass-vs-pressure.

My data — current state

Matchups — more / less

Read it on the plate

• Watch the yellow COP dot migrate; check the lead (blue) dot is in the ball of the foot as you hit peak vertical.
• Compare your solid-strike trace vs your mishit trace — that's your template, not a textbook shape.

Dependencies & links

• Feeds: vertical-force-peak (point of application), low point.
• Related: trail-pressure-load, line-of-pressure.

Notes

Style-dependent on purpose. The non-negotiable is ball-of-foot, early on the lead side — you can't push vertically off your heels (Ep.5/Ep.8 dunk analogy).

Vertical Unweighting (counter-movement valley)

Definition

The dip in vertical force below body weight in transition — the mini-squat / "offloading" that loads the spring before the big vertical spike. It's the load, not a flaw.

Source positions

Consensus / divergence

• Strong agreement: S2M valley 63–65% ≈ TPI ~65% (big hitters). TPI names the mechanism: a stretch-shorten cycle (squat before the jump) storing elastic energy for a bigger peak.

My data — current state

Matchups — more / less

Read it on the plate

• On the vertical-force graph, find the lowest valley (yellow line below the 100% "new zero") in transition; read the %.

Seen in the data (validation)

• Ryan Gerard (4OZ7Fh1u2MQ): unloads to ~72% (TPI says big hitters ~65%) before spiking to 211% — the squat-jump / stretch-shorten cycle in a tour swing.

Dependencies & links

• Feeds: vertical-force-peak (no valley → low peak).
• Related: kinetic-sequence.

Notes

Depth is individual — set your own target from your best strikes, not a fixed number.

Impulse (force × time)

Definition

Force multiplied by the time it's applied = area under the curve = the actual quantity of motion produced. Peak force alone doesn't tell you how much you transferred. Piece #4 of the Pie (curve shape).

Source positions

Net impulse — three reads that matter

• AP (linear) net impulse: negative = good (lead away from ball → pelvis opens / space). Positive = thrust toward ball → early extension (your miss). → anterior-posterior-forces.
• Torque net impulse: positive = good (net rotation toward target); reach net-zero just after transition, not late.
• Lateral net impulse: net positive toward target (high > 7.5, low < 5 N·s/kg).

Impulse can improve when the peak doesn't. Greg Rose: in ~2–3 years impulse will be most of what we talk about — it's how much you actually delivered, not how big the spike was.

My data — current state

Matchups — more / less

Read it on the plate

• Set the two time points (three-dots dialog), read the shaded area and the +/- impulse values (N·s/kg). Net = positive − negative.

Dependencies & links

• Summarizes: the shape of lateral-force, rotational-force, vertical-force-peak over time.
• Related: kinetic-sequence.

Notes

The continuous counterpart to the discrete peaks — it's how much you actually delivered, not just how big the spike was.

Club & Ball — Goal Hierarchy

The order I'm working toward · control before power

Nail these in order — each assumes the one above it is owned: 1. Distance control — repeatable carry numbers (tight distance dispersion). Scoring lives here. 2. Start line — a reliable launch window (≈ face angle). 3. Curve — first get the ball curving one direction dependably (a one-way miss), then reduce the amount. 4. Distance — add raw speed/carry last, once control is owned (don't trade control for yards).

The chain for every goal

GOAL → the metrics that drive it → the swing change that moves the metric → the implications/compensations on the rest of the swing. The last column is the whole point: a change is never free.

Per goal — quick read

1. Distance control — own a tight band of carry numbers. Mostly strike (center face + repeatable low point) + spin consistency. Force levers: forward pressure + ball-of-foot COP (trail-pressure-load, cop-trace). Never sacrifice this for distance.
2. Start line — own the face at impact. Lives in grip, lead-wrist, release timing (face-vs-start-line). The classic trap is the cascade below.
3. Curve — own face-to-path. Step 1: a one-way shape (pick draw or fade, never see the other side). Step 2: reduce the gap to tighten it (ball-flight-laws, shallowing-methods).
4. Distance — own club/ball speed. This is where the Force tab pays off (vertical force, sequence, finishing GRFs early). Add it once 1–3 hold.

