SkiErg · Knee Flexion at Finish

Why this matters

Knee flexion at the finish is the second half of the hinge-vs-squat diagnostic. The first half (Hip Flexion at Finish) says how much the torso folded; this measurement says how much the knees bent.

The interaction is what matters:

Hip Flexion	Knee Flexion	Pattern
90°–110°	125°–145°	Hinge — correct
90°–110°	100°–125°	Mixed — slight squat creep
< 100°	< 120°	Squat fault — hips dropping straight down
90°–110°	> 150°	Stiff legs — no rebound load

The squat fault is the canonical SkiErg form-break. It feels powerful (legs are strong, the analyst trusts that pattern) but the geometry doesn't deliver — the handles barely move relative to the body's center of mass.

What good looks like

• Knees soft, slightly bent — not locked, not deeply flexed.
• Shins close to vertical (the body is hinged behind the heels).
• A clear distinction between this position and a squat: the hips are behind the heels, not above them.

Common faults

Squat Fault (< 120°)

The defining SkiErg form break. Hips drop straight down, knees bend deeply, the torso stays vertical. Power is in the legs but the handles barely travel.

Causes: strong leg dominance, unfamiliarity with hinging under load, anxiety about the depth of the fold (the squat feels safer).

Effect: dramatically reduced stroke length. Cardio cost stays the same; output drops.

Locked Legs (> 150°)

Knees almost straight. No elastic load — the rebound back to the catch has no spring to ride. The analyst recovers from a stiff position, which is slow.

Causes: mis-coaching ("straight legs!" taken too literally), tight hamstrings preventing knee bend.

Effect: slower rate ceiling.

Coaching cues

• "Hips back, not down" — addresses the squat fault directly.
• "Soft knees, like a Romanian deadlift" — names the correct pattern by analogy.
• "Shins stay vertical" — geometric cue that disallows the deep knee bend.

How to draw

1. Same deepest-handle frame as Hip Flexion at Finish.
2. First line: greater trochanter → lateral femoral condyle (thigh).
3. Second line: lateral femoral condyle → lateral malleolus (shank).
4. Interior angle at the knee is the reading.

Related measurements

• Hip Flexion at Finish — read together for the hinge-vs-squat diagnostic.
• Terminal Elbow Extension — same frame; the upper-body counterpart.