Strength Imbalance

What the metric means

For related exercises (same joint, same action family), lifters reliably show predictable strength ratios — for example, an overhead press is typically 60–70% of a bench press, and a squat is typically 1.3–1.5× a bench press. LiftShift computes your ratio for 13 such pairs and compares it against population statistics (roughly 28 million logged lifts for the highest-confidence pairs).

When your ratio falls outside the typical band, LiftShift surfaces it as a watch (borderline) or flag (far outside), with the lagging exercise linked for inspection. A flagged ratio is a hint — it can mean a real imbalance, different training history, or a logging difference — never a verdict on your form.

How strength is measured

• Window — the last 90 days of training.
• Per session — the best estimated 1RM of the session (Epley formula, weight × (1 + reps/30), working sets of 5–15 reps, warm-ups excluded).
• Strength level — the 75th percentile of your 5 most recent session bests, so one-off PRs or stale peaks don’t dominate.
• Unilateral lifts — per-arm exercises (lateral raises, dumbbell presses) are doubled so they compare fairly against bilateral totals.
• Minimum data — both sides of a pair need at least 2 sessions in the window, and the data overall needs at least 3 sessions, before anything is reported.

Reading the trend chart

Each finding shows your weekly laggard percentage — the weaker lift as a % of the stronger one — over the last 3 months, with the typical band shaded green and a dot marking your current level. The line is smoothed with a 3-week average. A chip above the chart says whether the gap is closing or widening, based on the last ~5 weeks only (a recent slide isn’t masked by earlier progress), with fitted start and end values, e.g. “Gap closing · 50% → 60% over 2 months”.

Limitations

• Ratio bands are population statistics. Individual body mechanics, leverages, and training history vary — treat bands as references, not rules.
• Machine weights differ across brands, and technique conventions (range of motion, tempo) affect ratios.
• Low-experience lifters have compressed ratios; the minimum-session guards exist for this reason.
• The metric is a hint for your next sessions, not a diagnosis or injury claim.

Learn more

See the How it works guide for the full methodology and the FAQ for common questions.