The compensation cascade (why a change is never isolated)

RJ's example: open the face → start line right (direct). But push it too far right and the body senses the miss and releases/flips the hands to square the face → face timing becomes variable, path swings left from the save, strike thins, and the start line you were chasing gets less repeatable. Map the cascade — don't chase a metric in isolation. Every lever card carries a "Compensation cascade" section.

Sources & conflicts (expect a mess — that's handled)

This priority order is RJ's. The swing changes to hit each goal come from his lessons (multiple coaches) → a new source repo Lesson Transcripts/. Conflicting advice is expected and fine: each lesson is a source, conflicts surface in the Conflicts tab, and the worked/hasn't verdict + your Trackman data settle which coaching actually held up for you.

Links

• Levers: ball-flight-laws, face-vs-start-line, shallowing-methods, force-to-ballflight.
• Force levers feed Distance & Distance-control: vertical-force-peak, line-of-pressure, trail-pressure-load, kinetic-sequence.

Ball-Flight Laws (the anchors)

The rule / what it is

Every club/ball relationship below reduces to two laws: - Start direction ≈ mostly FACE (~85% face, ~15% path). - Curve ≈ FACE-TO-PATH (face open of path → fade/slice; face closed of path → draw/hook). - (Strike + AoA + dynamic loft set launch/spin/low-point, but start & curve are the anchors.)

Cause → effect

• Move the face → start line moves with it (and curve, via the new face-to-path gap).
• Move the path → curve moves (face-to-path), start line barely (path is only ~15%).

Cross-implications (what else moves)

You can't change face or path in isolation — changing one changes the face-to-path gap, so curve moves unless you move the other to match.

Offsets (to hold a target outcome)

• Hold the curve: keep the face-to-path gap constant (move face and path together).
• Hold the start line: keep the face roughly constant (it's ~85% of start).

Source

Ball-flight laws / D-plane — the physics everything else is measured against.

Worked / hasn't (my verdict)

Links

• Used by every other Club & Ball card; force version in force-to-ballflight.

Closing the Face → Start Line (and the shallow interaction)

The rule / what it is

RJ's own example, encoded: close the face → start line goes left (face is ~85% of start) — unless I shallow it out early, in which case the path goes more right, which changes what the closed face does to the curve.

Cause → effect

• Close face, nothing else: start left; face-to-path opens closed → more draw/hook.
• Close face + shallow early (path moves right / more in-to-out): start still ~face (slightly left), but face-to-path gap widens closed → bigger draw, and low point/AoA shift with the shallower path.

Cross-implications (what else moves)

• Shallowing to move the path right also tends to move low point back / AoA up (watch fat/thin, hooks).
• A closed face + righter path is the hook recipe if overdone.

Compensation cascade

• Open the face → start right (direct, all else equal).
• Push it too far right → the body senses the miss → flips/releases the hands to square it → face timing now variable, path swings left from the save, strike thins → the start line you were chasing gets less repeatable, not more.
• Takeaway: change the face only within a range the body trusts, or pair it with a path change — don't force a number the hands will fight to undo.

Offsets (to hold a target outcome)

• Hold a straight-ish start: if you close the face, you must accept a left-er start or open the path back (steeper) to keep face near target.
• Hold the same curve: match path to face — close the face and move the path left by the same amount (face-to-path constant).

Source

Lesson concept — fill in which coach taught it + date so we can track which coaching held up.

Worked / hasn't (my verdict)

Links

• ball-flight-laws (the anchors) · shallowing-methods (how the path moves right) · force version: force-to-ballflight.

Ways to Shallow — methods & trade-offs

The rule / what it is

Several different moves all "shallow" the club (less steep, path more from the inside) — but each has different side effects elsewhere. Same outcome, different costs. Match what's worked vs hasn't for me.

The methods → what each drags with it

Compensation cascade

• Shallow via trail shoulder / side-bend → trail side hangs back → body stands up (early extension) to make room → two-way miss (block and hook).
• Shallow via hands / lead-wrist → face shuts → brain adds a hold-off to stop the hook → blocks creep in.
• Takeaway: every shallowing method creates its own save. Pick the one whose compensation you can live with — and confirm which it is on your data.

