Or what if you can’t safely lift the dumbbells that correlate to 75 percent or 100 percent of your body weight? It’s better to start small and work yourself up, per Attia’s instructions.

Enter: the one-rep max (1RM), or “the maximum amount of weight that you can lift for just one repetition,” says physical ...

Elite athletes have achieved lifts of up to 1,200 pounds. Here's what's made that possible — and what the limit may be.