Sandbag Lunge — Stride Length

Why this matters

The sandbag lunge is a ground-covering station — 100 m of loaded walking lunges — so how far each lunge travels is half the pacing equation (the other half is Rep Rate). Stride length is the distance the front foot is planted ahead of the back foot at the bottom of the lunge, and it sets a direct trade-off: a longer stride covers more ground per rep, meaning fewer total reps over the 100 m, but it loads the front knee and patellar tendon harder and demands more from the trailing hip; a shorter stride is lighter on the knee but needs more reps. The fastest sustainable approach is the longest stride the athlete can hold with clean depth and good knee tracking — not the longest stride they can hit once.

Unlike running step length, there's no efficiency penalty for a short lunge stride here — it just means more reps — which is why both the short and long bands are informational rather than warnings. The value is in pacing and in spotting a stride that drifts longer (and harder on the knee) as the athlete tires and starts lunging for the finish.

Why a ratio, not raw distance

A pixel span depends on camera zoom and distance, so a raw pixel length means nothing between clips. Dividing the front-to-back foot span by the athlete's own leg length (greater trochanter → lateral malleolus, drawn in the same frame) cancels the camera out: the result is a scale-invariant ratio comparable across clips, athletes and zoom levels with no calibration, and normalising to leg length is biomechanically honest — a "long lunge" only means something relative to the legs taking it.

Real metres (optional calibration)

For an absolute figure, calibrate the clip with the Scale tool: draw a line over any object of known length in the same plane (a marked floor line, the sandbag, a plate), enter its real length, and the clip gains a pixels-per-metre scale. The Stride Length tool then reports metres on that clip instead of the × leg ratio. The ratio stays the default and needs no setup; metres are an opt-in upgrade per clip. Absolute stride has no universal target band (it scales with the athlete's height), which is why the ratio is what gets classified.

What good looks like

A span of 0.7–1.1× leg at the bottom of the lunge, the front knee tracking over the foot and reaching clean depth, repeated at a steady stride from the first metre to the last.

Common faults

• Long stride (> 1.1× leg) — covers ground fast but loads the front knee and patellar tendon hard; manageable in training but something to watch over 100 race reps, especially if it grows as the athlete fatigues.
• Short stride (< 0.7× leg) — covers less ground per rep (more total reps), often a conservative or fatigued choice. Not a fault — just the other end of the pacing trade-off.

Coaching cues

• "Same step, every rep." A consistent stride keeps both the rep count and the knee load predictable.
• "Sink down, not forward." Stops a long stride turning into a knee-dominant lunge under the sandbag.

Related measurements

• Rep Rate — the cadence half of lunge pacing; stride × rate sets the split.
• Front Knee Flexion at Depth — the depth and knee load a longer stride drives up.