Revision 7T · Full Tutorial Edition · Updated 1 September 2026
PWR-004 · SUPERVISED full tutorial
Brake a moving load through one marked lowering arc
Eccentric work happens when muscle produces force while lengthening. Here, quadriceps activity brakes a machine arm as a seated knee bends. This is neither a slow lift nor a static hold. Learn receive-lower-unload: accept supported tension, allow continuous descent, resist from first marker through final marker, unload, then relax for passive return. Curve-reading exercises expose four failures—catch-and-drop, stall, mid-arc hole and end-range dump. A rehabilitation clinician selects apparatus, range, velocity, resistance, repetition count and recovery.
What you will produceIn one authorised appointment, a participant performs a continuously resisted knee-extension descent, completes passive return without lifting, logs later response and distinguishes full-arc control from an impressive but invalid torque spike.
Method8 numbered Power-specific steps
Practice authorityFull method with qualified supervision where stated
Full step-by-step individual tutorial · TLU-PWR-004
In one authorised appointment, a participant performs a continuously resisted knee-extension descent, completes passive return without lifting, logs later response and distinguishes full-arc control from an impressive but invalid torque spike.
Support each hand-off, guard movement, operate emergency release, provide passive return and classify curve validity.
Never do this from the page alone
Do not improvise overload with free weights, household objects, partner-held resistance or equipment lacking safe escape.
Do not hoist an eccentric-only load into position, kick it upward during reset or alter depth, speed, resistance or volume independently.
Do not continue after sharp pain, a pop, instability, sudden weakness, uncontrolled acceleration or an unreviewed delayed reaction.
2 · Get ready
Gather what you need and check the starting conditions
What you need
Clinician-controlled isokinetic or resistance apparatus with emergency release and assisted reset
Stable seating plus fitted pelvic, thigh and lower-leg supports
Start, middle and finish markers
Velocity display or tempo cue
Descent worksheet for angle bins, torque continuity, speed, unload point, reset mode and symptoms
Delayed-response log plus a separate supported step-down sheet
Before you start
Report recent injury, operation, swelling, instability, unexplained weakness, severe soreness or any previous unusual response to lengthening exercise.
Describe today's action: apparatus starts with lower leg raised, then travels downward while quadriceps acts as a brake.
Sweep through planned angles without working resistance. Identify beginning, midpoint and finish; mention pinching or guarding immediately.
Practise three commands. Receive means meet supported tension. Lower means allow movement while resisting. Unload means stop resisting for mechanical removal.
Rehearse once lightly. The lever must keep moving during lower; a frozen arm signals a different contraction.
Agree how same-day and next-morning effects will reach the responsible clinician.
3 · The method
Follow these steps in order
Map travel direction
Point from start angle to finish angle. Say, 'My knee bends while I brake this arm.' Name midpoint as a separate landmark.
Why: Direction determines whether quadriceps fibres shorten, hold length or lengthen.
Check: Participant identifies correct limb, direction and three landmarks without looking at torque.
Fit supports and rehearse
Sit against backrest while clinician aligns knee axis, secures pelvis and positions shin pad. Perform an unloaded sweep, then a light receive-lower-unload rehearsal.
Why: Stable geometry keeps measured work inside a repeatable arc and exposes uncomfortable contact before loading.
Check: No pelvic slide, thigh lift, knee twist, pinching or numbness appears.
Receive supported tension
Remain relaxed while apparatus places its arm at start. On receive, meet already-supported resistance smoothly—no upward pull, kick or sudden catch.
Why: Snatching produces an early torque spike without showing braking capacity.
Check: Curve begins without impact and arm waits at start until lower command.
Allow movement while braking
On lower, permit knee flexion while maintaining pressure against moving arm, like controlling a heavy door. Avoid freezing or letting descent run away.
Why: Lengthening control requires force during movement; stalling becomes an isometric hold, whereas runaway motion becomes a drop.
Check: Angular velocity remains inside its declared corridor and braking torque persists through first half.
Brake through the final third
Continue resisting beyond midpoint to finish. Keep pelvis level and torso supported. If control disappears, signal abort instead of catching a falling arm.
Why: Strong early output can hide release near terminal angles.
