Sandbag Lunge · Front Knee Tracking

Why this matters

The sandbag lunge loads the front knee under a heavy, shifting weight, dozens of reps deep into a race. When the knee caves inward — valgus — the load stops running cleanly down the leg and starts shearing across the joint. It's rarely injurious in a single rep, but the sandbag lunge is a volume station, and cumulative ligament stress over that rep count is exactly where knee-tracking faults do their damage.

A knee that tracks over the foot keeps injury risk low and force transfer clean. A valgus shift under fatigue or load is common, not yet injurious, but worth correcting before the rep count adds up.

What good looks like

From the front, at the bottom of the lunge, the thigh and shank form a straight line down to the foot — the kneecap points over the middle of the foot, not inside it. The knee holds that line as the athlete drives back up.

Reading the result

• Neutral (tracks over the foot): knee tracks correctly; low injury risk — continue current programming.
• Moderate valgus: a small inward shift, common under fatigue or load; cumulative ligament stress over rep volume makes it worth correcting.
• Large valgus: a pronounced collapse — pull the athlete back to lighter load or fewer reps and rebuild the pattern.

Coaching cues

• "Knee to the little toe" — biases the knee back out over the foot.
• Off the platform: glute-med and abductor strength so the knee holds its line under fatigue.

How to mark

1. Use an anterior-view clip and pause at the bottom of the lunge (deepest front-knee flexion).
2. Thigh: front hip → front knee centre.
3. Shank: front knee centre → front ankle centre.
4. The tool reports the deviation — inward collapse reads as valgus.

Related measurements

• Front Knee Flexion at Depth — same frame; how deep the lunge is set, which the knee then has to hold in line.