Offsets (to hold a target outcome)

• Most shallowing moves open the AoA / move low point back → if so, play the ball slightly back to re-center strike.
• Face-closing methods (hands, lead-wrist) need a path that matches or you hook it — see face-vs-start-line.

Source

Came from multiple coaches over the years — fill in who taught which method + date, so we can see which one actually held up under your own data (the whole point of owning the process).

Worked / hasn't (my verdict)

Links

• Ground method ties to line-of-pressure, lateral-force, center-of-mass-vs-pressure.
• face-vs-start-line (path-right interaction) · ball-flight-laws.
• Shauheen: the backswing forearm structure gates whether you can shallow at all → backswing-shaft-forearm; the hip/chest matchup that leaves you stuck → hips-spinning-open.

Force Levers → Ball Flight

The rule / what it is

The force-plate levers mapped to club/ball outcomes — the bridge between the Force tab and ball flight. Each is a hypothesis to validate against your Trackman deltas (confidence rises once your own data confirms it). RH golfer.

Cause → effect (the matrix)

Cross-implications (what else moves)

• "Turn harder" is the headline case: path left → fade bias unless you close the face to match — your own example lives in face-vs-start-line.
• Forward shift is the low-point lever; vertical is the speed lever; both interact with strike.

Compensation cascade

• Turn harder → path left. If the face doesn't keep up you start fading; the body may flip to hold the line → face timing variable. Pair the turn with a face/grip change instead of letting the hands save it.

Offsets (to hold a target outcome)

• Hold the curve (default when changing a power lever): keep face-to-path constant — move the face to match any path change.
• Hold the start line: keep the face near target; accept the curve change.

Source

Migrated from matchups.md (L1–L4) + ball-flight laws. Anchored on ball-flight-laws.

Worked / hasn't (my verdict)

Links

• Force cards: rotational-force, lateral-force, vertical-force-peak, line-of-pressure.
• ball-flight-laws · face-vs-start-line · shallowing-methods.

Hips Spinning Open Too Fast → Stuck

The rule / what it is

"My hips spin open too fast" is usually a matchup problem, not a hip-speed problem. Shauheen: slowing the hips is rarely the best fix — the real issue is that the backswing turn and the downswing rotation (hips vs chest) don't match.

Coaching takes (by source)

Cause → effect

Hand path follows body rotation: more backswing turn → hands deeper/flatter; more downswing rotation → hands move out. Mismatch → steep + over-the-top (pattern 1) or under + stuck (pattern 2).

Compensation cascade

Pattern 2 (likely yours): hips fast → chest lags → hands/club drop under → stuck → you flip/save to square it → hooks or blocks. Slowing the hips "works" but caps speed; matching the chest keeps the speed and removes the stuck.

Offsets (to hold a target outcome)

Want to keep hip speed for power? Deepen the backswing turn and/or speed the chest — don't throttle the hips.

Source

Shauheen Nakhjavani — "Hips Spinning Open Too Fast" (51dgDbSqOVY).

Worked / hasn't (my verdict)

Links

• backswing-shaft-forearm, shallowing-methods; force side: rotational-force, kinetic-sequence.

Backswing Forearm Rotation & Shaft (laid-off vs across-the-line)

The rule / what it is

Lead-forearm rotation in the backswing sets the shaft at the top and gates whether you can shallow in transition. Pronation (lead palm turning down) → laid off; supination (palm up) → across the line / steep/vertical.

Coaching takes (by source)

Cause → effect

• Too laid off at the top → forced steep / over-the-top coming down (no room to shallow).
• Across the line / steep at the top → can be shallowed, but is its own miss.

Compensation cascade

Laid off → rebound supination on the way down → steep → body compensates (stand up / hang back / early extension) to avoid chunking → two-way miss. (Ties to your across-the-line + stuck tendencies.)

Offsets (to hold a target outcome)

Don't chase "shallow it on the way down" without fixing the top — a laid-off backswing makes shallowing nearly impossible.

Source

Shauheen Nakhjavani — "Forearm Rotation and Shaft Issues in the Backswing" (oBkFMpbareU).

Worked / hasn't (my verdict)

Links

• shallowing-methods (the forearm method — this gates it), hips-spinning-open.