Check: Final bins retain torque without acceleration, twisting or shortened travel.
Unload, then accept passive return
At finish, follow unload command. Relax quadriceps while apparatus removes resistance and restores start position. Never lift during reset.
Why: An active upward reset adds concentric work, changing dose and meaning.
Check: Trace shows a distinct unload boundary followed by assisted return with no participant-generated positive work.
Classify descent shape
Before reading peak N·m, label each curve smooth arc, catch-and-drop, mid-arc hole or end-range dump. Check angular speed beside torque in every bin.
Check: Validity decision cites exact bin and velocity departure rather than overall impression.
Log delayed response
After recovery, document immediate symptoms and separate step-down observation. Add later-that-day and next-morning soreness, swelling and ordinary-activity change before another loaded decision.
Why: Lengthening work may produce effects after departure.
Check: Both delayed entries exist and clinician reviews them before changing any parameter.
4 · Worked example
See the whole method used once
Scenario
Clinician programs right-knee travel from 30 to 80 degrees of flexion at 60 degrees per second. Apparatus performs every reset. A supported step-down remains a separate observation.
Walkthrough
Ana identifies 30-degree start, midpoint and 80-degree finish, then describes braking while her knee bends.
After support fitting, an unloaded sweep and light rehearsal show comfortable travel.
Descent A begins smoothly, holds velocity near 60 degrees per second and retains torque through all bins; peak equals 146 N·m.
Descent B spikes at 155 N·m, stalls, then loses torque from 58 to 70 degrees. It receives catch-and-drop plus mid-arc-hole labels and is rejected.
Descent C remains continuous through 80 degrees, peaks at 149 N·m and ends in passive return.
Ana keeps 146 and 149 N·m as full-arc results. She does not average invalid 155 N·m into them.
Later log records soreness and stair response that evening and next morning. Clinician reviews those entries before scheduling any comparable descent.
Result
Two continuous descents demonstrate angle- and velocity-specific braking. A larger interrupted spike does not count. Nothing here establishes concentric strength, tendon safety or independent stair ability.
5 · Right and wrong
Compare correct or safer execution with the common wrong version
Right and wrong comparison
Moment
Right / safer
Wrong / riskier
Why it matters
Receiving resistance
Meet an already-supported machine arm smoothly.
Snatch resistance or lift it into place.
Impact and lifting precede intended lengthening phase.
Descending
Brake while apparatus continues travelling.
Freeze midway or suddenly let go.
A freeze becomes holding; release becomes dropping.
Terminal angles
Maintain braking through final marker.
Relax after midpoint because finish is close.
Premature release creates an end-range dump.
Reset
Relax for mechanical passive return.
Kick upward to save time.
Active reset adds positive concentric work.
Curve selection
Check torque continuity and velocity bin by bin.
Choose tallest N·m spike.
A spike can precede a torque hole or runaway segment.
Next decision
Review immediate and delayed response together.
Increase resistance because soreness or one number seems impressive.
Neither soreness nor isolated magnitude proves useful progression.
6 · Common mistakes
Spot the error and apply the correction
Common mistakes and corrections
Mistake
Fix
Participant describes a slow lift instead of braking.
Trace direction from raised start toward bent-knee finish and repeat receive-lower-unload.
Arm stops at midpoint.
Mark a stall; use velocity cue during any further clinician-authorised rehearsal.
Torque vanishes near finish.
Label exact missing bins as an end-range dump; never hide them with peak averaging.
Participant drives reset upward.
Segment descent, unload and passive return; exclude contaminated repetition.
Only immediate discomfort is noted.
Complete evening and next-morning entries before another loaded choice.
Device torque becomes a stair-safety claim.
Keep supported step-down data separate and limit interpretation to programmed arc and speed.
7 · Practice
Turn the steps into a usable skill
First session
Screen readiness and agree abort signal plus delayed-contact plan.
Name limb, direction, angles, velocity and three landmarks.
Rehearse receive-lower-unload without working resistance.
Complete authorised descents with supported start and passive reset.
Classify every curve before inspecting peak N·m.
Log separate step-down, evening response and next-morning response.
