Almost every lifter has a stronger side. One arm locks out first on the bench, one leg drives harder out of the hole, one dumbbell feels lighter than its twin. The question that follows is usually the same: is that imbalance a problem I need to fix, or just normal human variation? The research on inter-limb asymmetry is larger than most people expect, and more humbling. It has a lot to say about how asymmetry is measured, very little firm evidence for the popular thresholds,