Every strength coach eventually draws the same picture: a squatting figure with a straight vertical line running from the bar through mid-foot. The physics is simple enough to fit on a napkin — a loaded bar that drifts away from the line over your feet creates leverage you have to fight, and fighting leverage is strength you're not spending on the actual squat. The shortest path between standing and standing is a straight line, and the strongest squat travels it.

Here's what the napkin drawing leaves out: the line isn't really about the bar. It's about you.

The balance line — the rule under the rule

Strip the barbell away and squat with empty hands. There's still a line that wants to be vertical: your shoulder line over mid-foot. Let it drift forward — chest chasing the knees, weight surfing onto the toes — and the same leverage penalty shows up, just paid in balance instead of barbell inches. A bodyweight squat, a goblet squat, and a heavy back squat all obey the same rule; the barbell just raises the fine for breaking it.

This is worth understanding because of what a phone camera can honestly measure. CoachVision doesn't track a barbell — it tracks your body. What it measures from a side-on clip is how far your shoulder line wanders off its starting point over your feet during the rep, in body-relative units so tall and short lifters compare fairly. When you tell the app you're back-squatting, that shoulder line and the bar's path are effectively the same line — a barbell rides on your shoulders, so where they go, it goes. Bodyweight or goblet, it's your balance line, and it wants exactly the same verticality. Same rule, honestly named.

What drift is telling you

A small wander — a fraction of a torso-length — is a strong, quiet squat. Bigger drift is nearly always forward, and it's rarely the original sin. Forward drift travels with its causes:

  • A chest that dips on the drive. The torso tips, the shoulders swing forward, the line bends. If your torso-hold measurement is also flagging, the dip came first — fix the dip and the line straightens itself.
  • Weight creeping to the toes on the descent. Often born from ankles or from rushing — the free-fall descent that lands you on your forefoot at the worst possible moment.
  • A setup that starts off-line. Some lifters begin the rep with the shoulders already forward of mid-foot. The drift was pre-committed before anything moved.

Read the drift with the torso numbers to find which story is yours. The chain matters more than the symptom.

The drill — Empty-Bar Groove Sets

The line is grooved light, then loaded. 2 sets of 10 at the start of every session — empty bar, or hands crossed at your chest — filmed side-on. One assignment: the shoulder line travels straight down and straight up over mid-foot, nothing else invited. Think "elevator shaft" — the whole rep happens inside it.

Cues that help: full foot on the floor, big toe and heel both pressing; eyes on a spot at eye height, not the floor; hips down between the heels, not back behind them.

Then verify weekly. Film a side-on working set and watch the drift number shrink toward that quiet fraction of a torso-length. When the line goes vertical, squats feel lighter at the same load — not magic, just leverage finally on your side. Straight line. Every style. That's the whole napkin.