Repeat plan
For retention, classify an anonymised curve and recall receive-lower-unload at least 48 hours later without performing loaded movement. A delayed physical retest requires clinician authorisation after review of evening and next-morning entries. Reproduce apparatus, limb, seating, supports, angles, angular velocity, commands and validity rules. Do not deepen range, raise resistance or add volume to manufacture progression.
Progress when
Supported hand-off occurs without catch; every descent stays moving.
Torque persists across all bins while angular speed remains inside corridor.
Every reset is passive and delayed response stays inside individually agreed limits.
A later authorised session reproduces geometry and again shows continuous braking.
Do not progress when
A catch, stall, torque hole, dump, posture shift or active reset remains.
Pain, swelling, instability, weakness, altered sensation or delayed reaction increases.
Apparatus cannot provide safe support, emergency release or assisted reset.
Evening and next-morning entries remain unavailable or unreviewed.
8 · Check the result
Measure what changed
Continuous negative-work knee-extension descent across specified angles and angular velocity
How: Store programmed angles, velocity, resistance setting, supports, bin-by-bin torque, speed departures, unload boundary, return mode, symptoms and pattern label. Decide smooth arc versus catch-and-drop, stall, mid-arc hole, end-range dump or active-reset contamination before summarising peak and mean N·m. Preserve evening and next-morning response plus separate step-down observation.
Good result: At least two authorised descents retain torque and commanded velocity from start through finish, followed by assisted reset. A delayed comparison reproduces geometry, commands and symptom safeguards.
This does not prove: This profile does not prove shortening strength, tendon integrity, injury immunity, safe independent loading or transfer to stairs, running, landing, work or sport.
Self-check
Can you explain muscle lengthening while braking?
Can you identify start, midpoint, finish and travel direction?
Can you demonstrate receive-lower-unload without lifting?
Can you distinguish moving control from a stall?
Can you locate a mid-arc hole or end-range dump on a curve?
Can you explain why passive return and delayed logging matter?
9 · Stop, adapt or get help
Keep the safety boundary practical
Stop and get help
Abort for sharp pain, pop, sudden weakness, swelling, instability, numbness or uncontrolled apparatus motion.
Stop if support loosens, velocity escapes, travel leaves marked arc or emergency release becomes unavailable.
Seek clinician review for unusual or worsening delayed effects; seek prompt medical advice for marked swelling, profound weakness, systemic illness or dark urine.
Accessibility and adaptations
Offer high-contrast or tactile angle landmarks plus spoken or visual commands.
Use transfer help, pressure relief and fitted supports; preserve each adaptation in session configuration.
Provide an annotated plot naming catch, continuous braking, torque hole, finish, unload and assisted reset.
10 · Evidence and limits
Why these instructions are here
primary research
Strength gains in one contraction mode do not automatically generalise to another mode or to functional mobility.
Progress is saved only in this browser on this device.
Step-by-step learner mode
Each activity includes its success check, a nearby accessible alternative and an “I’m stuck” correction path. Alternatives preserve the target where possible; when they change the task, Titan labels them as related rather than equivalent.
01
Map travel direction
Point from start angle to finish angle. Say, 'My knee bends while I brake this arm.' Name midpoint as a separate landmark.
Why this step exists
Direction determines whether quadriceps fibres shorten, hold length or lengthen.
Success check
Participant identifies correct limb, direction and three landmarks without looking at torque.
I’m stuck on this step
Reset: Re-read this authored instruction — “Point from start angle to finish angle. Say, 'My knee bends while I brake this arm.' Name midpoint as a separate landmark.” — and its success check, then attempt only this step.
Possible snag: Participant describes a slow lift instead of braking.
Correction: Trace direction from raised start toward bent-knee finish and repeat receive-lower-unload.
Stop / get help: Abort for sharp pain, pop, sudden weakness, swelling, instability, numbness or uncontrolled apparatus motion.
02
Fit supports and rehearse
Sit against backrest while clinician aligns knee axis, secures pelvis and positions shin pad. Perform an unloaded sweep, then a light receive-lower-unload rehearsal.
Why this step exists
Stable geometry keeps measured work inside a repeatable arc and exposes uncomfortable contact before loading.
Success check
No pelvic slide, thigh lift, knee twist, pinching or numbness appears.
