Left–right asymmetry: the gap that predicts injury
Almost everyone has one. It matters more than overall weakness — and most training programmes hide it instead of finding it.
Everybody has a stronger side. That's normal and mostly harmless. What isn't harmless is a large gap you don't know about, because barbell training is extremely good at hiding it — the strong side quietly takes more of every rep for years.
Why it matters more than raw strength
In the research on athletic injury, side-to-side differences are consistently a better predictor of injury risk than absolute strength. A large imbalance means one limb is repeatedly absorbing more force than the other, and it means rotation is creeping into movements that should be symmetrical.
The commonly used threshold is around 10–15% difference between sides. Beyond that, it's worth addressing deliberately rather than hoping it evens out.
Finding yours
Bilateral lifts won't show you. You need single-sided tests: a single-leg squat to a box, a single-leg calf raise to failure, a side plank hold, a suitcase carry for distance. Do the weaker side first and match the stronger side to it — not the other way round.
Also test range, not just strength. Hip internal rotation and ankle dorsiflexion asymmetries are extremely common and drive the strength differences downstream.
Training it
Lead every session's accessory work with the weaker side, and cap the stronger side at what the weaker one managed. This feels unsatisfying and it works. Unilateral carries, split squats, Copenhagen planks and side planks are the tools — anything that can't be quietly assisted by the other side.
Left–right gaps predict injury better than weakness does. They get fixed before numbers go up.
Give it time
Asymmetries built over years don't close in a fortnight. Re-test every 8–12 weeks and track the number. If it isn't closing, the programme changes.