This is the short version of setting up a reliable isometric knee extension assessment and preparing the patient for their first MVIC. Print or post it next to the testing station; use the longer articles for the why behind each item.
The protocol below targets isometric knee extension at 60° flexion. Adapt knee-angle and seat-position items for other joints; cueing and trial protocol items apply across joints.
Before the patient sits down
- Plinth or chair set to your usual default height
- Back support in place (padded backrest or folded towel against the wall)
- Strap connected to dynamometer with carabiner or rigid tether
- Tether anchored at a point in line with the shin
- Dynamometer powered on and paired in the platform
- Patient's height, bodyweight, and injured side entered on the patient profile (so torque, mass normalization, and LSI compute correctly)
- Goniometer accessible
Patient positioning
- Hips at 85 to 90° flexion
- Popliteal crease clear of the seat edge (about 2 cm)
- Waist strap across the pelvis, or patient gripping the plinth firmly
- Chest strap if patient has poor trunk control
- Ankle strap (10 to 12 cm wide, padded) just proximal to the medial malleolus
- Initial knee angle set to about 70° (the knee will retract roughly 10° at peak)
- Tether perpendicular (90°) to the shin at peak position
- Moment arm measured if you're using direct measurement (lateral femoral epicondyle to ankle-strap center, in meters)
Familiarization
- Explain the test in plain language: "isometric, doesn't move, three trials, five seconds each, thirty seconds rest"
- Confirm the patient understands that the strap is fixed and won't break away
- Run three practice trials at 50%, 75%, 100% effort
- Confirm at 100% practice that knee is at 60° and tether is perpendicular; adjust if not, re-do practice
- First recorded trial after this; familiarization is not on the patient's record
Each recorded trial
- Patient settled, baseline quiet for two to three seconds
- Pretension cue: "Push at about 10% to take up slack"
- Effort cue: "Push as hard and as fast as you can, hold for five seconds"
- Standardized verbal encouragement during the hold ("Push, push, push")
- Watch the chart for: sharp onset, smooth ramp, sustained plateau, controlled release
- Five seconds; if the curve is still rising at the five-second mark, rest five minutes and re-cue with clearer "fast" emphasis
Between trials
- 30 seconds rest before the next maximal-effort trial
- Quick visual check of the chart for: countermovement dip at onset, drift through the plateau, post-release rebound that doesn't return to baseline
- If baseline is visibly drifting between trials, retare the dynamometer
- If a trial looks bad (countermovement, hesitant start, drift), exclude it on the session and move on
After the set
- Three clean trials per side recorded
- Excluded trials marked with a note about why (so the next clinician knows)
- Onset overrides applied where the auto-detected onset is off
- Bilateral assessment: same protocol on the uninvolved side
- Session ended (the platform saves the session on end, not during recording)
What to do next
- Print this page and keep it at the testing station. It's faster to glance at than to remember.
- For the rationale behind each item, read the full protocol article and the patient-prep article. This page is a memory aid, not a substitute for understanding.
- For data-quality decisions made during or after the test (exclude vs delete, onset override, drift warnings), see the Data Quality section.