I’m stuck on this step
Reset: Re-read this authored instruction — “Sit against backrest while clinician aligns knee axis, secures pelvis and positions shin pad. Perform an unloaded sweep, then a light receive-lower-unload rehearsal.” — and its success check, then attempt only this step.
Possible snag: Arm stops at midpoint.
Correction: Mark a stall; use velocity cue during any further clinician-authorised rehearsal.
Stop / get help: Abort for sharp pain, pop, sudden weakness, swelling, instability, numbness or uncontrolled apparatus motion.
03
Receive supported tension
Remain relaxed while apparatus places its arm at start. On receive, meet already-supported resistance smoothly—no upward pull, kick or sudden catch.
Why this step exists
Snatching produces an early torque spike without showing braking capacity.
Success check
Curve begins without impact and arm waits at start until lower command.
I’m stuck on this step
Reset: Re-read this authored instruction — “Remain relaxed while apparatus places its arm at start. On receive, meet already-supported resistance smoothly—no upward pull, kick or sudden catch.” — and its success check, then attempt only this step.
Possible snag: The result from “Remain relaxed while apparatus places its arm at start. On receive, meet already-supported resistance smoothly—no upward pull, kick or sudden catch.” does not yet meet this declared check: Curve begins without impact and arm waits at start until lower command.
Correction: Return to the start of “Receive supported tension”, reduce complexity or pace, and repeat only the part needed to satisfy: “Curve begins without impact and arm waits at start until lower command.”
Stop / get help: Abort for sharp pain, pop, sudden weakness, swelling, instability, numbness or uncontrolled apparatus motion.
04
Allow movement while braking
On lower, permit knee flexion while maintaining pressure against moving arm, like controlling a heavy door. Avoid freezing or letting descent run away.
Why this step exists
Lengthening control requires force during movement; stalling becomes an isometric hold, whereas runaway motion becomes a drop.
Success check
Angular velocity remains inside its declared corridor and braking torque persists through first half.
I’m stuck on this step
Reset: Re-read this authored instruction — “On lower, permit knee flexion while maintaining pressure against moving arm, like controlling a heavy door. Avoid freezing or letting descent run away.” — and its success check, then attempt only this step.
Possible snag: The result from “On lower, permit knee flexion while maintaining pressure against moving arm, like controlling a heavy door. Avoid freezing or letting descent run away.” does not yet meet this declared check: Angular velocity remains inside its declared corridor and braking torque persists through first half.
Correction: Return to the start of “Allow movement while braking”, reduce complexity or pace, and repeat only the part needed to satisfy: “Angular velocity remains inside its declared corridor and braking torque persists through first half.”
Stop / get help: Abort for sharp pain, pop, sudden weakness, swelling, instability, numbness or uncontrolled apparatus motion.
05
Brake through the final third
Continue resisting beyond midpoint to finish. Keep pelvis level and torso supported. If control disappears, signal abort instead of catching a falling arm.
Why this step exists
Strong early output can hide release near terminal angles.
Success check
Final bins retain torque without acceleration, twisting or shortened travel.
I’m stuck on this step
Reset: Re-read this authored instruction — “Continue resisting beyond midpoint to finish. Keep pelvis level and torso supported. If control disappears, signal abort instead of catching a falling arm.” — and its success check, then attempt only this step.
Possible snag: The result from “Continue resisting beyond midpoint to finish. Keep pelvis level and torso supported. If control disappears, signal abort instead of catching a falling arm.” does not yet meet this declared check: Final bins retain torque without acceleration, twisting or shortened travel.
Correction: Return to the start of “Brake through the final third”, reduce complexity or pace, and repeat only the part needed to satisfy: “Final bins retain torque without acceleration, twisting or shortened travel.”
Stop / get help: Abort for sharp pain, pop, sudden weakness, swelling, instability, numbness or uncontrolled apparatus motion.
06
Unload, then accept passive return
At finish, follow unload command. Relax quadriceps while apparatus removes resistance and restores start position. Never lift during reset.
Why this step exists
An active upward reset adds concentric work, changing dose and meaning.
Success check
Trace shows a distinct unload boundary followed by assisted return with no participant-generated positive work.
I’m stuck on this step
Reset: Re-read this authored instruction — “At finish, follow unload command. Relax quadriceps while apparatus removes resistance and restores start position. Never lift during reset.” — and its success check, then attempt only this step.
Possible snag: Participant drives reset upward.
Correction: Segment descent, unload and passive return; exclude contaminated repetition.
Stop / get help: Abort for sharp pain, pop, sudden weakness, swelling, instability, numbness or uncontrolled apparatus motion.
07
Classify descent shape
Before reading peak N·m, label each curve smooth arc, catch-and-drop, mid-arc hole or end-range dump. Check angular speed beside torque in every bin.
Validity decision cites exact bin and velocity departure rather than overall impression.
I’m stuck on this step
Reset: Re-read this authored instruction — “Before reading peak N·m, label each curve smooth arc, catch-and-drop, mid-arc hole or end-range dump. Check angular speed beside torque in every bin.” — and its success check, then attempt only this step.
Possible snag: Torque vanishes near finish.
Correction: Label exact missing bins as an end-range dump; never hide them with peak averaging.
Stop / get help: Abort for sharp pain, pop, sudden weakness, swelling, instability, numbness or uncontrolled apparatus motion.
08
Log delayed response
After recovery, document immediate symptoms and separate step-down observation. Add later-that-day and next-morning soreness, swelling and ordinary-activity change before another loaded decision.
Why this step exists
Lengthening work may produce effects after departure.
Success check
Both delayed entries exist and clinician reviews them before changing any parameter.
I’m stuck on this step
Reset: Re-read this authored instruction — “After recovery, document immediate symptoms and separate step-down observation. Add later-that-day and next-morning soreness, swelling and ordinary-activity change before another loaded decision.” — and its success check, then attempt only this step.
Possible snag: Only immediate discomfort is noted.
Correction: Complete evening and next-morning entries before another loaded choice.
Possible snag: Device torque becomes a stair-safety claim.
Correction: Keep supported step-down data separate and limit interpretation to programmed arc and speed.
Stop / get help: Abort for sharp pain, pop, sudden weakness, swelling, instability, numbness or uncontrolled apparatus motion.
Correct versus incorrect execution
These accessible process diagrams are built from the tutorial’s own right/wrong teaching. They are not anatomical illustrations and do not add technique beyond the canonical tutorial.
Receiving resistance — Impact and lifting precede intended lengthening phase.
Correct / safer
Meet an already-supported machine arm smoothly.
Wrong / riskier
Snatch resistance or lift it into place.
Descending — A freeze becomes holding; release becomes dropping.
Correct / safer
Brake while apparatus continues travelling.
Wrong / riskier
Freeze midway or suddenly let go.
Terminal angles — Premature release creates an end-range dump.
Correct / safer
Maintain braking through final marker.
Wrong / riskier
Relax after midpoint because finish is close.
Reset — Active reset adds positive concentric work.
Correct / safer
Relax for mechanical passive return.
Wrong / riskier
Kick upward to save time.
Curve selection — A spike can precede a torque hole or runaway segment.
Correct / safer
Check torque continuity and velocity bin by bin.
Wrong / riskier
Choose tallest N·m spike.
Next decision — Neither soreness nor isolated magnitude proves useful progression.
Correct / safer
Review immediate and delayed response together.
Wrong / riskier
Increase resistance because soreness or one number seems impressive.
Method-structure checklist
10 of 10 structural checks present
✓ Ordered, Power-specific instructions — present
✓ Every activity has a success check — present
✓ Materials or supplied records are declared — present
✓ Measurement or assessment rule is present — present
✓ Tutorial-specific troubleshooting is present — present
✓ Stopping or escalation boundary is present — present
✓ Every activity has an adjacent alternative — present
✓ Correct-versus-incorrect comparison is present — present
✓ Evidence context is bound to the Power record — present
✓ Planning metadata is present — present
The method-readiness band and presence checklist assess tutorial presentation and are separate from evidence quality for the underlying Power. They are automated editorial aids, not human approval.
Manual editorial sign-off: Pending. This tutorial must not display a human-approved state until an identified editor signs the exact content hash.